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Sample records for asteroid impact led

  1. Asteroid impact risk

    OpenAIRE

    Rumpf, Clemens

    2016-01-01

    Asteroid impacts are a hazard to human populations. A method to assess the impact risk of hazardous asteroids was developed in this work, making use of the universal concept of risk culminating in the Asteroid Risk Mitigation Optimization and Research (ARMOR) tool. Using this tool, the global spatial risk distribution of a threatening asteroid can be calculated and expressed in the units of expected casualties (= fatalities). Risk distribution knowledge enables disaster managers to plan for a...

  2. Experimental evidence that an asteroid impact led to the extinction of many species 65 million years ago

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, L.W.

    1982-09-01

    The development of the theory that the mass extinction of the dinosaurs at the Cretaceous-Tertiary boundary was caused by an asteroid impact is reviewed. The personnel involved, the objections to the theory, and the evidence refuting those objections are presented chronologically. (ACR)

  3. Asteroid Impact Mission: relevance to asteroid mining

    Science.gov (United States)

    Michel, P.; Kueppers, M.; Carnelli, I.

    2017-09-01

    The Asteroid Impact Mission (AIM) is the European (ESA) component of the AIDA mission in collaboration with NASA. The objectives of AIDA are: (1) to perform a test of asteroid deflection using a kinetic impactor with the USA (NASA) component DART, and (2) with AIM, to investigate the binary near-Earth asteroid Didymos, in particular its secondary and target of DART, with data of high value for mining purposes.

  4. AIDA: Asteroid impact & Deflection Assessment

    OpenAIRE

    Cheng, A F; Michel, P; Ulamec, S.; Reed, C

    2015-01-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission is a kinetic impactor experiment to demonstrate asteroid impact hazard mitigation by deflecting an asteroid. AIDA is an international cooperation between NASA and ESA, consisting of two mission elements: the NASA Double Asteroid Redirection Test (DART) mission and the ESA Asteroid Impact Mission (AIM) rendezvous mission. The primary goals of AIDA are (i) to demonstrate the kinetic impact technique on a potentially hazardous near-Ea...

  5. Asteroid impact monitoring

    Directory of Open Access Journals (Sweden)

    Milani A.

    2006-01-01

    Full Text Available Some asteroids and comets with Earth-crossing orbit may impact our planet, thus we need to be able to identify the cases which could have a dangerous close approach within a century. This must be done as soon as such an asteroid is discovered, allowing for follow up observations which might contradict the impact possibility, and in the worst case to organize mitigation, possibly including deflection. The mathematical problem of predicting possible impacts, even with very low probabilities, has been solved by our group in the last few years. This paper presents the basic theory of these impact prediction, and discusses how they are practically used in the impact monitoring systems now operational, in particular the CLOMON2 robot of the Universities of Pisa and Valladolid.

  6. The Asteroid Impact Mission (AIM)

    Science.gov (United States)

    Küppers, M.; Carnelli, I.; Galvez, A.; Mellab, K.; Michel, P.; AIM Team

    2015-10-01

    The Asteroid Impact Mission (AIM) is ESA's contribution to an international cooperation targeting the demonstration of deflection of a hazardous nearearth asteroid as well as the first in-depth investigation of a binary asteroid. After launch in 2020, AIM will rendezvous the binary near-Earth asteroid (65803) Didymos in 2022 and observe the system before, during, and after the impact of NASA's Double Asteroid Redirection Test (DART) spacecraft. The AIM mission will test new technologies like optical telecommunications by laser and Cubesats with nano-payloads and will perform scientific measurements at the asteroid system.

  7. Impacts into porous asteroids

    Science.gov (United States)

    Housen, Kevin R.; Sweet, William J.; Holsapple, Keith A.

    2018-01-01

    Many small bodies in the solar system have bulk density well below the solid density of the constituent mineral grains in their meteorite counterparts. Those low-density bodies undoubtedly have significant porosity, which is a key factor that affects the formation of impact craters. This paper summarizes the results of lab experiments in which materials with porosity ranging from 43% to 96% were impacted at ∼1800 m/s. The experiments were performed on a geotechnical centrifuge, in order to reproduce the lithostatic overburden stress and ejecta ballistics that occur in large-scale cratering events on asteroids or planetary satellites. Experiments performed at various accelerations, up to 514G, simulate the outcomes of impacts at size scales up to several tens of km in diameter. Our experiments show that an impact into a highly porous cohesionless material generates a large ovoid-shaped cavity, due to crushing by the outgoing shock. The cavity opens up to form a transient crater that grows until the material flow is arrested by gravity. The cavity then collapses to form the final crater. During collapse, finely crushed material that lines the cavity wall is carried down and collected in a localized region below the final crater floor. At large simulated sizes (high accelerations), most of the crater volume is formed by compaction, because growth of the transient crater is quickly arrested. Nearly all ejected material falls back into the crater, leaving the crater without an ejecta blanket. We find that such compaction cratering and suppression of the ejecta blankets occur for large craters on porous bodies when the ratio of the lithostatic stress at one crater depth to the crush strength of the target exceeds ∼0.005. The results are used to identify small solar system bodies on which compaction cratering likely occurs. A model is developed that gives the crater size and ejecta mass that would result for a specified impact into a porous object.

  8. Asteroid Impact and Deflection Assessment (AIDA) Mission: The double Asteroid redirection test (DART)

    OpenAIRE

    Cheng, A F; Michel, P; Barnouin, O.S.; Campo-Bagatin, A.; Miller, P.; Pravec, P.; Richardson, D. C.; Rivkin, A. S.; Schwartz, S.R.; Stickel, A.; Tsiganis, K.; Ulamec, S.

    2016-01-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor. AIDA is a joint ESA-NASA cooperative project [1,2], that includes the ESA Asteroid Impact Mission (AIM) rendezvous spacecraft and the NASA Double Asteroid Redirection Test (DART) mission. The AIDA target is the near- Earth binary asteroid 65803 Didymos, which will make an unusually close approach to Earth in October, 20...

  9. Chemical, thermal and impact processing of asteroids

    Science.gov (United States)

    Scott, E. R. D.; Taylor, G. J.; Newsom, H. E.; Herbert, F.; Zolensky, M.

    1989-01-01

    The geological effects of impacts, heating, melting, core formation, and aqueous alteration on asteroids are reviewed. A review of possible heat sources appears to favor an important role for electrical induction heating. The effects of each geologic process acting individually and in combination with others, are considered; it is concluded that there is much evidence for impacts during alteration, metamorphism and melting. These interactions vastly increased the geologic diversity of the asteroid belt. Subsequent impacts of cool asteroids did not reduce this diversity. Instead new rock types were created by mixing, brecciation and minor melting.

  10. Martian cratering. II - Asteroid impact history.

    Science.gov (United States)

    Hartmann, W. K.

    1971-01-01

    This paper considers the extent to which Martian craters can be explained by considering asteroidal impact. Sections I, II, and III of this paper derive the diameter distribution of hypothetical asteroidal craters on Mars from recent Palomar-Leiden asteroid statistics and show that the observed Martian craters correspond to a bombardment by roughly 100 times the present number of Mars-crossing asteroids. Section IV discusses the early bombardment history of Mars, based on the capture theory of Opik and probable orbital parameters of early planetesimals. These results show that the visible craters and surface of Mars should not be identified with the initial, accreted surface. A backward extrapolation of the impact rates based on surviving Mars-crossing asteroids can account for the majority of Mars craters over an interval of several aeons, indicating that we see back in time no further than part-way into a period of intense bombardment. An early period of erosion and deposition is thus suggested. Section V presents a comparison with results and terminology of other authors.

  11. Damage from the impacts of small asteroids

    Energy Technology Data Exchange (ETDEWEB)

    Hills, J.G.; Goda, M.P.

    1996-08-15

    The fragmentation of a small asteroid in the atmosphere greatly increases its aerodynamic drag and rate of energy dissipation. The differential atmospheric pressure across it disperses its fragments at a velocity that increases with atmospheric density and impact velocity and decreases with asteroid density. Extending our previous work, we use a spherical atmosphere and a fitted curve to its density profile to find the damage done by an asteroid entering the atmosphere at various zenith angles. In previous work we estimated the blast damage by scaling from data on nuclear explosions in the atmosphere during the 1940s, 1950s and early 1960s. This underestimated the blast from asteroid impacts because nuclear fireballs radiate away a larger fraction of their energy than do meteors, so less of their energy goes into the blast wave. We have redone the calculations to allow for this effect. We have found the area of destruction around the impact point in which the over pressure in the blast wave exceeds 4 pounds/inch{sup 2} = 2.8 X 10{sup 5} dynes/cm{sup 3}, which is enough to knock over trees and destroy buildings. About every 100 years an impactor should blast an area of 300 km{sup 2} or more somewhere on the land area of Earth. The optical flux from asteroids 60 meters or more in diameter is enough to ignite pine forests. However, the blast from an impacting asteroid goes beyond the radius within which the fire starts. It tends to blow out the fire, so it is likely that the impact will char the forest (as at Tunguska), but it will not produce a sustained fire. Because of the atmosphere, asteroids less than about 200 m in diameter are not effective in producing craters and earthquakes. They are also not effective in producing water waves and tsunami in ocean impacts. Tsunami is probably the most devastating type of damage for asteroids that are between 200 meters and 1 km in diameter.

  12. Asteroid-Generated Tsunami and Impact Risk

    Science.gov (United States)

    Boslough, M.; Aftosmis, M.; Berger, M. J.; Ezzedine, S. M.; Gisler, G.; Jennings, B.; LeVeque, R. J.; Mathias, D.; McCoy, C.; Robertson, D.; Titov, V. V.; Wheeler, L.

    2016-12-01

    The justification for planetary defense comes from a cost/benefit analysis, which includes risk assessment. The contribution from ocean impacts and airbursts is difficult to quantify and represents a significant uncertainty in our assessment of the overall risk. Our group is currently working toward improved understanding of impact scenarios that can generate dangerous tsunami. The importance of asteroid-generated tsunami research has increased because a new Science Definition Team, at the behest of NASA's Planetary Defense Coordinating Office, is now updating the results of a 2003 study on which our current planetary defense policy is based Our group was formed to address this question on many fronts, including asteroid entry modeling, tsunami generation and propagation simulations, modeling of coastal run-ups, inundation, and consequences, infrastructure damage estimates, and physics-based probabilistic impact risk assessment. We also organized the Second International Workshop on Asteroid Threat Assessment, focused on asteroid-generated tsunami and associated risk (Aug. 23-24, 2016). We will summarize our progress and present the highlights of our workshop, emphasizing its relevance to earth and planetary science. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

  13. The Asteroid Impact Mission - Deflection Demonstration (AIM - D2)

    Science.gov (United States)

    Küppers, M.; Michel, P.; Carnelli, I.

    2017-09-01

    The Asteroid Impact Mission (AIM) is ESA's contribution to the international Asteroid Impact Deflection Assessment (AIDA) cooperation, targeting the demonstration of deflection of a hazardous near-earth asteroid. AIM will also be the first in-depth investigation of a binary asteroid and make measurements that are relevant for the preparation of asteroid resource utilisation. AIM is foreseen to rendezvous with the binary near-Earth asteroid (65803) Didymos and to observe the system before, during, and after the impact of NASA's Double Asteroid Redirection Test (DART) spacecraft. Here we describe the observations to be done by the simplified version Asteroid Impact Mission - Deflection Demonstration (AIM-D2) and show that most of the original AIM objectives can still be achieved.

  14. Consequences of Predicted or Actual Asteroid Impacts

    Science.gov (United States)

    Chapman, C. R.

    2003-12-01

    Earth impact by an asteroid could have enormous physical and environmental consequences. Impactors larger than 2 km diameter could be so destructive as to threaten civilization. Since such events greatly exceed any other natural or man-made catastrophe, much extrapolation is necessary just to understand environmental implications (e.g. sudden global cooling, tsunami magnitude, toxic effects). Responses of vital elements of the ecosystem (e.g. agriculture) and of human society to such an impact are conjectural. For instance, response to the Blackout of 2003 was restrained, but response to 9/11 terrorism was arguably exaggerated and dysfunctional; would society be fragile or robust in the face of global catastrophe? Even small impacts, or predictions of impacts (accurate or faulty), could generate disproportionate responses, especially if news media reports are hyped or inaccurate or if responsible entities (e.g. military organizations in regions of conflict) are inadequately aware of the phenomenology of small impacts. Asteroid impact is the one geophysical hazard of high potential consequence with which we, fortunately, have essentially no historical experience. It is thus important that decision makers familiarize themselves with the hazard and that society (perhaps using a formal procedure, like a National Academy of Sciences study) evaluate the priority of addressing the hazard by (a) further telescopic searches for dangerous but still-undiscovered asteroids and (b) development of mitigation strategies (including deflection of an oncoming asteroid and on- Earth civil defense). I exemplify these issues by discussing several representative cases that span the range of parameters. Many of the specific physical consequences of impact involve effects like those of other geophysical disasters (flood, fire, earthquake, etc.), but the psychological and sociological aspects of predicted and actual impacts are distinctive. Standard economic cost/benefit analyses may not

  15. A Probabilistic Asteroid Impact Risk Model

    Science.gov (United States)

    Mathias, Donovan L.; Wheeler, Lorien F.; Dotson, Jessie L.

    2016-01-01

    Asteroid threat assessment requires the quantification of both the impact likelihood and resulting consequence across the range of possible events. This paper presents a probabilistic asteroid impact risk (PAIR) assessment model developed for this purpose. The model incorporates published impact frequency rates with state-of-the-art consequence assessment tools, applied within a Monte Carlo framework that generates sets of impact scenarios from uncertain parameter distributions. Explicit treatment of atmospheric entry is included to produce energy deposition rates that account for the effects of thermal ablation and object fragmentation. These energy deposition rates are used to model the resulting ground damage, and affected populations are computed for the sampled impact locations. The results for each scenario are aggregated into a distribution of potential outcomes that reflect the range of uncertain impact parameters, population densities, and strike probabilities. As an illustration of the utility of the PAIR model, the results are used to address the question of what minimum size asteroid constitutes a threat to the population. To answer this question, complete distributions of results are combined with a hypothetical risk tolerance posture to provide the minimum size, given sets of initial assumptions. Model outputs demonstrate how such questions can be answered and provide a means for interpreting the effect that input assumptions and uncertainty can have on final risk-based decisions. Model results can be used to prioritize investments to gain knowledge in critical areas or, conversely, to identify areas where additional data has little effect on the metrics of interest.

  16. Unveiling Clues from Spacecraft Missions to Comets and Asteroids through Impact Experiments

    Science.gov (United States)

    Lederer, Susan M.; Jensen, Elizabeth; Fane, Michael; Smith, Douglas; Holmes, Jacob; Keller, Lindasy P.; Lindsay, Sean S.; Wooden, Diane H.; Whizin, Akbar; Cintala, Mark J.; hide

    2016-01-01

    The Deep Impact Spacecraft mission was the first to boldly face the challenge of impacting the surface of a comet, 9P/Tempel 1, to investigate surface and subsurface 'pristine' materials. The Stardust mission to Comet 81P/Wild 2 brought back an exciting surprise: shocked minerals which were likely altered during the comet's lifetime. Signatures of shock in meteorites also suggest that the violent past of the solar system has left our small bodies with signatures of impacts and collisions. These results have led to the question: How have impacts affected the evolutionary path taken by comets and asteroids, and what signatures can be observed? A future planetary mission to a near-Earth asteroid is proposing to take the next steps toward understanding small bodies through impacts. The mission would combine an ESA led AIM (Asteroid Impact Mission) with a JHU/APL led DART (Double Asteroid Redirect Mission) spacecraft to rendezvous with binary near-Earth asteroid 65803 Didymus (1996 G2). DART would impact the smaller asteroid, 'Didymoon' while AIM would characterize the impact and the larger Didymus asteroid. With these missions in mind, a suite of experiments have been conducted at the Experimental Impact Laboratory (EIL) at NASA Johnson Space Center to investigate the effects that collisions may have on comets and asteroids. With the new capability of the vertical gun to cool targets in the chamber through the use of a cold jacket fed by liquid nitrogen, the effects of target temperature have been the focus of recent studies. Mg-rich forsterite and enstatite (orthopyroxene), diopside (monoclinic pyroxene) and magnesite (Mg-rich carbonate) were impacted. Target temperatures ranged from 25 deg to -100 deg, monitored by connecting thermocouples to the target container. Impacted targets were analyzed with a Fourier Transform Infrared Spectrometer (FTIR) and Transmission Electron Microscope (TEM). Here we present the evidence for impact-induced shock in the minerals through

  17. Large asteroid families modelled by impact events

    Science.gov (United States)

    Benavidez, P.; Durda, D.; Enke, B.; Campo Bagatin, A.; Richardson, D. C.; Asphaug, E.; Bottke, W. F.

    2017-09-01

    We present a study of large asteroid families modeled by impact events. To extend the work started by [1] and [2], we performed a new set of simulations in the gravity regime for monolithic and rubble-pile targets of 400 km diameter. Here we analyze and discuss if the studied families are best matched by the modeled size-frequency distribution (SFD) resulting from a monolithic or rubble-pile parent body.

  18. The Asteroid Impact and Deflection Assessment Mission and its Potential Contributions to Human Exploration of Asteroids

    Science.gov (United States)

    Abell, Paul A.; Rivkin, Andy S.

    2014-01-01

    The joint ESA and NASA Asteroid Impact and Deflection Assessment (AIDA) mission will directly address aspects of NASA's Asteroid Initiative and will contribute to future human exploration. The NASA Asteroid Initiative is comprised of two major components: the Grand Challenge and the Asteroid Mission. The first component, the Grand Challenge, focuses on protecting Earth's population from asteroid impacts by detecting potentially hazardous objects with enough warning time to either prevent them from impacting the planet, or to implement civil defense procedures. The Asteroid Mission, involves sending astronauts to study and sample a near-Earth asteroid (NEA) prior to conducting exploration missions of the Martian system, which includes Phobos and Deimos. AIDA's primary objective is to demonstrate a kinetic impact deflection and characterize the binary NEA Didymos. The science and technical data obtained from AIDA will aid in the planning of future human exploration missions to NEAs and other small bodies. The dual robotic missions of AIDA, ESA's Asteroid Impact Monitor (AIM) and NASA's Double Asteroid Redirection Test (DART), will provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in-depth scientific examinations of the binary target Didymos both prior to and after the kinetic impact demonstration. The knowledge gained from this mission will help identify asteroidal physical properties in order to maximize operational efficiency and reduce mission risk for future small body missions. The AIDA data will help fill crucial strategic knowledge gaps concerning asteroid physical characteristics that are relevant for human exploration considerations at similar small body destinations.

  19. Impact on Comets and Asteroids

    Science.gov (United States)

    OKeefe, John D.; Stewart, Sarah T.; Ahrens, Thomas J.

    2001-01-01

    We characterized the impact physics in collisions on porous bodies by various density projectiles and defined different penetration modes (compression, spreading, or breakup) based on transitions between instability regimes. Additional information is contained in the original extended abstract.

  20. Sensitivity of Asteroid Impact Risk to Uncertainty in Asteroid Properties and Entry Parameters

    Science.gov (United States)

    Wheeler, Lorien; Mathias, Donovan; Dotson, Jessie L.; NASA Asteroid Threat Assessment Project

    2017-10-01

    A central challenge in assessing the threat posed by asteroids striking Earth is the large amount of uncertainty inherent throughout all aspects of the problem. Many asteroid properties are not well characterized and can range widely from strong, dense, monolithic irons to loosely bound, highly porous rubble piles. Even for an object of known properties, the specific entry velocity, angle, and impact location can swing the potential consequence from no damage to causing millions of casualties. Due to the extreme rarity of large asteroid strikes, there are also large uncertainties in how different types of asteroids will interact with the atmosphere during entry, how readily they may break up or ablate, and how much surface damage will be caused by the resulting airbursts or impacts.In this work, we use our Probabilistic Asteroid Impact Risk (PAIR) model to investigate the sensitivity of asteroid impact damage to uncertainties in key asteroid properties, entry parameters, or modeling assumptions. The PAIR model combines physics-based analytic models of asteroid entry and damage in a probabilistic Monte Carlo framework to assess the risk posed by a wide range of potential impacts. The model samples from uncertainty distributions of asteroid properties and entry parameters to generate millions of specific impact cases, and models the atmospheric entry and damage for each case, including blast overpressure, thermal radiation, tsunami inundation, and global effects. To assess the risk sensitivity, we alternately fix and vary the different input parameters and compare the effect on the resulting range of damage produced. The goal of these studies is to help guide future efforts in asteroid characterization and model refinement by determining which properties most significantly affect the potential risk.

  1. Meteoroid Impact Detection for Exploration of Asteroids (MIDEA): Meteoroid Impact Rates on Potential Asteroid Targets

    Science.gov (United States)

    Lee, N.; Close, S.

    2016-12-01

    Meteoroid impacts on asteroid surfaces produce a plasma that can be sampled by a nearby spacecraft. This plasma provides a mechanism for exploring the surface composition of asteroids using a constellation of free-flying, ultralight sensors. The requirements for detection of the expanding impact plasma is that the meteoroid is large and fast enough to produce sufficient charge, and that the asteroid surface is electrically biased so that the electrons are captured and positive ions are ejected. For a sensor positioned at a distance of 100-500 m, nanogram-sized meteoroids impacting at speeds greater than 20 km/s onto a sunlit surface can produce a detectable signal. We used NASA's Meteoroid Engineering Model (MEM) and the Grün interplanetary flux model to estimate the impact rate of meteoroids on a selection of asteroid candidates. These include near-Earth asteroids (NEAs) as well as several bodies in the main belt. Orbital trajectories were obtained using JPL's Horizons interface, and the sunward-facing meteoroid flux was computed using MEM for µg-sized meteoroids at speeds of 20 km/s or greater. The Grün model was used to scale the flux to ng-sized meteoroids. The figure below shows the maximum and minimum impact rate for each of the target bodies, ordered by their orbital semi-major axis. The NEAs have maximum rates of 0.18 to 0.30 m-2 day-1, corresponding to an impact on each square meter every 3.3 to 5.4 days. The main-belt bodies are impacted far less frequently. However, 1999 JD8, which has a high eccentricity of 0.47, has a maximum impact rate about ten times greater than Elst-Pizarro, despite having a similar semi-major axis. Because of the gossamer nature of the ultralight sensors envisioned for this exploration concept, mission duration is limited by degradation of the electronics. The impacts predicted for NEAs and for some high-eccentricity asteroids in the main belt are frequent enough to allow an asteroid to be well characterized in under a month.

  2. The evolutionary and ecological benefits of asteroid and comet impacts.

    Science.gov (United States)

    Cockell, Charles S; Bland, Philip A

    2005-04-01

    Commonly viewed solely as agents of destruction, asteroid and comet impact events can also have a beneficial influence on processes from the molecular to the evolutionary scale. On the heavily bombarded early Earth, impacts might have delivered and caused the synthesis of prebiotic compounds that eventually led to life. At the organismal and ecosystem level, impact events can provide new habitats through the shock processing of target materials and by enhancing water availability, such as within intracrater lakes. At the evolutionary level, by destroying entire groups of organisms, impacts might have been instrumental in enabling the rise of new groups, such as the dinosaurs and mammals. Here, we synthesize the emerging literature on the beneficial effects of impacts to provide a novel perspective on these extraterrestrial agents of biological change.

  3. Seismo-Acoustic Numerical Investigation of Land Impacts, Water Impacts, or Air Bursts of Asteroids

    Science.gov (United States)

    Ezzedine, S. M.; Miller, P. L.; Dearborn, D. S.

    2016-12-01

    The annual probability of an asteroid impact is low, but over time, such catastrophic events are inevitable. Interest in assessing the impact consequences has led us to develop a physics-based framework to seamlessly simulate the event from entry to impact, including air, water and ground shock propagation and wave generation. The non-linear effects are simulated using the hydrodynamics code GEODYN. As effects propagate outward, they become a wave source for the linear-elastic-wave propagation code and simulated using SAW or SWWP, depends on whether the asteroid impacts the land or the ocean, respectively. The GEODYN-SAW-SWWP coupling is based on the structured adaptive-mesh-refinement infrastructure, SAMRAI, and has been used in FEMA table-top exercises conducted in 2013 and 2014, and more recently, the 2015 Planetary Defense Conference exercise. Moreover, during atmospheric entry, asteroids create an acoustic trace that could be used to infer several physical characteristics of asteroid itself. Using SAW we explore the physical space parameters in order to rank the most important characteristics; Results from these simulations provide an estimate of onshore and offshore effects and can inform more sophisticated inundation and structural models. The capabilities of this methodology are illustrated by providing results for different impact locations, and an exploration of asteroid size on the waves arriving at the shoreline of area cities. We constructed the maximum and minimum envelops of water-wave heights or acceleration spectra given the size of the asteroid and the location of the impact along the risk corridor. Such profiles can inform emergency response and disaster-mitigation efforts. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  4. Dealing with the Asteroid Impact Hazard

    Science.gov (United States)

    Morrison, David

    2001-01-01

    The small fraction of the asteroids with Earth-crossing or Earth-approaching orbits is of special interest to us because many will eventually impact our planet. The time-averaged impact flux as a function of projectile energy can be derived from lunar cratering statistics, although we have little information on the possible variability of this flux over time. The effects of impacts of various energies can be modeled, using data from historic impacts (such as the KT impactor 65 million years ago), nuclear explosive testing, and the observed 1994 bombardment of Jupiter by fragments of comet Shoemaker-Levy 9. It is of particular interest to find from such models that the terrestrial environment is highly vulnerable to perturbation from impacts, so that even such a small event as the KT impact (by a projectile roughly 15 km in diameter) can lead to a mass extinction. Combining the impact flux with estimates of environmental and ecological effects reveals that the greatest contemporary hazard is associated with impactors near one million megatons energy. The current impact hazard is significant relative to other natural hazards, and arguments can be developed to illuminate a variety of public policy issues. These include the relative risk of different impact scenarios and the associated costs and probability of success of countermeasures. It is generally agreed that the first step is to survey and catalogue the thousand-or-so Near Earth Asteroids (NEAs), and we review the status of the Spaceguard NEA Survey. We compare the efficiency of various ground and space-based approaches and consider the challenges of international coordination and the problems and opportunities associated with communicating the results with the press and the public. It is also important to reflect on how the impact hazard might be dealt with by both national governments and international decision-making bodies, and to anticipate ways of mitigating the danger if a NEA were located on an apparent

  5. Collision rates and impact velocities in the Main Asteroid Belt

    Science.gov (United States)

    Farinella, Paolo; Davis, Donald R.

    1992-01-01

    Wetherill's (1967) algorithm is presently used to compute the mutual collision probabilities and impact velocities of a set of 682 asteroids with large-than-50-km radius representative of a bias-free sample of asteroid orbits. While collision probabilities are nearly independent of eccentricities, a significant decrease is associated with larger inclinations. Collisional velocities grow steeply with orbital eccentricity and inclination, but with curiously small variation across the asteroid belt. Family asteroids are noted to undergo collisions with other family members 2-3 times more often than with nonmembers.

  6. Origin of asteroid rotation rates in catastrophic impacts.

    Science.gov (United States)

    Love, S G; Ahrens, T J

    1997-03-13

    The rotation rates of asteroids, which are deduced from periodic fluctuations in their brightnesses, are controlled by mutual collisions. The link between asteroid spin and collision history is usually made with reference to impact experiments on centimetre-scale targets, where material strength governs the impact response. Recent work, however, indicates that for objects of the size of most observed asteroids (> or = 1 km in diameter), gravity rather than intrinsic strength controls the dynamic response to collisions. Here we explore this idea by modelling the effect of impacts on large gravitating bodies. We find that the fraction of a projectile's angular momentum that is retained by a target asteroid is both lower and more variable than expected from laboratory experiments, with spin evolution being dominated by 'catastrophic' collisions that eject approximately 50 per cent of the target's mass. The remnant of an initially non-rotating silicate asteroid that suffers such a collision rotates at a rate of approximately 2.9 per day, which is close to the observed mean asteroid rotation rate of approximately 2.5 d-1. Moreover, our calculations suggest that the observed trend in the mean spin frequency for different classes of asteroids (2.2 d-1 for C-type asteroids, 2.5 d-1 for S-type, and 4.0 d-1 for M-type) is due to increasing mean density, rather than increasing material strength.

  7. Unveiling clues from Spacecraft Missions to Comets and Asteroids through Impact Experiments

    Science.gov (United States)

    Lederer, Susan M.; Jensen, Elizabeth; Fane, Michael; Smith, Douglas; Holmes, Jacob; Keller, Lindsay P.; Lindsay, Sean S.; Wooden, Diane H.; Whizin, Akbar; Cintala, Mark J.; Zolensky, Michael

    2016-10-01

    The Deep Impact Spacecraft mission was the first to boldly face the challenge of impacting the surface of a comet, 9P/Tempel 1, to investigate surface and subsurface 'pristine' materials. The Stardust mission to Comet 81P/Wild 2 brought back an exciting surprise: shocked minerals which were likely altered during the comet's lifetime. Signatures of shock in meteorites also suggest that the violent past of the solar system has left our small bodies with signatures of impacts and collisions. These results have led to the question: How have impacts affected the evolutionary path taken by comets and asteroids, and what signatures can be observed?A future planetary mission to a near-Earth asteroid is proposing to take the next steps toward understanding small bodies through impacts. The mission would combine an ESA led AIM (Asteroid Impact Mission) with a JHU/APL led DART (Double Asteroid Redirect Mission) spacecraft to rendezvous with binary near-Earth asteroid 65803 Didymus (1996 G2). DART would impact the smaller asteroid, 'Didymoon' while AIM would characterize the impact and the larger Didymus asteroid.With these missions in mind, a suite of experiments have been conducted at the Experimental Impact Laboratory (EIL) at NASA Johnson Space Center to investigate the effects that collisions may have on comets and asteroids. With the new capability of the vertical gun to cool targets in the chamber through the use of a cold jacket fed by liquid nitrogen, the effects of target temperature have been the focus of recent studies. Mg-rich forsterite and enstatite (orthopyroxene), diopside (monoclinic pyroxene) and magnesite (Mg-rich carbonate) were impacted. Target temperatures ranged from 25°C to -100°C, monitored by connecting thermocouples to the target container. Impacted targets were analyzed with a Fourier Transform Infrared Spectrometer (FTIR) and Transmission Electron Microscope (TEM). Here we present the evidence for impact-induced shock in the minerals through

  8. Planetary geology: Impact processes on asteroids

    Science.gov (United States)

    Chapman, C. R.; Davis, D. R.; Greenberg, R.; Weidenschilling, S. J.

    1982-01-01

    The fundamental geological and geophysical properties of asteroids were studied by theoretical and simulation studies of their collisional evolution. Numerical simulations incorporating realistic physical models were developed to study the collisional evolution of hypothetical asteroid populations over the age of the solar system. Ideas and models are constrained by the observed distributions of sizes, shapes, and spin rates in the asteroid belt, by properties of Hirayama families, and by experimental studies of cratering and collisional phenomena. It is suggested that many asteroids are gravitationally-bound "rubble piles.' Those that rotate rapidly may have nonspherical quasi-equilibrium shapes, such as ellipsoids or binaries. Through comparison of models with astronomical data, physical properties of these asteroids (including bulk density) are determined, and physical processes that have operated in the solar system in primordial and subsequent epochs are studied.

  9. Asteroid Geophysics and Quantifying the Impact Hazard

    Science.gov (United States)

    Sears, D.; Wooden, D. H.; Korycanksy, D. G.

    2015-01-01

    Probably the major challenge in understanding, quantifying, and mitigating the effects of an impact on Earth is understanding the nature of the impactor. Of the roughly 25 meteorite craters on the Earth that have associated meteorites, all but one was produced by an iron meteorite and only one was produced by a stony meteorite. Equally important, even meteorites of a given chemical class produce a wide variety of behavior in the atmosphere. This is because they show considerable diversity in their mechanical properties which have a profound influence on the behavior of meteorites during atmospheric passage. Some stony meteorites are weak and do not reach the surface or reach the surface as thousands of relatively harmless pieces. Some stony meteorites roll into a maximum drag configuration and are strong enough to remain intact so a large single object reaches the surface. Others have high concentrations of water that may facilitate disruption. However, while meteorite falls and meteorites provide invaluable information on the physical nature of the objects entering the atmosphere, there are many unknowns concerning size and scale that can only be determined by from the pre-atmospheric properties of the asteroids. Their internal structure, their thermal properties, their internal strength and composition, will all play a role in determining the behavior of the object as it passes through the atmosphere, whether it produces an airblast and at what height, and the nature of the impact and amount and distribution of ejecta.

  10. The Big Splash: Tsunami from Large Asteroid and Comet Impacts

    Science.gov (United States)

    Hills, J.; Goda, M.

    Asteroid and comet impacts produce a large range of damage. Tsunami may produce most of the economic damage in large asteroid impacts. Large asteroid impacts produce worldwide darkness lasting several months that may kill more people by mass starvation, especially in developing countries, than would tsunami, but the dust should not severely affect economic infrastructure. The tsunami may even kill more people in developed countries with large coastal populations, such as the United States, than the starvation resulting from darkness. We have been determining which regions of Earth are most susceptible to asteroid tsunami by simulating the effect of a large asteroid impact into mid-ocean. We have modeled the effect of midAtlantic and midPacific impacts that produce craters 300 to 150 km in diameter. A KT-size impactor would cause the larger of these craters. We used a computer code that has successfully determined the runup and inundation from historical earthquake-generated tsunami. The code has been progressively improved to eliminate previous problems at the domain boundaries, so it now runs until the tsunami inundation is complete. We find that the larger of these two midAtlantic impacts would engulf the entire Florida Peninsula. The smaller one would inundate the eastern third of the peninsula while a tsunami passing through the Gulf of Cuba would inundate the West Coast of Florida. Impacts at three different sites in the Pacific show the great vulnerability of Tokyo and its surroundings to asteroid tsunami. Mainland Asia is relatively protected from asteroid tsunami. In Europe, the Iberian Peninsula and the Atlantic Providences of France are highly vulnerable to asteroid tsunami.

  11. Asteroid Impact Risk: Ground Hazard versus Impactor Size

    Science.gov (United States)

    Mathias, Donovan; Wheeler, Lorien; Dotson, Jessie L.; Aftosmis, Michael; Tarano, Ana Maria

    2017-10-01

    The Asteroid Threat Assessment Project at NASA Ames Research Center has developed a Probabilistic Asteroid Impact Risk (PAIR) model to assess the level of risk posed by potential asteroid strikes on Earth. The PAIR model combines analytic models of asteroid entry and damage in a probabilistic Monte Carlo framework to assess the ensemble risk posed by a wide range of potential impacts. The model samples from uncertainty distributions of asteroid properties and entry parameters to generate millions of specific impact cases, and models the atmospheric entry and damage for each case.We present the recent results of an expanded asteroid impact risk assessment. The expanded assessment models 60 million impact cases, covering asteroid sizes from 20m up to 10km in diameter, and evaluates damage due to local blast overpressure and thermal radiation, tsunami inundation, and global effects for each case. Advancements include: (a) incorporation of a tsunami model that is able to estimate specific flood damage for each ocean strike, accounting for local ocean depth, coastal topography, and populations; (b) use of improved height-of-burst maps for estimating the blast overpressure footprints, developed based on high-fidelity blast propagation simulations; and (c) representation of multiple damage levels for local blast overpressure and thermal radiation exposure. Results demonstrate the relative contributions of the various hazard sources to the total risk, and the significance of including lower damage levels in risk assessment metrics. The annualized expected risk is dominated by the global-effects causing large (> 1 km) object impacts. Local damage, due to blast overpressure and thermal radiation, expectations peak for impactors in the few hundred-meter size range, but the annualized damage is an order of magnitude less than that of the larger objects. Asteroid generated tsunami poses very little ensemble risk compared to both local land and global scenarios.

  12. Near-field effects of asteroid impacts in deep water

    Energy Technology Data Exchange (ETDEWEB)

    Gisler, Galen R [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Gittings, Michael L [Los Alamos National Laboratory

    2009-06-11

    Our previous work has shown that ocean impacts of asteroids below 500 m in diameter do not produce devastating long-distance tsunamis. Nevertheless, a significant portion of the ocean lies close enough to land that near-field effects may prove to be the greatest danger from asteroid impacts in the ocean. Crown splashes and central jets that rise up many kilometres into the atmosphere can produce, upon their collapse, highly non-linear breaking waves that could devastate shorelines within a hundred kilometres of the impact site. We present illustrative calculations, in two and three dimensions, of such impacts for a range of asteroid sizes and impact angles. We find that, as for land impacts, the greatest dangers from oceanic impacts are the short-term near-field, and long-term atmospheric effects.

  13. ASTEROIDS

    Directory of Open Access Journals (Sweden)

    Željko Andreić

    2016-02-01

    Full Text Available Asteroids are the largest minor bodies in the Solar System. Nowadays they are in the research focus due to several facts about them: first, a subclass of asteroids can collide with Earth, and consequences of such a collision are dramatic. Second, they are now seen as source of materials that are becoming scarce on Earth, and they will be needed in future space constructions anyway. Third, they are holding clues about the origin and evolution of the Solar System. In this article, a short overview of current knowledge about asteroids is presented. Last, but not least, as several Croatian scientists were recently honored by naming an asteroid after them, a short overview of the naming process is given.

  14. The asteroid impact connection of planetary evolution with special reference to large Precambrian and Australian impacts

    CERN Document Server

    Glikson, Andrew Y

    2014-01-01

    When in 1981 Louis and Walter Alvarez, the father and son team, unearthed a tell-tale Iridium-rich sedimentary horizon at the 65 million years-old Cretaceous-Tertiary boundary at Gubbio, Italy, their find heralded a paradigm shift in the study of terrestrial evolution.  Since the 1980s the discovery and study of asteroid impact ejecta in the oldest well-preserved terrains of Western Australia and South Africa, by Don Lowe, Gary Byerly, Bruce Simonson, Scott Hassler, the author and others, and the documentation of new exposed and buried impact structures in several continents, have led to a resurgence of the idea of the catastrophism theory of Cuvier, previously largely supplanted by the uniformitarian theory of Hutton and Lyell. Several mass extinction of species events are known to have occurred in temporal proximity to large asteroid impacts, global volcanic eruptions and continental splitting. Likely links are observed between asteroid clusters and the 580 Ma acritarch radiation, end-Devonian extinction, ...

  15. Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission

    Science.gov (United States)

    Michel, Patrick; Cheng, A.; Küppers, M.; Pravec, P.; Blum, J.; Delbo, M.; Green, S. F.; Rosenblatt, P.; Tsiganis, K.; Vincent, J. B.; Biele, J.; Ciarletti, V.; Hérique, A.; Ulamec, S.; Carnelli, I.; Galvez, A.; Benner, L.; Naidu, S. P.; Barnouin, O. S.; Richardson, D. C.; Rivkin, A.; Scheirich, P.; Moskovitz, N.; Thirouin, A.; Schwartz, S. R.; Campo Bagatin, A.; Yu, Y.

    2016-06-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to test the kinetic impactor technique to deflect an asteroid. The European Asteroid Impact Mission (AIM) is set to rendezvous with the asteroid system to fully characterize the smaller of the two binary components a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near-Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions. The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Having direct information on the surface and internal properties of small asteroids will allow us to understand how the various processes they undergo work and transform these small bodies as well as, for this particular case, how a binary system forms. Making these measurements from up close and comparing them with ground-based data from telescopes will also allow us to calibrate remote observations and improve our data interpretation of other systems. With DART, thanks to the characterization of the target by AIM, the mission will be the first fully documented impact experiment at asteroid scale, which will include the characterization of the target's properties and the outcome of the impact. AIDA will thus offer a great opportunity to test and refine our understanding and models at the actual scale of an asteroid, and to check whether the current extrapolations of material strength from laboratory-scale targets to the scale of AIDA's target are valid. Moreover, it will offer a first check of the

  16. Contribution of Asteroid Generated Tsunami to the Impact Hazard

    Science.gov (United States)

    Morrison, David; Venkatapathy, Ethiraj

    2017-01-01

    The long-standing uncertainty about the importance of asteroid-generated tsunami was addressed at a workshop in August 2016, co-sponsored by NASA and NOAA. Experts from NASA, NOAA, the DoE tri-labs (LLNL, SNL, and LANL), DHS, FEMA, and academia addressed the hazard of tsunami created by asteroid impacts, focusing primarily on NEAs with diameter less than 250m. Participants jointly identified key issues and shared information for nearly a year to coordinate their results for discussion at the workshop. They used modern computational tools to examine 1) Near-field wave generation by the impact; 2) Long-distance wave propagation; 3) Damage from coastal run-up and inundation, and associated hazard. The workshop resulted in broad consensus that the asteroid impact tsunami threat is not as great as previously thought.

  17. Consequences of impacts of small asteroids and comets with Earth

    Science.gov (United States)

    Hills, J. G.

    1994-01-01

    The fragmentation of a small asteroid in the atmosphere greatly increases its cross sections for aerodynamic braking and energy dissipation. At a typical impact velocity of 22 km/s, the atmosphere absorbs more than half the kinetic energy of stony meteoroids with diameters, D(sub m), less than 220 m and iron meteoroids with D(sub m) less than 80 m. The corresponding diameter for comets with impact velocity 50 km/s is D(sub m) less than 1600 m. Most of the atmospheric energy dissipation occurs in a fraction of a scale height, so large meteors appear to 'explode' or 'flare' at the end of their visible paths. This dissipation of energy in the atmosphere protects the earth from direct impact damage (e.g., craters), but it produces a blast wave that can do considerable damage. The area of destruction around the impact point in which the over-pressure in the blast wave exceeds 4 lb/sq in = 2.8 x 10(exp 5) dynes/cu cm, which is enough to knock over trees and destroy buildings, increases rapidly from zero for chondritic meteoroids less than 56 m in diameter (15 megatons) to about 200 sq km for those 80 m in diameter (48 megatons); the probable diameter of the tunguska impactor of 1908 is about 80 m. Crater formation and earthquakes are not significant in land impacts by stony asteroids less than about 200 m in diameter because of the air protection. A tsunami is probably the most devastating type of damage for asteroids 200 m to 1 km in diameter. An impact by an asteroid this size anywhere in the Atlantic would devastate coastal areas on both sides of the ocean. An asteroid a few kilometers across would produce a tsunami that would reach the foothills of the Appalachian Mountains in the upper half of the East Coast of the United States. Most of Florida is protected from a tsunami by the gradual slope of the ocean off its coast, which causes most of the tsunami energy to be reflected back into the Atlantic. The atmosphere plume produced by asteroids with diameters exceeding

  18. Numerical Investigation of the Consequences of Land Impacts, Water Impacts, or Air Bursts of Asteroids

    Science.gov (United States)

    Ezzedine, S. M.; Dearborn, D. S.; Miller, P. L.

    2015-12-01

    The annual probability of an asteroid impact is low, but over time, such catastrophic events are inevitable. Interest in assessing the impact consequences has led us to develop a physics-based framework to seamlessly simulate the event from entry to impact, including air and water shock propagation and wave generation. The non-linear effects are simulated using the hydrodynamics code GEODYN. As effects propagate outward, they become a wave source for the linear-elastic-wave propagation code, WPP/WWP. The GEODYN-WPP/WWP coupling is based on the structured adaptive-mesh-refinement infrastructure, SAMRAI, and has been used in FEMA table-top exercises conducted in 2013 and 2014, and more recently, the 2015 Planetary Defense Conference exercise. Results from these simulations provide an estimate of onshore effects and can inform more sophisticated inundation models. The capabilities of this methodology are illustrated by providing results for different impact locations, and an exploration of asteroid size on the waves arriving at the shoreline of area cities. We constructed the maximum and minimum envelops of water-wave heights given the size of the asteroid and the location of the impact along the risk corridor. Such profiles can inform emergency response and disaster-mitigation efforts, and may be used for design of maritime protection or assessment of risk to shoreline structures of interest. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675390-DRAFT.

  19. Ground Hazards from 100 - 300 m Asteroid Impacts

    Science.gov (United States)

    Robertson, Darrel; Stern, Eric; Mathias, Donovan

    2017-10-01

    Observation programs have found over 15 000 of the estimated 1 million asteroids larger than 30 m in diameter. Current estimates suggest one such object will strike the Earth, on average, each century. As observation and tracking capabilities improve it is increasingly likely we will find asteroids on a collision course before they hit us. The ability to accurately predict ground damage from an impact is useful in determining appropriate response, whether through in-space mitigation or civil defense measures. For cases where in-space mitigation is unlikely, the specific damage consequences help emergency planners reduce casualties. The current work extends the understanding of impact damage by comparing the damage caused by blast overpressure, thermal radiation, and seismic waves due to 100 - 300 m diameter asteroids which are large enough to impact the ground yet small enough that global effects are not the primary concern. Land impacts were simulated with the ALE3D hydrocode to determine the amount of incident kinetic energy converted to each of the potential hazards. The resulting damage areas are compared considering the effects of asteroid size and composition as well as ground composition and porosity. We compare the simulation results to semi-analytical models from the literature.

  20. NUMERICAL MODELING OF MOON ASTEROID IMPACTS TSUNAMIS ON THE MOON

    Directory of Open Access Journals (Sweden)

    Charles L. Mader

    2017-06-01

    Full Text Available Asteroid impacts on the moon were modeled using the full Navier-Stokes AMR compressible hydrodynamic code called MAGNS. The size of the cavity and its time history are strongly dependent upon the strength characteristics of the moon rock. The initial impact pressures and temperatures are well above shock melting conditions at the impact surface of the moon. The formation of a moon crater, its rings and mascon is modeled.

  1. Short term impact risk assessment for asteroids 2011 AG5

    Science.gov (United States)

    Bancelin, D.; Pravec, P.; Nolan, M.

    2013-04-01

    Among the potentially hazardous asteroids (PHAs) in orbit around the Earth, some of them can become a real threat. The most famous PHA presently known is asteroid (99942) Apophis which briefly presented an unusually high impact probability (up to 2.3 %) for a collision with the Earth in 2029. It remains the only asteroid to have reached level 4 of the Torino Scale. Even if Apophis is not a threat anymore, other PHAs are still monitored and now, only one asteroid is scaled to 1 with the highest impact probability. Asteroid 2011 AG5 has 1 chance over 500 to hit the Earth on 2040. This asteroid is challenging because it will remain of faint magnitude around 23.0 until its close encounter with the Earth in February 2023. It will come close to the Earth by 0.012 AU. Intensive ground-based (optical and mainly radar measurements) will be performed. Before this date, optical measurements would be possible (provided that large telescopes are used) and orbital refinement could be performed in order to improve the orbital uncertainty of this asteroid. Nevertheless, no physical data can be derived before 2023 and therefore, the influence of non gravitational forces, mainly Yarkovsky effect, can not be precisely determined. This non gravitational effect produces a secular drift da/dt (positive or negative) of the semi-major axis due to the anisotropic re-emission of the incident solar radiation. We propose here a dynamical study of the asteroid 2011 AG5. We discuss first the location of primary and secondary keyholes in the target plane of 2023 as well as the quantification of the impact probability. Secondary keyholes are due to two consecutive close encounters, the second usually happening near a keyhole or a resonant return. Then, we will address how those quantities evolve with future dedicated ground-based measurements. In a second part, we will discuss non gravitational perturbations through Yarkovsky effect. Assuming that this asteroid is a C or S-type, we can

  2. Collision lifetimes and impact statistics of near-Earth asteroids

    Science.gov (United States)

    Bottke, W. F., Jr.; Nolan, M. C.; Greenberg, R.

    1993-01-01

    We have examined the lifetimes of Near-Earth asteroids (NEA's) by directly computing the collision probabilities with other asteroids and with the terrestrial planets. We compare these to the dynamical lifetimes, and to collisional lifetimes assumed by other workers. We discuss the implications of the differences. The lifetimes of NEA's are important because, along with the statistics of craters on the Earth and Moon, they help us to compute the number of NEA's and the rate at which new NEA's are brought to the vicinity of the Earth. Assuming that the NEA population is in steady-state, the lifetimes determine the flux of new bodies needed to replenish the population. Earlier estimates of the lifetimes ignored (or incompletely accounted for) the differences in the velocities of asteroids as they move in their orbits, so our results differ from (for example) Greenberg and Chapman (1983, Icarus 55, 455) and Wetherill (1988, Icarus 76, 1) by factors of 2 to 10. We have computed the collision rates and relative velocities of NEA's with each other, the main-belt asteroids, and the terrestrial planets, using the corrected method described by Bottke et. al. (1992, GRL, in press). We find that NEA's typically have shorter collisional lifetimes than do main-belt asteroids of the same size, due to their high eccentricities, which typically give them aphelia in the main belt. Consequently, they spend a great deal of time in the main belt, and are moving much slower than the bodies around them, making them 'sitting ducks' for impacts with other asteroids. They cross the paths of many objects, and their typical collision velocities are much higher (10-15 km/s) than the collision velocities (5 km/s) among objects within the main belt. These factors combine to give them substantially shorter lifetimes than had been previously estimated.

  3. Damage from comet-asteroid impacts with earth

    Science.gov (United States)

    Hills, Jack G.; Goda, M. Patrick

    Only a small fraction of the Earth-crossing asteroids, ECAs, have been found and cataloged. Uncataloged ECAs can hit the atmosphere of Earth without warning. Long-period comets may give as little as two months warning before impact. The damage ranges from fires and blastwaves from energy dissipation in the atmosphere to craters, earthquakes, and tsunami from ground impact. Tsunami damage is particularly severe. An asteroid 5-6km in diameter impacting in the mid Atlantic would cause substantial tsunami damage to both Europe and North America: the tsunami would run all the way to the Appalachians in the upper two-thirds of the United States and to the mountains of the Iberian Peninsula in Europe. Tsunami heights along the Iberian Peninsula can reach several hundred meters. The tsunami heights would be less in Northern Europe due to the shallow continental shelf in this region.

  4. From Discovery to Impact - Near Earth Asteroids

    Directory of Open Access Journals (Sweden)

    Miloš Tichý

    2012-10-01

    Full Text Available The Near-Earth Objects (NEOs are the most important of the small bodies of the solar system, having the capability of close approaches to the Earth and the chance to collide with the Earth.  We present here the current system of discovery of these dangerous objects, standards for selecting useful and important targets for NEO follow-up astrometry, system of impact probabilities calculations, and also determination of impact site and evacuation area.

  5. Calculations of Asteroid Impacts into Deep and Shallow Water

    Science.gov (United States)

    Gisler, Galen; Weaver, Robert; Gittings, Michael

    2011-06-01

    Contrary to received opinion, ocean impacts of small (dangerous features of ocean impacts, just as for land impacts, are the atmospheric effects. We present illustrative hydrodynamic calculations of impacts into both deep and shallow seas, and draw conclusions from a parameter study in which the size of the impactor and the depth of the sea are varied independently. For vertical impacts at 20 km/s, craters in the seafloor are produced when the water depth is less than about 5-7 times the asteroid diameter. Both the depth and the diameter of the transient crater scale with the asteroid diameter, so the volume of water excavated scales with the asteroid volume. About a third of the crater volume is vaporised, because the kinetic energy per unit mass of the asteroid is much larger than the latent heat of vaporisation of water. The vaporised water carries away a considerable fraction of the impact energy in an explosively expanding blast wave which is responsible for devastating local effects and may affect worldwide climate. Of the remaining energy, a substantial portion is used in the crown splash and the rebound jet that forms as the transient crater collapses. The collapse and rebound cycle leads to a propagating wave with a wavelength considerably shorter than classical tsunamis, being only about twice the diameter of the transient crater. Propagation of this wave is hindered somewhat because its amplitude is so large that it breaks in deep water and is strongly affected by the blast wave's perturbation of the atmosphere. Even if propagation were perfect, however, the volume of water delivered per metre of shoreline is less than was delivered by the Boxing Day 2004 tsunami for any impactor smaller than 500 m diameter in an ocean of 5 km depth or less. Near-field effects are dangerous for impactors of diameter 200 m or greater; hurricane-force winds can extend tens of kilometers from the impact point, and fallout from the initial splash can be extremely violent

  6. Three-Dimensional Simulations of Oblique Asteroid Impacts into Water

    Science.gov (United States)

    Gisler, G. R.; Ferguson, J. M.; Heberling, T.; Plesko, C. S.; Weaver, R.

    2016-12-01

    Waves generated by impacts into oceans may represent the most significant danger from near-earth asteroids and comets. For impacts near populated shores, the crown splash and subsequent waves, accompanied by sediment lofting and high winds, could be more damaging than storm surges from the strongest hurricanes. For asteroids less than 500 m in diameter that impact into deep water far from shores, the waves produced will be detectable over large distances, but probably not significantly dangerous. We present new three-dimensional simulations of oblique impacts into deep water, with trajectory angles ranging from 20 degrees to 60 degrees (where 90 degrees is vertical). These simulations are performed with the Los Alamos Rage hydrocode, and include atmospheric effects including ablation and airbursts. These oblique impact simulations are specifically performed in order to help determine whether there are additional dangers from the obliquity of impact not covered by previous two-dimensional studies. Water surface elevation profiles, surface pressures, and depth-averaged mass fluxes within the water are prepared for use in propagation studies.

  7. Meteorites: impact and damage. An inside view of asteroidal microstructure

    Science.gov (United States)

    Eastwood, David; Garcea, Serafina; McDonald, Sam; Dobson, Kate; Jones, Rhian; Woods, Jenny; Bourne, Neil; Rau, Christoph; Gray, George T., III

    2017-06-01

    Meteorites provide an important window into the formation and evolution of the solar system and planets. Chondrite meteorites preserve a record of the epoch when the solar system consisted of a cloud of dusty gas surrounding the newly formed Sun, as well as recording 4.6 billion years of geological history on asteroids. From meteorite studies we know that many asteroids contained water when they first accreted. In many cases this water later melted and flowed through the rock, leaving evidence of its tracks in the remaining minerals. Water and other fluids dissolved some of the original material, leaving void spaces. We have used tomography to assess the extent to which the original components of chondrites were affected by dissolution, by observing the nature and distribution of the resulting void space. Tomography allows us to assess the relative abundances of each to the overall porosity, and to visualize connectivity through pore space. Based on such information we can hypothesise about the agglomeration processes and the effect of impact processes on asteroid formation and microstructure.

  8. Global Catastrophes in Perspective: Asteroid Impacts vs Climate Change

    Science.gov (United States)

    Boslough, M. B.; Harris, A. W.

    2008-12-01

    When allocating resources to address threats, decision makers are best served by having objective assessments of the relative magnitude of the threats in question. Asteroids greater than about 1 km in diameter are assumed by the planetary impact community to exceed a "global catastrophe threshold". Impacts from smaller objects are expected to cause local or regional destruction, and would be the proximate cause of most associated fatalities. Impacts above the threshold would be expected to alter the climate, killing billions of people and causing a collapse of civilization. In this apocalyptic scenario, only a small fraction of the casualties would be attributable to direct effects of the impact: the blast wave, thermal radiation, debris, ground motion, or tsunami. The vast majority of deaths would come later and be due to indirect causes: starvation, disease, or violence as a consequence of societal disruption related to the impact-induced global climate change. The concept of a catastrophe threshold comes from "nuclear winter" studies, which form the basis for quantitative estimates of the consequences of a large impact. The probability estimates come from astronomical observations and statistical analysis. Much of the impact threat, at its core, is a climate-change threat. Prior to the Spaceguard Survey of Near-Earth Objects (NEOs), the chance of dying from an asteroid impact was estimated to be 1 in 25,000 (Chapman & Morrison, 1994). Most of the large asteroids have now been discovered, and none is on an impact trajectory. Moreover, new data show that mid-sized asteroids (tens to hundreds of meters across) are less abundant than previously thought, by a factor of three. We now estimate that the lifetime odds of being killed by the impact of one of the remaining undiscovered NEOs are about one in 720,000 for individuals with a life expectancy of 80 years (Harris, 2008). One objective way to compare the relative magnitude of the impact threat to that of

  9. Climatic Effects of Medium-Sized Asteroid Impacts on Land

    Science.gov (United States)

    Bardeen, C.; Garcia, R. R.; Toon, O. B.; Otto-Bliesner, B. L.; Wolf, E. T.

    2015-12-01

    Using the Community Earth System Model (CESM), a three-dimensional coupled climate model with interactive chemistry, we have simulated the climate response to a medium-sized (1 km) asteroid impact on the land. An impact of this size would cause local fires and may also generate submicron dust particles. Dust aerosols are injected into the upper atmosphere where they persist for ~3 years. Soot aerosols from fires are injected into the troposphere and absorb solar radiation heating the air which helps loft the soot into the stratosphere where it persists for ~10 years. Initially, these aerosols cause a heating of over 240 K in the stratosphere and up to a 70% reduction in downwelling solar radiation at the surface. Global average surface temperature cools by as much as -8.5 K, ocean temperature cools by -4.5 K, precipitation is reduced by 50%, and the ozone column is reduced by 55%. The surface UV Index exceeds 20 in the tropics for several years. These changes represent a significant hazard to life on a global scale. These results extend the work of Pierazzo et al. (2010), also using CESM, which found a significant impact on stratospheric ozone, but little change in surface temperature or precipitation, from a 1 km asteroid impact in the ocean.

  10. A Comparison of Oceanic and Continental Asteroid Impacts

    Science.gov (United States)

    de Carli, Paul S.; Jones, Adrian P.

    2005-07-01

    Ever since the recognition that Lunar craters are impact craters rather than volcanos, it has been possible to seriously consider the role of comet or asteroid impacts as possible drivers of geologic events on the Earth. For example, the Chicxulub impact event is widely accepted as a cause of the mass extinction at the end of the Cretaceous. Currently, the subject of impact-induced volcanism is fiercely debated. In the absence of compelling field evidence, the debate is centered on the results of computational modeling of large impacts and on the estimated frequency of such large impacts. Both sides of the debate agree that a sufficiently large impact would excavate to such a depth that decompression melting of the Earth's mantle would be triggered. The anti-impact volcanism faction argues that the impact event would have to be so large that it is unlikely to have occurred during the past 3.5 billion years. The pro-impact volcanism faction argues that an event comparable to or slightly larger the the Chicxulub impact would be sufficient, provided that the impact were oceanic. Here we present detailed calculations to address the systematic differences between oceanic and continental impacts. In partiular, we incorporate the hysteretic phase transition behavior of granite in our material model.

  11. Comet/Asteroid Impacts and Human Society An Interdisciplinary Approach

    CERN Document Server

    Bobrowsky, Peter T

    2007-01-01

    In 1908 an atmospheric explosion in northern Siberia released energy equivalent to 15 Mton of TNT. Can a comparable or larger NEO affect us again? When the next NEO strikes Earth will it be large enough to destroy a city? Will the climate change significantly? Can archaeology and anthropology provide insights into the expected cultural responses with NEO interactions? Does society have a true grasp of the actual risks involved? Is the Great Depression a good model for the economic collapse that could follow a NEO catastrophe? This volume provides a necessary link between various disciplines and comet/asteroid impacts.

  12. Impact and cratering processes on asteroids, satellites, and planets

    Science.gov (United States)

    Chapman, Clark R.; Davis, Donald R.; Weidenschilling, Stuart J.

    1987-01-01

    A new model for scaling the outcome of catastrophic collisions from laboratory scale experiments was developed and applied to large bodies where gravitational binding is dominant. This algorithm includes a pressure dependent impact strength which predicts that large asteroids behave as intrinsically strong objects due to compressive loading of overburden throughout their interiors. For small bodies, where the gravitational loading is negligible, this model assumes that the impact strength is independent of size. There was considerable discussion of scaling laws for disruption when these results were presented to one authors colleagues. The pressure strengthening impact strength model was viewed as physically quite plausible; however, it was argued that the impact strength should decrease with increasing size in the size range where gravitational compression is negligible.

  13. TWO- AND THREE-DIMENSIONAL SIMULATIONS OF ASTEROID OCEAN IMPACTS

    Directory of Open Access Journals (Sweden)

    Michael Gittings

    2003-01-01

    Full Text Available We have performed a series of two-dimensional and three-dimensional simulations of asteroid impacts into an ocean using the SAGE code from Los Alamos National Laboratory and Science Applications International Corporation. The SAGE code is a compressible Eulerian hydrodynamics code using continuous adaptive mesh refinement for following discontinuities with a fine grid while treating the bulk of the simulation more coarsely. We have used realistic equations of state for the atmosphere, sea water, the oceanic crust, and the mantle. In two dimensions, we simulated asteroid impactors moving at 20 km/s vertically through an exponential atmosphere into a 5 km deep ocean. The impactors were composed of mantle material (3.32 g/cc or iron (7.8 g/cc with diameters from 250m to 10 km. In our three-dimensional runs we simulated asteroids of 1 km diameter composed of iron moving at 20 km/s at angles of 45 and 60 degrees from the vertical. All impacts, including the oblique ones, produce a large underwater cavities with nearly vertical walls followed by a collapse starting from the bottom and subsequent vertical jetting. Substantial amounts of water are vaporized and lofted high into the atmosphere. In the larger impacts, significant amounts of crustal and even mantle material are lofted as well. Tsunamis up to a kilometer in initial height are generated by the collapse of the vertical jet. These waves are initially complex in form, and interact strongly with shocks propagating through the water and the crust. The tsunami waves are followed out to 100 km from the point of impact. Their periods and wavelengths show them to be intermediate type waves, and not (in general shallow-water waves. At great distances, the waves decay as the inverse of the distance from the impact point, ignoring sea-floor topography. For all impactors smaller than about 2 km diameter, the impacting body is highly fragmented and its remains lofted into the stratosphere with the water

  14. Site of asteroid impact changed the history of life on Earth: the low probability of mass extinction.

    Science.gov (United States)

    Kaiho, Kunio; Oshima, Naga

    2017-11-09

    Sixty-six million years ago, an asteroid approximately 9 km in diameter hit the hydrocarbon- and sulfur-rich sedimentary rocks in what is now Mexico. Recent studies have shown that this impact at the Yucatan Peninsula heated the hydrocarbon and sulfur in these rocks, forming stratospheric soot and sulfate aerosols and causing extreme global cooling and drought. These events triggered a mass extinction, including dinosaurs, and led to the subsequent macroevolution of mammals. The amount of hydrocarbon and sulfur in rocks varies widely, depending on location, which suggests that cooling and extinction levels were dependent on impact site. Here we show that the probability of significant global cooling, mass extinction, and the subsequent appearance of mammals was quite low after an asteroid impact on the Earth's surface. This significant event could have occurred if the asteroid hit the hydrocarbon-rich areas occupying approximately 13% of the Earth's surface. The site of asteroid impact, therefore, changed the history of life on Earth.

  15. The impact trajectory of asteroid 2008 TC3

    Science.gov (United States)

    Farnocchia, Davide; Jenniskens, Peter; Robertson, Darrel K.; Chesley, Steven R.; Dimare, Linda; Chodas, Paul W.

    2017-09-01

    The impact of asteroid 2008 TC3 was an unprecedented event-the first ever predicted impact of a near-Earth object. When it was first detected about 20 h before impact, 2008 TC3 was still farther away than the Moon. Once it was recognized as an impactor and announced as such, 2008 TC3 began to receive considerable attention from astronomical observers. Using the unprecedented dataset of nearly 900 astrometric observations and the latest observation debiasing and weighting techniques, we estimate the precise trajectory of 2008 TC3 and its impact ground track. At the entry point into the atmosphere, the 3-σ formal uncertainty in predicted position is an ellipse only 1.4 km × 0.15 km in size. The locations of the many meteorites recovered from the desert floor mark the asteroid's actual ground track and provide a unique opportunity to validate trajectory models. We find that the second-order zonal harmonics of the Earth gravity field moves the ground track by more than 1 km and the location along the ground track by more than 2 km, while non-zonal and higher order harmonics change the impact prediction by less than 20 m. The contribution of atmospheric drag to the trajectory of 2008 TC3 is similar to the numerical integration error level, a few meters, down to an altitude of 50 km. Integrating forward to lower altitudes and ignoring the break-up of 2008 TC3, atmospheric drag causes an along-track deviation that can be as large as a few kilometers at sea level.

  16. Threat of Human Earth and Natural Resource Supply by Asteroid Impacts

    Science.gov (United States)

    Miura, Y.; Kato, T.; Tanosaki, T.

    2017-02-01

    Meteoritic impact can be stopped before entry among three major shocked events, which is observed from two sites to be changed the orbits in advance. Asteroid impacts produce also to form Earth's resources, which is applied to other space resources.

  17. The Remote Observing Working Group for the Asteroid Impact and Deflection Assessment (AIDA)

    Science.gov (United States)

    Rivkin, A. S.; Pravec, P.; Thomas, C. A.; Thirouin, A.; Snodgrass, C.; Green, S.; Licandro, J.; Sickafoose, A. A.; Erasmus, N.; Howell, E. S.; Osip, D.; Thomas-Osip, J.; Moskovitz, N.; Scheirich, P.; Oszkiewicz, D.; Richardson, D. C.; Polishook, D.; Ryan, W. H.; Busch, M. W.

    2017-09-01

    The Asteroid Impact and Deflection Assessment (AIDA) is a joint US-European mission concept designed to demonstrate the effectiveness of an kinetic impactor for planetary defense. Ground-based observing is a key component to AIDA and critical for its success. We present the observing campaign we have been conducting of the asteroid Didymos, the AIDA target, and plans for future work.

  18. Asteroid flux and impact cratering rate on Venus

    Science.gov (United States)

    Shoemaker, E. M.; Wolfe, R. F.; Shoemaker, C. S.

    1991-01-01

    By the end of 1990, 65 Venus-crossing asteroids were recognized; these represent 59 percent of the known Earth-crossing asteroids. Further studies, chiefly numerical integrations of orbit evolution, may reveal one or two more Venus crossers among the set of discovered asteroids. A Venus crosser was defined as an asteroid whose orbit can intersect the orbit of Venus as a result of secular (long range) perturbations. Venus crossers revolving on orbits that currently overlap the orbit of Venus are called Venapol asteroids, and those on orbit that don't overlap are called Venamor asteroids; 42 Venapols and 23 Venamors were recognized. Collision probabilities with Venus for 60 of the known Venus crossers were determined.

  19. Delivery of organics to Mars through asteroid and comet impacts

    Science.gov (United States)

    Frantseva, K.; Mueller, M.; van der Tak, F. F. S.; ten Kate, I. L.; Greenstreet, S.

    2017-09-01

    Preliminary results show that the asteroid-borne organic flux on Mars is comparable to the IPD rate; asteroids certainly cannot be neglected. Comets, on the other hand, contribute only 0.01% of the IDP-borne rate and can be neglected in the process of organic delivery to Mars.

  20. Steve Ostro and the Near-Earth Asteroid Impact Hazard

    Science.gov (United States)

    Chapman, Clark R.

    2009-09-01

    The late Steve Ostro, whose scientific interests in Near-Earth Asteroids (NEAs) primarily related to his planetary radar research in the 1980s, soon became an expert on the impact hazard. He quickly realized that radar provided perspectives on close-approaching NEAs that were both very precise as well as complementary to traditional astrometry, enabling good predictions of future orbits and collision probabilities extending for centuries into the future. He also was among the few astronomers who considered the profound issues raised by this newly recognized hazard and by early suggestions of how to mitigate the hazard. With Carl Sagan, Ostro articulated the "deflection dilemma" and other potential low-probability but real dangers of mitigation technologies that might be more serious than the low-probability impact hazard itself. Yet Ostro maintained a deep interest in developing responsible mitigation technologies, in educating the public about the nature of the impact hazard, and in learning more about the population of threatening bodies, especially using the revealing techniques of delay-doppler radar mapping of NEAs and their satellites.

  1. First known terrestrial impact of a binary asteroid from a main belt breakup event.

    Science.gov (United States)

    Ormö, Jens; Sturkell, Erik; Alwmark, Carl; Melosh, Jay

    2014-10-23

    Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt, which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. We here provide evidence that Lockne and its nearby companion, the 0.7-km diameter, contemporaneous, Målingen crater, formed by the impact of a binary, presumably 'rubble pile' asteroid. This newly discovered crater doublet provides a unique reference for impacts by combined, and poorly consolidated projectiles, as well as for the development of binary asteroids.

  2. Cat Mountain: A meteoritic sample of an impact-melted chondritic asteroid

    Science.gov (United States)

    Kring, David A.

    1993-01-01

    Although impact cratering and collisional disruption are the dominant geologic processes affecting asteroids, samples of impact melt breccias comprise less than 1 percent of ordinary chondritic material and none exist among enstatite and carbonaceous chondrite groups. Because the average collisional velocity among asteroids is sufficiently large to produce impact melts, this paucity of impact-melted material is generally believed to be a sampling bias, making it difficult to determine the evolutionary history of chondritic bodies and how impact processes may have affected the physical properties of asteroids (e.g., their structural integrity and reflectance spectra). To help address these and related issues, the first petrographic description of a new chondritic impact melt breccia sample, tentatively named Cat Mountain, is presented.

  3. The Impact Imperative: Laser Ablation for Deflecting Asteroids, Meteoroids, and Comets From Impacting the Earth

    Science.gov (United States)

    Campbell, Jonathan W.; Phipps, Claude; Smalley, Larry; Reilly, Jim; Boccis, Dona; Howell, Joe T., Jr. (Technical Monitor)

    2002-01-01

    Impacting at hypervelocity, an asteroid struck the Earth approximately 65 million years ago in the Yucatan Peninsula area. This triggered the extinction of almost 70% of the species of life on Earth including the dinosaurs. Other impacts prior to this one have caused even greater extinctions. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most important immediate space challenge facing human civilization. This is the Impact Imperative. We now believe that while there are about 2000 earth orbit crossing rocks greater than 1 kilometer in diameter, there may be as many as 200,000 or more objects in the 100 m size range, Can anything be done about this fundamental existence question facing our civilization? The answer is a resounding yes! By using an intelligent combination of Earth and space based sensors coupled with an infra-structure of high-energy laser stations and other secondary mitigation options, we can deflect inbound asteroids, meteoroids, and comets and prevent them from striking the Earth.

  4. The impact and recovery of asteroid 2008 TC(3).

    Science.gov (United States)

    Jenniskens, P; Shaddad, M H; Numan, D; Elsir, S; Kudoda, A M; Zolensky, M E; Le, L; Robinson, G A; Friedrich, J M; Rumble, D; Steele, A; Chesley, S R; Fitzsimmons, A; Duddy, S; Hsieh, H H; Ramsay, G; Brown, P G; Edwards, W N; Tagliaferri, E; Boslough, M B; Spalding, R E; Dantowitz, R; Kozubal, M; Pravec, P; Borovicka, J; Charvat, Z; Vaubaillon, J; Kuiper, J; Albers, J; Bishop, J L; Mancinelli, R L; Sandford, S A; Milam, S N; Nuevo, M; Worden, S P

    2009-03-26

    In the absence of a firm link between individual meteorites and their asteroidal parent bodies, asteroids are typically characterized only by their light reflection properties, and grouped accordingly into classes. On 6 October 2008, a small asteroid was discovered with a flat reflectance spectrum in the 554-995 nm wavelength range, and designated 2008 TC(3) (refs 4-6). It subsequently hit the Earth. Because it exploded at 37 km altitude, no macroscopic fragments were expected to survive. Here we report that a dedicated search along the approach trajectory recovered 47 meteorites, fragments of a single body named Almahata Sitta, with a total mass of 3.95 kg. Analysis of one of these meteorites shows it to be an achondrite, a polymict ureilite, anomalous in its class: ultra-fine-grained and porous, with large carbonaceous grains. The combined asteroid and meteorite reflectance spectra identify the asteroid as F class, now firmly linked to dark carbon-rich anomalous ureilites, a material so fragile it was not previously represented in meteorite collections.

  5. Protecting Earth from comet/asteroid impacts through international cooperation: Issues & current status

    Energy Technology Data Exchange (ETDEWEB)

    Tedeschi, W.

    1994-05-01

    Compelling evidence of a catastrophic asteroid impact on Earth 65 million years ago has given rise to international discussions about the probability, consequences, and prevention of future impacts. Because asteroid and comet impacts pose a grave danger to all humanity, preventive defensive measures should appropriately be based on international cooperation and action. Action may consist of detection research, experimentation to prevent the impact, public education on the issues, emergency planning, and actual protection if required. This paper provides background information on the threat posed by Near-Earth Objects (NEOs) and discusses associated technical and geopolitical issues and the current status of some related international activities.

  6. A probabilistic asteroid impact risk model: assessment of sub-300 m impacts

    Science.gov (United States)

    Mathias, Donovan L.; Wheeler, Lorien F.; Dotson, Jessie L.

    2017-06-01

    A comprehensive asteroid threat assessment requires the quantification of both the impact likelihood and resulting consequence across the range of possible events. This paper presents a probabilistic asteroid impact risk (PAIR) assessment model developed for this purpose. The model incorporates published impact frequency rates with state-of-the-art consequence assessment tools, applied within a Monte Carlo framework that generates sets of impact scenarios from uncertain input parameter distributions. Explicit treatment of atmospheric entry is included to produce energy deposition rates that account for the effects of thermal ablation and object fragmentation. These energy deposition rates are used to model the resulting ground damage, and affected populations are computed for the sampled impact locations. The results for each scenario are aggregated into a distribution of potential outcomes that reflect the range of uncertain impact parameters, population densities, and strike probabilities. As an illustration of the utility of the PAIR model, the results are used to address the question of what minimum size asteroid constitutes a threat to the population. To answer this question, complete distributions of results are combined with a hypothetical risk tolerance posture to provide the minimum size, given sets of initial assumptions for objects up to 300 m in diameter. Model outputs demonstrate how such questions can be answered and provide a means for interpreting the effect that input assumptions and uncertainty can have on final risk-based decisions. Model results can be used to prioritize investments to gain knowledge in critical areas or, conversely, to identify areas where additional data have little effect on the metrics of interest.

  7. Delivery of Organic Material and Water through Asteroid Impacts

    NARCIS (Netherlands)

    Mueller, Michael; Frantseva, Kateryna; van der Tak, Floris; Helmich, Frank P.

    2014-01-01

    Meteorites, specifically carbonaceous chondrites, are frequently invoked as the primary source of Earth's water and organic materials, crucial ingredients for the formation of life. We have started developing a dynamical model of the delivery of their parent bodies, primitive low-albedo asteroids,

  8. The Formation of Asteroid Satellites in Catastrophic Impacts: Results from Numerical Simulations

    Science.gov (United States)

    Durda, D. D.; Bottke, W. F., Jr.; Enke, B. L.; Asphaug, E.; Richardson, D. C.; Leinhardt, Z. M.

    2003-01-01

    We have performed new simulations of the formation of asteroid satellites by collisions, using a combination of hydrodynamical and gravitational dynamical codes. This initial work shows that both small satellites and ejected, co-orbiting pairs are produced most favorably by moderate-energy collisions at more direct, rather than oblique, impact angles. Simulations so far seem to be able to produce systems qualitatively similar to known binaries. Asteroid satellites provide vital clues that can help us understand the physics of hypervelocity impacts, the dominant geologic process affecting large main belt asteroids. Moreover, models of satellite formation may provide constraints on the internal structures of asteroids beyond those possible from observations of satellite orbital properties alone. It is probable that most observed main-belt asteroid satellites are by-products of cratering and/or catastrophic disruption events. Several possible formation mechanisms related to collisions have been identified: (i) mutual capture following catastrophic disruption, (ii) rotational fission due to glancing impact and spin-up, and (iii) re-accretion in orbit of ejecta from large, non-catastrophic impacts. Here we present results from a systematic investigation directed toward mapping out the parameter space of the first and third of these three collisional mechanisms.

  9. Seismic resurfacing by a single impact on the asteroid 433 Eros.

    Science.gov (United States)

    Thomas, P C; Robinson, Mark S

    2005-07-21

    Impact cratering creates a wide range of topography on small satellites and asteroids. The population of visible craters evolves with impacts, and because there are no competing endogenic processes to modify the surface, determining the various ways younger craters add to or subtract from the population is a fundamental aspect of small-body geology. Asteroid 433 Eros, the most closely studied small body, has regions of substantially different crater densities that remain unexplained. Here we show that the formation of a relatively young crater (7.6 km in diameter) resulted in the removal of other craters as large as 0.5 km over nearly 40 percent of the asteroid. Burial by ejecta cannot explain the observed pattern of crater removal. The limitation of reduced crater density to a zone within a particular straight-line distance through the asteroid from the centre of the large crater suggests degradation of the topography by seismic energy released during the impact. Our observations indicate that the interior of Eros is sufficiently cohesive to transmit seismic energy over many kilometres, and the outer several tens of metres of the asteroid must be composed of relatively non-cohesive material.

  10. Design of Spacecraft Missions to Test Kinetic Impact for Asteroid Deflection

    Science.gov (United States)

    Barbee, Brent W.; Hernandez, Sonia

    2012-01-01

    Earth has previously been struck with devastating force by near-Earth asteroids (NEAs) and will be struck again. Telescopic search programs aim to provide advance warning of such an impact, but no techniques or systems have yet been tested for deflecting an incoming NEA. To begin addressing this problem, we have analyzed the more than 8000 currently known NEAs to identify those that offer opportunities for safe and meaningful near-term tests of the proposed kinetic impact asteroid deflection technique. In this paper we present our methodology and results, including complete mission designs for the best kinetic impactor test mission opportunities.

  11. Tsunami Generation from Asteroid Airburst and Ocean Impact and Van Dorn Effect

    Science.gov (United States)

    Robertson, Darrel

    2016-01-01

    Airburst - In the simulations explored energy from the airburst couples very weakly with the water making tsunami dangerous over a shorter distance than the blast for asteroid sizes up to the maximum expected size that will still airburst (approx.250MT). Future areas of investigation: - Low entry angle airbursts create more cylindrical blasts and might couple more efficiently - Bursts very close to the ground will increase coupling - Inclusion of thermosphere (>80km altitude) may show some plume collapse effects over a large area although with much less pressure center dot Ocean Impact - Asteroid creates large cavity in ocean. Cavity backfills creating central jet. Oscillation between the cavity and jet sends out tsunami wave packet. - For deep ocean impact waves are deep water waves (Phase speed = 2x Group speed) - If the tsunami propagation and inundation calculations are correct for the small (asteroids in these simulations where they impact deep ocean basins, the resulting tsunami is not a significant hazard unless particularly close to vulnerable communities. Future work: - Shallow ocean impact. - Effect of continental shelf and beach profiles - Tsunami vs. blast damage radii for impacts close to populated areas - Larger asteroids below presumed threshold of global effects (Ø200 - 800m).

  12. Dynamical Origin and Terrestrial Impact Flux of Large Near-Earth Asteroids

    Science.gov (United States)

    Nesvorný, David; Roig, Fernando

    2018-01-01

    Dynamical models of the asteroid delivery from the main belt suggest that the current impact flux of diameter D> 10 km asteroids on the Earth is ≃0.5–1 Gyr‑1. Studies of the Near-Earth Asteroid (NEA) population find a much higher flux, with ≃ 7 D> 10 km asteroid impacts per Gyr. Here we show that this problem is rooted in the application of impact probability of small NEAs (≃1.5 Gyr‑1 per object), whose population is well characterized, to large NEAs. In reality, large NEAs evolve from the main belt by different escape routes, have a different orbital distribution, and lower impact probabilities (0.8 ± 0.3 Gyr‑1 per object) than small NEAs. In addition, we find that the current population of two D> 10 km NEAs (Ganymed and Eros) is a slight fluctuation over the long-term average of 1.1+/- 0.5 D> 10 km NEAs in a steady state. These results have important implications for our understanding of the occurrence of the K/T-scale impacts on the terrestrial worlds.

  13. Delivery of water and organics to Mercury through asteroid and comet impacts

    Science.gov (United States)

    Frantseva, Kateryna; Mueller, Michael; van der Tak, Floris F. S.

    2017-10-01

    Detection and observation of the bright and dark polar deposits in permanently shadowed northpolar regions of Mercury suggest that these regions contain water and organic compounds. This is somehow surprising taking into account the planet’s proximity to the Sun. Water flux on Mercury was studied in the past and have shown that interplanetary dust particles, asteroids and comets are possible sources of water on Mercury.We are studying how much water and organics certain asteroids (C-type) and comets can deliver to Mercury. We have performed numerical gravity simulations of impact rates on Mercury within the past few Myr. We use the N-body integrator RMVS/Swifter to propagate the Sun and the eight planets from their current positions. Separately, we add comets and asteroids to the simulations as massless test particles, based on their current orbital distributions. In our asteroid simulations we focus on organic-rich (C-class), basing ourselves on the dynamical model by Greenstreet et al. (2012) and on the measured distribution of taxonomic types across the Main Asteroid Belt. For the comets we assume a constant organic fraction. We expect to present first results at the meeting.

  14. Asteroid thermophysical modeling

    OpenAIRE

    Delbo, Marco; Mueller, Michael; Emery, Joshua P.; Rozitis, Ben; Capria, Maria Teresa

    2015-01-01

    The field of asteroid thermophysical modeling has experienced an extraordinary growth in the last ten years, as new thermal infrared data became available for hundreds of thousands of asteroids. The infrared emission of asteroids depends on the body's size, shape, albedo, thermal inertia, roughness and rotational properties. These parameters can therefore be derived by thermophysical modeling of infrared data. Thermophysical modeling led to asteroid size estimates that were confirmed at the f...

  15. Geological record and reconstruction of the late Pliocene impact of the Eltanin asteroid in the Southern Ocean.

    Science.gov (United States)

    Gersonde, R; Kyte, F T; Bleil, U; Diekmann, B; Flores, J A; Gohl, K; Grahl, G; Hagen, R; Kuhn, G; Sierro, F J; Volker, D; Abelmann, A; Bostwick, J A

    1997-11-27

    In 1995, an expedition on board the research vessel FS Polarstern explored the impact site of the Eltanin asteroid in the Southern Ocean, the only known asteroid impact into a deep ocean basin. Analyses of the geological record of the impact region place the event in the late Pliocene (approximately 2.15 Myr) and constrain the size of the asteroid to be >1 km. The explosive force inferred for this event places it at the threshold of impacts believed to have global consequences, and its study should therefore provide a baseline for the reconstruction and modelling of similar events, which are common on geological timescales.

  16. Secular resonances with massive asteroids and their impact on the dynamics of small bodies

    Science.gov (United States)

    Tsirvoulis, Georgios; Novaković, Bojan; Djošović, Valdimir

    2015-08-01

    The quest for understanding the dynamical structure of the main belt has been a long-lasting endeavor. From the discovery of the Kirkwood gaps and the Hirayama families, to the more recent advances in secular perturbation theory, the refinement of the proper elements and the discovery of the three-body mean-motion resonances, only to name a few, the progress has been immense. Dynamical models coupled with the outbursts in computational power and observations have greatly improved our knowledge of the dynamical evolution of the small bodies in the Solar System.While our set of tools for studying the dynamical porperties of the main belt is believed to be sufficiently complete, our assumptions on how to use them seem to have hindered this effort.The concensus has been that, judging by their mass, only the planets, especially the giant ones, can act as efficient perturbers of the orbits of asteroids. Thus a lot of studies have been made on the locations and effects of secular resonances with the giant planets in different parts of the main belt, explaining among other things the presence of gaps in the distribution of asteroids, strange shapes of some asteroid families and transport mechanisms of asteroids to the near-Earth region.Our work is motivated by the first discovery that a secular resonance with the most massive asteroid, Ceres, is the dominant dynamical mechanism responsible for the post-impact evolution of the Hoffmeister family members. Thus the concensus is wrong. Knowing now, that secular resonances with massive asteroids can be effective on asteroid dynamics, we set out to construct a dynamical map of these resonances across the main belt.Our study is focused on the linear and degree four non-linear secular resonances with the two most massive asteroids (1) Ceres and (4) Vesta. First we determine the locations of these secular resonances in the proper elements space, acquiring an understanding of the potentially affected regions, and then we perform

  17. Nanoindenting the Chelyabinsk Meteorite to Learn about Impact Deflection Effects in asteroids

    Energy Technology Data Exchange (ETDEWEB)

    Moyano-Cambero, Carles E.; Trigo-Rodríguez, Josep M.; Martínez-Jiménez, Marina; Lloro, Ivan [Institute of Space Sciences (IEEC-CSIC), Meteorites, Minor Bodies and Planetary Sciences Group, Campus UAB Bellaterra, c/Can Magrans s/n, 08193 Cerdanyola del Vallès (Barcelona) (Spain); Pellicer, Eva [Departament de Física, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Spain); Williams, Iwan P. [School of Physics and Astronomy, Queen Mary, University of London, 317 Mile End Road, E1 4NS London (United Kingdom); Blum, Jürgen [Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38106 Braunschweig (Germany); Michel, Patrick [Lagrange Laboratory, University of Nice, CNRS, Côte d’Azur Observatory (France); Küppers, Michael [European Space Agency, European Space Astronomy Centre, P.O. Box 78, Villanueva de la Cañada E-28691 (Spain); Sort, Jordi, E-mail: moyano@ice.csic.es, E-mail: trigo@ice.csic.es [Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Spain)

    2017-02-01

    The Chelyabinsk meteorite is a highly shocked, low porosity, ordinary chondrite, probably similar to S- or Q-type asteroids. Therefore, nanoindentation experiments on this meteorite allow us to obtain key data to understand the physical properties of near-Earth asteroids. Tests at different length scales provide information about the local mechanical properties of the minerals forming this meteorite: reduced Young’s modulus, hardness, elastic recovery, and fracture toughness. Those tests are also useful to understand the potential to deflect threatening asteroids using a kinetic projectile. We found that the differences in mechanical properties between regions of the meteorite, which increase or reduce the efficiency of impacts, are not a result of compositional differences. A low mean particle size, attributed to repetitive shock, can increase hardness, while low porosity promotes a higher momentum multiplication. Momentum multiplication is the ratio between the change in momentum of a target due to an impact, and the momentum of the projectile, and therefore, higher values imply more efficient impacts. In the Chelyabinsk meteorite, the properties of the light-colored lithology materials facilitate obtaining higher momentum multiplication values, compared to the other regions described for this meteorite. Also, we found a low value of fracture toughness in the shock-melt veins of Chelyabinsk, which would promote the ejection of material after an impact and therefore increase the momentum multiplication. These results are relevant to the growing interest in missions to test asteroid deflection, such as the recent collaboration between the European Space Agency and NASA, known as the Asteroid Impact and Deflection Assessment mission.

  18. Impact Record of a Asteroid Regolith Recorded in a Carbonaceous Chrondrite

    Science.gov (United States)

    Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Chan, Queenie H. S.; Le, Loan; Kring, David; Cato, Michael; Fagan, Amy L.; hide

    2017-01-01

    C-class asteroids frequently exhibit reflectance spectra consistent with thermally metamor-phosed carbonaceous chondrites [1], or a mixture of phyllosilicate-rich material along with regions where they are absent [2]. One particularly important example appears to be asteroid 162173 Ryugu, the target of the Hayabusa 2 mission [1], although most spectra of Ryugu are featureless, suggesting a heterogeneous regolith [3]. Here we explore an alternative cause of dehydration of regolith of C-class asteroids - impact shock melting. Impact shock melting has been proposed to ex-plain some mineralogical characteristics of CB chondrites [4], but has rarely been considered a major process for hydrous carbonaceous chondrites [5]. Jbilet Winselwan (JW) is a very fresh CM breccia from Morocco, with intriguing characteristics. While some lithologies are typical of CM2s (Figure 1, top), other clasts show evidence of brief, though significant impact brecciation and heating. The first evidence for this came from preliminary petrographic and stable isotope studies [6,7]. We contend that highly-brecciated, partially-shocked, and dehydrated lithologies like those in JW dominate C-class asteroid regolith.

  19. IS THE LARGE CRATER ON THE ASTEROID (2867) STEINS REALLY AN IMPACT CRATER?

    Energy Technology Data Exchange (ETDEWEB)

    Morris, A. J. W.; Price, M. C.; Burchell, M. J., E-mail: m.j.burchell@kent.ac.uk [Centre for Astrophysics and Planetary Science, School of Physical Science, University of Kent, Canterbury, Kent CT2 7NH (United Kingdom)

    2013-09-01

    The large crater on the asteroid (2867) Steins attracted much attention when it was first observed by the Rosetta spacecraft in 2008. Initially, it was widely thought to be unusually large compared to the size of the asteroid. It was quickly realized that this was not the case and there are other examples of similar (or larger) craters on small bodies in the same size range; however, it is still widely accepted that it is a crater arising from an impact onto the body which occurred after its formation. The asteroid (2867) Steins also has an equatorial bulge, usually considered to have arisen from redistribution of mass due to spin-up of the body caused by the YORP effect. Conversely, it is shown here that, based on catastrophic disruption experiments in laboratory impact studies, a similarly shaped body to the asteroid Steins can arise from the break-up of a parent in a catastrophic disruption event; this includes the presence of a large crater-like feature and equatorial bulge. This suggests that the large crater-like feature on Steins may not be a crater from a subsequent impact, but may have arisen directly from the fragmentation process of a larger, catastrophically disrupted parent.

  20. Solar Sailing Kinetic Energy Interceptor (KEI) Mission for Impacting/Deflecting Near-Earth Asteroids

    Science.gov (United States)

    Wie, Bong

    2005-01-01

    A solar sailing mission architecture, which requires a t least ten 160-m, 300-kg solar sail spacecraft with a characteristic acceleration of 0.5 mm/sqs, is proposed as a realistic near- term option for mitigating the threat posed by near-Earth asteroids (NEAs). Its mission feasibility is demonstrated for a fictional asteroid mitigation problem created by AIAA. This problem assumes that a 200-m asteroid, designated 2004WR, was detected on July 4, 2004, and that the expected impact will occur on January 14, 2015. The solar sailing phase of the proposed mission for the AIAA asteroid mitigation problem is comprised of the initial cruise phase from 1 AU t o 0.25 AU (1.5 years), the cranking orbit phase (3.5 years), and the retrograde orbit phase (1 year) prior to impacting the target asteroid at its perihelion (0.75 AU from the sun) on January 1, 2012. The proposed mission will require at least ten kinetic energy interceptor (KEI) solar sail spacecraft. Each KEI sailcraft consists of a 160- m, 150-kg solar sail and a 150-kg microsatellite impactor. The impactor is to be separated from a large solar sail prior to impacting the 200-m target asteroid at its perihelion. Each 150-kg microsatellite impactor, with a relative impact velocity of at least 70 km/s, will cause a conservatively estimated AV of 0.3 cm/s in the trajectory of the 200-m target asteroid, due largely to the impulsive effect of material ejected from the newly-formed crater. The deflection caused by a single impactor will increase the Earth-miss-distance by 0.45Re (where Re denotes the Earth radius of 6,378 km). Therefore, at least ten KEI sailcraft will be required for consecutive impacts, but probably without causing fragmentation, to increase the total Earth-miss-distance by 4.5Re. This miss-distance increase of 29,000 km is outside of a typical uncertainty/error of about 10,000 km in predicting the Earth-miss- distance. A conventional Delta I1 2925 launch vehicle is capable of injecting at least two KEI

  1. Computer modeling of large asteroid impacts into continental and oceanic sites: Atmospheric, cratering, and ejecta dynamics

    Science.gov (United States)

    Roddy, D. J.; Schuster, S. H.; Rosenblatt, M.; Grant, L. B.; Hassig, P. J.; Kreyenhagen, K. N.

    1988-01-01

    Numerous impact cratering events have occurred on the Earth during the last several billion years that have seriously affected our planet and its atmosphere. The largest cratering events, which were caused by asteroids and comets with kinetic energies equivalent to tens of millions of megatons of TNT, have distributed substantial quantities of terrestrial and extraterrestrial material over much or all of the Earth. In order to study a large-scale impact event in detail, computer simulations were completed that model the passage of a 10 km-diameter asteroid through the Earth's atmosphere and the subsequent cratering and ejecta dynamics associated with impact of the asteroid into two different targets, i.e., an oceanic site and a continental site. The calcuations were designed to broadly represent giant impact events that have occurred on the Earth since its formation and specifically represent an impact cratering event proposed to have occurred at the end of Cretaceous time. Calculation of the passage of the asteroid through a U.S. Standard Atmosphere showed development of a strong bow shock that expanded radially outward. Behind the shock front was a region of highly shock compressed and intensely heated air. Behind the asteroid, rapid expansion of this shocked air created a large region of very low density that also expanded away from the impact area. Calculations of the cratering events in both the continental and oceanic targets were carried to 120 s. Despite geologic differences, impacts in both targets developed comparable dynamic flow fields, and by approx. 29 s similar-sized transient craters approx. 39 km deep and approx. 62 km across had formed. For all practical purposes, the atmosphere was nearly completely removed from the impact area for tens of seconds, i.e., air pressures were less than fractions of a bar out to ranges of over 50 km. Consequently, much of the asteroid and target materials were ejected upward into a near vacuum. Effects of secondary

  2. The Seismic Effect of Impacts on Asteroid Surface Morphology: Early Modeling Results

    Science.gov (United States)

    Richardson, J. E.; Melosh, H. J.; Greenberg, R.

    2004-01-01

    In recent years, spacecraft observations of asteroids 951 Gaspra, 243 Ida, 253 Mathilde, and 433 Eros have shown the overriding dominance of impact processes with regard to the structure and appearance of these small, irregular bodies. One currently unanswered question is: to what degree does seismic shaking from impacts affect the surface morphology of these bodies? Through detailed modeling, we begin to address this question.

  3. Looking before we leap: an ongoing, quantative investigation of asteroid and comet impact hazard mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Plesko, Catherine S [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Bradley, Paul A [Los Alamos National Laboratory; Huebner, Walter F [Los Alamos National Laboratory

    2010-01-01

    There are many outstanding questions about the correct response to an asteroid or comet impact threat on Earth. Nuclear munitions are currently thought to be the most efficient method of delivering an impact-preventing impulse to a potentially hazardous object (PHO). However, there are major uncertainties about the response of PHOs to a nuclear burst, and the most appropriate ways to use nuclear munitions for hazard mitigation.

  4. Asteroid Impacts, Crater Scaling Laws, and a Proposed Younger Age for Venus's Surface

    Science.gov (United States)

    Bottke, William; Ghent, Rebecca; Mazrouei, Sara; Robbins, Stuart; Vokrouhlicky, David

    2015-11-01

    A fascinating on-going debate concerns the asteroid sizes needed to form certain large craters. For example, numerical hydrocode models predict that ~12-14 km and ~8 km diameter asteroids are needed to produce craters like Chicxulub (~180 km) and Popigai (~100 km), respectively. The abundance of extraterrestrial Ir/Os measured at well-characterized impact boundaries on land and in oceanic cores, however, predict far smaller projectiles, 4-6 km and 2.5-4 km, respectively (e.g., Paquay et al. 2014; F. Kyte, pers. comm). To test who might be right by proxy, we transformed the near-Earth object (NEO) size distribution (Harris & D'Abramo 2015), where > 90% of the D > 1 km asteroids are known, into a model crater size distribution and compared it to the distribution of D > 20 km craters formed on the Moon, Mars, and Venus over the last ~1-3 Gyr. Here we kept things simple and assumed that f described the ratio between all crater and asteroid diameters of interest (i.e., f = D_crater / D_proj).To our surprise, we found f ~ 23-26 produced excellent matches for the crater size distributions on the Moon, Mars, and Venus, despite their differences in gravity, surface properties, impact velocities, etc. These same values work well for the Earth as well. Consider that terrestrial crater production rates derived by Shoemaker (1998) indicate 340 +/- 170 D > 20 km craters formed over the last 120 Myr. Using f = 25, we get the same value; a D > 0.8 km asteroid makes a D > 20 km crater, and they hit Earth every 0.35 Myr on average (e.g., Bottke et al. 2002), for a total of ~340 over 120 Myr. Accordingly, we predict Chicxulub and Popigai were made by D ~ 7 and D ~ 4 km asteroids, respectively, values close to their predicted sizes from Ir/Os measurements. This result also potentially explains why Chicxulub formed ~65 Myr ago; the interval between D ~ 7 km impacts on Earth is close to this rate.The NEO model by Bottke et al. (2002) also suggests asteroids hit Venus at roughly the same

  5. An Optimal Mitigation Strategy Against the Asteroid Impact Threat with Short Warning Time

    Science.gov (United States)

    Wie, Bong; Barbee, Brent W.

    2015-01-01

    This paper presents the results of a NASA Innovative Advanced Concept (NIAC) Phase 2 study entitled "An Innovative Solution to NASA's Near-Earth Object (NEO) Impact Threat Mitigation Grand Challenge and Flight Validation Mission Architecture Development." This NIAC Phase 2 study was conducted at the Asteroid Deflection Research Center (ADRC) of Iowa State University in 2012-2014. The study objective was to develop an innovative yet practically implementable mitigation strategy for the most probable impact threat of an asteroid or comet with short warning time (less than 5 years). The mitigation strategy described in this paper is intended to optimally reduce the severity and catastrophic damage of the NEO impact event, especially when we don't have sufficient warning times for non-disruptive deflection of a hazardous NEO. This paper provides an executive summary of the NIAC Phase 2 study results.

  6. Asteroid Impacts, Microbes, and the Cooling of the Atmosphere

    Science.gov (United States)

    Oberbeck, Verne R.; Mancinelli, Rocco L.

    1994-01-01

    Earth's surface temperature constrained microbial evolution, according to Schwartzman et al. (1993). Their hypothesis states that the maximal temperature that extant organisms of a given type tolerate is the surface temperature occurring when that type of organism arose. Schwartzman and his colleagues concluded that the temperature changed from 100 C to 50 C between 3.75 billion years ago (BYA) and 1 BYA. These temperatures are consistent with those derived from oxygen isotope ratios in ancient sediments (Karhu and Epstein 1986, Knauth and Lowe 1978). The 100 C surface temperature they derive for 3.75 BYA is also the same as Earth's surface temperature 4.4 BYA (Kosting and Ackerman 1986). In this article, we address the cause of the delay in surface cooling until 3.75 BYA, and we explore the implications for microbial evolution of a high temperature on early Earth. We propose that three effects of the early heavy bombardment of Earth by asteroids and comets, until 3.8 BYA, could have delayed onset of surface cooling.

  7. Impact experiments onto heterogeneous targets and their interpretation in relation with formation of the asteroid families

    Science.gov (United States)

    Leliwa-Kopystynski, J.; Arakawa, M.

    2014-07-01

    Results of laboratory impact experiments, when extrapolated to the planetary scale of events, are aimed for better understanding of cratering and/or disruption of asteroids, satellites, and cometary nuclei. There is absolutely no reason to assume that these bodies are uniform rocky or icy monoliths. So, we studied reactions of the heterogeneous targets on the impacts. A series of impact experiments onto solid decimeter-sized cylinders made of porous gypsum mixed with approximately one-centimeter-sized pebbles have been performed. The mean density of the material of the targets was 1867 kg m^{-3}, the mean mass ratio (pebbles / gypsum) = 0.856 / 0.144, and the mean volume ratio (pebbles / gypsum / pores) = 0.585 / 0.116 / 0.299. The target densities and their heterogeneous structures could be representative of those of the asteroids Ida, Eros, and many others, because asteroid sub-surface volumes could be composed of consolidated boulders formed by self-compaction and/or by impact compaction. Impact velocities in the experiments ranged from 2.0 km/s to 6.7 km/s (collision velocity in the asteroid main belt is approximately 5 km/s). By means of weighting and counting the post-impact fragments, their distribution function was found. Let Q [J/kg] be the specific energy of impact per unit of the target mass. Of particular interest is the value of impact strength, that is, the specific energy of disruption Q^*, corresponding to the ratio (mass of the largest fragment) / (mass of the target) = m_l/M = 0.5, which is, by convention, the value separating the cratering events from the catastrophic disruption impacts. Mass or size distribution of the post-impact fragments is expressed by the power law N ∝ m^{-p} ∝ r^{-3p}, p=p(Q/Q^{*}) A parameter that can be measured in the laboratory is the exponent p. For the case of a swarm of asteroids forming an asteroid family, the observationally estimated value is not the exponent p but rather the exponent q = 3p, since the sizes

  8. Release of hydrogen sulfide by asteroid impacts in Black Sea and risks for inland human population.

    Science.gov (United States)

    Badescu, Viorel

    2007-10-01

    The hydrogen sulfide rich waters of the Black Sea pose a potential danger for the surrounding land regions. The impact of an asteroid may cause a catastrophic poisonous gas release in the atmosphere. Some effects of this last phenomenon on the Eastern Black Sea coastal regions are evaluated in this article. Two simple models are proposed to describe the generation of the H(2)S cloud. The initial diameter of the cloud depends on asteroid size. The initial thickness of the cloud depends, in addition, on sea depth at impact location. The wind speed plays an important role in H(2)S cloud dynamics. At 10 m/s wind-speed the cloud margins may be seen at about 150 km from impact location in about 3.2 h. The maximum distance traveled by the hydrogen sulfide cloud increases by increasing the asteroid size and wind speed. The influence of the impact position on the distance traveled by hydrogen sulfide clouds is rather weak, as far as the seawater depth does not change significantly. Two values are considered when referring to the effect of hydrogen sulfide concentrations on humans: the lower concentration limit of 19.88 ppm (which corresponds to fatigue, loss of appetite, headache, irritability, poor memory, dizziness) and the upper concentration limit of 497 ppm (which corresponds to death after single exposures). The land surface area covered by the H(2)S cloud generated by a 1000 m size asteroid during the run-in ranges between about 6080 and 11,520 km(2). This may affect between 145,000 and 276,000 people. When a 250 m size asteroid is considered, the covered land surface area ranges between about 840 and 1,890 km(2) and between 20,000 and 45,000 people may be affected. In case of a 70 m size asteroid, the cloud covers up to 105 km(2) of land during the run-in. This may affect about 2500 people. These are moderate estimates. They do not include the urban population and may be 10 times underestimated for some particular wind directions. General recommendations to diminish

  9. Understanding the Effects of Collisional Evolution and Spacecraft Impact Experiments on Comets and Asteroids

    Science.gov (United States)

    Lederer, S.M.; Jensen, E.A.; Fane, M.; Smith, D.C.; Holmes, J.; Keller, L.P.; Lindsay, S.S.; Wooden, D.H.; Whizin, A.; Cintala, M.J.; hide

    2017-01-01

    Comets and asteroids have endured impacts from other solar system bodies that result in outcomes ranging from catastrophic collisions to regolith evolution due to micrometeorid bombardment of the surface ices and refactory components. Experiments designed to better understand these relics of solar system formation have been conducted on Earth in a laboratory setting, as well as in space through, e.g., the Deep Impact Mission to Comet Tempel 1. Deep Impact fired a high-speed impactor into the roughly 6 km nucleus of the comet. The ejecta plume generated by the impact was studied by both spacecraft instrumentation and groundbased telescopes.

  10. Annihilation of ecosystems by large asteroid impacts on the early earth

    Science.gov (United States)

    Sleep, Norman H.; Zahnle, Kevin J.; Kasting, James F.; Morowitz, Harold J.

    1989-01-01

    Large asteroid impacts produced globally lethal conditions by evaporating large volumes of ocean water on the early earth. The earth may have been continuously habitable by ecosystems that did not depend on photosynthesis as early as 4.44 Gyr BP (before present). Only a brief interval after 3.8 Gyr exists between the time when obligate photosynthetic organisms could continuously evolve and the time when the palaeontological record indicates highly evolved photosynthetic ecosystems.

  11. Collisional Histories of Comets and Trojan Asteroids: Insights from Forsterite and Enstatite Impact Studies

    Science.gov (United States)

    Lederer. S. M.; Jensen, E. A.; Wooden, D. H.; Lindsay, S. S.; Smith, D. C.; Cintala, M. J.; Nakamura-Messenger, K.; Keller, L. P.

    2012-01-01

    Impacts into forsterite and orthoenstatite at speeds typically encountered by comets demonstrate that shock imparted by collisions is detectable in the infrared signatures of their dust. The spectral signatures can be traced to physical alterations in their crystalline structures, as observed in TEM imaging and modeled using a dipole approximation. These results yield tantalizing insights into the collisional history of our solar system, as well as the history of individual comets and Trojan asteroids.

  12. Devastating Transboundary Impacts of Sea Star Wasting Disease on Subtidal Asteroids.

    Science.gov (United States)

    Montecino-Latorre, Diego; Eisenlord, Morgan E; Turner, Margaret; Yoshioka, Reyn; Harvell, C Drew; Pattengill-Semmens, Christy V; Nichols, Janna D; Gaydos, Joseph K

    2016-01-01

    Sea star wasting disease devastated intertidal sea star populations from Mexico to Alaska between 2013-15, but little detail is known about its impacts to subtidal species. We assessed the impacts of sea star wasting disease in the Salish Sea, a Canadian / United States transboundary marine ecosystem, and world-wide hotspot for temperate asteroid species diversity with a high degree of endemism. We analyzed roving diver survey data for the three most common subtidal sea star species collected by trained volunteer scuba divers between 2006-15 in 5 basins and on the outer coast of Washington, as well as scientific strip transect data for 11 common subtidal asteroid taxa collected by scientific divers in the San Juan Islands during the spring/summer of 2014 and 2015. Our findings highlight differential susceptibility and impact of sea star wasting disease among asteroid species populations and lack of differences between basins or on Washington's outer coast. Specifically, severe depletion of sunflower sea stars (Pycnopodia helianthoides) in the Salish Sea support reports of major declines in this species from California to Alaska, raising concern for the conservation of this ecologically important subtidal predator.

  13. Devastating Transboundary Impacts of Sea Star Wasting Disease on Subtidal Asteroids.

    Directory of Open Access Journals (Sweden)

    Diego Montecino-Latorre

    Full Text Available Sea star wasting disease devastated intertidal sea star populations from Mexico to Alaska between 2013-15, but little detail is known about its impacts to subtidal species. We assessed the impacts of sea star wasting disease in the Salish Sea, a Canadian / United States transboundary marine ecosystem, and world-wide hotspot for temperate asteroid species diversity with a high degree of endemism. We analyzed roving diver survey data for the three most common subtidal sea star species collected by trained volunteer scuba divers between 2006-15 in 5 basins and on the outer coast of Washington, as well as scientific strip transect data for 11 common subtidal asteroid taxa collected by scientific divers in the San Juan Islands during the spring/summer of 2014 and 2015. Our findings highlight differential susceptibility and impact of sea star wasting disease among asteroid species populations and lack of differences between basins or on Washington's outer coast. Specifically, severe depletion of sunflower sea stars (Pycnopodia helianthoides in the Salish Sea support reports of major declines in this species from California to Alaska, raising concern for the conservation of this ecologically important subtidal predator.

  14. Asteroids IV

    Science.gov (United States)

    Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    Asteroids are fascinating worlds. Considered the building blocks of our planets, many of the authors of this book have devoted their scientific careers to exploring them with the tools of our trade: ground- and spacebased observations, in situ space missions, and studies that run the gamut from theoretical modeling efforts to laboratory work. Like fossils for paleontologists, or DNA for geneticists, they allow us to construct a veritable time machine and provide us with tantalizing glimpses of the earliest nature of our solar system. By investigating them, we can probe what our home system was like before life or even the planets existed. The origin and evolution of life on our planet is also intertwined with asteroids in a different way. It is believed that impacts on the primordial Earth may have delivered the basic components for life, with biology favoring attributes that could more easily survive the aftermath of such energetic events. In this fashion, asteroids may have banished many probable avenues for life to relative obscurity. Similarly, they may have also prevented our biosphere from becoming more complex until more recent eras. The full tale of asteroid impacts on the history of our world, and how human life managed to emerge from myriad possibilities, has yet to be fully told. The hazard posed by asteroid impacts to our civilization is low but singular. The design of efficient mitigation strategies strongly relies on asteroid detection by our ground- and spacebased surveys as well as knowledge of their physical properties. A more positive motivation for asteroid discovery is that the proximity of some asteroids to Earth may allow future astronauts to harvest their water and rare mineral resources for use in exploration. A key goal of asteroid science is therefore to learn how humans and robotic probes can interact with asteroids (and extract their materials) in an efficient way. We expect that these adventures may be commonplace in the future

  15. Impact-induced seismic activity on asteroid 433 Eros: a surface modification process.

    Science.gov (United States)

    Richardson, James E; Melosh, H Jay; Greenberg, Richard

    2004-11-26

    High-resolution images of the surface of asteroid 433 Eros revealed evidence of downslope movement of a loose regolith layer, as well as the degradation and erasure of small impact craters (less than approximately 100 meters in diameter). One hypothesis to explain these observations is seismic reverberation after impact events. We used a combination of seismic and geomorphic modeling to analyze the response of regolith-covered topography, particularly craters, to impact-induced seismic shaking. Applying these results to a stochastic cratering model for the surface of Eros produced good agreement with the observed size-frequency distribution of craters, including the paucity of small craters.

  16. Intrinsic Collision Probabilities and Impact Velocities for Asteroids in Outer Belt Families

    Science.gov (United States)

    Díaz, G.; Gil-Hutton, R.

    Intrinsic collision probabilities and impact velocities have been obtained for asteroids in outer belt families. For each family, the mean intrinsic collision probability with objects of the family is two to three times greater than the same value calculated for interactions with the main belt, but the mean impact velocity between members of the same family is lower than the mean impact velocity against the main belt. Furthermore, the results obtained for three objects, 133 P/Elst-Pizarro, P/2005U1 and 118401 LINEAR, suggest that the cometary activity reported could be the result of collisions with particles from the Themis family.

  17. Asteroid and comet impacts: the ultimate environmental catastrophe.

    Science.gov (United States)

    Morrison, David

    2006-08-15

    Cosmic impacts represent the most extreme class of natural hazards, combining a very low probability of occurrence with a capability of killing hundreds of millions and destabilizing global civilization. Fortunately, these disasters are amenable to precise prediction and even (in principle) can be avoided entirely by appropriate application of space technology. However, impacts take place so rarely that they have only recently been recognized as a significant natural hazard. Concerted international action to deal with impacts depends on increased public awareness.

  18. Granular impact cratering by liquid drops: Understanding raindrop imprints through an analogy to asteroid strikes.

    Science.gov (United States)

    Zhao, Runchen; Zhang, Qianyun; Tjugito, Hendro; Cheng, Xiang

    2015-01-13

    When a granular material is impacted by a sphere, its surface deforms like a liquid yet it preserves a circular crater like a solid. Although the mechanism of granular impact cratering by solid spheres is well explored, our knowledge on granular impact cratering by liquid drops is still very limited. Here, by combining high-speed photography with high-precision laser profilometry, we investigate liquid-drop impact dynamics on granular surface and monitor the morphology of resulting impact craters. Surprisingly, we find that despite the enormous energy and length difference, granular impact cratering by liquid drops follows the same energy scaling and reproduces the same crater morphology as that of asteroid impact craters. Inspired by this similarity, we integrate the physical insight from planetary sciences, the liquid marble model from fluid mechanics, and the concept of jamming transition from granular physics into a simple theoretical framework that quantitatively describes all of the main features of liquid-drop imprints in granular media. Our study sheds light on the mechanisms governing raindrop impacts on granular surfaces and reveals a remarkable analogy between familiar phenomena of raining and catastrophic asteroid strikes.

  19. A summary of LED lighting impacts on health

    Directory of Open Access Journals (Sweden)

    Cosmin Ticleanu

    2017-06-01

    Full Text Available Lighting can affect the health of people in buildings. This goes beyond the safety aspects of providing enough illumination to see by; lighting affects mood and human circadian rhythms, while poor lighting can cause glare, headaches, eyestrain, aches and pains associated with poor body posture or, in extreme cases, skin conditions and various types of sight loss. These aspects ought to be considered by designers and building owners and occupiers in order to improve the lit environment and use adequate lighting and lighting controls that meet the recommendations of codes and standards. Various types of lighting can have different impacts depending on their spectral, optical and electrical characteristics. This paper discusses potential impacts of LED lighting on human health, and is based on a recent BRE review of research investigating the most typical effects of lighting on human health.

  20. High-resolution calculations of asteroid impacts into the Venusian atmosphere.

    Science.gov (United States)

    Korycansky, D G; Zahnle, K J; Mac Law, M M

    2000-08-01

    We present results from a number of 2D high-resolution hydrodynamical simulations of asteroids striking the atmosphere of Venus. These cover a wide range of impact parameters (velocity, size, and incidence angle), but the focus is on 2-3 km diameter asteroids, as these are responsible for most of the impact craters on Venus. Asteroids in this size range are disintegrated, ablated, and significantly decelerated by the atmosphere, yet they retain enough impetus to make large craters when they meet the surface. We find that smaller impactors (diameter 2-3 km) fragmentation by mechanical ablation is preferred. The pancaking model has been modified to take into account effects of hydrodynamical instabilities. The general observation that most larger impactors disintegrate by shedding fragments generated from hydrodynamic instabilities spurs us to develop a simple heuristic model of the mechanical ablation of fragments based on the growth rates of Rayleigh-Taylor instabilities. Although in principle the model has many free parameters, most of these have little effect provided that they are chosen reasonably. In practice the range of model behavior can be described with one free parameter. The resulting model reproduces the mass and momentum fluxes rather well, doing so with reasonable values of all physical parameters.

  1. Melting, vaporization, and energy partitioning for impacts on asteroidal and planetary objects

    Science.gov (United States)

    Smither, Catherine L.; Ahrens, Thomas J.

    1992-01-01

    A three-dimensional smoothed particle hydrodynamics code was used to model normal and oblique impacts of silicate projectiles on asteroidal and planetary bodies. The energy of the system, initially in the kinetic energy of the impactor, is partitioned after impact into internal and kinetic energy of the impactor and the target body. These simulations show that, unlike the case of impacts onto a half-space, a significant amount of energy remains in the kinetic energy of the impacting body, as parts of it travel past the main planet and escape the system. This effect is greater for more oblique impacts, and for impacts onto the small planets. Melting and vaporization of both bodies were also examined. The amount of the target body melted was much greater in the case of smaller targets than for an impact of a similar scale on a larger body.

  2. Asteroid impacts on terrestrial planets: the effects of super-Earths and the role of the ν6 resonance

    Science.gov (United States)

    Smallwood, Jeremy L.; Martin, Rebecca G.; Lepp, Stephen; Livio, Mario

    2018-01-01

    With N-body simulations of a planetary system with an asteroid belt, we investigate how the asteroid impact rate on the Earth is affected by the architecture of the planetary system. We find that the ν6 secular resonance plays an important role in the asteroid collision rate with the Earth. Compared to exoplanetary systems, the Solar system is somewhat special in its lack of a super-Earth mass planet in the inner Solar system. We therefore first consider the effects of the presence of a super-Earth in the terrestrial planet region. We find a significant effect for super-Earths with a mass of around 10 M⊕ and a separation greater than about 0.7 au. For a super-Earth which is interior to the Earth's orbit, the number of asteroids colliding with Earth increases the closer the super-Earth is to the Earth's orbit. This is the result of multiple secular resonance locations causing more asteroids to be perturbed on to Earth-crossing orbits. When the super-Earth is placed exterior to Earth's orbit, the collision rate decreases substantially because the ν6 resonance no longer exists in the asteroid belt region. We also find that changing the semimajor axis of Saturn leads to a significant decrease in the asteroid collision rate, though increasing its mass increases the collision rate. These results may have implications for the habitability of exoplanetary systems.

  3. Laboratory simulation of pelagic asteroidal impact Atmospheric injection, benthic topography, and the surface wave radiation field

    Science.gov (United States)

    Gault, D. E.; Sonett, C. P.

    1982-01-01

    The hypervelocity impact (1.25-6 km/s) of projectiles into water overlying unconsolidated strata is reported for a variety of water depths. Variation of the background atmospheric pressure is found to be an important additional parameter. The relation of these exploratory experiments to pelagic impact of asteroidal-sized objects is discussed from the standpoint of atmospheric injection of sea water, the modification of bottom (benthic) topography, and the generation of a field of mega-amplitude sea waves and their propagation away from the source.

  4. A concept for providing warning of earth impacts by small asteroids

    Science.gov (United States)

    Dunham, D. W.; Reitsema, H. J.; Lu, E.; Arentz, R.; Linfield, R.; Chapman, C.; Farquhar, R.; Ledkov, A. A.; Eismont, N. A.; Chumachenko, E.

    2013-07-01

    The atmospheric detonation of a 17 m-asteroid above Chelyabinsk, Russia on 2013 February 15 shows that even small asteroids can cause extensive damage. Earth-based telescopes have found smaller harmless objects, such as 2008 TC3, a 4 m-asteroid that was discovered 20h before it exploded over northeastern Sudan (Jenniskens, 2009). 2008 TC3 remains the only asteroid discovered before it hit Earth because it approached Earth from the night side, where it was observed by large telescopes searching for near-Earth objects (NEO's). The larger object that exploded over Chelyabinsk approached Earth from the day side, from too close to the Sun to be detected from Earth. A sizeable telescope in an orbit about the Sun-Earth L1 (SE-L1) libration point could find objects like the "Chelyabinsk" asteroid approaching approximately from the line of sight to the Sun about a day before Earth closest approach. Such a system would have the astrometric accuracy needed to determine the time and impact zone for a NEO on a collision course. This would give at least several hours, and usually 2-4 days, to take protective measures, rather than the approximately two-minute interval between the flash and shock wave arrival that occurred in Chelyabinsk. A perhaps even more important reason for providing warning of these events, even smaller harmless ones that explode high in the atmosphere with the force of an atomic bomb, is to prevent mistaking such an event for a nuclear attack that could trigger a devastating nuclear war. A concept using a space telescope similar to that needed for an SE-L1 monitoring satellite, is already conceived by the B612 Foundation, whose planned Sentinel Space Telescope could find nearly all 140 m and larger NEO's, including those in orbits mostly inside the Earth's orbit that are hard to find with Earth-based telescopes, from a Venus-like orbit (Lu, 2013). Few modifications would be needed to the Sentinel Space Telescope to operate in a SE-L1 orbit, 0.01 AU from

  5. Anatomy of an Asteroid Breakup

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    A team of scientists has observed the breakup of an asteroid as it orbits the Sun. In a new study, they reveal what theyve learned from their ground- and space-based observations of this disintegration.These Hubble images show the fragments of R3 in higher resolution over the span of October 2013 to February 2014. [Jewitt et al. 2017]Observations of DisintegrationActive asteroids are objects that move on asteroid-like orbits while displaying comet-like behavior. The cause of their activity can vary ranging from outgassing as the asteroid heats up in its solar approach, to expelled debris from a collision, to the entire asteroid flying apart because its spinning too fast.Led by David Jewitt (University of California at Los Angeles), a team of scientists has analyzed observations of the disintegrating asteroid P/2013 R3. The observations span two years and were made by a number of telescopes, including Hubble, Keck (in Hawaii), Magellan (in Chile), and the Very Large Telescope (in Chile).A schematic diagram of the different fragments of R3 and how they relate to each other. Black numbers estimate the fragment separation velocities; red numbers estimate the separation date. [Jewitt et al. 2017]Jewitt and collaborators then used these observations and a bit of modeling to understand what asteroid R3 was like originally, what its pieces are doing now, and what caused it to break up.Cause of the BreakupThe team found that P/2013 R3 broke up into at least 13 pieces, the biggest of which was likely no more than 100-200 meters in size. The original asteroid was probably less than 400 m in radius.By measuring the velocities of the fragments in the various observations, Jewitt and collaborators were able to work backward to determine when each piece broke off. They found that the fragmentation process was spread out over the span of roughly 5 months suggesting that the asteroids breakup wasnt impact-related (otherwise the fragmentation would likely have been all at once

  6. Asteroid structure

    Science.gov (United States)

    Asphaug, E.

    2014-07-01

    Even before the first space missions to asteroids, in the mid-1990s, it was known that asteroids have weird structures. Photometry indicated complicated shapes, and the pioneering radar investigations by Ostro and colleagues followed by adaptive optics campaigns and flybys showed odd binary forms, and confirmed the common presence of satellites, and indications of highly varying surface roughness. Some asteroids turned out to be dominated by a single major cratering event, while others showed no evidence of a major crater, or perhaps for global crater erasure. The first space mission to orbit an asteroid, NEAR, found a mixture of heavily cratered terrains and geomorphically active 'ponds', and indicated evidence for global seismicity from impact. The next mission to orbit an asteroid, Hayabusa, found what most agree is a rubble pile, with no major craters and an absence of fines. There is to date no direct evidence of asteroid interior geology, other than measurements of bulk density, and inferences made for mass distribution asymmetry based on dynamics, and inferences based on surface lineaments. Interpolating from the surface to the interior is always risky and usually wrong, but of course the answer is important since we are someday destined to require this knowledge in order to divert a hazardous asteroid from impact with the Earth. Even considering the near-subsurface, here we remain as ignorant as we were about the Moon in the early 1960s, whether the surface will swallow us up in dust, or will provide secure landing and anchoring points. Laboratory experimentation in close to zero-G is still in its early stages. Adventures such as mining and colonization will surely have to wait until we better know these things. How do we get from here to there? I will focus on 3 areas of progress: (1) asteroid cratering seismology, where we use the surface craters to understand what is going on inside; (2) numerical modeling of collisions, which predicts the internal

  7. Thinking of biology: asteroid impacts, microbes, and the cooling of the atmosphere

    Science.gov (United States)

    Oberbeck, V. R.; Mancinelli, R. L.

    1994-01-01

    The authors examine the cooling of the Earth's surface from 3.75 to 1 billion years ago. Three effects of the bombardment of Earth by asteroids and comets that may have delayed surface cooling include time to form continents, volatilization of carbonate rocks which released carbon dioxide into the atmosphere, and inability of microbes to inhabit land masses during large impact events. Continental microbes may have helped reduce high temperatures from 3.75 to 3.5 billion years ago. If so, the evolutionary sequence of microbes is proposed to be anaerobic heterotrophs, chemoautotrophs, and then photoautotrophs.

  8. Nanoscale Mineralogy and Composition of Experimental Regolith Agglutinates Produced under Asteroidal Impact Conditions

    Science.gov (United States)

    Christoffersen, Roy; Cintala, M. J.; Keller, L. P.; See, T. H.; Horz, F.

    2013-01-01

    On the Moon, the energetics of smaller impactors and the physical/chemical characteristics of the granular regolith target combine to form a key product of lunar space weathering: chemically reduced shock melts containing optically-active nanophase Fe metal grains (npFe0) [1]. In addition to forming the optically dark glassy matrix phase in lunar agglutinitic soil particles [1], these shock melts are becoming increasingly recognized for their contribution to optically active patina coatings on a wide range of exposed rock and grain surfaces in the lunar regolith [2]. In applying the lessons of lunar space weathering to asteroids, the potential similarities and differences in regolith-hosted shock melts on the Moon compared to those on asteroids has become a topic of increasing interest [3,4]. In a series of impact experiments performed at velocities applicable to the asteroid belt [5], Horz et al. [6] and See and Horz [7] have previously shown that repeated impacts into a gabbroic regolith analog target can produce melt-welded grain aggregates morphologically very similar to lunar agglutinates [6,7]. Although these agglutinate-like particles were extensively analyzed by electron microprobe and scanning electron microscopy (SEM) as part of the original study [7], a microstructural and compositional comparison of these aggregates to lunar soil agglutinates at sub-micron scales has yet to be made. To close this gap, we characterized a representative set of these aggregates using a JEOL 7600 field-emission scanning electron microscope (FE-SEM), and JEOL 2500SE field-emission scanning transmission electron microscope (FE-STEM) both optimized for energy dispersive X-ray spectroscopy (EDX) compositional spectrum imaging at respective analytical spatial resolutions of 0.5 to 1 micron, and 2 to 4 nm.

  9. Cratering on Asteroids

    Science.gov (United States)

    Marchi, S.; Chapman, C. R.; Barnouin, O. S.; Richardson, J. E.; Vincent, J.-B.

    Impact craters are a ubiquitous feature of asteroid surfaces. On a local scale, small craters puncture the surface in a way similar to that observed on terrestrial planets and the Moon. At the opposite extreme, larger craters often approach the physical size of asteroids, thus globally affecting their shapes and surface properties. Crater measurements are a powerful means of investigation. Crater spatial and size distributions inform us of fundamental processes, such as asteroid collisional history. A paucity of craters, sometimes observed, may be diagnostic of mechanisms of erasure that are unique on low-gravity asteroids. Byproducts of impacts, such as ridges, troughs, and blocks, inform us of the bulk structure. In this chapter we review the major properties of crater populations on asteroids visited by spacecraft. In doing so we provide key examples to illustrate how craters affect the overall shape and can be used to constrain asteroid surface ages, bulk properties, and impact-driven surface evolution.

  10. Collisional Histories of Comets and Trojan Asteroids: Diopside, Magnesite, and Fayalite Impact Studies

    Science.gov (United States)

    Lederer, S. M.; Jensen, E. A.; Wooden, D. H.; Lindsay, S. S.; Nakamura-Messenger, K.; Smith, D. C.; Keller, L. P.; Cintala, M. J.; Zolensky, M. E.

    2012-01-01

    Comets and asteroids have weathered dynamic histories, as evidenced by their rough surfaces. The Nice model describes a violent reshuffling of small bodies during the Late Heavy Bombardment, with collisions acting to grind these planetesimals away. This creates an additional source of impact material that can re-work the surfaces of the larger bodies over the lifetime of the solar system. Here, we investigate the possibility that signatures due to impacts (e.g. from micrometeoroids or meteoroids) could be detected in their spectra, and how that can be explained by the physical manifestation of shock in the crystalline structure of minerals. All impact experiments were conducted in the Johnson Space Center Experimental Impact Laboratory using the vertical gun. Impact speeds ranged from approx.2.0 km/s to approx.2.8 km/s. All experiments were conducted at room temperature. Minerals found in comets and asteroids were chosen as targets, including diopside (MgCaSi2O6, monoclinic pyroxene), magnesite (MgCO3, carbonate), and fayalite (FeSiO4, olivine). Impacted samples were analyzed using a Fourier Transform Infrared Spectrometer (FTIR) and a Transmission Electron Microscope (TEM). Absorbance features in the 8-13 m spectral region demonstrate relative amplitude changes as well as wavelength shifts. Corresponding TEM images exhibit planar shock dislocations in the crystalline structure, attributed to deformation at high strain and low temperatures. Elongating or shortening the axes of the crystalline structure of forsterite (Mg2SiO4, olivine) using a discrete dipole approximation model (Lindsay et al., submitted) yields changes in spectral features similar to those observed in our impacted laboratory minerals.

  11. The Chicxulub asteroid impact and mass extinction at the Cretaceous-Paleogene boundary.

    Science.gov (United States)

    Schulte, Peter; Alegret, Laia; Arenillas, Ignacio; Arz, José A; Barton, Penny J; Bown, Paul R; Bralower, Timothy J; Christeson, Gail L; Claeys, Philippe; Cockell, Charles S; Collins, Gareth S; Deutsch, Alexander; Goldin, Tamara J; Goto, Kazuhisa; Grajales-Nishimura, José M; Grieve, Richard A F; Gulick, Sean P S; Johnson, Kirk R; Kiessling, Wolfgang; Koeberl, Christian; Kring, David A; MacLeod, Kenneth G; Matsui, Takafumi; Melosh, Jay; Montanari, Alessandro; Morgan, Joanna V; Neal, Clive R; Nichols, Douglas J; Norris, Richard D; Pierazzo, Elisabetta; Ravizza, Greg; Rebolledo-Vieyra, Mario; Reimold, Wolf Uwe; Robin, Eric; Salge, Tobias; Speijer, Robert P; Sweet, Arthur R; Urrutia-Fucugauchi, Jaime; Vajda, Vivi; Whalen, Michael T; Willumsen, Pi S

    2010-03-05

    The Cretaceous-Paleogene boundary approximately 65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the Cretaceous-Paleogene boundary. The temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling) lead us to conclude that the Chicxulub impact triggered the mass extinction.

  12. Lunar formation. Dating the Moon-forming impact event with asteroidal meteorites.

    Science.gov (United States)

    Bottke, W F; Vokrouhlický, D; Marchi, S; Swindle, T; Scott, E R D; Weirich, J R; Levison, H

    2015-04-17

    The inner solar system's biggest and most recent known collision was the Moon-forming giant impact between a large protoplanet and proto-Earth. Not only did it create a disk near Earth that formed the Moon, it also ejected several percent of an Earth mass out of the Earth-Moon system. Here, we argue that numerous kilometer-sized ejecta fragments from that event struck main-belt asteroids at velocities exceeding 10 kilometers per second, enough to heat and degas target rock. Such impacts produce ~1000 times more highly heated material by volume than do typical main belt collisions at ~5 kilometers per second. By modeling their temporal evolution, and fitting the results to ancient impact heating signatures in stony meteorites, we infer that the Moon formed ~4.47 billion years ago, which is in agreement with previous estimates. Copyright © 2015, American Association for the Advancement of Science.

  13. Secondary submicrometer impact cratering on the surface of asteroid 25143 Itokawa

    Science.gov (United States)

    Harries, Dennis; Yakame, Shogo; Karouji, Yuzuru; Uesugi, Masayuki; Langenhorst, Falko

    2016-09-01

    Particle RA-QD02-0265 returned by the Hayabusa spacecraft from near-Earth asteroid 25143 Itokawa displayed a unique abundance of submicrometer-sized (≤500 nm) impact craters, which are rarely observed among the Hayabusa samples. The particle consists of intensely twinned diopside that was subjected to a large-scale shock event before exposure to the space environment on the surface of 25143 Itokawa. Intense (sub-)micrometer-scale impact cratering may suggest a long surface exposure and, hence, a long residence time of regolith material on the surface of small asteroids, bearing implications for the dynamical evolution of these bodies. However, our combined FE-SEM and FIB/TEM study shows that the degree of solar wind-induced space weathering and the accumulation of solar flare tracks are not exceptionally different from other Hayabusa particles with surface exposure ages estimated to be less than 1 ka. A 500 nm wide crater on the surface of RA-QD02-0265 exhibits microstructural damage to a depth of 400 nm below its floor and contains residues of Fe-Ni metal, excluding a formation by space craft exhausts or curatorial handling. The geometrical clustering among the 15 craters is unlikely random, and we conclude that the craters have formed through the impacts of secondary projectiles (at least partially Fe-Ni metal) created in a nearby (micro-)impact event. Besides structural damage by the solar wind and deposition of impact-generated melts and vapors, secondary impact cratering on the submicrometer-scale is another potential mechanism to modify the spectral properties of individual regolith grains. The lack of extensively exposed regolith grains supports a dynamic regolith on the surface of 25143 Itokawa.

  14. NASA Space Missions to Asteroids: Protecting the Earth from NEO Impacts

    Science.gov (United States)

    Morrison, David; Berry, William E. (Technical Monitor)

    1996-01-01

    There is now a general recognition of the hazard of impacts on Earth by comets and asteroids, but there is yet no consensus concerning international actions that should be taken to protect the planet from such impacts. An essential step in the analysis of the situation involves estimating the relative hazard posed by comets and asteroids of different sizes and orbits. All recent studies agree that the larger impacts pose the greater danger, and that our primary concern from the perspective of total risk should be on impacts that are large enough to cause global ecological catastrophe. These global catastrophes are also of special interest, since they (alone among natural disasters) have the potential to destroy civilization. Studies of the sensitivity of the Earth's environment suggest that the energy threshold energy for causing a global catastrophe is at about 1 million megatons, corresponding to impactor diameters of 1.5 to 2 km. This information leads naturally to a strategy of concentrating on the larger NEOs, say those 1 km or more in diameter. This is the rationale for the Spaceguard Survey, which must be the highest priority in mitigation efforts. The second question concerns the value of developing standing defensive systems that could deflect or destroy an incoming NEO. In the case of the asteroids larger than 1 km in diameter, no such system is needed, since there will be ample time (at least several decades) between the discovery of the threatening object by Spaceguard and the requirement to take action against it. In the case of objects smaller than 1 km diameter, development of defensive systems is not cost-effective; there are many greater dangers to persons and property that are much more urgent. Only in the case of large long-period comets is there a rationale for standing defense systems. The question is also raised whether the risks inherent in developing and maintaining a defense system might be greater than the impact risks it is intended to

  15. Crater production on Venus and Earth by asteroid and comet impact

    Science.gov (United States)

    Shoemaker, Eugene M.; Wolfe, Ruth F.

    1987-01-01

    New calculations of the collision probabilities of asteroids and comets with Venus were carried out based on the orbits of the known Venus-crossing asteroids and comets. For comparison, asteroid and comet collision probabilities and cratering rates on the Earth and Moon were recalculated and the estimated cratering rates on Venus were normalized to those of the Earth.

  16. Impact-generated activity period of the asteroid 7968 Elst-Pizarro in 1996: Identification of the asteroid 427 Galene as the most probable parent body of the impactors

    Science.gov (United States)

    Toth, I.

    2000-08-01

    One of the most interesting objects among the small bodies in the Solar System is the intermediate object 7968 Elst-Pizarro classified as an asteroid-comet orbiting in the Themis region of the main belt, which showed a temporary dust tail activity in 1996. The impact-induced processes generated by multiple collisions with a debris cloud associated with another asteroid, are the preferred explanations for this activity. A computer search has shown that the most probable candidate for the parent body of the impactors to generate this temporary outburst activity, is the field asteroid 427 Galene.

  17. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products, Part 3: LED Environmental Testing

    Energy Technology Data Exchange (ETDEWEB)

    Tuenge, Jason R.; Hollomon, Brad; Dillon, Heather E.; Snowden-Swan, Lesley J.

    2013-03-01

    This report covers the third part of a larger U.S. Department of Energy (DOE) project to assess the life-cycle environmental and resource impacts in the manufacturing, transport, use, and disposal of light-emitting diode (LED) lighting products in relation to incumbent lighting technologies. All three reports are available on the DOE website (www.ssl.energy.gov/tech_reports.html). • Part 1: Review of the Life-Cycle Energy Consumption of Incandescent, Compact Fluorescent and LED Lamps; • Part 2: LED Manufacturing and Performance; • Part 3: LED Environmental Testing. Parts 1 and 2 were published in February and June 2012, respectively. The Part 1 report included a summary of the life-cycle assessment (LCA) process and methodology, provided a literature review of more than 25 existing LCA studies of various lamp types, and performed a meta-analysis comparing LED lamps with incandescent and compact fluorescent lamps (CFLs). Drawing from the Part 1 findings, Part 2 performed a more detailed assessment of the LED manufacturing process and used these findings to provide a comparative LCA taking into consideration a wider range of environmental impacts. Both reports concluded that the life-cycle environmental impact of a given lamp is dominated by the energy used during lamp operation—the upstream generation of electricity drives the total environmental footprint of the product. However, a more detailed understanding of end-of-life disposal considerations for LED products has become increasingly important as their installation base has grown. The Part 3 study (reported herein) was undertaken to augment the LCA findings with chemical analysis of a variety of LED, CFL, and incandescent lamps using standard testing procedures. A total of 22 samples, representing 11 different models, were tested to determine whether any of 17 elements were present at levels exceeding California or Federal regulatory thresholds for hazardous waste. Key findings include: • The selected

  18. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products Part 2: LED Manufacturing and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Scholand, Michael; Dillon, Heather E.

    2012-05-01

    Part 2 of the project (this report) uses the conclusions from Part 1 as a point of departure to focus on two objectives: producing a more detailed and conservative assessment of the manufacturing process and providing a comparative LCA with other lighting products based on the improved manufacturing analysis and taking into consideration a wider range of environmental impacts. In this study, we first analyzed the manufacturing process for a white-light LED (based on a sapphire-substrate, blue-light, gallium-nitride LED pumping a yellow phosphor), to understand the impacts of the manufacturing process. We then conducted a comparative LCA, looking at the impacts associated with the Philips Master LEDbulb and comparing those to a CFL and an incandescent lamp. The comparison took into account the Philips Master LEDbulb as it is now in 2012 and then projected forward what it might be in 2017, accounting for some of the anticipated improvements in LED manufacturing, performance and driver electronics.

  19. The asteroid and comet impact hazard: risk assessment and mitigation options.

    Science.gov (United States)

    Gritzner, Christian; Dürfeld, Kai; Kasper, Jan; Fasoulas, Stefanos

    2006-08-01

    The impact of extraterrestrial matter onto Earth is a continuous process. On average, some 50,000 tons of dust are delivered to our planet every year. While objects smaller than about 30 m mainly disintegrate in the Earth's atmosphere, larger ones can penetrate through it and cause damage on the ground. When an object of hundreds of meters in diameter impacts an ocean, a tsunami is created that can devastate coastal cities. Further, if a km-sized object hit the Earth it would cause a global catastrophe due to the transport of enormous amounts of dust and vapour into the atmosphere resulting in a change in the Earth's climate. This article gives an overview of the near-Earth asteroid and comet (near-Earth object-NEO) impact hazard and the NEO search programmes which are gathering important data on these objects. It also points out options for impact hazard mitigation by using deflection systems. It further discusses the critical constraints for NEO deflection strategies and systems as well as mitigation and evacuation costs and benefits. Recommendations are given for future activities to solve the NEO impact hazard problem.

  20. Lay Led Ministries in USAREUR: Impact on Command and Community.

    Science.gov (United States)

    1985-04-17

    allowed to meet in chapel facilities. * Is the growing movement of lay led ministries in any- way reflective of inadequate parish ministry and...one was an officer (Jewish, Major) and one (1) was a civilian missionary. There seemed to be a good scattering of denominations; four (4) Pentecostal ...Holiness/ Pentecostal . It is important to note these categories when considering the data. Admittedly, the survey was limited in the number of sources

  1. Post Deflection Impact Risk Analysis of the Double Asteroid Redirection Test (DART)

    Science.gov (United States)

    Eggl, S.; Hestroffer, D.

    2017-09-01

    Collisions between potentially hazardous near-Earth objects and our planet are among the few natural disasters that can be avoided by human intervention. The complexity of such an endeavor necessitates an asteroid orbit deflection test mission, however, ensuring all relevant knowledge is present when an asteroid on a collision course with the Earth is indeed discovered. The double asteroid redirection test (DART) mission concept currently investigated by NASA would serve such a purpose. The aim of our research is to make certain that DART does not turn a previously harmless asteroid into a potentially dangerous one.

  2. Comparing the Earth Impact Flux from Comets and Near-Earth Asteroids

    Science.gov (United States)

    Yeomans, Donald K.; Chamberlin, Alan B.

    2011-01-01

    Long-period comets (LPC), defined here as those active comets with orbital periods greater than 200 years, are the most difficult objects to mitigate should one be found on an Earth threatening trajectory. The arrival of these objects from the distant Oort cloud cannot be predicted and the impact warning time would be measured in a few months - not years. At the distance of Jupiter, an inactive cometary nucleus with a diameter of one kilometer and a geometric albedo equal to 0.04 would have an apparent magnitude fainter than 25 near opposition and, hence would be well outside the detection capability of current NEO search telescopes. In general LPCs do not become active, and hence discoverable, until inside the orbit of Jupiter and it takes but nine months for a LPC to travel the distance from Jupiter's orbit to that of the Earth.Estimating the impact energy for long-period comets is particularly difficult because the sizes and masses of these objects are not well known. Their solid nuclei are hidden from ground-based telescopes by their gas and dust atmospheres and even when nearby spacecraft observations can determine a size and shape for a cometary nucleus, there are no direct determinations of any cometary mass or bulk density to date. However, a variety of indirect bulk density determinations consistently provide values below one gram per cubic centimeter, the value for water. From measurements made by the Deep Impact spacecraft during its encounter with comet Tempel 1 in July 2005, the bulk density was estimated to be 0.6 grams per cubic centimeter. The mean impact velocity of a LPC is about 51 km/s, three times the 17 km/s value for a typical near-Earth asteroid (NEA) so the impact energy for an LPC would be 9 times that of a NEA of similar mass. However, the bulk density of a comet (approx. 0.6 g/cu cm) is several times less than the density of a stony NEA (approx. 2.6 g/ cu cm) so for a LPC and a stony NEA of the same size, the LPC's impact energy would be

  3. Asteroid surface impact sampling: dependence of the cavity morphology and collected mass on projectile shape.

    Science.gov (United States)

    Cheng, Bin; Yu, Yang; Baoyin, Hexi

    2017-08-30

    In-situ exploration and remote thermal infrared observation revealed that a large fraction of Solar System small bodies should be covered with granular regolith. The complex and varied geology of the regolith layer may preserve the historical records of the surface modification and topographic evolution experienced by asteroids, especially cratering processes, in which the projectile shape plays a crucial role. Regarding the impact sampling scheme, the projectile-shape dependence of both the cavity morphology and the collected mass remains to be explored. This paper studies the process of the low-speed impact sampling on granular regolith using projectiles of different shapes. The results demonstrate that the projectile shape significantly influences the excavation stage, forming cavities with different morphologies, i.e., cone-shaped, bowl-shaped and U-shaped. We further indicate that the different velocity distributions of the ejecta curtains due to the various projectile shapes result in various amounts of collected mass in sampler canister, regarding which the 60° conical projectile exhibits preferable performance for impact sampling scheme. The results presented in this article are expected to reveal the dependence of the excavation process on projectile shape under micro gravity and provide further information on the optimal designs of impact sampling devices for future sample-return space missions.

  4. Effects of a large asteroid impact on ultra-violet radiation in the atmosphere

    Science.gov (United States)

    Ishida, Haruma; Kaiho, Kunio; Asano, Shoji

    2007-12-01

    The effects of sulfate aerosols produced as a result of an asteroid impact on the ultra-violet (UV) radiation are investigated by radiative transfer calculations. After an impact, a reduction in the solar incident radiation and ozone depletion are expected to occur, each of which, in turn, are counteract their on effects on the UV radiation. We estimate reasonable ranges for the amounts of sulfate aerosols and ozone depletion after an impact, and calculate the UV radiation at the Earth's surface, besides absorption in the stratosphere, by changing the aerosol and ozone concentrations within the ranges. The calculation results reveal that the UV-B (0.28-0.315 μm) radiation depends on both aerosol and ozone concentrations. The reflection of UV-B radiation by sulfate aerosols cancels out the increase in surface UV-B radiation due to ozone depletion. This study suggests that, immediately after the Chicxulub impact event, the UV-B radiation at the Earth's surface would not increase as compared to the pre-impact levels, since large amount of sulfate aerosols would exist in the stratosphere. Several years after the impact, the UV-B radiation would increase, because most of the sulfate aerosols would be removed from the atmosphere but their amount would still be enough to destroy ozone and keep it below the harmful level for terrestrial life. In case of the Chicxulub impact, an increase in the UV-B radiation would have occurred several years after the impact and might have contributed to the mass extinction at the end of the Cretaceous period.

  5. Ejecta evolutions and fates from the AIDA impact on the secondary of the binary asteroid Didymos: a NEOShield-2 project contribution

    Science.gov (United States)

    Michel, P.; Yu, Y.

    2017-09-01

    We simulated the evolutions and fates of ejecta produced by the impact of a projectile of the secondary of the binary asteroid Didymos, in the framework of the AIDA space mission project. Our results show how these evolutions and fates depend on the impact location on the secondary and ejection speeds of the ejecta. This information can be used to defined safe positions for an observing spacecraft and to better understand the outcome of an impact in the environment of a binary asteroid.

  6. Numerical and probabilistic analysis of asteroid and comet impact hazard mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Plesko, Catherine S [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Huebner, Walter F [Los Alamos National Laboratory

    2010-09-09

    The possibility of asteroid and comet impacts on Earth has received significant recent media and scientific attention. Still, there are many outstanding questions about the correct response once a potentially hazardous object (PHO) is found. Nuclear munitions are often suggested as a deflection mechanism because they have a high internal energy per unit launch mass. However, major uncertainties remain about the use of nuclear munitions for hazard mitigation. There are large uncertainties in a PHO's physical response to a strong deflection or dispersion impulse like that delivered by nuclear munitions. Objects smaller than 100 m may be solid, and objects at all sizes may be 'rubble piles' with large porosities and little strength. Objects with these different properties would respond very differently, so the effects of object properties must be accounted for. Recent ground-based observations and missions to asteroids and comets have improved the planetary science community's understanding of these objects. Computational power and simulation capabilities have improved such that it is possible to numerically model the hazard mitigation problem from first principles. Before we know that explosive yield Y at height h or depth -h from the target surface will produce a momentum change in or dispersion of a PHO, we must quantify energy deposition into the system of particles that make up the PHO. Here we present the initial results of a parameter study in which we model the efficiency of energy deposition from a stand-off nuclear burst onto targets made of PHO constituent materials.

  7. Comparison of Damage from Hydrocode Simulations of an Asteroid Airburst or Impact on Land, in Deep, or in Shallow Water

    Science.gov (United States)

    Robertson, Darrel; Wheeler, Lorien; Mathias, Donovan

    2017-01-01

    If an asteroid is discovered to be on a collision course with Earth and there is insufficient time for a deflection effort to make it miss Earth completely, should it be redirected to a land or ocean impact? While distance from densely populated areas should obviously be maximized, the differing ability of air blast, seismic waves, and tsunami waves to cause damage at distance does not make the choice between land and ocean impacts an immediately obvious one. More broadly this work is a step towards improving damage models from asteroid impacts. This extended abstract follows the hypothetical scenario of the 2017 IAA Planetary Defense Conference where a 100-250m diameter asteroid is on a potential impact course with Earth. A hydrocode was used to simulate impacts into the most sparsely populated areas along the eastern end of the hypothetical impact corridor- specifically in the Gobi Desert, in the shallow waters of the Sea of Japan, and in the deep waters of the Japan Trench in the Pacific Ocean.

  8. Discovery of a 25-cm asteroid clast in the giant Morokweng impact crater, South Africa.

    Science.gov (United States)

    Maier, W D; Andreoli, M A G; McDonald, I; Higgins, M D; Boyce, A J; Shukolyukov, A; Lugmair, G W; Ashwal, L D; Gräser, P; Ripley, E M; Hart, R J

    2006-05-11

    Meteorites provide a sample of Solar System bodies and so constrain the types of objects that have collided with Earth over time. Meteorites analysed to date, however, are unlikely to be representative of the entire population and it is also possible that changes in their nature have occurred with time. Large objects are widely believed to be completely melted or vaporized during high-angle impact with the Earth. Consequently, identification of large impactors relies on indirect chemical tracers, notably the platinum-group elements. Here we report the discovery of a large (25-cm), unaltered, fossil meteorite, and several smaller fragments within the impact melt of the giant (> 70 km diameter), 145-Myr-old Morokweng crater, South Africa. The large fragment (clast) resembles an LL6 chondrite breccia, but contains anomalously iron-rich silicates, Fe-Ni sulphides, and no troilite or metal. It has chondritic chromium isotope ratios and identical platinum-group element ratios to the bulk impact melt. These features allow the unambiguous characterization of an impactor at a large crater. Furthermore, the unusual composition of the meteorite suggests that the Morokweng asteroid incorporated part of the LL chondrite parent body not represented by objects at present reaching the Earth.

  9. The impact of oil-derived products on the behaviour and biochemistry of the eleven-armed asteroid Coscinasterias muricata (Echinodermata).

    Science.gov (United States)

    Georgiades, E T; Holdway, D A; Brennan, S E; Butty, J S; Temara, A

    2003-04-01

    The present study examines the impact of exposure to oil-derived products on the behaviour and physiology of the Australian 11-armed asteroid Coscinasterias muricata. Asteroids were exposed to dilutions of water-accommodated fraction (WAF) of Bass Strait stabilised crude oil, dispersed oil or burnt oil (n = 8) for 4 days whereby, prey-localisation behaviour was examined immediately after exposure, and following 2, 7, and 14 days depuration in clean seawater. The prey-localisation behaviour of asteroids exposed to WAF and dispersed oil was significantly affected though recovery was apparent following 7 and 14 days depuration, respectively. In contrast, there was no significant change in the prey-localisation behaviour of asteroids exposed to burnt oil. Behavioural impacts were correlated with the total petroleum hydrocarbon concentrations (C6-C36) in each exposure solution, WAF (1.8 mg l(-1)), dispersed oil (3.5 mg l(-1)) and burnt oil (1.14 mg l(-1), respectively. The total microsomal cytochrome P450 content was significantly lower (P(Dunnett test) asteroids exposed to dispersed oil than in any other asteroids, whilst asteroid alkaline phosphatase activity was not significantly affected (P(ANOVA) = 0.11). This study further documents the deleterious impact of dispersed oil to marine organisms and supports further research in the area of in situ burning as a less damaging oil spill response measure towards benthic macro-invertebrates.

  10. ASTEROID OCCULTATIONS

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid occultation events through Feb. 23, 2005, as well as asteroid occultation axes derived...

  11. Severity of ocean acidification following the end-Cretaceous asteroid impact.

    Science.gov (United States)

    Tyrrell, Toby; Merico, Agostino; Armstrong McKay, David Ian

    2015-05-26

    Most paleo-episodes of ocean acidification (OA) were either too slow or too small to be instructive in predicting near-future impacts. The end-Cretaceous event (66 Mya) is intriguing in this regard, both because of its rapid onset and also because many pelagic calcifying species (including 100% of ammonites and more than 90% of calcareous nannoplankton and foraminifera) went extinct at this time. Here we evaluate whether extinction-level OA could feasibly have been produced by the asteroid impact. Carbon cycle box models were used to estimate OA consequences of (i) vaporization of up to 60 × 10(15) mol of sulfur from gypsum rocks at the point of impact; (ii) generation of up to 5 × 10(15) mol of NOx by the impact pressure wave and other sources; (iii) release of up to 6,500 Pg C as CO2 from vaporization of carbonate rocks, wildfires, and soil carbon decay; and (iv) ocean overturn bringing high-CO2 water to the surface. We find that the acidification produced by most processes is too weak to explain calcifier extinctions. Sulfuric acid additions could have made the surface ocean extremely undersaturated (Ωcalcite <0.5), but only if they reached the ocean very rapidly (over a few days) and if the quantity added was at the top end of literature estimates. We therefore conclude that severe ocean acidification might have been, but most likely was not, responsible for the great extinctions of planktonic calcifiers and ammonites at the end of the Cretaceous.

  12. Impact of pharmacist-led medication management in care transitions

    Directory of Open Access Journals (Sweden)

    Seungwon Yang

    2017-11-01

    Full Text Available Abstract Background When patients are discharged from hospital to home, it is a highlighted vulnerable period for which medication - related problems are prevalent. Researchers have proposed a telephone follow-up intervention as a means to reduce hospital readmissions. However, the outcome of the intervention with the engagement of pharmacists in managing patients’ medicines after discharge has not been well explored. The objectives of this study were (1 to determine whether a pharmacist telephone follow-up intervention focusing on patients’ medicines management support is associated with a reduction in 30-day readmission rates and (2 to describe the number and types of pharmacist interventions in care transitions. Methods This was a case-cohort study conducted in two acute hospitals in the UK. Pharmacists performed a telephone follow-up intervention to discharged patients to provide medicines management support. Patients who received pharmacist telephone follow-up calls within 14 days of discharge formed the intervention group. A subset of medical patient population discharged in the month of May 2013 formed the comparison group. During a series of two-telephone follow-up, pharmacists identified post-discharge pharmaceutical problems and provided patient-tailored interventions accordingly. The impact of pharmacist interventions was assessed using a risk assessment matrix tool by two senior pharmacists. Overall 30-day readmission rates in the intervention group were measured and compared with the comparison group using a chi-square test. Results Between 5th and 25th June 2013, a total of 62 medical patients participated in the study. Pharmacists provided 192 interventions as a result of pharmacist telephone follow-up intervention. The most prevalent type of interventions was the provision of drug information (n=40, followed by screening patient adherence (n=30 and advising on adverse drug reactions (n=27. The impact of interventions was

  13. Identification and Dynamical Properties of Asteroid Families

    OpenAIRE

    Nesvorny, D.; Broz, M.; Carruba, V.

    2015-01-01

    Asteroids formed in a dynamically quiescent disk but their orbits became gravitationally stirred enough by Jupiter to lead to high-speed collisions. As a result, many dozen large asteroids have been disrupted by impacts over the age of the Solar System, producing groups of fragments known as asteroid families. Here we explain how the asteroid families are identified, review their current inventory, and discuss how they can be used to get insights into long-term dynamics of main belt asteroids...

  14. Impact of large-scale installation of LED lamps in a distribution system

    OpenAIRE

    UDDIN, SOHEL; SHAREF, HUSSAIN; KRAUSE, OLAV; Mohamed, Azah; HANNAN, MOHAMMAD ABDUL; ISLAM, NAZ NIAMUL

    2015-01-01

    The aim of this paper was to examine the utilization of a large number of nonlinear light emitting diode (LED) lamps in a distribution system and its impact on system power quality. Initially, harmonic and others electrical characteristics were identified by carrying out an experiment on four types of LED lamps available on the local market. On the basis of the identified characteristics, a new LED lamp model was developed in MATLAB Simulink. This model is called the time-dependent current so...

  15. Impact-Induced Activity of the Asteroid-Comet P/1996N2 Elst-Pizarro: Yes or No?

    Science.gov (United States)

    Boehnhardt, H.; Sekanina, Z.; Fiedler, A.; Rauer, H.; Schulz, R.; Tozzi, G.

    P/1996 N2 Elst-Pizarro was discovered with a tail of dust in July 1996 and was thus classified as periodic comet. From the orbit point of view it belongs to the outer asteroid belt and is very likely a member of the Themis family, a group of bodies orginating from an asteroid collision. The absence of a coma and the presence of the needle-like anti-tail in August 1996 did not exclude the possibility of a sudden emission event which could have been caused by the impact of another minor body on the object. However, with the development of a normal tail between September and November 1996 it became obvious that the dust emission episode continued at least for 2 months after perihelion, a scenario that is typical for gas-driven cometary activity. However, it is still possible that a collision triggered the event. The authors summarize the observational pro and cons for impact-induced activity in this object, possibly the first ever detected comet-asteroid of the solar system.

  16. The nature and effects of impact cratering on small bodies. [asteroids and natural satellites in solar system

    Science.gov (United States)

    Cintala, M. J.; Head, J. W.; Wilson, L.

    1979-01-01

    Collisions between asteroids and other forms of solar system debris are discussed, especially relatively high-energy, non-catastrophic collisions, the resulting craters, and the effects they should have on the surfaces and interiors of target bodies. Attention is given to the nature and formation of impact craters, as well as to shock waves and the energy (kinetic, internal) imparted through them, crater scaling, stress wave-surface interactions, impact melt, and the effects of non-escaping ejecta on the surface of the target body (rock, fine-grained regolith, porous media).

  17. Computer simulations of large asteroid impacts into oceanic and continental sites--preliminary results on atmospheric, cratering and ejecta dynamics

    Science.gov (United States)

    Roddy, D.J.; Schuster, S.H.; Rosenblatt, M.; Grant, L.B.; Hassig, P.J.; Kreyenhagen, K.N.

    1987-01-01

    Computer simulations have been completed that describe passage of a 10-km-diameter asteroid through the Earth's atmosphere and the subsequent cratering and ejecta dynamics caused by impact of the asteroid into both oceanic and continental sites. The asteroid was modeled as a spherical body moving vertically at 20 km/s with a kinetic energy of 2.6 ?? 1030 ergs (6.2 ?? 107 Mt ). Detailed material modeling of the asteroid, ocean, crustal units, sedimentary unit, and mantle included effects of strength and fracturing, generic asteroid and rock properties, porosity, saturation, lithostatic stresses, and geothermal contributions, each selected to simulate impact and geologic conditions that were as realistic as possible. Calculation of the passage of the asteroid through a U.S. Standard Atmosphere showed development of a strong bow shock wave followed by a highly shock compressed and heated air mass. Rapid expansion of this shocked air created a large low-density region that also expanded away from the impact area. Shock temperatures in air reached ???20,000 K near the surface of the uplifting crater rim and were as high as ???2000 K at more than 30 km range and 10 km altitude. Calculations to 30 s showed that the shock fronts in the air and in most of the expanding shocked air mass preceded the formation of the crater, ejecta, and rim uplift and did not interact with them. As cratering developed, uplifted rim and target material were ejected into the very low density, shock-heated air immediately above the forming crater, and complex interactions could be expected. Calculations of the impact events showed equally dramatic effects on the oceanic and continental targets through an interval of 120 s. Despite geologic differences in the targets, both cratering events developed comparable dynamic flow fields and by ???29 s had formed similar-sized transient craters ???39 km deep and ???62 km across. Transient-rim uplift of ocean and crust reached a maximum altitude of nearly

  18. LED lighting increases the ecological impact of light pollution irrespective of color temperature.

    Science.gov (United States)

    Pawson, S M; Bader, M K-F

    Recognition of the extent and magnitude of night-time light pollution impacts on natural ecosystems is increasing, with pervasive effects observed in both nocturnal and diurnal species. Municipal and industrial lighting is on the cusp of a step change where energy-efficient lighting technology is driving a shift from “yellow” high-pressure sodium vapor lamps (HPS) to new “white” light-emitting diodes (LEDs). We hypothesized that white LEDs would be more attractive and thus have greater ecological impacts than HPS due to the peak UV-green-blue visual sensitivity of nocturnal invertebrates. Our results support this hypothesis; on average LED light traps captured 48% more insects than were captured with light traps fitted with HPS lamps, and this effect was dependent on air temperature (significant light × air temperature interaction). We found no evidence that manipulating the color temperature of white LEDs would minimize the ecological impacts of the adoption of white LED lights. As such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations. Our findings highlight the urgent need for collaborative research between ecologists and electrical engineers to ensure that future developments in LED technology minimize their potential ecological effects.

  19. Characterizing Asteroid Internal Structure Through Tectonic Analyses

    Science.gov (United States)

    Wyrick, D. Y.; Buczkowski, D. L.; Durda, D. D.

    2017-02-01

    Critical data gaps remain in characterizing the mechanical strength and internal structure of asteroids. Understanding asteroid internal coherency is required to develop effective mitigation, diversion, or destruction strategies against impact threat.

  20. Asteroid photometry

    Science.gov (United States)

    Li, Jian-Yang; Helfenstein, Paul; Buratti, Bonnie J.; Takir, Driss; Beth Ellen Clark,; Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    2015-01-01

    Asteroid photometry has three major applications: providing clues about asteroid surface physical properties and compositions, facilitating photometric corrections, and helping design and plan ground-based and spacecraft observations. The most significant advances in asteroid photometry in the past decade were driven by spacecraft observations that collected spatially resolved imaging and spectroscopy data. In the mean time, laboratory measurements and theoretical developments are revealing controversies regarding the physical interpretations of models and model parameter values. We will review the new developments in asteroid photometry that have occurred over the past decade in the three complementary areas of observations, laboratory work, and theory. Finally we will summarize and discuss the implications of recent findings.

  1. Impact winter and the Cretaceous/Tertiary extinctions: Results of a Chicxulub asteroid impact model

    Science.gov (United States)

    Pope, Kevin O.; Baines, Kevin H.; Ocampo, Adriana C.; Ivanov, Boris A.

    1994-01-01

    The Chicxulub impact crater in Mexico is the site of the impact purported to have caused mass extinctions at the Cretaceous/Tertiary (K/T) boundary. 2-D hydrocode modeling of the impact, coupled with studies of the impact site geology, indiate that between 0.4 and 7.0 x 10(exp 17) g of sulfur were vaporized by the impact into anhydrite target rocks. A small portion of the sulfur was released as SO3 or SO4, which converted rapidly into H2SO4 aerosol and fell as acid rain. A radiative transfer model, coupled with a model of coagulation indicates that the aerosol prolonged the initial blackout period caused by impact dust only if the aerosol contained impurities. A larger portion of sulfur was released as SO2, which converted to aerosol slowly, due to the rate-limiting oxidation of SO2. Our radiative transfer calculations, combined with rates of acid production, coagulation, and diffusion indicate that solar transmission was reduced to 10-20% of normal for a period of 8-13 yr. This reduction produced a climate forcing (cooling) of -300 W/sq.m, which far exceeded the +8 W/sq.m greenhouse warming, caused by the CO2 released through the vaporization of carbonates, and therefore produced a decade of freezing and near-freezing temperatures. Several decades of moderate warming followed the decade of severe cooling due to the long residence time of CO2. The prolonged impact winter may have been a major cause of the K/T extinctions.

  2. Large-scale melting and impact mixing on early-formed asteroids

    DEFF Research Database (Denmark)

    Greenwood, Richard; Barrat, J.-A.; Scott, Edward Robert Dalton

    Large-scale melting of asteroids and planetesimals is now known to have taken place ex-tremely early in solar system history [1]. The first-generation bodies produced by this process would have been subject to rapid collisional reprocessing, leading in most cases to fragmentation and/or accretion...

  3. Unmelted meteoritic debris in the Late Pliocene iridium anomaly - Evidence for the ocean impact of a nonchondritic asteroid

    Science.gov (United States)

    Kyte, F. T.; Brownlee, D. E.

    1985-01-01

    Ir-bearing particles have been recovered from two piston cores in the Antarctic Basin in the southeastern Pacific. In core E13-3, the particles closely correspond to the Late Pliocene Ir anomaly and have a fluence of about 100 mg/cm sq. In core E13-4, 120 km to the southwest, the particle fluence is about 4 mg/cm sq. Particles with diameters from 0.5 to 4 mm contain at least 35 percent of the Ir in this horizon. Three types of particles have been identified: (1) vesicular, (2) basaltic, and (3) metal. The vesicular particles appear to be shock-melted debris derived from the oceanic impact of a howarditic asteroid containing a minor metal component. These particles have recrystallized from a melt and impact into the ocean has resulted in the incorporation of Na, K, Cl, and radiogenic Sr from the ocean water target. The basaltic clasts appear to be unmelted fragments of the original asteroid which may have separated from the main body prior to impact. Combined vesicular and basaltic particles are believed to have formed by collisions in the debris cloud. Estimates of the diameter of the projectile range from 100 to 500 m. By many orders of magnitude, this is the most massive achondrite sampled by a single meteorite fall.

  4. Modeling of Giant Impact into a Differentiated Asteroid and Implications for the Large-Scale Troughs on Vesta

    Science.gov (United States)

    Buczkowski, D.; Iyer, K.; Raymond, C. A.; Wyrick, D. Y.; Kahn, E.; Nathues, A.; Gaskell, R. W.; Roatsch, T.; Preusker, F.; Russell, C. T.

    2012-12-01

    Linear structures have been identified in a concentric orientation around impact craters on several asteroids (e.g. Ida [1], Eros [2], Lutetia [3]) and their formation tied to the impact event [1,2]. Images of Vesta taken by the Dawn spacecraft reveal large-scale linear structural features in a similar orientation around the Rheasilvia and Veneneia basins [4]. However, the dimensions and shape of these features suggest that they are graben similar to those observed on terrestrial planets, not fractures or grooves such as are found on Ida, Eros and Lutetia [5]. Although the fault plane analysis [4] implies that impact may have been responsible for triggering the formation of these features as on the smaller asteroids, we suggest the significantly different morphology implies that some other component must also have been involved in their development. It has been established that Vesta is a differentiated body with a core [6]. This differentiated interior could be a factor in the troughs' resemblance to planetary faults rather than asteroidal fractures, as it is predicted that the stresses resultant from impact would be amplified and reoriented compared to a similar impact on an undifferentiated body. Preliminary CTH hydrocode [7] models of a 530 km sphere composed of a basalt analog with a 220 km iron core [6] show that the impact of a 50 km object results in different patterns of tensile stress and pressure compared to an undifferentiated sphere of the same material and diameter. While these first-order models have yet to fully mimic the observations we've made on Vesta, they do demonstrate that the density contrast in Vesta's differentiated interior affects the stresses resulting from the Rheasilivia and Veneneia impacts. It is this impedance mismatch that we suggest is responsible for the development of Vesta's planet-like troughs. Thus, future identification of planetary-style tectonic features on small solar system bodies may then imply a differentiated

  5. Baby, it's cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous

    Science.gov (United States)

    Brugger, Julia; Feulner, Georg; Petri, Stefan

    2017-01-01

    Sixty-six million years ago, the end-Cretaceous mass extinction ended the reign of the dinosaurs. Flood basalt eruptions and an asteroid impact are widely discussed causes, yet their contributions remain debated. Modeling the environmental changes after the Chicxulub impact can shed light on this question. Existing studies, however, focused on the effect of dust or used one-dimensional, noncoupled atmosphere models. Here we explore the longer-lasting cooling due to sulfate aerosols using a coupled climate model. Depending on aerosol stratospheric residence time, global annual mean surface air temperature decreased by at least 26°C, with 3 to 16 years subfreezing temperatures and a recovery time larger than 30 years. The surface cooling triggered vigorous ocean mixing which could have resulted in a plankton bloom due to upwelling of nutrients. These dramatic environmental changes suggest a pivotal role of the impact in the end-Cretaceous extinction.

  6. The Impact and Oxidation Survival of Selected Meteoritic Compounds: Signatures of Asteroid Organic Material on Planetary Surfaces

    Science.gov (United States)

    Cooper, George; Horz, Fred; Oleary, Alanna; Chang, Sherwood

    2013-01-01

    Polar, non-volatile organic compounds may be present on the surfaces (or near surfaces) of multiple Solar System bodies. If found, by current or future missions, it would be desirable to determine the origin(s) of such compounds, e.g., asteroidal or in situ. To test the possible survival of meteoritic compounds both during impacts with planetary surfaces and under subsequent (possibly) harsh ambient conditions, we subjected known meteoritic compounds to relatively high impact-shock pressures and/or to varying oxidizing/corrosive conditions. Tested compounds include sulfonic and phosphonic acids (S&P), polyaromatic hydrocarbons (PAHs) amino acids, keto acids, dicarboxylic acids, deoxy sugar acids, and hydroxy tricarboxylic acids (Table 1). Meteoritic sulfonic acids were found to be relatively abundant in the Murchison meteorite and to possess unusual S-33 isotope anomalies (non mass-dependent isotope fractionations). Combined with distinctive C-S and C-P bonds, the S&P are potential signatures of asteroidal organic material.

  7. 2015 Barcelona Asteroid Day

    CERN Document Server

    Gritsevich, Maria; Palme, Herbert

    2017-01-01

    This volume is a compilation of the research presented at the International Asteroid Day workshop which was celebrated at Barcelona on June 30th, 2015. The proceedings discuss the beginning of a new era in the study and exploration of the solar system’s minor bodies. International Asteroid Day commemorates the Tunguska event of June 30th, 1908. The workshop’s goal was to promote the importance of dealing proactively with impact hazards from space. Multidisciplinary experts contributed to this discussion by describing the nature of comets and asteroids along with their offspring, meteoroids. New missions to return material samples of asteroids back to Earth such as Osiris-REx and Hayabusa 2, as well as projects like AIM and DART which will test impact deflection techniques for Potentially Hazardous Asteroids encounters were also covered. The proceedings include both an outreach level to popularize impact hazards and a scientific character which covers the latest knowledge on these topics, as well as offeri...

  8. Asteroid team

    Science.gov (United States)

    Matson, D. L.

    1986-09-01

    Work on asteroid classification continued was rewarded with the discovery of two Earth-approaching M asteroids. The M class is rare and these are the first found among the near-Earth asteroids to have the spectral albedo characteristic of this class. The two asteroids are newly discovered 1986 DA and 1986 EB which were observed at N and Q bandpasses (i.e., 10 and 20 microns) with the 3 m IRTF telescope and at five wavelengths from 0.36 to 0.85 microns from Kitt peak National Observatory's 0.36 m telescope. The derived diameters are about 2 km for both objects. In the asteroid radiometry program N or Q photometry was obtained for more than 40 asteroids in Feb. 1986. Radiometric diameter calibration support were provided for stellar occultations of stars by 230 Athamantis and 129 Antigone. The data were reduced but not analyzed. Infrared spectra (0.8 to 2.6 microns) of 60 asteroids were reduced and are now ready for compositional analysis.

  9. Asteroid team

    Science.gov (United States)

    Matson, D. L.

    1986-01-01

    Work on asteroid classification continued was rewarded with the discovery of two Earth-approaching M asteroids. The M class is rare and these are the first found among the near-Earth asteroids to have the spectral albedo characteristic of this class. The two asteroids are newly discovered 1986 DA and 1986 EB which were observed at N and Q bandpasses (i.e., 10 and 20 microns) with the 3 m IRTF telescope and at five wavelengths from 0.36 to 0.85 microns from Kitt peak National Observatory's 0.36 m telescope. The derived diameters are about 2 km for both objects. In the asteroid radiometry program N or Q photometry was obtained for more than 40 asteroids in Feb. 1986. Radiometric diameter calibration support were provided for stellar occultations of stars by 230 Athamantis and 129 Antigone. The data were reduced but not analyzed. Infrared spectra (0.8 to 2.6 microns) of 60 asteroids were reduced and are now ready for compositional analysis.

  10. Asteroid Generated Tsunami Workshop: Summary of NASA/NOAA Workshop

    Science.gov (United States)

    Morrison, David; Venkatapathy, Ethiraj

    2017-01-01

    A two-day workshop on tsunami generated by asteroid impacts in the ocean resulted in a broad consensus that the asteroid impact tsunami threat is not as great as previously thought, that airburst events in particular are unlikely to produce significant damage by tsunami, and that the tsunami contribution to the global ensemble impact hazard is substantially less than the contribution from land impacts. The workshop, led by Ethiraj Venkatapathy and David Morrison of NASA Ames, was organized into three sessions: 1) Near-field wave generation by the impact; 2) Long distance wave propagation; 3) Damage from coastal run-up and inundation, and associated hazard. Workshop approaches were to compare simulations to understand differences in the results and gain confidence in the modeling for both formation and propagation of tsunami from asteroid impacts, and to use this information for preliminary global risk assessment. The workshop focus was on smaller asteroids (diameter less than 250m), which represent the most frequent impacts.

  11. Peer-Led Learning Communities: Exploring Integrative High-Impact Educational Practices for Leadership Education

    Science.gov (United States)

    Priest, Kerry L.; de Campos Paula, Ana Luiza

    2016-01-01

    The use of high-impact practices is well documented in higher education literature. This brief describes the integrative practice of undergraduate peer-led leadership learning communities as a model of delivery within a large introductory leadership education course for first-year students. Utilizing open-ended questions embedded within…

  12. The Manson impact crater: Estimation of the energy of formation, possible size of the impacting asteroid or comet, and ejecta volume and mass

    Science.gov (United States)

    Roddy, D. J.; Shoemaker, E. M.; Anderson, R. R.

    1993-01-01

    A research program on the Manson impact structure has substantially improved our knowledge of the detailed features of this eroded crater. As part of our structural studies, we have derived a value of 21 km for the diameter of the final transient cavity formed during crater excavation. With this information, we can estimate the energy of formation of the Manson crater and the possible size of the impacting asteroid or comet. In addition, we have estimated the near- and far-field ejecta volumes and masses.

  13. The impact of individual materials parameters on color temperature reproducibility among phosphor converted LED sources

    Science.gov (United States)

    Schweitzer, Susanne; Nemitz, Wolfgang; Sommer, Christian; Hartmann, Paul; Fulmek, Paul; Nicolics, Johann; Pachler, Peter; Hoschopf, Hans; Schrank, Franz; Langer, Gregor; Wenzl, Franz P.

    2014-09-01

    For a systematic approach to improve the white light quality of phosphor converted light-emitting diodes (LEDs) for general lighting applications it is imperative to get the individual sources of error for color temperature reproducibility under control. In this regard, it is imperative to understand how compositional, optical and materials properties of the color conversion element (CCE), which typically consists of phosphor particles embedded in a transparent matrix material, affect the constancy of a desired color temperature of a white LED source. In this contribution we use an LED assembly consisting of an LED die mounted on a printed circuit board (PCB) by chip-on-board technology and a CCE with a glob-top configuration as a model system and discuss the impact of potential sources for color temperature deviation among individual devices. Parameters that are investigated include imprecisions in the amount of materials deposition, deviations from the target value for the phosphor concentration in the matrix material, deviations from the target value for the particle sizes of the phosphor material, deviations from the target values for the refractive indexes of phosphor and matrix material as well as deviations from the reflectivity of the substrate surface. From these studies, some general conclusions can be drawn which of these parameters have the largest impact on color deviation and have to be controlled most precisely in a fabrication process in regard of color temperature reproducibility among individual white LED sources.

  14. Structure and origin of Australian ring and dome features with reference to the search for asteroid impact events

    Science.gov (United States)

    Glikson, Andrew

    2018-01-01

    Ring, dome and crater features on the Australian continent and shelf include (A) 38 structures of confirmed or probable asteroid and meteorite impact origin and (B) numerous buried and exposed ring, dome and crater features of undefined origin. A large number of the latter include structural and geophysical elements consistent with impact structures, pending test by field investigations and/or drilling. This paper documents and briefly describes 43 ring and dome features with the aim of appraising their similarities and differences from those of impact structures. Discrimination between impact structures and igneous plugs, volcanic caldera and salt domes require field work and/or drilling. Where crater-like morphological patterns intersect pre-existing linear structural features and contain central morphological highs and unique thrust and fault patterns an impact connection needs to tested in the field. Hints of potential buried impact structures may be furnished by single or multi-ring TMI patterns, circular TMI quiet zones, corresponding gravity patterns, low velocity and non-reflective seismic zones.

  15. Summary of Results from Analyses of Deposits of the Deep-Ocean Impact of the Eltanin Asteroid

    Science.gov (United States)

    Kyte, Frank T.; Kuhn, Gerhard; Gersonde, Rainer

    2005-01-01

    Deposits of the late Pliocene (2.5 Ma) Eltanin impact are unique in the known geological record. The only known example of a km-sized asteroid to impact a deep-ocean (5 km) basin, is the most meterorite-rich locality known. This was discovered as an Ir anomaly in sediments from three cores collected in 1965 by the USNS Eltanin. These cores contained mm-sized shock-melted asteroid materials and unmelted meteorite fragments. Mineral chemistry of meteorite fragments, and siderophole concentrations in melt rocks, indicate that the parent asteroid was a low-metal (4\\%) mesosiderite. A geological exploration of the impact in 1995 by Polarstern expedition ANT-XIV4 was near the Freeden Seamounts (57.3S, 90.5 W), and successfully collected three cores with impact deposits. Analyses showed that sediments as old as Eocene were eroded by the impact disturbance and redeposited in three distinct units. The lowermost is a chaotic assemblage of sediment fragments up to 50 cm in size. Above this is a laminated sand-rich unit that deposited as a turbulent flow, and this is overlain by a more fine-grained deposit of silts and clays that settled from a cloud of sediment suspended in the water column. Meteoritic ejecta particles were concentrated near the base of the uppermost unit, where coarse ejecta caught up with the disturbed sediment. Here we will present results from a new suite of cores collected on Polarstern expedition ANT-XVIIU5a. In 2001, the Polarstern returned to the impact area and explored a region of 80,000 sq-km., collecting at least 16 sediment cores with meteoritic ejecta. The known strewn field extends over a region 660 by 200 km. The meteoritic ejecta is most concentrated in cores on the Freeden seamounts, and in the basins to the north, where the amount of meteoritic material deposited on the ocean floor was as much as 3 g/sq-cm. These concentrations drop off to the north and the east to levels as low as approximately 0.1 g/sq-cm. We were unable to sample the

  16. The asteroid lightcurve database

    Czech Academy of Sciences Publication Activity Database

    Warner, B. D.; Harris, A. W.; Pravec, Petr

    2009-01-01

    Roč. 202, č. 1 (2009), s. 134-146 ISSN 0019-1035 R&D Projects: GA ČR(CZ) GA205/05/0604 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * rotation * photometry Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.340, year: 2009

  17. Thermochemical equilibrium calculations of high-temperature O2 generation on the early Earth: Giant asteroid impacts on land

    Directory of Open Access Journals (Sweden)

    PAVLE I. PREMOVIC

    2003-02-01

    Full Text Available Earth’s atmosphere is composed primarily of N2 and O2. The origin of free O2 in the early Earth’s atmosphere is still subject of considerable debate.1 Theoretical models suggest that the initial form of free O2 in the atmosphere has been oceanic H2O. Recent computation modelling has suggested that a superheated (ca. 2000 K H2O vapor atmosphere of 1.4x1021 kg (the present mass of the oceans lasting for about 3000 y could probably have been formed on Earth by an enormous (ca. 1028 J asteroid impact. In this report, the occurrence of the thermochemical dissociation of the vapor, creating a primitive oxygenic (ca. 0.1 of the present level (PAL of free O2 atmosphere.

  18. [Comment on “Old and new ideas visited for comet and asteroid hazard mitigation strategies” by J. Wakefield] Clarifying a few points about impact mitigation strategies

    Science.gov (United States)

    Morrison, David

    The article on impact mitigation studies [Eos, August 30, 1994] raises some interesting points about the hazard of asteroid and comet impacts but betrays a major misunderstanding of the mitigation strategies under study. It refers repeatedly to Strategic Defense Initiative (SDI) or “Star Wars” systems and tries to discuss their merits without giving the reader any hint of what these mysterious new technologies are or how they may relate to mitigation of impacts. In fact, detecting, intercepting, and deflecting a kilometer-scale asteroid or comet at ranges from the Earth of tens of millions of kilometers has little in common with the missile detection and defense systems developed as part of the SDI program, no more than you would use a rifle to shoot down an Inter-Continental Ballistic Missile. The one example mentioned, the Air Force GEODSS system of wide-field telescopes, was not a part of SDI. In addition, the article seriously overstates the current discovery rate of kilometer-scale near Earth asteroids, which are currently found at a rate of several per year, not several per month (the several per month refers to all near Earth asteroids found, most of which are less than 1 km in diameter).

  19. Environments and extinctions at the K-T boundary in eastern Montana are compatible with an asteroid impact

    Energy Technology Data Exchange (ETDEWEB)

    Fastovsky, D.E. (Univ. of Rhode Island, Kingston, RI (United States)); Sheehan, P.M. (Milwaukee Public Museum, WI (United States))

    1992-01-01

    In the terrestrial latest Cretaceous Hell Creek (HC) Formation, both non-biotic events and patterns of extinction and survivorship are consistent with an asteroid impact causing the extinctions. Environments through the last 2--3 million-year interval represented by the HC remained relatively constant: an aggrading coastal lowland dissected by meandering rivers. The K-T boundary occurred during an abrupt change to impeded drainage represented by coals and pond deposits formed under low-energy conditions. Because of the close temporal proximity of the sediments of the Paleocene Cannonball Sea to the K-T boundary in South Dakota, impeded drainage in the earliest Paleocene in eastern Montana may be attributable to riverine base-level changes associated with a renewed transgression of the western interior sea during the K-T transition. Patterns within the biota mirror those of the paleoenvironments. The ecological diversity of HC dinosaurs remains statistically unchanged through HC time. Analyses of vertebrates at the species level indicate a differential extinction in which the terrestrial biota underwent far more extinction than its aquatic counterpart. There is no evidence for changing environments in the upper HC, and there is circumstantial evidence that the latest Cretaceous was a time of renewed transgression rather than regression. Likewise, biotic patterns do not accord with gradual, environmentally driven extinctions. While the paleoenvironmental change that marks the K-T transition in eastern Montana accounts for some of the extinctions, the pattern of differential extinction is concordant with an asteroid impact. In this scenario, aquatic ecosystems and some land-based food chains would be buffered by detritus-based feeding. Terrestrial systems, dependent upon primary productivity, would undergo a short-term loss of resources causing extinctions.

  20. Implications of theories of asteroid and comet impact for policy options for management of spent nuclear fuel and high-level radioactive wastes

    Science.gov (United States)

    Trask, Newell J.

    1994-01-01

    Concern with the threat posed by terrestrial asteroid and comet impacts has heightened as the catastrophic consequences of such events have become better appreciated. Although the probabilities of such impacts are very small, a reasonable question for debate is whether such phenomena should be taken into account in deciding policy for the management of spent fuel and high-level radioactive waste. The rate at which asteroid or comet impacts would affect areas of surface storage of radioactive waste is about the same as the estimated rate at which volcanic activity would affect the Yucca Mountain area. The Underground Retrievable Storage (URS) concept could satisfactorily reduce the risk from cosmic impact with its associated uncertainties in addition to providing other benefits described by previous authors.

  1. Asteroid airburst altitude vs. strength

    Science.gov (United States)

    Robertson, D. K.; Wheeler, L.; Mathias, D.

    2016-12-01

    The entry and break-up of small asteroids were simulated with a hydrocode to examine the effect of strength, size, composition, entry angle, and speed on the resulting airburst. A strong asteroid, such as a monolithic boulder, structurally fail and deposit most of their energy around the altitude at which dynamic ram pressure exceeds the cohesive strength of the asteroid. A weaker asteroid, such as a loose rubble pile, will structurally fail at high altitude, but continue to fly through the atmosphere as a single unit until reaching lower altitudes where the increased aerodynamic pressure is sufficient to disrupt and disperse the rubble resulting in a flare. Airburst from weak asteroids consequently have a peak energy deposition at similar altitudes.This study focuses on small NEO asteroids which are likely to airburst rather than impact the ground where the damage created on the ground depends strongly on the altitude at which most of the energy is deposited in the atmosphere. The ability to accurately predict ground damage is useful in determining appropriate evacuation or shelter plans and emergency management. Airbursting asteroids are not a threat on a national level but can still cause a significant amount of local damage as demonstrated by the Chelyabinsk event where there was over $33 million worth of damage (1 billion roubles) and 1500 were injured by flying glass.

  2. Computer simulations of 10-km-diameter asteroid impacts into oceanic and continental sites: Preliminary results on atmospheric passage, cratering and ejecta dynamics

    Science.gov (United States)

    Roddy, D. J.; Schuster, S. H.; Rosenblatt, Martin; Grant, L. B.; Hassig, P. J.; Kreyenhagen, K. N.

    1987-01-01

    A series of analytical calculations of large scale cratering events for both oceanic and continental sites were made in order to examine their effects on the target media and atmosphere. The first analytical studies that were completed consists of computer simulations of the dynamics of: (1) the passage of a 10 km diameter asteroid moving at 20 km/sec through the Earth's atmosphere, and (2) the impact cratering events in both oceanic and continental environments. Calculation of the dynamics associated with the passage of the asteroid through the atmosphere showed strong effects on the surrounding air mass. The calculations of the impact cratering events showed equally dramatic effects on the oceanic and continental environments. These effects are briefly discussed.

  3. On the possibility of using small asteroids for deflecting near-Earth asteroids

    Science.gov (United States)

    Akiyama, Yuki; Bando, Mai; Hokamoto, Shinji

    2016-04-01

    This paper presents the trajectory design and analysis of the near-Earth asteroid (NEA) deflection mission enabled by a kinetic impact of an intermediate asteroid. The sequential transfer trajectory is designed by solving two Lambert's problems that yield a chain collision between a spacecraft and an intermediate asteroid, followed by a collision between the intermediate asteroid and an NEA. The characteristics of the low-cost trajectories are then identified with respect to the optimal collision point. We show that the feasibility of the mission depends on the existence of an intermediate asteroid with small minimum orbit interception distance (MOID) with the NEA. Moreover the selection strategy of an intermediate asteroid that makes the mission feasible is discussed. We show that several asteroids exist that allow a 10 ton spacecraft with limited ΔV to be launched and impact the NEA 99442 Apophis allowing a deflection given several years warning time.

  4. Double Asteroid Redirection Test (DART) element of AIDA mission

    Science.gov (United States)

    Cheng, A.; Michel, P.; Rivkin, A.; Barnouin, O.; Stickle, A.; Miller, P.; Chesley, S.; Richardson, D.

    2017-09-01

    The AIDA mission, an international cooperation between NASA and ESA, will be the first demonstration of a kinetic impactor spacecraft to deflect an asteroid. AIDA will perform the first hypervelocity impact on an asteroid where the impact conditions are fully known and the target properties are also characterized. AIDA will reduce risks for any future asteroid hazard mitigation.

  5. Determining the Motions of Near Earth Asteroids Through Optical Observations

    National Research Council Canada - National Science Library

    Campbell, Douglas

    2000-01-01

    An Earth impact with an asteroid has potentially devastating consequences. In order to avoid global destruction, astronomers have been attempting to map out the orbits of all possibly hazardous Near-Earth Asteroids (NEAs...

  6. Investigating the Effects of Temperature on the Signatures of Shocks Propagated Through Impacts into Minerals Found in Comets and Asteroids

    Science.gov (United States)

    Lederer, Susan M.; Jensen, E. A.; Fane, M.; Smith, D. C.; Holmes, J.; Keller, L. P.; Lindsay, S. S.; Wooden, D. H.; Cintala, M. J.; Zolensky, M. E.

    2015-01-01

    Comets and asteroids are subjected to extremely cold conditions throughout their lifetimes. During their sojourns in the solar system, they are subjected to collisions at speeds that are easily capable of generating shock waves in their constituent materials. In addition to ices, more common silicate minerals such as olivines and pyroxenes are important components of these objects. The collision-induced shocks could affect the spectral signatures of those mineral components, which could in turn be detected telescopically. We have embarked on a project to determine how impact-generated shock might affect the reflectance spectra and structures of select silicates as both impact speed and target temperature are varied systematically. While the effects of impact speed (in the form of shock stress) on numerous materials have been and continue to be studied, the role of target temperature has received comparatively little attention, presumably because of the operational difficulties it can introduce to experimentation. Our experiments were performed with the vertical gun in the Experimental Impact Laboratory of the Johnson Space Center. A liquid-nitrogen system was plumbed to permit cooling of the target container and its contents under vacuum to temperatures as low as -100 C (173 K). Temperatures were monitored by thermocouples mounted on the outside of the target container. Because those sensors were not in contact with the target material at impact, the measured temperatures are treated as lower limits for the actual values. Peridot (Mg-rich olivine) and enstatite (Mg-rich orthopyroxene) were used as targets, which involved the impact of alumina (Al2O3) spheres at speeds of 2.0 - 2.7 km s(exp -1) and temperatures covering 25 C to -100 C (298 K to 173 K). We have begun collecting and analyzing data in the near to mid-IR with a Fourier-transform infrared spectrometer, and preliminary analyses show that notable differences in absorption-band strength and position occur

  7. Child-led and interest-inspired learning, home education, learning differences and the impact of regulation

    National Research Council Canada - National Science Library

    Liberto, Giuliana

    2016-01-01

    ...), Australia, identified clear benefits of a child-led, interest-inspired approach to learning and a negative impact on student learning and well-being outcomes, particularly for learning-differenced...

  8. An Investigation of LED Street Lighting's Impact on Sky Glow

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, Bruce R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Perrin, Tess E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Miller, Naomi J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kocifaj, Miroslav [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Aube, Martin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lamphar, Hector A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-04-25

    A significant amount of public attention has recently focused on perceived impacts of converting street lighting from incumbent lamp-based products to LED technology. Much of this attention pertains to the higher content of short wavelength light (commonly referred to as "blue light") of LEDs and its attendant influences on sky glow (a brightening of the night sky that can interfere with astronomical observation and may be associated with a host of other issues). The complexity of this topic leads to common misunderstandings and misperceptions among the public, and for this reason the U.S. Department of Energy Solid-State Lighting Program embarked on a study of sky glow using a well-established astronomical model to investigate some of the primary factors influencing sky glow. This report details the results of the investigation and attempts to present those results in terms accessible to the general lighting community. The report also strives to put the results into a larger context, and help educate interested readers on various topics relevant to the issues being discussed.

  9. Initial velocity V-shapes of young asteroid families

    Science.gov (United States)

    Bolin, Bryce T.; Walsh, Kevin J.; Morbidelli, Alessandro; Delbó, Marco

    2018-01-01

    Ejection velocity fields of asteroid families are largely unconstrained due to the fact that members disperse relatively quickly on Myr time-scales by secular resonances and the Yarkovsky effect. The spreading of fragments in a by the Yarkovsky effect is indistinguishable from the spreading caused by the initial ejection of fragments. By examining families Asteroid families that are asteroid families including the 1993 FY12, Aeolia, Brangane, Brasilia, Clarissa, Iannini, Karin, Konig, Koronis(2), Theobalda and Veritas asteroid families. We find that the majority of asteroid families have initial ejection velocity fields consistent with ∼D-1 supporting laboratory impact experiments and computer simulations of disrupting asteroid parent bodies.

  10. Data Report: A Search for Deposits of the Late Pliocene Impact of the Eltanin Asteroid in Rise Sediments from the Antarctic Peninsula, Site 1096

    Science.gov (United States)

    Kyte, Frank T.

    2003-01-01

    Concentrations of Ir have been measured in 87 sediment samples from Ocean Drilling Program Site 1096 in search of evidence of fallout from the impact of the Eltanin asteroid, which occurred at 2.15 Ma, approx. 1300 km northwest of the site. An additional six samples were measured from a unique sand layer and adjacent sediments that are dated at approx. 1.6 Ma. These 93 sediment samples are all silts and muds that were deposited on a continental rise drift of the Antarctic Peninsula. No evidence of the Eltanin impact deposit was found in this study.

  11. Impact of an asteroid or comet in the ocean and extinction of terrestrial life

    Science.gov (United States)

    Ahrens, T. J.; Okeefe, J. D.

    1982-01-01

    Finite difference calculations describing the impact mechanics associated with a 10 to 30 km diameter silicate or water object impacting a 5 km deep ocean overlying a silicate solid planet demonstrate that from 12 to 15% of the bolide energy resides in the water. It is speculated that minimal global tsunami run-up heights on the continents would be 300-400 meters, and that such waves would inundate all low altitude continental areas, and strip and silt-over virtually all vegetation. As a result the terrestrial animal food chain would be seriously perturbed. This could in turn cause extinction of large terrestrial animals.

  12. Variations in magnetic properties of target basalts with the direction of asteroid impact: Example from Lonar crater, India

    Science.gov (United States)

    Arif, Md.; Basavaiah, N.; Misra, S.; Deenadayalan, K.

    2012-08-01

    The Lonar crater in Maharashtra state, India, has been completely excavated on the Deccan Traps basalt (approximately 65 Ma) at approximately 570 ± 47 ka by an oblique impact of a possible chondritic asteroid that struck the preimpact target from the east at an angle of approximately 30-45o to the horizon where the total duration of the shock event was approximately 1 s. It is shown by our early work that the distribution of ejecta and deformation of target rocks around the crater rim are symmetrical to the east-west plane of impact (Misra et al. 2010). The present study shows that some of the rock magnetic properties of these shocked target basalts, e.g., low-field anisotropy of magnetic susceptibility (AMS), natural remanent magnetization (NRM)/bulk susceptibility (χ), and high-coercivity and high-temperature (HC_HT) magnetization component, are also almost symmetrically oriented with reference to the plane of impact. Studies on the relative displacements of K3 (minimum) AMS axes of shocked basalts from around the crater rim and from the adjacent target rocks to the approximately 2-3 km west of the crater center suggest that the impact stress could have branched out into the major southwestward and northwestward components in the downrange direction immediately after the impact. The biaxial distribution of AMS axes in stereographic plots for the unshocked basalts transforms mostly into triaxial distribution for the shocked basalts, although transitional type distribution also exists. The degree of anisotropy (P') of AMS ellipsoids of the shocked basalts decreases by approximately 2% when compared with those of the unshocked target (approximately 1.03). The NRM/χ (Am-1) values of the shocked basalts on the rim of the Lonar crater do not show much change in the uprange or downrange direction on and close to the east-west plane of impact, and the values are only approximately 1.5 times higher on average over the unshocked basalts around the crater. However, the

  13. Designing global climate and atmospheric chemistry simulations for 1 and 10 km diameter asteroid impacts using the properties of ejecta from the K-Pg impact

    Science.gov (United States)

    Toon, Owen B.; Bardeen, Charles; Garcia, Rolando

    2016-10-01

    About 66 million years ago, an asteroid about 10 km in diameter struck the Yucatan Peninsula creating the Chicxulub crater. The crater has been dated and found to be coincident with the Cretaceous-Paleogene (K-Pg) mass extinction event, one of six great mass extinctions in the last 600 million years. This event precipitated one of the largest episodes of rapid climate change in Earth's history, yet no modern three-dimensional climate calculations have simulated the event. Similarly, while there is an ongoing effort to detect asteroids that might hit Earth and to develop methods to stop them, there have been no modern calculations of the sizes of asteroids whose impacts on land would cause devastating effects on Earth. Here, we provide the information needed to initialize such calculations for the K-Pg impactor and for a 1 km diameter impactor. There is considerable controversy about the details of the events that followed the Chicxulub impact. We proceed through the data record in the order of confidence that a climatically important material was present in the atmosphere. The climatic importance is roughly proportional to the optical depth of the material. Spherules with diameters of several hundred microns are found globally in an abundance that would have produced an atmospheric layer with an optical depth around 20, yet their large sizes would only allow them to stay airborne for a few days. They were likely important for triggering global wildfires. Soot, probably from global or near-global wildfires, is found globally in an abundance that would have produced an optical depth near 100, which would effectively prevent sunlight from reaching the surface. Nanometer-sized iron particles are also present globally. Theory suggests these particles might be remnants of the vaporized asteroid and target that initially remained as vapor rather than condensing on the hundred-micron spherules when they entered the atmosphere. If present in the greatest abundance allowed

  14. Designing global climate and atmospheric chemistry simulations for 1 and 10 km diameter asteroid impacts using the properties of ejecta from the K-Pg impact

    Directory of Open Access Journals (Sweden)

    O. B. Toon

    2016-10-01

    Full Text Available About 66 million years ago, an asteroid about 10 km in diameter struck the Yucatan Peninsula creating the Chicxulub crater. The crater has been dated and found to be coincident with the Cretaceous–Paleogene (K-Pg mass extinction event, one of six great mass extinctions in the last 600 million years. This event precipitated one of the largest episodes of rapid climate change in Earth's history, yet no modern three-dimensional climate calculations have simulated the event. Similarly, while there is an ongoing effort to detect asteroids that might hit Earth and to develop methods to stop them, there have been no modern calculations of the sizes of asteroids whose impacts on land would cause devastating effects on Earth. Here, we provide the information needed to initialize such calculations for the K-Pg impactor and for a 1 km diameter impactor. There is considerable controversy about the details of the events that followed the Chicxulub impact. We proceed through the data record in the order of confidence that a climatically important material was present in the atmosphere. The climatic importance is roughly proportional to the optical depth of the material. Spherules with diameters of several hundred microns are found globally in an abundance that would have produced an atmospheric layer with an optical depth around 20, yet their large sizes would only allow them to stay airborne for a few days. They were likely important for triggering global wildfires. Soot, probably from global or near-global wildfires, is found globally in an abundance that would have produced an optical depth near 100, which would effectively prevent sunlight from reaching the surface. Nanometer-sized iron particles are also present globally. Theory suggests these particles might be remnants of the vaporized asteroid and target that initially remained as vapor rather than condensing on the hundred-micron spherules when they entered the atmosphere. If present in the

  15. Looking Before We Leap: Recent Results From An Ongoing Quantitative Investigation Of Asteroid And Comet Impact Hazard Mitigation.

    Science.gov (United States)

    Plesko, Catherine; Weaver, R. P.; Korycansky, D. G.; Huebner, W. F.

    2010-10-01

    The asteroid and comet impact hazard is now part of public consciousness, as demonstrated by movies, Super Bowl commercials, and popular news stories. However, there is a popular misconception that hazard mitigation is a solved problem. Many people think, `we'll just nuke it.’ There are, however, significant scientific questions remaining in the hazard mitigation problem. Before we can say with certainty that an explosive yield Y at height of burst h will produce a momentum change in or dispersion of a potentially hazardous object (PHO), we need to quantify how and where energy is deposited into the rubble pile or conglomerate that may make up the PHO. We then need to understand how shock waves propagate through the system, what causes them to disrupt, and how long gravitationally bound fragments take to recombine. Here we present numerical models of energy deposition from an energy source into various materials that are known PHO constituents, and rigid body dynamics models of the recombination of disrupted objects. In the energy deposition models, we explore the effects of porosity and standoff distance as well as that of composition. In the dynamical models, we explore the effects of fragment size and velocity distributions on the time it takes for gravitationally bound fragments to recombine. Initial models indicate that this recombination time is relatively short, as little as 24 hours for a 1 km sized PHO composed of 1000 meter-scale self-gravitating fragments with an initial velocity field of v/r = 0.001 1/s.

  16. Impact experiments. III - Catastrophic fragmentation of aggregate targets and relation to asteroids

    Science.gov (United States)

    Ryan, Eileen V.; Hartmann, William K.; Davis, Donald R.

    1991-01-01

    An experimental study is conducted of collisions employing artificial aggregates as targets, in order to ascertain the fragmentation characteristics of weakly bonded bodies that consist of stronger constituent particles, such as loosely aggregated planetesimals. It is established that weakly bonded aggregate bodies may exhibit unexpectedly high impact strengths due to constituent particles' energy dissipation. The cumulative size distributions of fragments that are larger than the constituent grains form power-law segments resembling those formed by the fragmentation of homogeneous targets.

  17. Widespread mixing and burial of Earth's Hadean crust by asteroid impacts.

    Science.gov (United States)

    Marchi, S; Bottke, W F; Elkins-Tanton, L T; Bierhaus, M; Wuennemann, K; Morbidelli, A; Kring, D A

    2014-07-31

    The history of the Hadean Earth (∼4.0-4.5 billion years ago) is poorly understood because few known rocks are older than ∼3.8 billion years old. The main constraints from this era come from ancient submillimetre zircon grains. Some of these zircons date back to ∼4.4 billion years ago when the Moon, and presumably the Earth, was being pummelled by an enormous flux of extraterrestrial bodies. The magnitude and exact timing of these early terrestrial impacts, and their effects on crustal growth and evolution, are unknown. Here we provide a new bombardment model of the Hadean Earth that has been calibrated using existing lunar and terrestrial data. We find that the surface of the Hadean Earth was widely reprocessed by impacts through mixing and burial by impact-generated melt. This model may explain the age distribution of Hadean zircons and the absence of early terrestrial rocks. Existing oceans would have repeatedly boiled away into steam atmospheres as a result of large collisions as late as about 4 billion years ago.

  18. Solar wind tans young asteroids

    Science.gov (United States)

    2009-04-01

    A new study published in Nature this week reveals that asteroid surfaces age and redden much faster than previously thought -- in less than a million years, the blink of an eye for an asteroid. This study has finally confirmed that the solar wind is the most likely cause of very rapid space weathering in asteroids. This fundamental result will help astronomers relate the appearance of an asteroid to its actual history and identify any after effects of a catastrophic impact with another asteroid. ESO PR Photo 16a/09 Young Asteroids Look Old "Asteroids seem to get a ‘sun tan' very quickly," says lead author Pierre Vernazza. "But not, as for people, from an overdose of the Sun's ultraviolet radiation, but from the effects of its powerful wind." It has long been known that asteroid surfaces alter in appearance with time -- the observed asteroids are much redder than the interior of meteorites found on Earth [1] -- but the actual processes of this "space weathering" and the timescales involved were controversial. Thanks to observations of different families of asteroids [2] using ESO's New Technology Telescope at La Silla and the Very Large Telescope at Paranal, as well as telescopes in Spain and Hawaii, Vernazza's team have now solved the puzzle. When two asteroids collide, they create a family of fragments with "fresh" surfaces. The astronomers found that these newly exposed surfaces are quickly altered and change colour in less than a million years -- a very short time compared to the age of the Solar System. "The charged, fast moving particles in the solar wind damage the asteroid's surface at an amazing rate [3]", says Vernazza. Unlike human skin, which is damaged and aged by repeated overexposure to sunlight, it is, perhaps rather surprisingly, the first moments of exposure (on the timescale considered) -- the first million years -- that causes most of the aging in asteroids. By studying different families of asteroids, the team has also shown that an asteroid

  19. Dynamical properties measurements for asteroid, comet and meteorite material applicable to impact modeling and mitigation calculations

    Science.gov (United States)

    Furnish, M. D.; Boslough, M. B.; Gray, G. T., III; Remo, J. L.

    We describe methods for measuring dynamical properties for two material categories of interest in understanding large-scale extraterrestrial impacts: iron-nickel and underdense materials (e.g. snow). Particular material properties measured by the present methods include Hugoniot release paths and constitutive properties (stress vs. strain). The iron-nickel materials lend themselves well to conventional shock and quasi-static experiments. As examples, a suite of experiments is described including six impact tests (wave profile compression/release) over the stress range 2-20 GPa, metallography, quasi-static and split Hopkinson pressure bar (SHPB) mechanical testing, and ultrasonic mapping and sound velocity measurements. Temperature sensitivity of the dynamic behavior was measured at high and low strain rates. Among the iron-nickel materials tested, an octahedrite was found to have behavior close to that of Armco iron under shock and quasi-static conditions, while an ataxite exhibited a significantly larger quasi-static yield strength than did the octahedrite or a hexahedrite. The underdense materials pose three primary experimental difficulties. First, the samples are friable; they can melt or sublimate during storage, preparation and testing. Second, they are brittle and crushable; they cannot withstand such treatment as traditional machining or launch in a gun system. Third, with increasing porosity the calculated Hugoniot density becomes rapidly more sensitive to errors in wave time-of-arrival measurements. Carefully chosen simulants eliminate preservation (friability) difficulties, but the other difficulties remain. A family of 36 impact tests was conducted on snow and snow simulants at Sandia, yielding reliable Hugoniot and reshock states, but limited release property information. Other methods for characterizing these materials are discussed.

  20. Basaltic Asteroids in the Solar System

    Science.gov (United States)

    Duffard, René

    2009-09-01

    Basaltic asteroids are small bodies connected to the processes of heating and melting that may have led to the mineralogical differentiation in the interiors of the largest asteroids. Therefore, a precise knowledge of the inventory of basaltic asteroids may help to estimate how many differentiated bodies actually formed in the asteroid Main Belt and this in turn may provide important constraints to the primordial conditions of the solar nebula. The identification of basaltic asteroids in the asteroid Main Belt and the description of their surface mineralogy are necessary to understand the diversity in the collection of basaltic meteorites. In this work the current work of our team is presented: (i) The mineralogical characterization of the Vesta family members; (ii) The search of new basaltic asteroids in the Main Belt. In the first case, the objective is to characterize the material excavated from the craterization event/s in the crust of Vesta. This work is related to the possible findings of DAWN mission when it arrives to Vesta in 2011. In the second case, the objective is to find the link between the diversity of basaltic material in the meteorite collection and the asteroids.

  1. Possibility of production of amino acids by impact reaction using a light-gas gun as a simulation of asteroid impacts.

    Science.gov (United States)

    Okochi, Kazuki; Mieno, Tetsu; Kondo, Kazuhiko; Hasegawa, Sunao; Kurosawa, Kosuke

    2015-06-01

    In order to investigate impact production of carbonaceous products by asteroids on Titan and other satellites and planets, simulation experiments were carried out using a 2-stage light gas gun. A small polycarbonate or metal bullet with about 6.5 km/s was injected into a pressurized target chamber filled with 1 atm of nitrogen gas, to collide with a ice + iron target or an iron target or a ice + hexane + iron target. After the impact, black soot including fine particles was deposited on the chamber wall. The soot was carefully collected and analyzed by High Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FT-IR), and Laser Desorption Time-of-Flight Mass Spectrometry (LD-ToF-MS). As a result of the HPLC analysis, about 0.04-8 pmol of glycine, and a lesser amount of alanine were found in the samples when the ice + hexane + iron target was used. In case of the ice + iron target and the iron target, less amino acids were produced. The identification of the amino acids was also supported by FTIR and LD-ToF-MS analysis.

  2. Possibility of Production of Amino Acids by Impact Reaction Using a Light-Gas Gun as a Simulation of Asteroid Impacts

    Science.gov (United States)

    Okochi, Kazuki; Mieno, Tetsu; Kondo, Kazuhiko; Hasegawa, Sunao; Kurosawa, Kosuke

    2015-06-01

    In order to investigate impact production of carbonaceous products by asteroids on Titan and other satellites and planets, simulation experiments were carried out using a 2-stage light gas gun. A small polycarbonate or metal bullet with about 6.5 km/s was injected into a pressurized target chamber filled with 1 atm of nitrogen gas, to collide with a ice + iron target or an iron target or a ice + hexane + iron target. After the impact, black soot including fine particles was deposited on the chamber wall. The soot was carefully collected and analyzed by High Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FT-IR), and Laser Desorption Time-of-Flight Mass Spectrometry (LD-ToF-MS). As a result of the HPLC analysis, about 0.04-8 pmol of glycine, and a lesser amount of alanine were found in the samples when the ice + hexane + iron target was used. In case of the ice + iron target and the iron target, less amino acids were produced. The identification of the amino acids was also supported by FTIR and LD-ToF-MS analysis.

  3. The asteroids as outcomes of catastrophic collisions

    Energy Technology Data Exchange (ETDEWEB)

    Farinella, P. (Osservatorio Astronomico di Brera, Merate, Italy); Paolicchi, P.

    1982-12-01

    The role of catastrophic collisions in the evoloution of the asteroids is discussed in detail, employing extrapolations of experimental results on the outcome of high velocity-impacts. The probability of impacts with a given projectile-to-target mass ratio for asteroids of different sizes is derived, taking into account different mass distributions of the asteroid population at the beginning of the collision process. The extrapolations show that collisional breakup against solid-state cohesions must be a widespread process for asteroids. The influence of self-gravitation and transfer of angular momentum during collision is shown to depend strongly on the traget size, resulting in a variety of possible outcomes in the intermediate size range. Comparason of the theoretical results with observations of asteroid rotations and shapes yields favorable results.

  4. Impact of dimming white LEDs: chromaticity shifts due to different dimming methods

    Science.gov (United States)

    Dyble, Marc; Narendran, Nadarajah; Bierman, Andrew; Klein, Terence

    2005-09-01

    The goal of this study was to characterize the chromaticity shift that mixed-color and phosphor-converted white LED systems undergo when dimmed. As light-emitting diodes continue to rapidly evolve as a viable light source for lighting applications, their color shift while being dimmed should meet the current requirements of traditional lighting sources. Currently, LED system manufacturers commonly recommend pulse-width-modulation or PWM dimming schemes for operation of LED systems. PWM has the ability to achieve lower intensity levels and more linear control of light intensity compared to continuous current dimming methods. However, little data has been published on the effect dimming has on chromaticity shift of white LED lighting systems. The primary objective of this study was to quantify chromaticity shifts in mixed-color and phosphor-converted white LED systems due to continuous current dimming and pulse-width-modulation dimming schemes. In this study, the light output of the LED system was reduced from 100% to 3% by means of continuous current reduction or PWM methods using a PC white LED system and a mixed-color RGB LED system. Experimental results from this study showed that the PC white LED system exhibited very little chromaticity shift (less than a 4-step MacAdam ellipse) when the light level was changed from 100% to 3% using both dimming schemes. Compared to PC white LEDs, the mixed-color RGB LED system tested in this study showed very large chromaticity shifts in a similar dimming range using both dimming schemes. If a mixed-color RGB system is required, then some active feedback system control must be incorporated to obtain non-perceivable chromaticity shift. In this regard the chromaticity shift caused by the PWM method is easier to correct than the chromaticity shift caused by the continuous current dimming method.

  5. Herschel observations of the Marco Polo-R asteroid 175706 (1996 FG3).

    Science.gov (United States)

    O'Rourke, L.; Barucci, A.; Gònzalez-Garcìa, B.; Dotto, E.; Küppers, M.

    2012-09-01

    Background: The Marco Polo-R mission has been selected for the assessment study phase of the ESA M3 missions. This ESA-led sample return mission to the binary asteroid 1996 FG3 (launch window between 2020 and 2024) is proposed with a design that allows it to fit within the pre-defined cost cap of a M-class mission. The binary nature of the target will allow more precise measurements of mass, gravity, and density than for a single object, as well as additional insights into the geology and geophysics of the system. The asteroid has been classified by Binzel et al. [1] as a C-type. It is considered to be a typical example of a primitive object [2]. Dynamically, this is an Apollo asteroid with semimajor axis a of 1.054 AU, eccentricity e of 0.35, and and inclination i of 1.98 degrees. Measurements of the albedo derived from thermal infrared observations give a value of pV = 0.042 (+0.035 -0.017), and a combined diameter of D = 1.84 (+0.56 -0.47) km [3]. The Herschel observations : The MACH-11 (Measurements of 11 Asteroids & Comets) Programme observed this binary asteroid in two occasions in November of 2012. The observations performed had a duration of 0.6 hours with the asteroid pair moving rapidly at 6'/hr thus making removal of the background quite straightforward. The observations were performed in two observing blocks; the first block consisted of a 2 repetition blue/red map, the second block consisted of a 2 repetition green/red map, with the intention to observe the target at different phase angles. Our Results : Our measurements will serve to update the known radiometric properties for this binary asteroid through their inclusion into a thermophysical model (TPM) [4] which has been validated against a large database of asteroids including targets of other spacecraft mission e.g. Lutetia [5], Itokawa [6]. Using existing sets of published thermal observations (Spitzer, TNG NICS), combined with our Herschel observations, applied within this thermophysical model

  6. Asteroid Family Associations of Active Asteroids

    Science.gov (United States)

    Hsieh, Henry H.; Novaković, Bojan; Kim, Yoonyoung; Brasser, Ramon

    2018-02-01

    We report on the results of a systematic search for associated asteroid families for all active asteroids known to date. We find that 10 out of 12 main-belt comets (MBCs) and five out of seven disrupted asteroids are linked with known or candidate families, rates that have ∼0.1% and ∼6% probabilities, respectively, of occurring by chance, given the overall family association rate of 37% for asteroids in the main asteroid belt. We find previously unidentified family associations between 238P/Read and the candidate Gorchakov family, 311P/PANSTARRS and the candidate Behrens family, 324P/La Sagra and the Alauda family, 354P/LINEAR and the Baptistina family, P/2013 R3-B (Catalina-PANSTARRS) and the Mandragora family, P/2015 X6 (PANSTARRS) and the Aeolia family, P/2016 G1 (PANSTARRS) and the Adeona family, and P/2016 J1-A/B (PANSTARRS) and the Theobalda family. All MBCs with family associations belong to families that contain asteroids with primitive taxonomic classifications and low average reported albedos (\\overline{{p}V}≲ 0.10), while disrupted asteroids with family associations belong to families that contain asteroids that span wider ranges of taxonomic types and average reported albedos (0.06p}V}young asteroid families could lead to the production of present-day MBCs.

  7. ATLAS: Finding the Nearest Asteroids

    Science.gov (United States)

    Heinze, Aren; Tonry, John L.; Denneau, Larry; Stalder, Brian

    2017-10-01

    The Asteroid Terrestrial-impact Last Alert System (ATLAS) became fully operational in June 2017. Our two robotic, 0.5 meter telescopes survey the whole accessible sky every two nights from the Hawaiian mountains of Haleakala and Mauna Loa. With sensitivity to magnitude 19.5 over a field of 30 square degrees, we discover several bright near-Earth objects every month - particularly fast moving asteroids, which can slip by other surveys that scan the sky more slowly. Several important developments in 2017 have enhanced our sensitivity to small, nearby asteroids and potential impactors. We report on these developments - including optical adjustments, automated screening of detections, closer temporal spacing of images, and tolerance for large deviations from Great Circle motion on the sky - and we describe their effect in terms of measuring and discovering real objects.

  8. Impact of LED irradiance on plant photosynthesis and action spectrum of plantlet

    Science.gov (United States)

    Naznin, Most Tahera; Lefsrud, Mark G.

    2014-09-01

    Light emitting diodes (LEDs) can be selected to target the wavelengths absorbed by plantlets, enabling the users to customize the wavelengths of light required for maximum production. The primary purpose of this experiment was to test the effect of different ratios of red to blue LEDs on tomato plantlets photosynthetic action spectrum. Four light treatments including: red LED (100%) and three ratios of red (661 nm) to blue (449 nm) light (5:1, 10:1 and 19:1) at 60 umol m-2 s-1 for this study. The tomato plantlets cultured without blue light showed a three and half-fold decrease in photosynthesis rate. The highest photosynthetic action spectrum was observed at 10:1 but was not significantly difference from the 5:1 and the lowest action spectrum was observed at 100% red LED light. The tomato plantlets grown without the blue light showed a single-fold increase in plantlet height but were not significantly different from the 10:1 red to blue LED light. This research will allow for improved selection of LED lighting for plant tissue culture.

  9. Assessing the Impact of a Multi-Disciplinary Peer-Led-Team Learning Program on Undergraduate STEM Education

    Science.gov (United States)

    Carlson, Kerri; Celotta, Dayius Turvold; Curran, Erin; Marcus, Mithra; Loe, Melissa

    2016-01-01

    There has been a national call to transition away from the traditional, passive, lecture-based model of STEM education towards one that facilitates learning through active engagement and problem solving. This mixed-methods research study examines the impact of a supplemental Peer-Led Team Learning (PLTL) program on knowledge and skill acquisition…

  10. Impact of watering with UV-LED-treated wastewater on microbial and physico-chemical parameters of soil.

    Science.gov (United States)

    Chevremont, A-C; Boudenne, J-L; Coulomb, B; Farnet, A-M

    2013-04-15

    Advanced oxidation processes based on UV radiations have been shown to be a promising wastewater disinfection technology. The UV-LED system involves innovative materials and could be an advantageous alternative to mercury-vapor lamps. The use of the UV-LED system results in good water quality meeting the legislative requirements relating to wastewater reuse for irrigation. The aim of this study was to investigate the impact of watering with UV-LED treated wastewaters (UV-LED WW) on soil parameters. Solid-state ¹³C NMR shows that watering with UV-LED WW do not change the chemical composition of soil organic matter compared to soil watered with potable water. Regarding microbiological parameters, laccase, cellulase, protease and urease activities increase in soils watered with UV-LED WW which means that organic matter brought by the effluent is actively degraded by soil microorganisms. The functional diversity of soil microorganisms is not affected by watering with UV-LED WW when it is altered by 4 and 8 months of watering with wastewater (WW). After 12 months, functional diversity is similar regardless of the water used for watering. The persistence of faecal indicator bacteria (coliform and enterococci) was also determined and watering with UV-LED WW does not increase their number nor their diversity unlike soils irrigated with activated sludge wastewater. The study of watering-soil microcosms with UV-LED WW indicates that this system seems to be a promising alternative to the UV-lamp-treated wastewaters. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. ASTEROID LIGHTCURVE DERIVED DATA

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a compilation of published rotational parameters derived from lightcurve data for asteroids, based on the Warner et al. (2009) Asteroid Lightcurve Database....

  12. Evaluation of a Peer-Led Hypertension Intervention for Veterans: Impact on Peer Leaders

    Science.gov (United States)

    Mosack, Katie E.; Patterson, Leslie; Brouwer, Amanda M.; Wendorf, Angela R.; Ertl, Kristyn; Eastwood, Dan; Morzinski, Jeffrey; Fletcher, Kathlyn; Whittle, Jeff

    2013-01-01

    Volunteer peer leaders (PLs) benefit from their involvement in health interventions but we know little about how they compare with other non-PL volunteers or with the intervention recipients themselves. We randomized 58 veterans' service organizations' posts (e.g. VFW) to peer- versus professionally led self-management support interventions. Our…

  13. Pathways to recovery (PTR): impact of peer-led group participation on mental health recovery outcomes.

    Science.gov (United States)

    Fukui, Sadaaki; Davidson, Lori J; Holter, Mark C; Rapp, Charles A

    2010-01-01

    This study examined the positive effects on recovery outcomes for people with severe and persistent mental illness using peer-led groups based on Pathways to Recovery: A Strengths Recovery Self-Help Workbook (PTR). PTR translates the evidence-supported practice of the Strengths Model into a self-help approach, allowing users to identify and pursue life goals based on personal and environmental strengths. A single-group pretest-posttest research design was applied. Forty-seven members in 6 consumer-run organizations in one Midwestern state participated in a PTR peer-led group, completing a baseline survey before the group and again at the completion of the 12-week sessions. The Rosenberg Self-Esteem Scale, the General Self-Efficacy Scale, Multidimensional Scale of Perceived Social Support, the Spirituality Index of Well-Being, and the Modified Colorado Symptom Index were employed as recovery outcomes. Paired Hotelling's T-square test was conducted to examine the mean differences of recovery outcomes between the baseline and the completion of the group. Findings revealed statistically significant improvements for PTR participants in self-esteem, self-efficacy, social support, spiritual well-being, and psychiatric symptoms. This initial research is promising for establishing PTR as an important tool for facilitating recovery using a peer-led group format. The provision of peer-led service has been emphasized as critical to integrating consumers' perspectives in recovery-based mental health services. Given the current federal funding stream for peer services, continued research into PTR and other peer-led services becomes more important.

  14. Asteroid volatiles inventory

    Science.gov (United States)

    Lebofsky, L. A.; Jones, T. D.; Herbert, F.

    1989-01-01

    Asteroids appear in light of telescopic and meteority studies to be the most accessible repositories of early solar system history available. In the cooler regions of the outer asteroid belt, apparently unaffected by severe heating, the C, P, and D populations appear to harbor significant inventories of volatiles; the larger primordial belt population may have had an even greater percentage of volatile-rich, low-albedo asteroids, constituting a potent asteroid for veneering early terrestrial planet atmospheres. The volatile-rich asteroids contain carbon, structurally bound and adsorbed water, as well as remnants of interstellar material predating the solar system.

  15. Integrating Family as a Discipline by Providing Parent Led Curricula: Impact on LEND Trainees' Leadership Competency.

    Science.gov (United States)

    Keisling, Bruce L; Bishop, Elizabeth A; Roth, Jenness M

    2017-05-01

    Background While the MCH Leadership Competencies and family as a discipline have been required elements of Leadership Education in Neurodevelopmental and related Disabilities (LEND) programs for over a decade, little research has been published on the efficacy of either programmatic component in the development of the next generation of leaders who can advocate and care for Maternal and Child Health (MCH) populations. Objective To test the effectiveness of integrating the family discipline through implementation of parent led curricula on trainees' content knowledge, skills, and leadership development in family-centered care, according to the MCH Leadership Competencies. Methods One hundred and two long-term (≥ 300 h) LEND trainees completed a clinical and leadership training program which featured intensive parent led curricula supported by a full-time family faculty member. Trainees rated themselves on the five Basic and Advanced skill items that comprise MCH Leadership Competency 8: Family-centered Care at the beginning and conclusion of their LEND traineeship. Results When compared to their initial scores, trainees rated themselves significantly higher across all family-centered leadership competency items at the completion of their LEND traineeship. Conclusions The intentional engagement of a full-time family faculty member and parent led curricula that include didactic and experiential components are associated with greater identification and adoption by trainees of family-centered attitudes, skills, and practices. However, the use of the MCH Leadership Competencies as a quantifiable measure of program evaluation, particularly leadership development, is limited.

  16. Asteroid rotation control via a tethered solar sail

    Science.gov (United States)

    Gao, Youtao; Wu, Jingyun

    2016-12-01

    The rotation of asteroids causes difficulties in the exploration of asteroids or prevention of asteroids impact on the Earth. We propose to use a solar sail to control, i.e., slow down or stop the rotational motion of an asteroid. First, the dynamic model of a tethered solar sail in the rotating gravitational field of an asteroid is presented. An optimal control method is employed to determine the control law of the tethered solar sail. The optimal control problem is converted into a nonlinear programming problem with the Gauss pseudospectral method. Simulation results show that this method can effectively slow down or even stop the rotation of an asteroid. A solar sail of 105 m2 can stop the rotation of the asteroid Apophis in 1000 days.

  17. Marketing data: has the rise of impact factor led to the fall of objective language in the scientific article?

    Science.gov (United States)

    Fraser, Véronique J; Martin, James G

    2009-05-11

    The language of science should be objective and detached and should place data in the appropriate context. The aim of this commentary was to explore the notion that recent trends in the use of language have led to a loss of objectivity in the presentation of scientific data. The relationship between the value-laden vocabulary and impact factor among fundamental biomedical research and clinical journals has been explored. It appears that fundamental research journals of high impact factors have experienced a rise in value-laden terms in the past 25 years.

  18. Potential environmental impacts from the metals in incandescent, compact fluorescent lamp (CFL), and light-emitting diode (LED) bulbs.

    Science.gov (United States)

    Lim, Seong-Rin; Kang, Daniel; Ogunseitan, Oladele A; Schoenung, Julie M

    2013-01-15

    Artificial lighting systems are transitioning from incandescent to compact fluorescent lamp (CFL) and light-emitting diode (LED) bulbs in response to the U.S. Energy Independence and Security Act and the EU Ecodesign Directive, which leads to energy savings and reduced greenhouse gas emissions. Although CFLs and LEDs are more energy-efficient than incandescent bulbs, they require more metal-containing components. There is uncertainty about the potential environmental impacts of these components and whether special provisions must be made for their disposal at the end of useful life. Therefore, the objective of this study is to analyze the resource depletion and toxicity potentials from the metals in incandescent, CFL, and LED bulbs to complement the development of sustainable energy policy. We assessed the potentials by examining whether the lighting products are to be categorized as hazardous waste under existing U.S. federal and California state regulations and by applying life cycle impact-based and hazard-based assessment methods (note that "life cycle impact-based method" does not mean a general life cycle assessment (LCA) but rather the elements in LCA used to quantify toxicity potentials). We discovered that both CFL and LED bulbs are categorized as hazardous, due to excessive levels of lead (Pb) leachability (132 and 44 mg/L, respectively; regulatory limit: 5) and the high contents of copper (111,000 and 31,600 mg/kg, respectively; limit: 2500), lead (3860 mg/kg for the CFL bulb; limit: 1000), and zinc (34,500 mg/kg for the CFL bulb; limit: 5000), while the incandescent bulb is not hazardous (note that the results for CFL bulbs excluded mercury vapor not captured during sample preparation). The CFLs and LEDs have higher resource depletion and toxicity potentials than the incandescent bulb due primarily to their high aluminum, copper, gold, lead, silver, and zinc. Comparing the bulbs on an equivalent quantity basis with respect to the expected lifetimes of

  19. The Rise of Student-to-Student Learning: Youth-led Programs Impacting Engineering Education Globally

    Directory of Open Access Journals (Sweden)

    Julian O'Shea

    2011-07-01

    Full Text Available Around the globe, students and young engineers are playing an increasing role in the coordination and delivery of engineering education programs. Many youth-led initiatives are now conducted with students involved in all aspects of their creation, organisation and delivery. This trend presents an exciting opportunity for the education of engineering students, both those involved in delivery of the courses and for participants. This paper profiles four leading youth-led engineering education programs and analyses their structure and growth in recent years. Profiled are initiatives coordinated by Engineers Without Borders – Australia (EWB-A; the Board of European Students of Technology (BEST; the Electrical Engineering Students’ European Association (EESTEC; and the Student Platform for Engineering Education Development (SPEED. Each case study includes a brief history of the organisation, program overview, growth analysis and future projections. The common features amongst these programs were analysed, as were the aspects which made them distinct from traditional university offerings. Key findings about the initiatives include: an international focus; the mixture of formal learning and social aspects; an integral role of volunteers within the organisation; the use of residential programs; and the role of internal professional development of committee members and volunteers. Additionally, this paper outlines the benefits for universities and provides a guide for how engineering faculties can support and nurture these initiatives and effectively create partnerships.

  20. Los Alamos and Lawrence Livermore National Laboratories Code-to-Code Comparison of Inter Lab Test Problem 1 for Asteroid Impact Hazard Mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Robert P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Miller, Paul [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Howley, Kirsten [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ferguson, Jim Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gisler, Galen Ross [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Plesko, Catherine Suzanne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Managan, Rob [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Owen, Mike [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wasem, Joseph [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bruck-Syal, Megan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-01-15

    The NNSA Laboratories have entered into an interagency collaboration with the National Aeronautics and Space Administration (NASA) to explore strategies for prevention of Earth impacts by asteroids. Assessment of such strategies relies upon use of sophisticated multi-physics simulation codes. This document describes the task of verifying and cross-validating, between Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), modeling capabilities and methods to be employed as part of the NNSA-NASA collaboration. The approach has been to develop a set of test problems and then to compare and contrast results obtained by use of a suite of codes, including MCNP, RAGE, Mercury, Ares, and Spheral. This document provides a short description of the codes, an overview of the idealized test problems, and discussion of the results for deflection by kinetic impactors and stand-off nuclear explosions.

  1. Caenorhabditis elegans as a model to study the impact of exposure to light emitting diode (LED) domestic lighting.

    Science.gov (United States)

    Abdel-Rahman, Fawzia; Okeremgbo, Bethel; Alhamadah, Fatimah; Jamadar, Sakha; Anthony, Kevin; Saleh, Mahmoud A

    2017-04-16

    This study aimed to investigate the biological impact of exposure on domestic light emitting diodes (LED) lighting using the free-living nematode Caenorhabditis elegans as a model. Nematodes were separately exposed to white LED light covering the range of 380-750 nm, blue light at 450 nm and black light at 380-420 nm for one life cycle (egg to adult) with dark exposure as the control. Each light range induced stress to the nematode C. elegans such as reducing the number of the hatched eggs and/or delayed the maturation of the hatched eggs to the adult stage. In addition, it lowered or prevented the ability of adults to lay eggs and impaired the locomotion in the exposed worms. The observed type of biological stress was also associated with the production of reactive oxygen species (ROS) as compared to nematodes grown in the dark. It is concluded that the blue light component of white LED light may cause health problems, and further investigation is required to test commercial brands of white LEDs that emit different amounts of blue light.

  2. Identifying asteroid families >2 Gyrs-old

    Science.gov (United States)

    Bolin, Bryce T.; Morbidelli, Alessandro; Delbo, Marco; Walsh, Kevin J.

    2017-10-01

    There are only a few known Main Belt (MB) asteroid families with ages >2 Gyr. The lack of ancient families may be due to a bias in current techniques used to identify families. Ancient asteroid family fragments disperse in their orbital elements (a,e,i), due to secular resonances and the Yarkovsky effect (YE) making them difficult to identify. We have developed a new technique that is insensitive to the resonant spreading of fragments in e and i by searching for V-shaped correlations between family members in a vs 1/Diameter space. Our V-shape technique is demonstrated on known families and used to discover a 4 Gyr-old family linking most dark asteroids in the inner MB previously not included in any known family. In addition, the 4 Gyr-old family reveals asteroids with D >35 km that are do not belong to any asteroid family implying that they originally accreted from the protoplanetary disk.The V-shape detection tool is also a powerful analysis tool by finding the boundary of an asteroid family and fitting for its shape. Following the proposed relationship between thermal inertia (TI) with D, we find that asteroids YE drift rate might have a more complex size dependence than previous thought, leading to a curved family boundary in a vs 1/D space. The V-shape tool is capable of detecting this on synthetic families and was deployed on >30 families located throughout the MB to find this effect and quantify the YE size-dependent drift rate. We find that there is no correlation between family age and V-shape curvature. In addition, the V-shape curvature decreases for asteroid families with larger a suggesting that the relationship between TI and D is weaker in the outer MB.By examining families asteroid families have initial velocity fields scaling with 1/D supporting impact experiments.

  3. The impact of a pharmacist-led educational interview on medication adherence of Saudi patients with epilepsy.

    Science.gov (United States)

    AlAjmi, Refah; Al-Aqeel, Sinaa; Baz, Salah

    2017-01-01

    To evaluate the effectiveness of a pharmacist-led educational interview in terms of adherence to antiepileptic drug administration among adult patients with epilepsy. Sixty adult patients with epilepsy who fulfilled the inclusion criteria were recruited. A pharmacist-led educational interview was conducted with the intervention group (n=30). Patients in the control group (n=30) were interviewed and contacted 6 weeks after the initial visit without receiving any intervention. Antiepileptic drug adherence was measured during clinic visits, and 6 weeks afterwards using the 8-item Morisky Medication Adherence Scale. This prospective interventional study was conducted between September and December 2013. Only 29 control patients and 27 intervention patients completed the 6 weeks post-intervention adherence measurement. The adherence score average in the intervention group was 5.26±0.98 at baseline and improved to 6.7±0.823 (Peducational interviews had a positive impact on medication adherence in patients with epilepsy.

  4. Clinical impact of a pharmacist-led inpatient anticoagulation service: a review of the literature

    Directory of Open Access Journals (Sweden)

    Lee T

    2016-05-01

    Full Text Available Tiffany Lee, Erin Davis, Jason Kielly School of Pharmacy, Memorial University, St John's, NL, Canada Background: Anticoagulant therapies provide management options for potentially life-threatening thromboembolic conditions. They also carry significant safety risks, requiring careful consideration of medication dose, close monitoring, and follow-up. Inpatients are particularly at risk, considering the widespread use of anticoagulants in hospitals. This has prompted the introduction of safety goals for anticoagulants in Canada and the USA, which recommend increased pharmacist involvement to reduce patient harm. The goal of this review is to evaluate the efficacy and safety of pharmacist-led inpatient anticoagulation services compared to usual or physician-managed care. Methods: This narrative review includes articles identified through a literature search of PubMed, Embase, and International Pharmaceutical Abstracts databases, as well as hand searches of the references of relevant articles. Full publications of pharmacist-managed inpatient anticoagulation services were eligible if they were published in English and assessed clinical outcomes. Results: Twenty-six studies were included and further divided into two categories: 1 autonomous pharmacist-managed anticoagulation programs (PMAPs and 2 pharmacist recommendation. Pharmacist management of heparin and warfarin appears to result in improvements in some surrogate outcomes (international normalized ratio [INR] stability and time in INR goal range, while results for others are mixed (time to therapeutic INR, length of stay, and activated partial thromboplastin time [aPTT] measures. There is also some indication that PMAPs may be associated with reduced patient mortality. When direct thrombin inhibitors are managed by pharmacists, there seems to be a shorter time to therapeutic aPTT and a greater percentage of time in the therapeutic range, as well as a decrease in the frequency of medication

  5. Near-Earth Asteroid Tracking (NEAT) Program

    Science.gov (United States)

    Helin, Eleanor F.; Pravdo, Steven H.; Rabinowitz, David L.; Lawrence, Kenneth J.

    1997-01-01

    The discoveries of near-Earth asteroids (NEA's) and comets have increased enormously over the last 10-20 years. This is a consequence in large par; of the success of programs that have systematically searched for these objects. These programs have been motivated by the relationships of NEA's to terrestrial impacts, meteorites, comets, and their relative accessibility to spacecraft missions. This paper will review the long-term Palomar Planet Crossing Asteroid Survey (PCAS) a photographic program and the current Near-Earth Asteroid Tracking (NEAT) system NASA's new electronic detection program. The primary goal of NEAT is to discover and inventory near-Earth asteroids and comets, collectively called near-Earth objects or NEO's, larger than 1 km in size. Details of the NEAT system and program results are presented and discussed.

  6. Light pollution modelling the UK Highways Agency new environmental policy, inc. astronomical impact of blue-rich LED luminaires.

    Science.gov (United States)

    Baddiley, Christopher James

    2015-08-01

    The Highways Agency are replacing their policy of full cut off class G6 road lighting specification on motorways (originally based on the author’s work), and are adopting a categorised environmental impact based point system that can accommodate technical advances, such as LED lighting. The Skyglow component of this will be based on the modelling of skyglow versus cut-off angle, developed for determining the relative light pollution environmental impact of different streetlight designs, by the author. Further modelling has been done concerning the effect of LED lighting, which potentially, has highly directional properties. But increasingly used blue rich colour temperatures may increase skyglow by 5 fold, compared to traditional lighting. This is due to enhanced reflection of vegetation and greatly increased atmospheric molecular Rayleigh scattering; a potential astronomical environmental disaster.Prior to this, the author carried out a dark sky survey of the Malvern Hills area of outstanding natural beauty (AONB), relating it to the same light pollution model. The results confirm the general predictions of the model and also clearly illustrate the relative significance of different designs of light sources at different distances, to the dark sky environment.The paper also briefly describes the results from the same model adapted to study the night-time environmental impact of a proposed very large sea based wind farm project in the English Channel, as a part of the planning process.

  7. The large crater on the small Asteroid (2867) Steins

    Science.gov (United States)

    Burchell, M. J.; Leliwa-Kopystynski, J.

    2010-12-01

    The maximum size of impact craters on finite bodies marks the largest impact that can occur short of impact induced disruption of the body. Recently attention has started to focus on large craters on small bodies such as asteroids and rocky and icy satellites. Here the large crater on the recently imaged Asteroid (2867) Steins (with crater diameter to mean asteroid radius ratio of 0.79) is shown to follow a limit set by other similar sized bodies with moderate macroporosity (i.e. fractured asteroids). Thus whilst large, the crater size is not novel, nor does it require Steins to possess an extremely large porosity. In one of the components of the binary Asteroid (90) Antiope there is the recently reported presence of an extremely large depression, possibly a crater, with depression diameter to mean asteroid radius ratio of ˜(1.4-1.62). This is consistent with the maximum size of a crater expected from previous observations of very porous rocky bodies (i.e. rubble-pile asteroids). Finally, a relationship between crater diameter (normalised to body radius) is proposed as a function of body porosity which suggests that the doubling of porosity between fractured asteroids and rubble-pile asteroids, nearly doubles the size ( D/ R value) of the largest crater sustainable on a rocky body.

  8. The Potentially Dangerous Asteroid (101955 Bennu

    Directory of Open Access Journals (Sweden)

    I. Włodarczyk

    2014-01-01

    searching for close approaches with the earth, which can lead to possible impacts up to 2200. With the A2 nongravitational parameter in the motion of the asteroid (101955 Bennu we computed possible impact solutions using different JPL planetary and lunar ephemerides and different number of additional massive perturbed asteroids. The possible impact path of risk for 2175 is presented. Additionally, we computed possible impact solutions using the normal places method of the selection of Bennu’s astrometric observations. Moreover, we computed time evolution of the mean orbital elements and the orbital nodes of Bennu 5 kyr in the backwards and 1 kyr in the future using the Yarkovsky effects. We computed the mean motion and secular orbital resonances of the Bennu. We also computed the influence of the JPL planetary and lunar ephemerides DE403, DE405, DE406, DE414, and DE423 on the close approaches of the asteroid (101955 Bennu with the earth.

  9. Transformation products formation of ciprofloxacin in UVA/LED and UVA/LED/TiO2 systems: Impact of natural organic matter characteristics.

    Science.gov (United States)

    Li, Si; Hu, Jiangyong

    2018-04-01

    The role of natural organic matter (NOM) in contaminants removal by photolysis and photocatalysis has aroused increasing interest. However, evaluation of the influence of NOM characteristics on the transformation products (TPs) formation and transformation pathways of contaminants has rarely been performed. This study investigated the decomposition kinetics, mineralization, TPs formation and transformation pathways of antibiotic ciprofloxacin (CIP) during photolysis and photocatalysis in the presence of three commercial NOM isolates (Sigma-Aldrich humic acid (SAHA), Suwannee River humic acid (SRHA) and Suwannee River NOM (SRNOM)) by using UVA light emitting diode (UVA/LED) as an alternative light source. NOM isolates insignificantly affected CIP photolysis but strongly inhibited CIP photocatalysis due to competitive radical quenching. The inhibitory effect followed the order of SAHA (49.6%) > SRHA (29.9%) > SRNOM (21.2%), consistent with their •OH quenching abilities, SUVA254 values and orders of aromaticity. Mineralization rates as revealed by F- release were negatively affected by NOM during CIP photocatalysis. TPs arising from hydroxylation and defluorination were generally suppressed by NOM isolates in UVA/LED and UVA/LED/TiO2 systems. In contrast, dealkylation and oxidation of piperazine ring were promoted by NOM. The enhancement in the apparent formation kinetics (kapp) of TP245, TP291, TP334a, TP334b and TP362 followed the order of SRNOM > SRHA > SAHA. kapp values were positively correlated with O/C ratio, carboxyl content, E2/E3 and fluorescence index (FI) of NOM and negatively related with SUVA254 values. The observed correlations indicate that NOM properties are important in determining the fate and transformation of organic contaminants during photolysis and photocatalysis. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Asteroids and Amateur Astronomers.

    Science.gov (United States)

    Gunter, Jay U.

    1985-01-01

    Traces asteroid discoveries by amateurs from the 19th century to the present. The importance and necessity of amateur work are noted, especially with reference to observing and documenting occultations (one object passes directly in front of another which is farther away). Suggestions are made for viewing asteroids as a hobby. (DH)

  11. SEVEN COLOR ASTEROID SURVEY

    Data.gov (United States)

    National Aeronautics and Space Administration — The Seven-color Asteroid Survey(SCAS) consists of photometry in seven filters from 0.9 to 2.3 microns, of a total of 126 asteroids of types S, K, and M.

  12. Consumer-led health-related online sources and their impact on consumers: An integrative review of the literature.

    Science.gov (United States)

    Laukka, Elina; Rantakokko, Piia; Suhonen, Marjo

    2017-04-01

    The aim of the review was to describe consumer-led health-related online sources and their impact on consumers. The review was carried out as an integrative literature review. Quantisation and qualitative content analysis were used as the analysis method. The most common method used by the included studies was qualitative content analysis. This review identified the consumer-led health-related online sources used between 2009 and 2016 as health-related online communities, health-related social networking sites and health-related rating websites. These sources had an impact on peer support; empowerment; health literacy; physical, mental and emotional wellbeing; illness management; and relationships between healthcare organisations and consumers. The knowledge of the existence of the health-related online sources provides healthcare organisations with an opportunity to listen to their consumers' 'voice'. The sources make healthcare consumers more competent actors in relation to healthcare, and the knowledge of them is a valuable resource for healthcare organisations. Additionally, these health-related online sources might create an opportunity to reduce the need for drifting among the healthcare services. Healthcare policymakers and organisations could benefit from having a strategy of increasing their health-related online sources.

  13. Access to diagnostics in primary care and the impact on a primary care led health service.

    LENUS (Irish Health Repository)

    O'Riordan, M

    2015-02-01

    We undertook a postal survey of GPs to establish their current access to radiological and endoscopic tests. More than one fifth of GPs do not have direct access to abdominal (n = 42, 21.4%) or pelvic (n = 49, 24.6%) ultrasound in the public system. Where access is available public patients have an average 14 week waiting period. In stark contrast in the private system virtually all GPs have direct access (n = 159, 99.2% and n = 156, 98.8% respectively for abdominal and pelvic ultrasound) with an average wait of just over four days. Direct access to CT scan in the public system is available to the minority of GPs, e.g. n = 31, 18.4% for chest scan, in the public system; even where available, there is an average 12 week wait for this. In comparison 151 (88.6%) GPs have access to CT chest scanning in the private sector with an average waiting time of 5.4 working days. Such limited access to diagnostics impacts on the delivery of a quality service.

  14. Thermal fatigue as the origin of regolith on small asteroids.

    Science.gov (United States)

    Delbo, Marco; Libourel, Guy; Wilkerson, Justin; Murdoch, Naomi; Michel, Patrick; Ramesh, K T; Ganino, Clément; Verati, Chrystele; Marchi, Simone

    2014-04-10

    Space missions and thermal infrared observations have shown that small asteroids (kilometre-sized or smaller) are covered by a layer of centimetre-sized or smaller particles, which constitute the regolith. Regolith generation has traditionally been attributed to the fall back of impact ejecta and by the break-up of boulders by micrometeoroid impact. Laboratory experiments and impact models, however, show that crater ejecta velocities are typically greater than several tens of centimetres per second, which corresponds to the gravitational escape velocity of kilometre-sized asteroids. Therefore, impact debris cannot be the main source of regolith on small asteroids. Here we report that thermal fatigue, a mechanism of rock weathering and fragmentation with no subsequent ejection, is the dominant process governing regolith generation on small asteroids. We find that thermal fragmentation induced by the diurnal temperature variations breaks up rocks larger than a few centimetres more quickly than do micrometeoroid impacts. Because thermal fragmentation is independent of asteroid size, this process can also contribute to regolith production on larger asteroids. Production of fresh regolith originating in thermal fatigue fragmentation may be an important process for the rejuvenation of the surfaces of near-Earth asteroids, and may explain the observed lack of low-perihelion, carbonaceous, near-Earth asteroids.

  15. The Asteroid Redirect Mission (ARM)

    Science.gov (United States)

    Abell, Paul; Gates, Michele; Johnson, Lindley; Chodas, Paul; Mazanek, Dan; Reeves, David; Ticker, Ronald

    2016-07-01

    To achieve its long-term goal of sending humans to Mars, the National Aeronautics and Space Administration (NASA) plans to proceed in a series of incrementally more complex human spaceflight missions. Today, human flight experience extends only to Low-Earth Orbit (LEO), and should problems arise during a mission, the crew can return to Earth in a matter of minutes to hours. The next logical step for human spaceflight is to gain flight experience in the vicinity of the Moon. These cis-lunar missions provide a "proving ground" for the testing of systems and operations while still accommodating an emergency return path to the Earth that would last only several days. Cis-lunar mission experience will be essential for more ambitious human missions beyond the Earth-Moon system, which will require weeks, months, or even years of transit time. In addition, NASA has been given a Grand Challenge to find all asteroid threats to human populations and know what to do about them. Obtaining knowledge of asteroid physical properties combined with performing technology demonstrations for planetary defense provide much needed information to address the issue of future asteroid impacts on Earth. Hence the combined objectives of human exploration and planetary defense give a rationale for the Asteroid Re-direct Mission (ARM). Mission Description: NASA's ARM consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), the first robotic mission to visit a large (greater than ~100 m diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, demonstrate a planetary defense technique, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will take the Orion capsule to rendezvous and dock with the robotic vehicle, conduct multiple extravehicular activities to explore the boulder, and return to Earth with samples. NASA's proposed

  16. Precessing Asteroids ftrom Radius Vector Models?

    Science.gov (United States)

    Drummond, Jack D.

    2014-11-01

    Examining a sample of asteroids (the first 99) for which radius vector models have been constructed from mostly lightcurves, located on a web site where such models are listed (http://astro.troja.mff.cuni.cz/projects/damit ; see Durech et al. (2010), DAMIT: a database of asteroid models, A&A, 513, A46), we fit their surfaces as triaxial ellipsoids and provide their three dimensions. In the process we also derive an Euler angular offset θ between each model's spin axis and its axis of maximum moment of inertia assuming a uniform distribution of mass. Most θ's conform to a chi-squared distribution having a maximum at 3° and a mean at 5°, and with the square root of the variance being 3°. However, seven models produce θ>20°, which we interpret as indicating possibly strong precessors, tumblers, or due to incorrect models: asteroids (68), (89), (125), (162), (167), (222), and (230). Nine others produce an excess over the distribution at 12°probability of an impact sufficient to change the angular momentum of the asteroid implied by θ during the damping time to return to rotation about the small axis is vanishingly small (less than 1 in 10000) for the 8 out of 16 asteroids with absolute dimensions. The most likely resolution, then, is that the rotational pole for the 16 asteroid models with high θ needs to be adjusted by θ degrees.

  17. Bayesian modeling of the mass and density of asteroids

    Science.gov (United States)

    Dotson, Jessie L.; Mathias, Donovan

    2017-10-01

    Mass and density are two of the fundamental properties of any object. In the case of near earth asteroids, knowledge about the mass of an asteroid is essential for estimating the risk due to (potential) impact and planning possible mitigation options. The density of an asteroid can illuminate the structure of the asteroid. A low density can be indicative of a rubble pile structure whereas a higher density can imply a monolith and/or higher metal content. The damage resulting from an impact of an asteroid with Earth depends on its interior structure in addition to its total mass, and as a result, density is a key parameter to understanding the risk of asteroid impact. Unfortunately, measuring the mass and density of asteroids is challenging and often results in measurements with large uncertainties. In the absence of mass / density measurements for a specific object, understanding the range and distribution of likely values can facilitate probabilistic assessments of structure and impact risk. Hierarchical Bayesian models have recently been developed to investigate the mass - radius relationship of exoplanets (Wolfgang, Rogers & Ford 2016) and to probabilistically forecast the mass of bodies large enough to establish hydrostatic equilibrium over a range of 9 orders of magnitude in mass (from planemos to main sequence stars; Chen & Kipping 2017). Here, we extend this approach to investigate the mass and densities of asteroids. Several candidate Bayesian models are presented, and their performance is assessed relative to a synthetic asteroid population. In addition, a preliminary Bayesian model for probablistically forecasting masses and densities of asteroids is presented. The forecasting model is conditioned on existing asteroid data and includes observational errors, hyper-parameter uncertainties and intrinsic scatter.

  18. Modeling Asteroid Dynamics using AMUSE: First Test Cases

    NARCIS (Netherlands)

    Frantseva, Kateryna; Mueller, Michael; van der Tak, Floris; Helmich, Frank P.

    2015-01-01

    We are creating a dynamic model of the current asteroid population. The goal is to reproduce measured impact rates in the current Solar System, from which we'll derive delivery rates of water and organic material by tracing low-albedo C-class asteroids (using the measured albedo distribution from

  19. Tidal stress and failure in the moon of binary asteroid systems: Application to asteroid (65803) Didymos

    Science.gov (United States)

    Sophal Pou, Laurent; Garcia, Raphael F.; Mimoun, David; Murdoch, Naomi; Karatekin, Ozgur

    2017-04-01

    Rocky remnants left over from the early formation of the Solar System, asteroids are a target of choice for planetary science since much about the history of planetary formation and small body evolution processes can be learnt by studying them. Here we consider the case of the binary asteroid (65803) Didymos, the target of several mission proposals e.g., AIM [1] and DART [2]. A mission to Didymos would be a great opportunity for in-situ geophysical investigation, providing information on the surface and interior of asteroids. Such studies would improve our knowledge of binary asteroid formation and subsequent evolution of asteroids, thus of the history of the Solar System. As Didymos is a binary asteroid [3] with the main 800-meter diameter asteroid named Didymain and a 150-meter sized moon named Didymoon, both are subject to tidal stress. Recent investigations suggest that Didymoon is tidally locked and moves in a retrograde motion around Didymain along an elliptic orbit with a 0.03 eccentricity at most. In the case of an eccentric orbit, the tidal stress varies periodically and may be strong enough to cause tidal quakes on Didymoon at some points of the orbit. For this study, we modelled Didymoon as a spherical, layered body with different internal structures: a homogeneous model, and two models with a 1-meter and 10-meter regolith layer on top of a stronger internal core. Simulations show that, for a cohesionless body with an internal friction angle of 30°, tidal stress is strong enough to cause failure at the surface of Didymoon. A maximal stress is reached around the poles and for a mean anomaly of 90°. These results would mean that if tidal quakes occur on Didymoon, then they are likely to happen at these locations. An extension of these results to an ellipsoidal model of Didymoon is also presented for comparison with the spherical case and for application to other bodies. [1]: P. Michel et al., Science case for the asteroid impact mission (aim): A

  20. Exploration of the Moon and Asteroids by Secondary Students

    Science.gov (United States)

    Shaner, A. J.; Bakerman, M. N.; Buxner, S.

    2016-12-01

    Since 2014, the Exploration of the Moon and Asteroids by Secondary Students, or ExMASS, program provides an opportunity for students to participate in authentic scientific research. The ExMASS program is an effort managed by the Center for Lunar Science and Exploration (CLSE). Led by the Lunar and Planetary Institute and Johnson Space Center, CLSE is one of nine teams comprising NASA's Solar System Exploration Research Virtual Institute (SSERVI). Over the course of one academic year, 10 teams of U.S. high school students conduct their own scientific investigations of Earth's Moon, or asteroids, with guidance from a scientist advisor. The program includes two elements: 1) two guided-inquiry introductory research activities that builds student knowledge of current lunar/asteroid science and lunar/asteroid data, and 2) an open-inquiry research project in which the students apply their knowledge to a self-defined project. Because the research is student-driven, it is not necessarily original research; original research is therefore not required. However, one team's research has been published in a professional journal. At the end of the school year, teams submit an abstract and research poster which are scored by a panel a judges. The top four scoring teams gather virtually to give short presentations to the judges. After presentations and time for Q&A, the judges choose one team to present in person at the Exploration Science Forum (ESF). The posters of all finalist schools are displayed at the ESF. The ExMASS program is evaluated by collecting data on changes in students' lunar/asteroid content knowledge, student attitudes toward science and science careers, and student perceptions of the processes of science in which their team participated. Exit surveys for teachers, students, and advisors are also distributed at the end of each program year to gather general feedback about the program and its impact. Results of this data from the first two years of the Ex

  1. The software IDA for investigation of asteroid dynamics and its use for study of some asteroid motion (Abstract)

    Science.gov (United States)

    Galushina, T.; Bykova, L.; Letner, O.; Baturin, A.

    2015-08-01

    This work is devoted to description of the application suite IDA that is designed for investigation of dynamics and probability orbital evolution of asteroids. IDA allows to predict asteroid motion, to reveal close encounters, possible collisions and orbital resonance with planets, to estimate impact probability, to demonstrate asteroid and planets motion on a computer screen and to solve some additional problems. The features of the suite are multifunctionality, high efficiency and a convenient interface. The application suite IDA consists of following subsystems: subsystem "Assol" which allows to study orbital evolution of the nominal orbit and to demonstrate the asteroid and planets motion on a computer screen; subsystem "Observations" which intended to asteroid orbit fitting to positional observations and construction of initial probability domain with non-linear methods; subsystem "Distribution" which developed for the visualization of distribution of observations along an asteroid orbit; subsystem "Clones ensemble" which allows to construct an initial probability domain with the linear method; subsystem "Evolution" which designed for the study of the orbital evolution of an ensemble of asteroid clones; subsystem "Megno" which intended to estimate of predictability time of asteroid motion by means of average MEGNO parameter. The results of the motion investigation of the asteroid 2012 MF7 are given to demonstrate use of the application suite. This object has nonzero collision probability with the Earth in 2046.

  2. 24-COLOR ASTEROID SURVEY

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset is comprised of asteroid flux data measured in 26 filters using the McCord dual beam photometer, and covering the range 0.32 - 1.08 microns for 285...

  3. SAWYER ASTEROID SPECTRA

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains 94 optical asteroid spectra obtained by Scott Sawyer as part of his Ph.D. dissertation at the University of Texas at Austin. Observational...

  4. 52-COLOR ASTEROID SURVEY

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains 52-color IR data of asteroids, taken using a double circularly variable filter. The short wavelength portion of the CVF covered the octave...

  5. LED colorimetry

    Science.gov (United States)

    Schanda, J.; Muray, K.; Kranicz, Balazs

    2002-06-01

    LEDs (Light Emitting Diodes) become the most important light sources in traffic signal applications, but their use increases in other areas, e.g. indoor and outdoor signals and information boards, now also in general lighting. They become popular also as instrumental radiation sources. LEDs emit in narrow emission bands, and as every semiconductor, their optical characteristics are temperature dependent. In outdoor applications they are exposed to extreme temperatures, influencing both their absolute intensity and their chromaticity. In the present paper we investigate the spectral power distribution of different types of real LEDs, as well as the change of their spectrum with temperature. The question of measuring these spectra will be re-visited. Instruments tested fall into three categories: high-end double spectrometer, single grating instrument and array type instruments of different quality. These instruments show very different stray light rejection, band-pass, and wavelength accuracy characteristics, leading to non- negligible errors of LED chromaticity if calibration is made with incandescent lamps. Results on the influence of these factors and of spectral bandwidth and sampling rate for measuring modern LEDs will be provided. Chromaticity will be calculated based on above spectral measurements and color differences will be evaluated. This becomes a hot topic with present LED cluster construction, as LEDs mounted in a panel side by side have to agree both in chromaticity and luminous intensity to an extent that is below visual acceptability levels.

  6. Asteroids@Home

    Science.gov (United States)

    Durech, Josef; Hanus, J.; Vanco, R.

    2012-10-01

    We present a new project called Asteroids@home (http://asteroidsathome.net/boinc). It is a volunteer-computing project that uses an open-source BOINC (Berkeley Open Infrastructure for Network Computing) software to distribute tasks to volunteers, who provide their computing resources. The project was created at the Astronomical Institute, Charles University in Prague, in cooperation with the Czech National Team. The scientific aim of the project is to solve a time-consuming inverse problem of shape reconstruction of asteroids from sparse-in-time photometry. The time-demanding nature of the problem comes from the fact that with sparse-in-time photometry the rotation period of an asteroid is not apriori known and a huge parameter space must be densely scanned for the best solution. The nature of the problem makes it an ideal task to be solved by distributed computing - the period parameter space can be divided into small bins that can be scanned separately and then joined together to give the globally best solution. In the framework of the the project, we process asteroid photometric data from surveys together with asteroid lightcurves and we derive asteroid shapes and spin states. The algorithm is based on the lightcurve inversion method developed by Kaasalainen et al. (Icarus 153, 37, 2001). The enormous potential of distributed computing will enable us to effectively process also the data from future surveys (Large Synoptic Survey Telescope, Gaia mission, etc.). We also plan to process data of a synthetic asteroid population to reveal biases of the method. In our presentation, we will describe the project, show the first results (new models of asteroids), and discuss the possibilities of its further development. This work has been supported by the grant GACR P209/10/0537 of the Czech Science Foundation and by the Research Program MSM0021620860 of the Ministry of Education of the Czech Republic.

  7. Asteroid Risk Assessment: A Probabilistic Approach.

    Science.gov (United States)

    Reinhardt, Jason C; Chen, Xi; Liu, Wenhao; Manchev, Petar; Paté-Cornell, M Elisabeth

    2016-02-01

    Following the 2013 Chelyabinsk event, the risks posed by asteroids attracted renewed interest, from both the scientific and policy-making communities. It reminded the world that impacts from near-Earth objects (NEOs), while rare, have the potential to cause great damage to cities and populations. Point estimates of the risk (such as mean numbers of casualties) have been proposed, but because of the low-probability, high-consequence nature of asteroid impacts, these averages provide limited actionable information. While more work is needed to further refine its input distributions (e.g., NEO diameters), the probabilistic model presented in this article allows a more complete evaluation of the risk of NEO impacts because the results are distributions that cover the range of potential casualties. This model is based on a modularized simulation that uses probabilistic inputs to estimate probabilistic risk metrics, including those of rare asteroid impacts. Illustrative results of this analysis are presented for a period of 100 years. As part of this demonstration, we assess the effectiveness of civil defense measures in mitigating the risk of human casualties. We find that they are likely to be beneficial but not a panacea. We also compute the probability-but not the consequences-of an impact with global effects ("cataclysm"). We conclude that there is a continued need for NEO observation, and for analyses of the feasibility and risk-reduction effectiveness of space missions designed to deflect or destroy asteroids that threaten the Earth. © 2015 Society for Risk Analysis.

  8. Update on an Interstellar Asteroid

    Science.gov (United States)

    Kohler, Susanna

    2018-01-01

    Whats the news coming from the research world on the interstellar asteroid visitor, asteroid 1I/Oumuamua? Read on for an update from a few of the latest studies.What is Oumuamua?In lateOctober2017, the discovery of minor planet 1I/Oumuamua was announced. This body which researchers first labeled asa comet and later revised to an asteroid had just zipped around the Sun and was already in the process of speeding away whenwe trained our telescopes on it. Its trajectory, however, marked it as being a visitor from outside our solar system: the first knownvisitorof its kind.Since Oumuamuasdiscovery, scientists have been gathering as many observations of this bodyas possible before it vanishes into the distance. Simultaneously, theorists have leapt at the opportunity to explain its presence and the implications its passage has on our understanding of our surroundings. Here we present just a few of the latest studies that have been published on this first detected interstellar asteroid including several timelystudies published in our new journal, Research Notes of the AAS.The galactic velocity of Oumuamua does not coincide with any of the nearest stars to us. [Mamajek 2018]Where Did Oumuamua Come From?Are we sure Oumuamua didnt originate in our solar system andget scattered into a weird orbit? Jason Wright (The Pennsylvania State University) demonstrates via a series of calculations that no known solar system body could have scattered Oumuamua onto its current orbit nor could any stillunknown object bound to our solar system.Eric Mamajek (Caltech and University of Rochester) showsthat thekinematics of Oumuamua areconsistent with what we might expect of interstellar field objects, though he argues that its kinematics suggest its unlikely to have originated from many of the neareststellar systems.What AreOumuamuas Properties?Oumuamuas light curve. [Bannister et al. 2017]A team of University of Maryland scientists led by Matthew Knight captured a light curve of Oumuamua using

  9. An investigation of factors that impact patients' subjective experience of nurse-led clinics: a qualitative systematic review.

    Science.gov (United States)

    Jakimowicz, Samantha; Stirling, Christine; Duddle, Maree

    2015-01-01

    To systematically review the qualitative evidence on factors that affect the experience of patients attending nurse-led clinics and compare with key elements of person-centred care. As the number of nurse-led clinics increases in response to health system needs, evaluation has focused on clinical outcomes and cost. Patient experiences are less researched and yet, they are an important influence on clinical outcomes and an indicator of person-centred care. A detailed review of existing research in this area is needed. A systematic review of primary, qualitative literature was conducted using the Joanna Briggs Institute methodology of meta-aggregation. Published research from 1990-2012 was located using CINAHL, PubMed, Medline and PsycINFO. Reference lists were searched and analysed. Two reviewers assessed the papers for methodological quality using instruments from the Joanna Briggs Institute to critically appraise, extract data and meta-aggregate findings. Eleven studies met all inclusion criteria. Three meta-synthesis statements were derived from 46 findings aggregated to nine categories. The key themes relating to establishment of a therapeutic relationship, effective communication, and clinical skills and collaboration mapped closely to the person-centred care framework. Concepts central to person-centred care proved to be factors impacting patients' subjective experience. Further research is warranted to meet the challenge to transform the key concepts of the person-centred care model into everyday nursing practice. Knowledge of patients' feelings and the importance of person-centred, individualised care may contribute to development of future training and re-training programs in basic nursing skills. This is significant in that it contributes to future positive patient experience. © 2014 John Wiley & Sons Ltd.

  10. Community Health Global Network: “Clustering” Together to Increase the Impact of Community Led Health and Development

    Directory of Open Access Journals (Sweden)

    Marianne Safe

    2014-01-01

    Full Text Available Background: Community Health Global Network (CHGN is a collaborative network, founded to strengthen collaboration between community-based health programs - many of which are faith based initiatives. It seeks to address this in two ways: through its global network of players in community health and in the formation of “Clusters.” CHGN Clusters are networks of community health programmes and individuals in specific geographical locations. This case report outlines the formation of the Kenya Cluster. Aims: To describe the steps in the formation of the Kenya Cluster and to outline the primary outcomes and potential impact of the network. To discuss how learning from the Kenya Cluster may assist other established Clusters and the initiation of new Clusters. Method: Information for this case report was gained from meetings and consultations with various individuals including leaders and members of the Kenya Cluster, other national community health experts, CHGN International staff and advisors to CHGN Uttarakhand Cluster in India. In addition, information was gained from personal observation during in-country field work. Results: The Kenya Cluster is emerging as a platform for community health programs to connect and network. These connections have led to transfer of information through stories, best practice, training, contacts and opportunities amongst Cluster members. The Cluster has also established links with government and multilaterals enabling greater access to support at the community level. Conclusions: There is early indication that the formation of the Kenya Cluster is supportive of the Cluster model as a unique way of strengthening collaboration between community health programs. Clusters have the potential to improve the link between faith-inspired initiatives and secular and multilateral development organisations. Lessons from the Kenya Cluster can progress the development of other Clusters. Further evaluation will be conducted to

  11. Early precambrian asteroid impact-triggered tsunami: excavated seabed, debris flows, exotic boulders, and turbulence features associated with 3.47-2.47 Ga-old asteroid impact fallout units, Pilbara Craton, Western Australia.

    Science.gov (United States)

    Glikson, Andrew Y

    2004-01-01

    Pioneering studies of Precambrian impact fallout units and associated tsunami deposits in the Hamersley Basin, Pilbara Craton, Western Australia, by B.M. Simonson and S.W. Hassler, document a range of tsunami deposits associated with impact fallout units whose impact connection is identified by associated microtektites and microkrystites (condensation spherules). The impact connection of these particles is demonstrated by iridium anomalies, unique platinum group elements patterns, and Ni-rich mineral phases. Densely packed tsunami-transported fragments and boulders overlie microkrystite units of the >2629 +/- 5 Ma top Jeerinah Impact Layer (JIL). Tsunami events closely follow spherule settling associated with the 2561 +/- 8 Ma Spherule Marker Bed SMB-1 and SMB-2 impact events, Bee Gorge Member, Wittenoom Formation. The two impact cycles are separated by a stratigraphically consistent silicified black siltstone, representing a "Quiet Interval." The SMB turbidites display turbulence eddies, climbing ripples, conglomerate pockets, slumps, and waterlogged sediment deformation features. Consequences of tsunami in the probably contemporaneous Carawine Dolomite (Pb-Pb carbonate ages of approximately 2.56-2.54 Ga), eastern Hamersley Basin, include sub-autochthonous below-wave base excavation and megabrecciation of sea floor substrata, resulting in a unique 10-30-m-thick spherule-bearing megabreccia marker mapped over a nearly 100-km north-south strike distance in the east Hamersley Basin. The field relations suggest a pretsunami settling of the bulk of the spherules. Tsunami wave effects include: (1). dispersal of the spherule-rich soft upper sea floor sediments as a subaqueous mud cloud and (2). excavation of consolidated substrata below the soft sediment zone. Excavation and megabrecciation included injection of liquefied spherule-bearing microbreccia into dilated fractures in the disrupted underlying carbonates. Near-perfect preservation of the spherules within the

  12. THERMAL TOMOGRAPHY OF ASTEROID SURFACE STRUCTURE

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Alan W.; Drube, Line, E-mail: alan.harris@dlr.de [German Aerospace Center (DLR) Institute of Planetary Research, Rutherfordstrasse 2, D-12489 Berlin (Germany)

    2016-12-01

    Knowledge of the surface thermal inertia of an asteroid can provide insight into its surface structure: porous material has a lower thermal inertia than rock. We develop a means to estimate thermal inertia values of asteroids and use it to show that thermal inertia appears to increase with spin period in the case of main-belt asteroids (MBAs). Similar behavior is found on the basis of thermophysical modeling for near-Earth objects (NEOs). We interpret our results in terms of rapidly increasing material density and thermal conductivity with depth, and provide evidence that thermal inertia increases by factors of 10 (MBAs) to 20 (NEOs) within a depth of just 10 cm. Our results are consistent with a very general picture of rapidly changing material properties in the topmost regolith layers of asteroids and have important implications for calculations of the Yarkovsky effect, including its perturbation of the orbits of potentially hazardous objects and those of asteroid family members after the break-up event. Evidence of a rapid increase of thermal inertia with depth is also an important result for studies of the ejecta-enhanced momentum transfer of impacting vehicles (“kinetic impactors”) in planetary defense.

  13. Near Earth Asteroid Characterization for Threat Assessment

    Science.gov (United States)

    Dotson, Jessie; Mathias, Donovan; Wheeler, Lorien; Wooden, Diane; Bryson, Kathryn; Ostrowski, Daniel

    2017-01-01

    Physical characteristics of NEAs are an essential input to modeling behavior during atmospheric entry and to assess the risk of impact but determining these properties requires a non-trivial investment of time and resources. The characteristics relevant to these models include size, density, strength and ablation coefficient. Some of these characteristics cannot be directly measured, but rather must be inferred from related measurements of asteroids and/or meteorites. Furthermore, for the majority of NEAs, only the basic measurements exist so often properties must be inferred from statistics of the population of more completely characterized objects. The Asteroid Threat Assessment Project at NASA Ames Research Center has developed a probabilistic asteroid impact risk (PAIR) model in order to assess the risk of asteroid impact. Our PAIR model and its use to develop probability distributions of impact risk are discussed in other contributions to PDC 2017 (e.g., Mathias et al.). Here we utilize PAIR to investigate which NEA characteristics are important for assessing the impact threat by investigating how changes in these characteristics alter the damage predicted by PAIR. We will also provide an assessment of the current state of knowledge of the NEA characteristics of importance for asteroid threat assessment. The relative importance of different properties as identified using PAIR will be combined with our assessment of the current state of knowledge to identify potential high impact investigations. In addition, we will discuss an ongoing effort to collate the existing measurements of NEA properties of interest to the planetary defense community into a readily accessible database.

  14. Thermal and impact history of the H chondrite parent asteroid during metamorphism: Constraints from metallic Fe-Ni

    Science.gov (United States)

    Scott, Edward R. D.; Krot, Tatiana V.; Goldstein, Joseph I.; Wakita, Shigeru

    2014-07-01

    We have studied cloudy taenite, metallographic cooling rates, and shock effects in 30 H3-6 chondrites to elucidate the thermal and early impact history of the H chondrite parent body. We focused on H chondrites with old Ar-Ar ages (>4.4 Gyr) and unshocked and mildly shocked H chondrites, as strongly shocked chondrites with such old ages are very rare. Cooling rates for most H chondrites at 500 °C are 10-50 °C/Myr and do not decrease systematically with increasing petrologic type as predicted by the onion-shell model in which types 3-5 are arranged in concentric layers around a type 6 core. Some type 4 chondrites cooled slower than some type 6 chondrites and type 3 chondrites did not cool faster than other types, contrary to the onion-shell model. Cloudy taenite particle sizes, which range from 40 to 120 nm, are inversely correlated with metallographic cooling rates and show that the latter were not compromised by shock heating. The three H4 chondrites that were used to develop the onion-shell model, Ste. Marguerite, Beaver Creek, and Forest Vale, cooled through 500 °C at ⩾5000 °C/Myr. Our thermal modeling shows that these rates are 50× higher than could be achieved in a body that was heated by 26Al and cooled without disturbance by impact. Published Ar-Ar ages do not decrease systematically with increasing petrologic type but do correlate inversely with cloudy taenite particle size suggesting that impact mixing decreased during metamorphism. Metal and silicate compositions in regolith breccias show that impacts mixed material after metamorphism without causing significant heating. Impacts during metamorphism created Portales Valley and two other H6 chondrites with large metallic veins, excavated the fast-cooled H4 chondrites around 3-4 Myr after accretion, and mixed petrologic types. Metallographic data do not require catastrophic disruption by impact during cooling.

  15. BAOBAB (Big And Outrageously Bold Asteroid Belt) Project

    Science.gov (United States)

    Mcfadden, L. A.; Thomas, C. A; Englander, J. A.; Ruesch, O.; Hosseini, S.; Goossens, S. J.; Mazarico, E. M.; Schmerr, N.

    2017-01-01

    One of the intriguing results of NASA's Dawn mission is the composition and structure of the Main Asteroid Belt's only known dwarf planet, Ceres [1]. It has a top layer of dehydrated clays and salts [2] and an icy-rocky mantle [3,4]. It is widely known that the asteroid belt failed to accrete as a planet by resonances between the Sun and Jupiter. About 20-30 asteroids >100 km diameter are probably differentiated protoplanets [5]. 1) how many more and which ones are fragments of protoplanets? 2) How many and which ones are primordial rubble piles left over from condensation of the solar nebula? 3) How would we go about gaining better and more complete characterization of the mass, interior structure and composition of the Main Belt asteroid population? 4) What is the relationship between asteroids and ocean worlds? Bulk parameters such as the mass, density, and porosity, are important to characterize the structure of any celestial body, and for asteroids in particular, they can shed light on the conditions in the early solar system. Asteroid density estimates exist but currently they are often based on assumed properties of taxonomic classes, or through astronomical survey data where interactions with asteroids are weak at best resulting in large measurement uncertainty. We only have direct density estimates from spacecraft encounters for a few asteroids at this time. Knowledge of the asteroids is significant not only to understand their role in solar system workings, but also to assess their potential as space resources, as impact hazards on Earth, or even as harboring life forms. And for the distant future, we want to know if the idea put forth in a contest sponsored by Physics Today, to surface the asteroids into highly reflecting, polished surfaces and use them as a massively segmented mirror for astrophysical exploration [6], is feasible.

  16. LED lamp

    Science.gov (United States)

    Galvez, Miguel; Grossman, Kenneth; Betts, David

    2013-11-12

    There is herein described a lamp for providing white light comprising a plurality of light sources positioned on a substrate. Each of said light sources comprises a blue light emitting diode (LED) and a dome that substantially covers said LED. A first portion of said blue light from said LEDs is transmitted through said domes and a second portion of said blue light is converted into a red light by a first phosphor contained in said domes. A cover is disposed over all of said light sources that transmits at least a portion of said red and blue light emitted by said light sources. The cover contains a second phosphor that emits a yellow light in response to said blue light. The red, blue and yellow light combining to form the white light and the white light having a color rendering index (CRI) of at least about 80.

  17. Shape Shifting Satellites in Binary Near-Earth Asteroids: Do Meteoroid Impacts Play a Role in BYORP Orbital Evolution?

    Science.gov (United States)

    Rubincam, David Parry

    2012-01-01

    Less than catastrophic meteoroid impacts over 10(exp 5) years may change the shape of small rubble-pile satellites in binary NEAs, lengthening the average BYORP (binary Yarkovsky-Radzievskii-Paddack) rate of orbital evolution. An estimate of shape-shifting meteoroid fluxes give numbers close enough to causing random walks in the semimajor axis of binary systems to warrant further investigation

  18. Optimal Impulse conditions for Deflecting Earth Crossing Asteroids

    National Research Council Canada - National Science Library

    Elder, Jeffrey

    1997-01-01

    .... The solution is based on two dimensional, two body, Earth intersecting elliptical orbits. Given the asteroid eccentricity, time prior to impact and impulse magnitude and direction, an analysis of impulse to minimum separation distance is generated...

  19. St. Jude Cancer Education for Children Program: The Impact of a Teacher-Led Intervention on Student Knowledge Gains.

    Science.gov (United States)

    Ayers, Katherine; Li, Zhenghong; Quintana, Yuri; Van Kirk Villalobos, Aubrey; Klosky, James L

    2017-12-01

    In 2006, St. Jude Children's Research Hospital (Memphis, Tennessee) began developing a school-based outreach program known as the St. Jude Cancer Education for Children Program (SJCECP). The aim of this program is to teach Memphis-area children about cells, cancer, and healthy habits that can prevent the development of cancer in adulthood. Initial plans for delivery of the program was for St. Jude staff to present the program at local schools. This plan for disseminating instruction was not feasible due to the limited availability of St. Jude staff. As a next step, during the 2012-2014 academic years, we conducted a study entitled SJCECP2, utilizing the SJCECP curriculum, with the objective of evaluating the impact of the educational intervention on knowledge acquisition and retention among fourth-grade students participating in a modified, teacher-led version of the program. Eighteen teachers and 426 students from 10 local schools in the greater Memphis area participated in the program evaluation. This study used a single-group, pre-test/post-test design to determine the impact of the SJCECP intervention on changes in knowledge scores among fourth-grade students. Testing was on cells, cancer, and healthy living. The mean scores increased from 6.45 to 8.12, 5.99 to 7.65, and 5.92 to 7.96 on cell, cancer, and health behaviors units, respectively (all p values teachers to improve student knowledge of knowledge of cells, cancer, and healthy living concepts at the fourth-grade level.

  20. Peer-Led Culinary Skills Intervention for Adolescents: Pilot Study of the Impact on Knowledge, Attitude, and Self-efficacy.

    Science.gov (United States)

    Oakley, Amanda R; Nelson, Sarah A; Nickols-Richardson, Sharon M

    To assess the impact and feasibility of a culinary skills intervention for adolescents led by peer educators compared with adult educators. Adolescents (aged 11-14 years) were randomized to peer educator (n = 22) or adult educator (n = 20) groups and attended 2 2.5-hour culinary skills lessons addressing knife skills, cooking methods, and recipes. Knowledge, attitude, and self-efficacy measurements were completed before and immediately after the intervention and at 3 and 6 months after the intervention. Fidelity checklists assessed the feasibility of program delivery. Differences within and between groups over time were assessed using ANOVA. Adolescents (n = 42) increased knowledge (3.7 ± 2.6 points [mean ± SD]; P culinary skills program for adolescents that increases knowledge. To affect attitude and self-efficacy, additional training of peer educators may be needed. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  1. Impact of community based nurse-led clinics on patient outcomes, patient satisfaction, patient access and cost effectiveness: A systematic review.

    Science.gov (United States)

    Randall, Sue; Crawford, Tonia; Currie, Jane; River, Jo; Betihavas, Vasiliki

    2017-08-01

    The role and scope of nursing practice has evolved in response to the dynamic needs of individuals, communities, and healthcare services. Health services are now focused on maintaining people in their communities, and keeping them out of hospital where possible. Community based nurse-led clinics are ideally placed to work towards this goal. The initial impetus for these services was to increase patient access to care, to provide a cost-effective and high quality streamlined service. This systematic review aimed to identify the impact of nurse-led clinics in relation to patient outcomes, patient satisfaction, impact on patient access to services, and cost effectiveness. A review of community based nurse-led clinic research in Medline, CINAHL and Embase was undertaken using MeSH terms: Nurse-managed centres, Practice, Patterns, Nurse, Ambulatory Care, keywords: nurse-led clinic, nurse led clinic, community and phrases primary health care and primary care. Papers were appraised using the Joanna Briggs Appraisal criteria. The final review comprised 15 studies with 3965 participants. Most studies explored patient satisfaction which was largely positive towards nurse-led clinics. Patient outcomes reported were typically from self-report, although some papers addressed objective clinical measures; again positive. Access was reported as being increased. Cost-effectiveness was the least reported impact measure with mixed results. Nurse-led clinics have largely shown positive impact on patient outcomes, patient satisfaction, access to care and mixed results on cost-effectiveness. Future research evaluating NLCs needs to adopt a standardised structure to provide rigorous evaluations that can rationalise further efforts to set up community based nurse-led clinical services. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Effective Scenarios for Exploring Asteroid Surfaces

    Science.gov (United States)

    Clark, Pamela E.; Clark, C.; Weisbin, C.

    2010-10-01

    In response to the proposal that asteroids be the next targets for exploration, we attempt to develop scenarios for exploring previously mapped asteroid 433 Eros, harnessing our recent experience gained planning such activity for return to the lunar surface. The challenges faced in planning Apollo led to the development of a baseline methodology for extraterrestrial field science. What `lessons learned’ can be applied for asteroids? Effective reconnaissance (advanced mapping at deep regolith (ponds). Unlike the Moon, an asteroid lacks sufficient gravity and most likely the necessary stability to support `normal’ driving or walking. In fact, the crew delivery vehicle might not even be `tetherable’ and would most likely `station keep’ to maintain a position. The most convenient local mobility mechanism for astronauts/robots would be `hand over hand’ above the surface at a field station supplemented by a `tetherless’ (small rocket-pack) control system for changing station or return to vehicle. Thus, we assume similar mobility constraints (meters to hundreds of meters at a local station, kilometers between stations) as those used for Apollo. We also assume the vehicle could `station keep’ at more than one location separated by tens of kilometers distance.

  3. The Maria asteroid family

    Science.gov (United States)

    Aljbaae, S.; Carruba, V.; Masiero, J. R.; Domingos, R. C.; Huaman, M.

    2017-11-01

    The Maria asteroid family is a group of S-type asteroids. Its location adjacent to the left side of the 3J:-1A mean-motion resonances could be the reason for the absence of the left side of the `V' shape in the (a, 1/D) domain. This family can be considered as a likely source of ordinary chondrite-like material. In this work, we make use of the time dependence of the asymmetric coefficient AS describing the degree of asymmetry of the C distribution of a fictitious Maria family generated with the value of the ejection velocity parameter VEJ = 35 m s-1 to obtain an age estimate of 1750_{+537}^{-231} Myr, in good agreement with the family age found in the literature. Analysing the contribution to the near-Earth object (NEO) population, we found that about 7.6 per cent of presently known near-Earth asteroids (NEAs) have orbits similar to asteroids from the Maria family. Only ˜1.7 per cent of our simulated family can stay in NEO space for more than 10 Myr, while only five asteroids become NEOs in the last 500 Myr of the simulation.

  4. Asteroids astronomical and geological bodies

    CERN Document Server

    Burbine, Thomas H

    2016-01-01

    Asteroid science is a fundamental topic in planetary science and is key to furthering our understanding of planetary formation and the evolution of the Solar System. Ground-based observations and missions have provided a wealth of new data in recent years, and forthcoming missions promise further exciting results. This accessible book presents a comprehensive introduction to asteroid science, summarising the astronomical and geological characteristics of asteroids. The interdisciplinary nature of asteroid science is reflected in the broad range of topics covered, including asteroid and meteorite classification, chemical and physical properties of asteroids, observational techniques, cratering, and the discovery of asteroids and how they are named. Other chapters discuss past, present and future space missions and the threat that these bodies pose for Earth. Based on an upper-level course on asteroids and meteorites taught by the author, this book is ideal for students, researchers and professional scientists ...

  5. Asteroids - NeoWs API

    Data.gov (United States)

    National Aeronautics and Space Administration — NeoWs (Near Earth Object Web Service) is a RESTful web service for near earth Asteroid information. With NeoWs a user can: search for Asteroids based on their...

  6. Asteroid Hazard: Core of the Problem

    Science.gov (United States)

    Lupishko, D. F.; Lupishko, T. A.

    2000-01-01

    In the last decade the asteroid or comet impact hazard have come to be "'discovered' by the human society in parallel with many other problems that might threaten the future of civilization. The new data about small bodies of the Solar system, discovery of more and more of the geological structures on the Earth associated with catastrophic impacts of large asteroids, Shoemaker-Levy comet's crash into Jupiter in July 1994, all these provide dramatic evidence of the potential danger to humanity if a large cosmic body strikes the Earth. The problem of asteroid hazard has been transformed from a theoretical curiosity into very distinct reality and therefore the awareness of the threat to civilization from asteroid/comet impacts has increased. It is becoming more clear that collisions of large asteroids or comets with the Earth played a very important role in the evolution of life in the past, and perhaps such impact events would become a turning-point in the evolutionary history of the Earth's life in the future. The major role in this process belongs to the population of near-Earth asteroids (NEAs) in unstable orbits which can approach or cross the Earth's orbit. More than 800 Earth-approaching and Earth-crossing asteroids (ECAs) have been discovered so far. Physical characteristics of these objects are on the average identical to those of the main-belt asteroids of comparable sizes. They have similar compositions, the same optical properties, similar shapes and the axis rotation. The principal differences of NEAs from main-belt asteroids are in their orbits and relatively small sizes. The largest NEA 1036 Ganymed is about 38 km in diameter though it belongs to the Amor-group asteroids which only approach the Earth's orbit. The largest among Earth-crossers is 1866 Sisyphus with diameter of eight kilometers. In the last years the NEAs are the subject of particular interest of scientists. From the point of view of fundamental science the problem of the NEAs origin, the

  7. Geography of the asteroid belt

    Science.gov (United States)

    Zellner, B. H.

    1978-01-01

    The CSM classification serves as the starting point on the geography of the asteroid belt. Raw data on asteroid types are corrected for observational biases (against dark objects, for instance) to derive the distribution of types throughout the belt. Recent work on family members indicates that dynamical families have a true physical relationship, presumably indicating common origin in the breakup of a parent asteroid.

  8. Manuel's asteroid disruption technique.

    Science.gov (United States)

    John, Manuel; Ipe, Abraham; Jacob, Ivan

    2015-06-01

    A seventy-year-old male presented with dense asteroid hyalosis in both eyes. He had undergone cataract extraction in one eye 3 years ago, and the other eye had immature cataract. Both the autorefractor and dilated streak retinoscopy did not give readings and subjective visual improvement could not be achieved. Immediately following YAG posterior capsulotomy and anterior vitreous asteroid disruption, the vision improved to 20/20 with recordable auto refractor and streak retinoscopy values. Our initial experience indicates that the treatment is simple, safe and effective but needs controlled and prospective studies to confirm its long-term safety.

  9. Teacher-led relaxation response curriculum in an urban high school: impact on student behavioral health and classroom environment.

    Science.gov (United States)

    Wilson, H Kent; Scult, Matthew; Wilcher, Marilyn; Chudnofsky, Rana; Malloy, Laura; Drewel, Emily; Riklin, Eric; Saul, Southey; Fricchione, Gregory L; Benson, Herbert; Denninger, John W

    2015-01-01

    Recent data suggest that severe stress during the adolescent period is becoming a problem of epidemic proportions. Elicitation of the relaxation response (RR) has been shown to be effective in treating anxiety, reducing stress, and increasing positive health behaviors. The research team's objective was to assess the impact of an RR-based curriculum, led by teachers, on the psychological status and health management behaviors of high-school students and to determine whether a train-the-trainer model would be feasible in a high-school setting. The research team designed a pilot study. The setting was a Horace Mann charter school within Boston's public school system. Participants were teachers and students at the charter school. The team taught teachers a curriculum that included (1) relaxation strategies, such as breathing and imagery; (2) psychoeducation regarding mind-body pathways; and (3) positive psychology. Teachers implemented this curriculum with students. The research team assessed changes in student outcomes (eg, stress, anxiety, and stress management behaviors) using preintervention/postintervention surveys, including the Perceived Stress Scale (PSS), the State-Trait Anxiety Inventory-Form Y (STAI-Y), the stress management subscale of the Health-promoting Lifestyle Profile II (HPLP-II), the Rosenberg Self-Esteem Scale (RSES), the Locus of Control (LOC) questionnaire, and the Life Orientation Test-Revised (LOTR). Classroom observations using the Classroom Assessment Scoring System (CLASS)-Secondary were also completed to assess changes in classroom environment. Using a Bonferroni correction (P students experienced a significant reduction (P students had significantly less perceived stress (P time spent on activities and instruction from pre- to postintervention). This study showed that teachers can lead an RR curriculum with fidelity and suggests that such a curriculum has positive benefits on student emotional and behavioral health and on classroom

  10. NASA's Asteroid Redirect Mission (ARM)

    Science.gov (United States)

    Abell, P. A.; Mazanek, D. D.; Reeves, D. M.; Chodas, P. W.; Gates, M. M.; Johnson, L. N.; Ticker, R. L.

    2017-01-01

    Mission Description and Objectives: NASA's Asteroid Redirect Mission (ARM) consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), a robotic mission to visit a large (greater than approximately 100 meters diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will explore and investigate the boulder and return to Earth with samples. The ARRM is currently planned to launch at the end of 2021 and the ARCM is scheduled for late 2026.

  11. Asteroids, meteorites, and comets

    CERN Document Server

    Elkins-Tanton, Linda T

    2010-01-01

    Asteroids, Comets, and Meteorites provides students, researchers, and general readers with the most up-to-date information on this fascinating field. From the days of the dinosaurs to our modern environment, this book explores all aspects of these cosmic invaders.

  12. Identification of a primordial asteroid family constrains the original planetesimal population.

    Science.gov (United States)

    Delbo', Marco; Walsh, Kevin; Bolin, Bryce; Avdellidou, Chrysa; Morbidelli, Alessandro

    2017-09-08

    A quarter of known asteroids is associated with more than 100 distinct asteroid families, meaning that these asteroids originate as impact fragments from the family parent bodies. The determination of which asteroids of the remaining population are members of undiscovered families, or accreted as planetesimals from the protoplanetary disk, would constrain a critical phase of planetary formation by unveiling the unknown planetesimal size distribution. We discovered a 4-billion-year-old asteroid family extending across the entire inner part of the main belt whose members include most of the dark asteroids previously unlinked to families. This allows us to identify some original planetesimals, which are all larger than 35 kilometers, supporting the view of asteroids being born big. Their number matches the known distinct meteorite parent bodies. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  13. Identification of a primordial asteroid family constrains the original planetesimal population

    Science.gov (United States)

    Delbo', Marco; Walsh, Kevin; Bolin, Bryce; Avdellidou, Chrysa; Morbidelli, Alessandro

    2017-09-01

    A quarter of known asteroids is associated with more than 100 distinct asteroid families, meaning that these asteroids originate as impact fragments from the family parent bodies. The determination of which asteroids of the remaining population are members of undiscovered families, or accreted as planetesimals from the protoplanetary disk, would constrain a critical phase of planetary formation by unveiling the unknown planetesimal size distribution. We discovered a 4-billion-year-old asteroid family extending across the entire inner part of the main belt whose members include most of the dark asteroids previously unlinked to families. This allows us to identify some original planetesimals, which are all larger than 35 kilometers, supporting the view of asteroids being born big. Their number matches the known distinct meteorite parent bodies.

  14. The financial impact of a nurse-led telemedicine service for inflammatory bowel disease in a large district general hospital.

    Science.gov (United States)

    Squires, Seth Ian; Boal, Allan John; Naismith, Graham Douglas

    2016-07-01

    It has become increasingly recognised that outpatient management is more cost-effective in inflammatory bowel disease (IBD). IBD Standards (Revised 2013) recommend telephone advice for patients with regard to symptoms and medication management. This report attempts to quantify the net financial impact of this service at our hospital since it was introduced in August 2013. The Royal Alexandra Hospital in Paisley (National Health Service, Greater Glasgow and Clyde) is a district general hospital with a catchment population of 200 000 with approximately 2500 patients with IBD. Data relating to the use of the IBD telemedicine service were prospectively recorded on a daily basis for a period of 5 months. We documented reasons for calling and the likely action taken by the patient had the telephone advice line not been available. Cost savings based on alternative outcomes were made in accordance with the Department of Health figures (Department of Health reference costs 2011-2012). The mean number of calls per month was 88 (IQR 24)-(the mean number of calls which were deemed non-IBD issues was 30 calls per month (IQR 8.0)) The mean cost of staffing the IBD advice line with an IBD clinical nurse specialist was £482.00 per month (IQR 195.5). The mean time spent on calls per month was 28.5 h (IQR 11.5). Cost savings over 5 months for avoidance of general practitioner (GP) consultation was £3408.00. Savings for avoidance of a consultant appointment made over the 5-month period was £27 454.00. Savings made from patients avoiding either an accident and emergency (A&E) or a hospital admission were £540.00 and £11 488.00, respectively, over the 5-month period. The net saving was £42 890.00. A nurse-led telephone advice line appears to be a cost-effective intervention. It may prevent patients from unnecessary hospital attendance. Savings can be made to both primary care and secondary care. Overall, it appears that the advice line is providing a highly valuable

  15. Geologic History of Asteroid 4 Vesta

    Science.gov (United States)

    Mittlefehldt, David W.

    2014-01-01

    Some types of meteorites - most irons, stony irons, some achondrites - hail from asteroids that were heated to the point where magmatism occurred within a very few million years of the formation of the earliest solids in the solar system. The largest clan of achondrites, the howardite, eucrite and diogenite (HED) meteorites, represent the crust of their parent asteroid]. Diogenites are cumulate harzburgites and orthopyroxenites from the lower crust whilst eucrites are basalts, diabases and cumulate gabbros from the upper crust. Howardites are impact-engendered breccias mostly of diogenites and eucrites. There remains only one large asteroid with a basaltic crust, 4 Vesta, which is thought to be the source of the HED clan. Differentiation models for Vesta are based on HED compositions. Proto-Vesta consisted of chondritic materials containing Al-26, a potent, short-lived heat source. Inferences from compositional data are that Vesta was melted to high degree (=50%) allowing homogenization of the silicate phase and separation of a metallic core. Convection of the silicate magma ocean allowed equilibrium crystallization, forming a harzburgitic mantle. After convective lockup occurred, melt collected between the mantle and the cool thermal boundary layer and underwent fractional crystallization forming an orthopyroxene-rich (diogenite) lower crust. The initial thermal boundary layer of chondritic material was replaced by a mafic upper crust through impact disruption and foundering. The mafic crust thickened over time as additional residual magma intrudes and penetrates the mafic crust forming plutons, dikes, sills and flows of cumulate and basaltic eucrite composition. This magmatic history may have taken only 2-3 Myr. This magma ocean scenario is at odds with a model of heat and magma transport that indicates that small degrees of melt would be rapidly expelled from source regions, precluding development of a magma ocean. Constraints from radiogenic Mg-26 distibutions

  16. Creating a student-led health magazine with an urban, multicultural, resource-restricted elementary school: Approach, process and impact.

    Science.gov (United States)

    Porepa, Michelle; Chan, Melissa; Huber, Joelene; Lam, Catherine G; Au, Hosanna; Birken, Catherine S

    2016-04-01

    Health magazines effectively deliver health information. No data regarding student-led magazines to promote health exist. To evaluate whether children's health knowledge, interests and lifestyle choices improve following distribution of a student-led health magazine. Elementary students worked with teachers and paediatric residents to publish a health magazine. A healthy lifestyle challenge page promoted reduction in soda pop consumption. Pre- and poststudent questionnaires explored knowledge, interests and behaviours related to health. Sex and grade distributions were similar in pre- and post-questionnaires. Ninety-seven percent of children reported the magazine helped them learn about health. Pre- and postknowledge scores did not differ (P=0.36). Following distribution, the percentage of students who reported drinking no soda increased from 43% to 67% (P=0.004), and those who reported drinking led health magazine was effective in motivating short-term student-reported behavioural change.

  17. Asteroid Ida Rotation Sequence

    Science.gov (United States)

    1994-01-01

    This montage of 14 images (the time order is right to left, bottom to top) shows Ida as it appeared in the field of view of Galileo's camera on August 28, 1993. Asteroid Ida rotates once every 4 hours, 39 minutes and clockwise when viewed from above the north pole; these images cover about one Ida 'day.' This sequence has been used to create a 3-D model that shows Ida to be almost croissant shaped. The earliest view (lower right) was taken from a range of 240,000 kilometers (150,000 miles), 5.4 hours before closest approach. The asteroid Ida draws its name from mythology, in which the Greek god Zeus was raised by the nymph Ida.

  18. Silicates in Alien Asteroids

    Science.gov (United States)

    2009-01-01

    This plot of data from NASA's Spitzer Space Telescopes shows that asteroid dust around a dead 'white dwarf' star contains silicates a common mineral on Earth. The data were taken primarily by Spitzer's infrared spectrograph, an instrument that breaks light apart into its basic constituents. The yellow dots show averaged data from the spectrograph, while the orange triangles show older data from Spitzer's infrared array camera. The white dwarf is called GD 40.

  19. Modeling of Fragmentation of Asteroids

    Science.gov (United States)

    Agrawal, Parul; Prabhu, Dinesh K.; Carlozzi, Alexander; Hart, Kenneth; Bryson, Katie; Sears, Derek

    2015-01-01

    The objective of this study is to understand fragmentation and fracture of a given asteroid and mechanisms of break-up. The focus of the present work is to develop modeling techniques for stony asteroids in 10m-100m range to answer two questions: 1) What is the role of material makeup of an asteroid in the stress distribution? 2)How is stress distribution altered in the presence of pre-existing defects?

  20. 3-µm Spectroscopy of Asteroid 16 Psyche

    Science.gov (United States)

    Takir, Driss; Reddy, Vishnu; Sanchez, Juan; Shepard, Michael K.

    2016-10-01

    Asteroid 16 Psyche, an M-type asteroid, is thought to be one of the most massive exposed iron metal object in the asteroid belt. The high radar albedos of Psyche suggest that this differentiated asteroid is dominantly composed of metal. Psyche was previously found to be featureless in the 3-µm spectral region. However, in our study we found that this asteroid exhibits a 3-µm absorption feature, possibly indicating the presence of hydrated silicates.We have observed Psyche in the 3-µm spectral region, using the long-wavelength cross-dispersed (LXD:1.9-4.2 µm) mode of the SpeX spectrograph/imager at the NASA Infrared Telescope Facility (IRTF). For data reduction, we used the IDL (Interactive Data Language)-based spectral reduction tool Spextool (v4.1). Psyche was observed over the course of three nights with an apparent visual magnitude of ~9.50: 8 December 2015 (3 sets), 9 December 2015 (1 set), and 10 March 2016 (1 set). These observations have revealed that Psyche may exhibit a 3-µm absorption feature, similar to the sharp group in the 2.9-3.3-µm spectral range. Psyche also exhibits an absorption feature similar to the one in Ceres and Ceres-like group in the spectral 3.3-4.0-µm range. These 3-µm observational results revealed that Psyche may not be as featureless as once thought in the 3-µm spectral region.Evidence for the 3-µm band was found on the surfaces of many M-type asteroids and a number of plausible alternative interpretations for the presence of this 3-µm band were previously suggested. These interpretations include the presence of anhydrous silicates containing structural OH, the presence of fluid inclusions, the presence of xenolithic hydrous meteorite components on asteroid surfaces from impacts, solar wind-implanted H, or the presence of troilite. The detection of the Ceres-like feature in the 3.3-4.0-µm spectral range, however, would rule out some of these alternative interpretations, especially the solar wind-implanted H.

  1. Modeling Asteroid Dynamics using AMUSE: First Test Cases

    Science.gov (United States)

    Frantseva, Kateryna; Mueller, Michael; van der Tak, Floris; Helmich, Frank P.

    2015-11-01

    We are creating a dynamic model of the current asteroid population. The goal is to reproduce measured impact rates in the current Solar System, from which we'll derive delivery rates of water and organic material by tracing low-albedo C-class asteroids (using the measured albedo distribution from WISE catalog), the parent bodies of carbonaceous chondrite meteorites. Ultimately, we aim at studying the role of "exo-asteroids" in the delivery of water to exoplanets.Our model is set up using the Astrophysical Multipurpose Software Environment (AMUSE; amusecode.org). AMUSE provides a common Python wrapper around numerous astrophysical codes including N-body gravity codes such as Mercury and Huayno.We report first results towards a validation of our model: long-term integrations of the planets alone as well as studies of the depletion of the Kirkwood gaps in the asteroid belt. Further model developments will be discussed.

  2. Impact of peer-led group education on the quality of life in patients with ankylosing spondylitis.

    Science.gov (United States)

    Kaya, Taciser; Goksel Karatepe, Altinay; Atici Ozturk, Pinar; Gunaydin, Rezzan

    2016-02-01

    To determine the effect of peer-led group education on the quality of life and depression in patients with ankylosing spondylitis (AS). Eighty patients with definite AS were allocated randomly to either the education or control group. The education group (n = 40) was subjected to a peer-led group education program about disease and was given an educational booklet, while the control group (n = 40) was given the educational booklet only. Levels of quality of life and depression were measured at baseline, immediately after education (fourth week) and at 6 months in both groups. The results are based on 56 (n = 27, education group; n = 29, control group) patients. The level of quality of life and depressive symptoms were not changed except for a deterioration in the social functioning subgroup of Short From (SF)-36 in both groups. When the groups were compared, there were no significant differences between changes in social functioning scores. Peer-led education did not alter quality of life levels and depression scores. However, because of the maintainance of quality of life levels, this type of intervention may be considered as a supplementary intervention to the standard medical care for management of AS. © 2013 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

  3. Physical studies of asteroids XX - Photoelectric photometry of asteroids

    Science.gov (United States)

    Debehogne, H.; Lagerkvist, C.-I.; Magnusson, P.; Hahn, G.

    The asteroids 8 Flora, 69 Hesperia, 80 Sappho, 130 Elektra and 173 Ino were observed with the ESO 50 cm and the Danish 50 cm telescopes at ESO, Chile. Composite lightcurves from four nights are presented for the asteroids Sappho, Elektra and Ino. For 173 Ino an improved rotation period of 6.15 hours was determined.

  4. Photometry of Karin family asteroids

    NARCIS (Netherlands)

    Hahn, G.; Mottola, S.; Sen, A. K.; Harris, A. W.; Kührt, E.; Mueller, M.

    2006-01-01

    We have performed photometric observations in the V-band of two asteroids belonging to the Karin asteroid family, (11728) Einer and (93690) 2000 VE21 , using the 2-m Himalayan Chandra Telescope, Hanle and 2k ×4k pixels CCD imager. We obtained measurements during two nights (November 25 and 26, 2005)

  5. Records of the Moon-forming impact and the 470 Ma disruption of the L chondrite parent body in the asteroid belt from U-Pb apatite ages of Novato (L6)

    Science.gov (United States)

    Yin, Qing-Zhu; Zhou, Qin; Li, Qiu-Li; Li, Xian-Hua; Liu, Yu; Tang, Guo-Qiang; Krot, Alexander N.; Jenniskens, Peter

    2014-08-01

    Novato, a newly observed fall in the San Francisco Bay area, is a shocked and brecciated L6 ordinary chondrite containing dark and light lithologies. We have investigated the U-Pb isotope systematics of coarse Cl-apatite grains of metamorphic origin in Novato with a large geometry ion microprobe. The U-Pb systematics of Novato apatite reveals an upper intercept age of 4472 ± 31 Ma and lower intercept age of 473 ± 38 Ma. The upper intercept age is within error identical to the U-Pb apatite age of 4452 ± 21 Ma measured in the Chelyabinsk LL5 chondrite. This age is interpreted to reflect a massive collisional resetting event due to a large impact associated with the peak arrival time at the primordial asteroid belt of ejecta debris from the Moon-forming giant impact on Earth. The lower intercept age is consistent with the most precisely dated Ar-Ar ages of 470 ± 6 Ma of shocked L chondrites, and the fossil meteorites and extraterrestrial chromite relicts found in Ordovician limestones with an age of 467.3 ± 1.6 Ma in Sweden and China. The lower intercept age reflects a major disturbance related to the catastrophic disruption of the L chondrite parent body most likely associated with the Gefion asteroid family, which produced an initially intense meteorite bombardment of the Earth in Ordovician period and reset and degassed at least approximately 35% of the L chondrite falls today. We predict that the 470 Ma impact event is likely to be found on the Moon and Mars, if not Mercury.

  6. Asteroid electrostatic instrumentation and modelling

    Science.gov (United States)

    Aplin, K. L.; Bowles, N. E.; Urbak, E.; Keane, D.; Sawyer, E. C.

    2011-06-01

    Asteroid surface material is expected to become photoelectrically charged, and is likely to be transported through electrostatic levitation. Understanding any movement of the surface material is relevant to proposed space missions to return samples to Earth for detailed isotopic analysis. Motivated by preparations for the Marco Polo sample return mission, we present electrostatic modelling for a real asteroid, Itokawa, for which detailed shape information is available, and verify that charging effects are likely to be significant at the terminator and at the edges of shadow regions for the Marco Polo baseline asteroid, 1999JU3. We also describe the Asteroid Charge Experiment electric field instrumentation intended for Marco Polo. Finally, we find that the differing asteroid and spacecraft potentials on landing could perturb sample collection for the short landing time of 20min that is currently planned.

  7. Asteroid electrostatic instrumentation and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Aplin, K L; Bowles, N E; Urbak, E [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Keane, D; Sawyer, E C, E-mail: k.aplin1@physics.ox.ac.uk [RAL Space, R25, Harwell Oxford, Didcot OX11 0QX (United Kingdom)

    2011-06-23

    Asteroid surface material is expected to become photoelectrically charged, and is likely to be transported through electrostatic levitation. Understanding any movement of the surface material is relevant to proposed space missions to return samples to Earth for detailed isotopic analysis. Motivated by preparations for the Marco Polo sample return mission, we present electrostatic modelling for a real asteroid, Itokawa, for which detailed shape information is available, and verify that charging effects are likely to be significant at the terminator and at the edges of shadow regions for the Marco Polo baseline asteroid, 1999JU3. We also describe the Asteroid Charge Experiment electric field instrumentation intended for Marco Polo. Finally, we find that the differing asteroid and spacecraft potentials on landing could perturb sample collection for the short landing time of 20min that is currently planned.

  8. Implementation of evidence-based humanitarian programs in military-led missions: part II. The impact assessment model.

    Science.gov (United States)

    Reaves, Erik J; Schor, Kenneth W; Burkle, Frederick M

    2008-12-01

    The Department of Defense does not implement health-sector humanitarian assistance impact assessments to complement those of the international humanitarian aid community. This oversight fails to meet the recent Department of Defense Directive 3000.05 mandate calling for the application of measures of effectiveness. The decision by the Department of Defense to incorporate humanitarian assistance in stability operations should be supported by evidence-based impact assessments. This article proposes implementation of an impact assessment model in Department of Defense humanitarian assistance operations. The use of an impact assessment model will refocus previously identified information gaps from traditional military input-output management toward a greater emphasis on outcomes. This will help answer which humanitarian activities are successful, which are not, and why. Over time, the use of an impact assessment model will ensure that the Department of Defense and its operational units are learning as an organization while applying evidence-based lessons learned to future stability operations. Most important, the use of this model will both provide better understanding of the role that the Department of Defense has in humanitarian activities and help interpret and transfer these activities to the host nation and international aid community in a timely and efficient manner.

  9. The impact of nurse-led annual telephone follow-up of patients with inflammatory bowel disease

    DEFF Research Database (Denmark)

    Bager, Palle

    2014-01-01

    % of the patients included were pleased with the service. The programme has shortened the waiting time for most other services, but no improvement in the workload was observed. The BIA showed limited savings. The CEA showed an annual saving of 100€ per patient when using the annual phone service over routine visits......Inflammatory bowel diseases (IBD) are characterised by periods of disease activity and period with disease in remission. In Denmark all patients are seen in hospital settings. The aim of this study was to introduce a nurse-led phone service for stable patients replacing annual visits. The study....... In conclusion, changing the method of contact from routine annual visits to annual phone calls from a nurse was feasible and well accepted for stable patients with IBD. The benefits of the service were most marked for the patients....

  10. OBSERVED ASTEROID SURFACE AREA IN THE THERMAL INFRARED

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, C. R. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Masiero, J.; Bauer, J.; Kramer, E.; Sonnett, S. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Wright, E. L. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States)

    2017-02-01

    The rapid accumulation of thermal infrared observations and shape models of asteroids has led to increased interest in thermophysical modeling. Most of these infrared observations are unresolved. We consider what fraction of an asteroid’s surface area contributes the bulk of the emitted thermal flux for two model asteroids of different shapes over a range of thermal parameters. The resulting observed surface in the infrared is generally more fragmented than the area observed in visible wavelengths, indicating high sensitivity to shape. For objects with low values of the thermal parameter, small fractions of the surface contribute the majority of thermally emitted flux. Calculating observed areas could enable the production of spatially resolved thermal inertia maps from non-resolved observations of asteroids.

  11. Ward-based, nurse-led, outpatient chest tube management: analysis of impact, cost-effectiveness and patient safety.

    Science.gov (United States)

    Tcherveniakov, Peter; De Siqueira, Jonathan; Milton, Richard; Papagiannopoulos, Kostas

    2012-06-01

    Prolonged drainage and air leaks are recognized complications of elective and acute thoracic surgery and carry significant burden on inpatient stay and outpatient resources. Since 2007, we have run a ward-based, nurse-led clinic for patients discharged with a chest drain in situ. The aim of this study is to assess its cost-effectiveness and safety. We present a retrospective review of the activity of the clinic for a period of 12 months (November 2009-10). An analysis of the gathered data is performed, focusing specifically on the duration of chest tube indwelling, the indications, complications and cost efficiency. The nurse-led clinic was housed in the thoracic ward with no additional fixed costs. Seventy-four patients were reviewed (53 males, 21 females, mean age of 59) and subsequently discharged from the clinic in this time period, accounting for 149 care episodes. Thirty-three (45%) of the patients underwent a video-assisted thoracoscopic surgery procedure, 35 (47%) of them a thoracotomy and 7 (9%) had a bedside chest tube insertion. Following hospital discharge, the chest tubes were removed after a median of 14 days (range 1-82 days). Fifty-eight percent of the patients were reviewed because of a prolonged air leak, 26% for persistent fluid drainage and 16% due to prolonged drainage following evacuation of empyemas. For the care episodes analysed, we estimate that the clinic has generated an income of €24,899 for the department. Hourly staffing costs for the service are significantly lower compared with those of the traditional outpatient clinic: €15 vs. €114. Our results show that a dedicated chest tube monitoring clinic is a safe and efficient alternative to formal outpatient clinic review. It can lead to shorter hospital stays and is cost effective.

  12. Cheap and Effective: The Impact of Student-Led Recitation Classes on Learning Outcomes in Introductory Economics

    Science.gov (United States)

    Stock, Wendy A.; Ward, Kevin; Folsom, Justin; Borrenpohl, Teresa; Mumford, Sophie; Pershin, Zach; Carriere, Danielle; Smart, Heather

    2013-01-01

    The authors examine the impacts of enrollment in a voluntary one-credit recitation class for ECON 101 students, focusing on course grades, course retention, and outcomes in later economics courses. The recitation classes were taught by undergraduate peer leaders with experience in upper-level microeconomics. Instead of being paid, the peer leaders…

  13. Impact of nurse-led behavioural counselling to improve metabolic health and physical activity among adults with mental illness.

    Science.gov (United States)

    Fraser, Sarah J; Brown, Wendy J; Whiteford, Harvey A; Burton, Nicola W

    2017-05-02

    The life expectancy of adults with mental illness is significantly less than that of the general population, and this is largely due to poor physical health. Behavioural counselling can improve physical health indicators among people with non-communicable disease. This repeated-measures, single-group intervention trial evaluated the effects of a 19-week behavioural counselling programme on metabolic health indicators and physical activity levels of outpatient adults with mental illness. Sixteen participants completed the intervention that comprised individual face-to-face counselling sessions with a registered nurse every 3 weeks, and progress reviews with a medical practitioner every 6 weeks. Assessment included self-report and objective measurement of physical activity, and measures of blood pressure and anthropometry. Statistically-significant changes were demonstrated between baseline and post intervention for participants' waist circumference (P = 0.035) and waist-to-height ratio (P = 0.037). Non-significant improvements were demonstrated in weight and physical activity. The findings indicated that adults with mental illness can engage in a nurse-led behavioural counselling intervention, with improvements in some metabolic health measures after 19 weeks. It is recommended that behavioural counselling programmes for adults with mental illness be sustained over time and have an 'open door' policy to allow for attendance interruptions, such as hospitalization. © 2017 Australian College of Mental Health Nurses Inc.

  14. Rapid short-term cooling following the Chicxulub impact at the Cretaceous-Paleogene boundary

    NARCIS (Netherlands)

    Vellekoop, Johan; Sluijs, Appy|info:eu-repo/dai/nl/311474748; Smit, Jan; Schouten, Stefan|info:eu-repo/dai/nl/137124929; Weijers, Johan W H|info:eu-repo/dai/nl/310911516; Sinninghe Damsté, Jaap S.|info:eu-repo/dai/nl/07401370X; Brinkhuis, Henk|info:eu-repo/dai/nl/095046097

    2014-01-01

    The mass extinction at the Cretaceous-Paleogene boundary, ~66 Ma, is thought to be caused by the impact of an asteroid at Chic-xulub, present-day Mexico. Although the precise mechanisms that led to this mass extinction remain enigmatic, most postulated scenarios involve a short-lived global cooling,

  15. Rapid short-term cooling following the Chicxulub impact at the Cretaceous-Paleogene boundary

    NARCIS (Netherlands)

    Vellekoop, J.; Sluijs, A.; Smit, J.; Schouten, S.; Weijers, J.W.H.; Sinninghe Damsté, J.S.; Brinkhuis, H.

    2014-01-01

    The mass extinction at the Cretaceous-Paleogene boundary, similar to 66 Ma, is thought to be caused by the impact of an asteroid at Chicxulub, present-day Mexico. Although the precise mechanisms that led to this mass extinction remain enigmatic, most postulated scenarios involve a short-lived global

  16. Rapid short-term cooling following the Chicxulub impact at the Cretaceous–Paleogene boundary

    NARCIS (Netherlands)

    Vellekoop, J.; Sluijs, A.; Smit, J.; Schouten, S.; Weijers, J.W.H.; Damsté, J.S.S.; Brinkhuis, H.

    2014-01-01

    The mass extinction at the Cretaceous-Paleogene boundary, ~66 Ma, is thought to be caused by the impact of an asteroid at Chic-xulub, present-day Mexico. Although the precise mechanisms that led to this mass extinction remain enigmatic, most postulated scenarios involve a short-lived global cooling,

  17. Tectonism and Magmatism on Asteroids

    Science.gov (United States)

    Buczkowski, D. L.; Wyrick, D. Y.

    2015-10-01

    Linear features generally accepted as tectonic structures have been observed on several asteroids and their presence has implications for the internal structure, strength and evolution of these various bodies. Observations of several small bodies have identified different physical mechanisms by which linear features can be formed. Analysis shows that asteroid lineaments appear to have different origins. We also discuss the potential for volcanism and/or magmatism on asteroids, especially in regard to Vesta which, as a differentiated proto-planet,is a unique body with which to study the role that internal rheologies and structures play on surface features.

  18. Near-Earth Asteroids as Possible Parent Bodies of Meteor Streams

    Directory of Open Access Journals (Sweden)

    M.G. Sokolova

    2016-12-01

    Full Text Available The genetic relationship of meteor streams with near-Earth asteroids (NEAs is being actively studied. A genetic link with the asteroid is possible only for streams in which meteoroids have the geocentric speed smaller than 50 km/s, thereby meaning the proportionality of their orbits with the orbits of asteroids. To date, there are about 40 such orphan streams with unknown parent bodies. In the paper, NEA groups (Aten, Apollo, Amor, and Atira have been considered from the perspective of possible search for the parent bodies of meteor streams among them. The groups have been compared based on the following parameters: eccentricity of asteroid orbits, as well as size and chemical composition of asteroids. Currently, it is considered that the surface of asteroids with elongated orbits is subjected to temperature fall: it is heated in perihelion and cooled in aphelion. Due to small orbital periods around the Sun (about 2–4 years, this may lead to formation of meteoroid clusters. Therefore, comparison of asteroids by their orbit shape and physicochemical parameters enables us to distinguish between NEA groups of asteroids and the Apollo group as most probable candidates to search for the parent bodies of meteor streams among NEAs. Unfortunately, finding physicochemical parameters poses great difficulties, since they are only detectable for some asteroids. At the same time, it is impossible to study asteroids dynamics, evolution, and relation with other bodies of the Solar system, as well as to realistically assess the impact of NEAs and products of their disintegration collision with the Earth and to develop systems of anti-asteroid protection without knowing the following parameters of asteroids: mineralogical composition, density, size, and accurate mass.

  19. Promoting research and audit at medical school: evaluating the educational impact of participation in a student-led national collaborative study.

    Science.gov (United States)

    Chapman, Stephen J; Glasbey, James C D; Khatri, Chetan; Kelly, Michael; Nepogodiev, Dmitri; Bhangu, Aneel; Fitzgerald, J Edward F

    2015-03-13

    Medical students often struggle to engage in extra-curricular research and audit. The Student Audit and Research in Surgery (STARSurg) network is a novel student-led, national research collaborative. Student collaborators contribute data to national, clinical studies while gaining an understanding of audit and research methodology and ethical principles. This study aimed to evaluate the educational impact of participation. Participation in the national, clinical project was supported with training interventions, including an academic training day, an online e-learning module, weekly discussion forums and YouTube® educational videos. A non-mandatory, online questionnaire assessed collaborators' self-reported confidence in performing key academic skills and their perceptions of audit and research prior to and following participation. The group completed its first national clinical study ("STARSurgUK") with 273 student collaborators across 109 hospital centres. Ninety-seven paired pre- and post-study participation responses (35.5%) were received (male = 51.5%; median age = 23). Participation led to increased confidence in key academic domains including: communication with local research governance bodies (p research, audit and study design (p study, which increased their confidence and appreciation of academic principles and skills. Encouraging active participation in collaborative, student-led, national studies offers a novel approach for delivering essential academic training.

  20. Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family

    CERN Document Server

    Reddy, Vishnu; Bottke, William; Cloutis, Ed; Izawa, Matt; O'Brien, Dave; Mann, Paul; Cuddy, Matt; Corre, Lucille Le; Gaffey, Michael; Fujihara, Gary

    2014-01-01

    We investigated the spectral and compositional properties of Chelyabinsk meteorite to identify its possible parent body in the main asteroid belt. Our analysis shows that the meteorite contains two spectrally distinct but compositionally indistinguishable components of LL5 chondrite and shock blackened/impact melt material. Our X-ray diffraction analysis confirms that the two lithologies of the Chelyabinsk meteorite are extremely similar in modal mineralogy. The meteorite is compositionally similar to LL chondrite and its most probable parent asteroid in the main belt is a member of the Flora family. Intimate mixture of LL5 chondrite and shock blackened/impact melt material from Chelyabinsk provides a spectral match with (8) Flora, the largest asteroid in the Flora family. The Baptistina family and Flora family overlap each other in dynamical space. Mineralogical analysis of (298) Baptistina and 9 small family members shows that their surface compositions are similar to LL chondrites, although their absorptio...

  1. Mobile Asteroid Surface Scout (MASCOT) - An asteroid lander package for the Hayabusa-2 mission

    Science.gov (United States)

    Lange, Caroline; Richter, Lutz; Dietze, Claudia; Ho, Tra-Mi; Lange, Michael; Sproewitz, Tom; Wagenbach, Susanne; Kroemer, Olaf; Witte, Lars; Braukhane, Andy

    2010-05-01

    The Hayabusa-2 mission is currently being studied by JAXA/JSPEC as a sample return mission to the C-type near-Earth asteroid 1999JU3. Hayabusa-2, with launch planned for 2014, would be the immediate successor to the currently flying Hayabusa mission. Originally in the context of the proposed ESA Cosmic Vision M-class mission Marco Polo, but then following an invitation by JAXA/JSPEC, the Institute of Space Systems of the German Aerospace Center (DLR) led a proposal for a separate lander package 'Mascot' (Mobile Asteroid Surface Scout) to be carried on the mission. A feasibility study was subsequently carried out that, upon consultation with the planetary science community, assessed different concepts for the lander that converged to a package with 3 kg of P/L, for a total mass of 10-15 kg. Presently, 'Mascot' enters the preliminary design phase while an Announcement of Opportunity for its payload complement is being prepared. The presentation will outline the current baseline design, with special consideration of how the highly demanding constraints that are being imposed on the system due to the general mission scenario, the asteroid environment and the tight budgetary limitations are being fulfilled in such a rather modest design, still offering an excellent science potential.

  2. Structural Stability of Asteroids

    Science.gov (United States)

    Hirabayashi, Toshi

    This thesis develops a technique for analyzing the internal structure of an irregularly shaped asteroid. This research focuses on asteroid (216) Kleopatra, a few-hundred-kilometer-sized main belt asteroid spinning about its maximum moment of inertia axis with a rotation period of 5.385 hours, to motivate the techniques. While Ostro et al. [117] reported its dog bone-like shape, estimation of its size has been actively discussed. There are at least three different size estimates: Ostro et al., Descamps et al., and Marchis et al. Descamps et al. reported that (216) Kleopatra has satellites and obtained the mass of this object. This research consists of determination of possible failure modes of (216) Kleopatra and its subsequent detailed stress analysis, with each part including an estimation of the internal structure. The first part of this thesis considers the failure mode of Kleopatra and evaluates the size from it. Possible failure modes are modeled as either material shedding from the surface or plastic failure of the internal structure. The surface shedding condition is met when a zero-velocity curve with the same energy level as one of the dynamical equilibrium points attaches to the surface at the slowest spin period, while the plastic failure condition is characterized by extending the theorem by Holsapple (2008) that the yield condition of the averaged stress over the whole volume is identical to an upper bound for global failure. The prime result shows that while surface shedding does not occur at the current spin period and thus cannot result in the formation of the satellites, the neck may be situated near its plastic deformation state. From the failure condition, we also find that the size estimated by Descamps et al. (2011) is the most structurally stable. The second part of this thesis discusses finite element analyses with an assumption of an elastic-perfectly plastic material and a non-associated flow rule. The yield condition is modeled as the

  3. The impact and effectiveness of nurse-led care in the management of acute and chronic pain: a review of the literature.

    Science.gov (United States)

    Courtenay, Molly; Carey, Nicola

    2008-08-01

    To identify, summarise and critically appraise the current evidence regarding the impact and effectiveness of nurse-led care in acute and chronic pain. A diverse range of models of care exist within the services available for the management of acute and chronic pain. Primary studies have been conducted evaluating these models, but, review and synthesis of the findings from these studies has not been undertaken. Literature review. Searches of Pubmed (NLM) Medline, CINAHL, Web of Knowledge (Science Index, Social Science index), British Nursing Index from January 1996-March 2007 were conducted. The searches were supplemented by an extensive hand search of the literature through references identified from retrieved articles and by contact with experts in the field. Twenty-one relevant publications were identified and included findings from both primary and secondary care. The areas, in which nurses, caring for patients in pain are involved, include assessment, monitoring, evaluation of pain, interdisciplinary collaboration and medicines management. Education programmes delivered by specialist nurses can improve the assessment and documentation of acute and chronic pain. Educational interventions and the use of protocols by specialist nurses can improve patients understanding of their condition and improve pain control. Acute pain teams, led by nurses, can reduce pain intensity and are cost effective. Nurses play key roles in the diverse range of models of care that exist in acute and chronic pain. However, there are methodological weaknesses across this body of research evidence and under researched issues that point to a need for further rigorous evaluation. Nurse-led care is an integral element of the pain services offered to patients. This review highlights the effect of this care and the issues that require consideration by those responsible for the development of nurse-led models in acute and chronic pain.

  4. The impact of the driving frequency on the output flux of high-power InGaAlP-LEDs during high-current pulsed operation

    Science.gov (United States)

    Schulz, Benjamin; Morgott, Stefan

    2017-09-01

    Direct red light-emitting diodes based on InGaAlP comprise a strong temperature sensitivity regarding their output flux. In étendue-limited applications, like digital projectors, these LEDs are usually driven at current densities exceeding 3 A/mm2 in pulsed mode. The losses inside the semiconductor lead to a large amount of heat, which has to be removed most efficiently by a heatsink to keep the junction temperature as low as possible and therefore to obtain the maximum output flux. One important performance parameter is the thermal resistance Rth of the LED, which has been improved during the last few years, e.g. by the development of new high-power chips and packages. In our present approach, we investigated the influence of the driving frequency - which is closely related to the thermal impedance Zth - on the luminous and the radiant flux of red LEDs. A simulation model based on the electro-thermal analogies was implemented in SPICE and the optical and electrical characteristics of one LED type (OSRAM OSTAR Projection Power LE A P1W) were measured under application-related driving conditions while varying the parameters frequency, duty cycle, forward current, and heatsink temperature. The experimental results show clearly that the luminous and the radiant flux go up when the driving frequency is increased while the other parameters are maintained. Moreover, it can be noticed that the degree of this effect depends on the other parameters. The largest impact can be observed at the lowest tested duty cycle (30 %) and the highest tested current density (4 A/mm2) and heatsink temperature (80 °C). At this operating point, the luminous and the radiant flux increase by 20 % and 14 % respectively when raising the frequency from 240 Hz to 1920 Hz.

  5. Near Earth Asteroid Scout Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In considering targets for human asteroid missions, there are several major factors that will make a significant difference in assessment of mission risks that...

  6. Asteroid Ida and Its Moon

    Science.gov (United States)

    1994-01-01

    This is the first full picture showing both asteroid 243 Ida and its newly discovered moon to be transmitted to Earth from the National Aeronautics and Space Administration's (NASA's) Galileo spacecraft--the first conclusive evidence that natural satellites of asteroids exist. Ida, the large object, is about 56 kilometers (35 miles) long. Ida's natural satellite is the small object to the right. This portrait was taken by Galileo's charge-coupled device (CCD) camera on August 28, 1993, about 14 minutes before the Jupiter-bound spacecraft's closest approach to the asteroid, from a range of 10,870 kilometers (6,755 miles). Ida is a heavily cratered, irregularly shaped asteroid in the main asteroid belt between Mars and Jupiter--the 243rd asteroid to be discovered since the first was found at the beginning of the 19th century. Ida is a member of a group of asteroids called the Koronis family. The small satellite, which is about 1.5 kilometers (1 mile) across in this view, has yet to be given a name by astronomers. It has been provisionally designated '1993 (243) 1' by the International Astronomical Union. ('1993' denotes the year the picture was taken, '243' the asteroid number and '1' the fact that it is the first moon of Ida to be found.) Although appearing to be 'next' to Ida, the satellite is actually in the foreground, slightly closer to the spacecraft than Ida is. Combining this image with data from Galileo's near-infrared mapping spectrometer, the science team estimates that the satellite is about 100 kilometers (60 miles) away from the center of Ida. This image, which was taken through a green filter, is one of a six-frame series using different color filters. The spatial resolution in this image is about 100 meters (330 feet) per pixel.

  7. Impact and acceptability of lay health trainer-led lifestyle interventions delivered in primary care: a mixed method study.

    Science.gov (United States)

    Visram, Shelina

    2017-07-01

    Aim To evaluate the impact and acceptability of offering one-to-one lifestyle interventions delivered by lay health trainers in the primary care setting. Chronic conditions represent major causes of ill-health, avoidable disability, pain and anxiety, and tend to be more prevalent in less affluent groups. This is due, in part, to the link between unhealthy lifestyles and lower socio-economic status, although factors such as poverty, worklessness and social exclusion play a larger role. Lay health trainers were introduced in England with the aim of providing personalised lifestyle advice, support and access to services for people living in disadvantaged areas. There is a body of literature on the effectiveness of lay or community health workers in the management of chronic conditions. However, little is known about their potential to promote lifestyle changes in newly diagnosed patients. An innovative health trainer service was piloted in the primary care setting, to work with people diagnosed with a chronic condition or identified as potentially benefitting from one-to-one support. A mixed method study design was utilised. Semi-structured interviews and focus groups were conducted with practice staff (n=11) and patients (n=15) from one primary care practice in North East England, United Kingdom. Discussions were audio-recorded and analysed using a thematic content approach. Routinely collected pre-/post-intervention data (n=246 patients at baseline; sample sizes varied at end line) were analysed and appropriate descriptive and summary statistics produced. Findings The discussions highlighted a high level of satisfaction with the health trainer model in terms of supporting positive lifestyle changes. Locating the intervention within the practice removed access barriers, particularly for those with long-term conditions. Anecdotal evidence of health improvement was supported by the quantitative analyses, which revealed statistically significant improvements in body

  8. Cellinoid Shape Model for Asteroids

    Science.gov (United States)

    Lu, Xiaoping; Zhao, Haibin; You, Zhong

    2014-08-01

    The ellipsoid shape model plays an important role in physical research on asteroids. However, its symmetric structure cannot practically simulate real asteroids. This article applies a general shape model, named the cellinoid, instead of the ellipsoid model to simulate the asymmetric shape of asteroids. The cellinoid shape model consists of eight octants of ellipsoids having different semi-axes, with the constraint that adjacent octants must have two equal semi-axes in common. Totally, the shape of the cellinoid model is controlled by six parameters, not three as in the case of the shape of the ellipsoid. Using this shape model, the brightness of asteroids observed from the Earth can be fitted numerically by the surface triangularization of the cellinoid. The Levenberg-Marquardt algorithm is also employed here to solve a nonlinear minimization problem. Owing to the asymmetric shape of the cellinoid, the physical parameters of asteroids, such as the rotation period and pole orientation, can be fitted more accurately than in the case of the ellipsoid model. Finally, this is confirmed numerically by applying the shape to both synthetic light curves and real light curves of asteroids. Additionally, the center of mass and moment of inertia of the cellinoid are analyzed explicitly.

  9. Powerful New Technique to Measure Asteroids' Sizes and Shapes

    Science.gov (United States)

    2009-02-01

    A team of French and Italian astronomers have devised a new method for measuring the size and shape of asteroids that are too small or too far away for traditional techniques, increasing the number of asteroids that can be measured by a factor of several hundred. This method takes advantage of the unique capabilities of ESO's Very Large Telescope Interferometer (VLTI). ESO PR Photo 04a/09 Asteroid Barbara (artist's impression) "Knowledge of the sizes and shapes of asteroids is crucial to understanding how, in the early days of our Solar System, dust and pebbles collected together to form larger bodies and how collisions and re-accumulation have since modified them," says Marco Delbo from the Observatoire de la Côte d'Azur, France, who led the study. Direct imaging with adaptive optics on the largest ground-based telescopes such as the Very Large Telescope (VLT) in Chile (see ESO 21/05 and 18/07), and space telescopes, or radar measurements (ESO 11/07) are the currently favoured methods of asteroid measurement. However, direct imaging, even with adaptive optics, is generally limited to the one hundred largest asteroids of the main belt, while radar measurements are mostly constrained to observations of near-Earth asteroids that experience close encounters with our planet. Delbo and his colleagues have devised a new method that uses interferometry to resolve asteroids as small as about 15 km in diameter located in the main asteroid belt, 200 million kilometres away. This is equivalent to being able to measure the size of a tennis ball a distance of a thousand kilometres. This technique will not only increase the number of objects that can be measured dramatically, but, more importantly, bring small asteroids that are physically very different from the well studied larger ones into reach. The interferometric technique combines the light from two or more telescopes. Astronomers proved their method using ESO's VLTI, combining the light of two of the VLT's 8.2-metre

  10. Spin rate distribution of small asteroids

    Czech Academy of Sciences Publication Activity Database

    Pravec, Petr; Harris, A. W.; Vokrouhlický, D.; Warner, B. D.; Kušnirák, Peter; Hornoch, Kamil; Pray, D. P.; Higgins, D.; Oey, J.; Galád, Adrián; Gajdoš, Š.; Kornoš, L.; Világi, J.; Husárik, M.; Krugly, Yu. N.; Shevchenko, V. G.; Chiorny, V. G.; Gaftonyuk, N. M.; Cooney jr., W. R.; Gross, J.; Terrell, D.; Stephens, R.; Dyvig, R.; Reddy, V.; Ries, J.G.; Colas, F.; Lecacheux, J.; Durkee, R.; Masi, G.; Koff, R.; Goncalves, R.

    2008-01-01

    Roč. 197, č. 2 (2008), s. 497-504 ISSN 0019-1035 R&D Projects: GA ČR(CZ) GA205/05/0604 Grant - others:NASA(US) NAG5-13244; NASA(US) NNG06GI32G; VEGA(SK) 1/3074/06; VEGA(SK) 1/3067/06; VEGA(SK) 2/7009/27 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids rotation * photometry * near-Earth objects Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.268, year: 2008

  11. A Mobile Asteroid Surface Scout for the AIDA Mission

    Science.gov (United States)

    Ho, Tra Mi; Lange, Caroline; Grimm, Christian; Thimo Grundmann, Jan; Rößler, Johannes; Schröder, Silvio; Skoczylas, Thomas; Ziach, Christian; Biele, Jens; Cozzoni, Barbara; Krause, Christian; Küchemann, Oliver; Maibaum, Michael; Ulamec, Stephan; Lange, Michael; Mierheim, Olaf; Maier, Maximilian; Herique, Alain; Mascot Study Team

    2016-04-01

    The Asteroid Impact Deflection, AIDA, mission is composed of a kinetic impactor, DART and an observer, the Asteroid Impact Monitor, AIM, carrying among other payload a surface package, MASCOT2 (MSC2). Its proposed concept is based on the MASCOT lander onboard the HAYABUSA2 Mission (JAXA) to near-Earth asteroid (162173) Ryugu. MASCOT is a compact platform ('shoe box size') carrying a suite of 4 scientific instruments and has a landed mass of ~10kg. Equipped with a mobility mechanism, the MASCOT lander is able to upright and relocate on the targeted asteroid; thus providing in-situ data at more than one site. In the context of the AIDA Mission, the MASCOT2 lander would be carried by the AIM spacecraft and delivered onto Didymoon, the secondary object in the (65803) Didymos binary near-Earth asteroid system. Since the mission objectives of the AIM mission within the joint AIDA mission concept differ from JAXA's sample return mission HAYABUSA2, several design changes need to be studied and implemented. To support one of the prime objectives of the AIM mission, the characterization of the bulk physical properties of Didymoon, the main scientific payload of MSC2 is a low-frequency radar (LFR) to investigate the internal structure of the asteroid moon. Since the total science payload on MASCOT2 is limited to approximately 2.3 kg, the mass remaining for a suite of other experiments is in the range of 0.1 to 0.5 kg per instrument. Further requirements have a significant impact on the MSC2 design which will be presented. Among these are the much longer required operational lifetime than for MASCOT on HAYABUSA2, and different conditions on the target body such as an extremely low gravity due to its small size of Ø_[Didymoon] ~ 150m.

  12. Determining the impact of a new physiotherapist-led primary care model for back pain: protocol for a pilot cluster randomized controlled trial.

    Science.gov (United States)

    Miller, Jordan; Barber, David; Donnelly, Catherine; French, Simon; Green, Michael; Hill, Jonathan; MacDermid, Joy; Marsh, Jacquelyn; Norman, Kathleen; Richardson, Julie; Taljaard, Monica; Wideman, Timothy; Cooper, Lynn; McPhee, Colleen

    2017-11-09

    Back pain is a leading contributor to disability, healthcare costs, and lost work. Family physicians are the most common first point of contact in the healthcare system for people with back pain, but physiotherapists (PTs) may be able to support the primary care team through evidence-based primary care. A cluster randomized trial is needed to determine the clinical, health system, and societal impact of a primary care model that integrates physiotherapists at the first visit for people with back pain. Prior to conducting a future fully powered cluster randomized trial, we need to demonstrate feasibility of the methods. Therefore, the purpose of this pilot study will be to: 1) Determine feasibility of patient recruitment, assessment procedures, and retention. 2) Determine the feasibility of training and implementation of a new PT-led primary care model for low back pain (LBP) 3) Explore the perspectives of patients and healthcare providers (HCPs) related to their experiences and attitudes towards the new service delivery model, barriers/facilitators to implementation, perceived satisfaction, perceived value, and impact on clinic processes and patient outcomes. This pilot cluster randomized controlled trial will enroll four sites and randomize them to implement a new PT-led primary care model for back pain or a usual physician-led primary care model. All adults booking a primary care visit for back pain will be invited to participate. Feasibility outcomes will include: recruitment and retention rates, completeness of assessment data, PT training participation and confidence after training, and PT treatment fidelity. Secondary outcomes will include the clinical, health system, cost, and process outcomes planned for the future fully powered cluster trial. Results will be analyzed and reported descriptively and qualitatively. To explore perspectives of both HCPs and patients, we will conduct semi-structured qualitative interviews with patients and focus groups with HCPs

  13. Binary asteroid population. 3. Secondary rotations and elongations

    Czech Academy of Sciences Publication Activity Database

    Pravec, Petr; Scheirich, Peter; Kušnirák, Peter; Hornoch, Kamil; Galád, Adrián; Naidu, S.P.; Pray, D. P.; Világi, J.; Gajdoš, Š.; Kornoš, L.

    2016-01-01

    Roč. 267, March (2016), s. 267-295 ISSN 0019-1035 R&D Projects: GA ČR GAP209/12/0229; GA ČR GA15-07193S Institutional support: RVO:67985815 Keywords : asteroids * rotation * dynamics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.131, year: 2016

  14. Physical modeling of near-Earth Asteroid (29075) 1950 DA

    Czech Academy of Sciences Publication Activity Database

    Busch, M.W.; Giorgini, J. D.; Ostro, S. J.; Benner, L. A. M.; Jurgens, R. F.; Rose, R.; Hicks, M. D.; Pravec, Petr; Kušnirák, Peter; Ireland, M.J.; Scheeres, D.J.; Broschart, S.B.; Magri, C.; Nolan, M. C.; Hine, A. A.; Margot, J. L.

    2007-01-01

    Roč. 190, č. 2 (2007), s. 608-621 ISSN 0019-1035 Grant - others:GA ČR(CZ) GA208/99/0255 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * composition * dynamics * rotation Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.869, year: 2007

  15. Impact of peer-led quality improvement networks on quality of inpatient mental health care: study protocol for a cluster randomized controlled trial.

    Science.gov (United States)

    Aimola, Lina; Jasim, Sarah; Tripathi, Neeraj; Tucker, Sarah; Worrall, Adrian; Quirk, Alan; Crawford, Mike J

    2016-09-21

    Quality improvement networks are peer-led programmes in which members of the network assess the quality of care colleagues provide according to agreed standards of practice. These networks aim to help members identify areas of service provision that could be improved and share good practice. Despite the widespread use of peer-led quality improvement networks, there is very little information about their impact. We are conducting a cluster randomized controlled trial of a quality improvement network for low-secure mental health wards to examine the impact of membership on the process and outcomes of care over a 12 month period. Standalone low secure units in England and Wales that expressed an interest in joining the quality improvement network were recruited for the study from 2012 to 2014. Thirty-eight units were randomly allocated to either the active intervention (participation in the network n = 18) or a control arm (delayed participation in the network n = 20). Using a 5 % significance level and 90 % power, it was calculated that a sample size of 60 wards was required taking into account a 10 % drop out. A total of 75 wards were assessed at baseline and 8 wards dropped out the study before the data collection at follow up. Researchers masked to the allocation status of the units assessed all study outcomes at baseline and follow-up 12 months later. The primary outcome is the quality of the physical environment and facilities on the wards. The secondary outcomes are: safety of the ward, patient-rated satisfaction with care and mental well-being, staff burnout, training and supervision. Relative to control wards, it is hypothesized that the quality of the physical environment and facilities will be higher on wards in the active arm of the trial 12 months after randomization. To our knowledge, this is the first randomized evaluation of a peer-led quality improvement network that has examined the impact of participation on both patient-level and

  16. Asteroid astrometry with Gaia: stellar occultations and beyond

    Science.gov (United States)

    Tanga, Paolo; Spoto, Federica; Hestroffer, Daniel; Altmann, Martin; Bouquillon, Sebastien; Desmars, Josselin

    2017-10-01

    The first data release of star astrometry by Gaia (Sept. 2016) has given an anticipation of the mission capabilities. By providing positions with uncertainties at the level of few milli-arcsec (mas) a new frame to calibrate ground-based observations has immediately become available, thus disclosing a new possibility of exploitation for archive data. We will discuss, in particular, the new role of stellar occulations.Successful observations of occultations have been used in the past to provide accurate shape and size of the targets and to calibrate other size determination methods. Now, a new possibility of exploitation exists, as occultation astrometry provides the possibility of measuring precise asteroid position, at the level of Gaia accuracy. This approach will have an increasing impact, also thanks to the much improved prediction accuracy that Gaia is going to provide, for smaller asteroids and fainter target stars.The scientific goals of improving asteroid astrometry are multiple. For instance, reaching sensitivity to Yarkovsky drift in the Main Belt might become possible, by occultation astrometry performed on smaller asteroids, thanks to future Gaia predictions.The second data release (April 2018) will also contain astrometry of asteroids observed directly by Gaia. The properties of this new data set, that will permit direct orbit improvement, will be illustrated.

  17. Constraining Binary Asteroid Mass Distributions Based On Mutual Motion

    Science.gov (United States)

    Davis, Alex B.; Scheeres, Daniel J.

    2017-06-01

    The mutual gravitational potential and torques of binary asteroid systems results in a complex coupling of attitude and orbital motion based on the mass distribution of each body. For a doubly-synchronous binary system observations of the mutual motion can be leveraged to identify and measure the unique mass distributions of each body. By implementing arbitrary shape and order computation of the full two-body problem (F2BP) equilibria we study the influence of asteroid asymmetries on separation and orientation of a doubly-synchronous system. Additionally, simulations of binary systems perturbed from doubly-synchronous behavior are studied to understand the effects of mass distribution perturbations on precession and nutation rates such that unique behaviors can be isolated and used to measure asteroid mass distributions. We apply our investigation to the Trojan binary asteroid system 617 Patroclus and Menoetius (1906 VY), which will be the final flyby target of the recently announced LUCY Discovery mission in March 2033. This binary asteroid system is of particular interest due to the results of a recent stellar occultation study (DPS 46, id.506.09) that suggests the system to be doubly-synchronous and consisting of two-similarly sized oblate ellipsoids, in addition to suggesting the presence mass asymmetries resulting from an impact crater on the southern limb of Menoetius.

  18. Impact of a pharmacist-led warfarin self-management program on quality of life and anticoagulation control: a randomized trial.

    Science.gov (United States)

    Verret, Lucie; Couturier, Justine; Rozon, Andréanne; Saudrais-Janecek, Sarah; St-Onge, Amélie; Nguyen, Angela; Basmadjian, Arsène; Tremblay, Simon; Brouillette, Denis; de Denus, Simon

    2012-10-01

    To evaluate the impact of a pharmacist-led warfarin patient self-management program on quality of life and anticoagulation control compared with management in a physician-led specialized anticoagulation clinic. Prospective, randomized, controlled, open-label trial. Tertiary care academic medical center. A total of 114 patients aged 18-75 years who were followed at a specialized anticoagulation clinic, had received warfarin for at least 6 months, and were expected to continue warfarin for a minimum of 4 months. All patients attended an educational session on anticoagulation provided by a pharmacist. Patients randomized to the self-management group (58 patients) also received practical training to use the CoaguChek XS device and a self-management dosing algorithm. Patients in the control group (56 patients) continued to undergo standard management at the anticoagulation clinic. Patients completed a validated quality-of-life questionnaire and the validated Oral Anticoagulation Knowledge test at the beginning and end of the study. The quality of anticoagulation control was evaluated by using the time spent in therapeutic range. After 4 months of follow-up, a significant improvement in the self-management group was observed compared with the control group in four of the five quality-of-life topics (pself-management group vs 75% in the control group, p=0.79) and in the extended therapeutic range ([target international normalized ratio ± 0.3] 93.2% in the self-management group vs 91.1% in the control group, p=0.30) were similar between groups. A self-management warfarin program led by pharmacists resulted in significant improvement in the quality of life of patients receiving warfarin therapy as well as a reduction in the time required for anticoagulation monitoring, while maintaining a level of anticoagulation control similar to a high-quality specialized anticoagulation clinic. © 2012 Pharmacotherapy Publications, Inc.

  19. The violent collisional history of asteroid 4 Vesta.

    Science.gov (United States)

    Marchi, S; McSween, H Y; O'Brien, D P; Schenk, P; De Sanctis, M C; Gaskell, R; Jaumann, R; Mottola, S; Preusker, F; Raymond, C A; Roatsch, T; Russell, C T

    2012-05-11

    Vesta is a large differentiated rocky body in the main asteroid belt that accreted within the first few million years after the formation of the earliest solar system solids. The Dawn spacecraft extensively imaged Vesta's surface, revealing a collision-dominated history. Results show that Vesta's cratering record has a strong north-south dichotomy. Vesta's northern heavily cratered terrains retain much of their earliest history. The southern hemisphere was reset, however, by two major collisions in more recent times. We estimate that the youngest of these impact structures, about 500 kilometers across, formed about 1 billion years ago, in agreement with estimates of Vesta asteroid family age based on dynamical and collisional constraints, supporting the notion that the Vesta asteroid family was formed during this event.

  20. Flight status of robotic asteroid sample return mission Hayabusa2

    Science.gov (United States)

    Tsuda, Yuichi; Nakazawa, Satoru; Kushiki, Kenichi; Yoshikawa, Makoto; Kuninaka, Hitoshi; Watanabe, Seiichiro

    2016-10-01

    The Japan Aerospace Exploration Agency launched the asteroid sample return spacecraft ;Hayabusa2; on December 3, 2014. Hayabusa2 will reach the C-type asteroid 1999 JU3 in 2018, and return back to the Earth in 2020. Sample collections from three sites, four surface rovers deployment and a 4 MJ-class kinetic impact crater generation are planned in the 1.5 years of the asteroid-proximity operation. The mission objective of Hayabusa2 has three aspects, science, engineering and exploration, all of which would be expanded by the successful round-trip journey. This paper describes the outline of the Hayabusa2 mission and the current flight status after the seven month of the interplanetary cruise.

  1. Asteroid Exploration and Exploitation

    Science.gov (United States)

    Lewis, John S.

    2006-01-01

    John S. Lewis is Professor of Planetary Sciences and Co-Director of the Space Engineering Research Center at the University of Arizona. He was previously a Professor of Planetary Sciences at MIT and Visiting Professor at the California Institute of Technology. Most recently, he was a Visiting Professor at Tsinghua University in Beijing for the 2005-2006 academic year. His research interests are related to the application of chemistry to astronomical problems, including the origin of the Solar System, the evolution of planetary atmospheres, the origin of organic matter in planetary environments, the chemical structure and history of icy satellites, the hazards of comet and asteroid bombardment of Earth, and the extraction, processing, and use of the energy and material resources of nearby space. He has served as member or Chairman of a wide variety of NASA and NAS advisory committees and review panels. He has written 17 books, including undergraduate and graduate level texts and popular science books, and has authored over 150 scientific publications.

  2. Impacts of Carrier Transport and Deep Level Defects on Delayed Cathodoluminescence in Droop-Mitigating InGaN/GaN LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhibo; Singh, Akshay; Chesin, Jordan; Armitage, Rob; Wildeson, Isaac; Deb, Parijat; Armstrong, Andrew; Kisslinger, Kim; Stach, Eric; Gradecak, Silvija

    2017-07-25

    Prevalent droop mitigation strategies in InGaN-based LEDs require structural and/or compositional changes in the active region but are accompanied by a detrimental reduction in external quantum efficiency (EQE) due to increased Shockley-Read-Hall recombination. Understanding the optoelectronic impacts of structural modifications in InGaN/GaN quantum wells (QW) remains critical for emerging high-power LEDs. In this work, we use a combination of electron microscopy tools along with standard electrical characterization to investigate a wide range of low-droop InGaN/GaN QW designs. We find that chip-scale EQE is uncorrelated with extended well-width fluctuations observed in scanning transmission electron microscopy. Further, we observe delayed cathodoluminescence (CL) response from designs in which calculated band profiles suggest facile carrier escape from individual QWs. Samples with the slowest CL responses also exhibit the lowest EQEs and highest QW defect densities in deep level optical spectroscopy. We propose a model in which the electron beam (i) passivates deep level defect states and (ii) drives charge carrier accumulation and subsequent reduction of the built-in field across the multi-QW active region, resulting in delayed radiative recombination. Finally, we correlate CL rise dynamics with capacitance-voltage measurements and show that certain early-time components of the CL dynamics reflect the open circuit carrier population within one or more QWs.

  3. Riding the rural radio wave: The impact of a community-led drug and alcohol radio advertising campaign in a remote Australian Aboriginal community.

    Science.gov (United States)

    Munro, Alice; Allan, Julaine; Shakeshaft, Anthony; Snijder, Mieke

    2017-10-01

    Aboriginal people experience a higher burden of disease as a consequence of drug and alcohol (D&A) abuse. Although media campaigns can be a popular tool for disseminating health promotion messages, evidence of the extent to which they reduce the impact of substance abuse is limited, especially for rural Aboriginal communities. This paper is the first to examine the impact a locally designed D&A radio advertising campaign for Aboriginal people in a remote community in Western NSW. A post-intervention evaluation. The radio campaign was implemented in Bourke, (population 2465, 30% Aboriginal). Fifty-three community surveys were completed. The self-reported level of awareness of the campaign and the number of self-referrals to local D&A workers in the intervention period. Most respondents (79%) reported they listen to radio on a daily basis, with 75% reporting that they had heard one or more of the advertisements. The advertisement that was remembered best contained the voice of a respected, local person. There was one self-referral to local health services during the intervention timeframe. The community-led radio advertising campaign increased community awareness of substance abuse harms, but had limited impact on formal help-seeking. This paper highlights the value of radio as a commonly used, trusted and culturally relevant health promotion medium for rural communities, especially when engaging local respected Aboriginal presenters. © 2017 National Rural Health Alliance Inc.

  4. The Nature of C Asteroid Regolith Revealed from the Jbilet Winselwan CM Chondrite

    Science.gov (United States)

    Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Chan, Queenie H. S.; Le, Loan; Kring, David; Cato, Michael; Fagan, Amy L.

    2016-01-01

    C-class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed carbonaceous chondrites, or a mixture of phyllosilicate-rich material along with regions where they are absent. One particularly important example appears to be asteroid 162173 Ryugu, the target of the Hayabusa 2 mission, although most spectra of Ryugu are featureless, suggesting a heterogeneous regolith. Here we explore an alternative cause of dehydration of regolith of C-class asteroids - impact shock melting. Impact shock melting has been proposed to ex-plain some mineralogical characteristics of CB chondrites, but has rarely been considered a major process for hydrous carbonaceous chondrites.

  5. An Investigation of the Ranges of Validity of Asteroid Thermal Models for Near-Earth Asteroid Observations

    Science.gov (United States)

    Mommert, M.; Jedicke, R.; Trilling, D. E.

    2018-02-01

    The majority of known asteroid diameters are derived from thermal-infrared observations. Diameters are derived using asteroid thermal models that approximate their surface temperature distributions and compare the measured thermal-infrared flux with model-dependent predictions. The most commonly used thermal model is the Near-Earth Asteroid Thermal Model (NEATM), which is usually perceived as superior to other models like the Fast-Rotating Model (FRM). We investigate the applicability of the NEATM and the FRM to thermal-infrared observations of Near-Earth Objects using synthetic asteroids with properties based on the real Near-Earth Asteroid (NEA) population. We find the NEATM to provide more accurate diameters and albedos than the FRM in most cases, with a few exceptions. The modeling results are barely affected by the physical properties of the objects, but we find a large impact of the solar phase angle on the modeling results. We conclude that the NEATM provides statistically more robust diameter estimates for NEAs observed at solar phase angles less than ∼65°, while the FRM provides more robust diameter estimates for solar phase angles greater than ∼65°. We estimate that <5% of all NEA diameters and albedos derived up to date are affected by systematic effects that are of the same order of magnitude as the typical thermal model uncertainties. We provide statistical correction functions for diameters and albedos derived using the NEATM and FRM as a function of solar phase angle.

  6. Excluding interlopers from asteroid families

    Science.gov (United States)

    Novakovic, B.; Radovic, V.

    2014-07-01

    Introduction: Asteroid families are believed to have originated from catastrophic collisions among asteroids. They are a very important subject of Solar System investigation, because practically any research topic carried out in asteroid-related science sooner or later encounters problems pertaining to asteroid families. One basic problem encountered when dealing with families is to determine reliably the list of its members, i.e. to reduce the number of interlopers as much as possible. This is an important problem, because many conclusions derived from analyses of the physical properties of family members must be necessarily based on firm and well established membership. However, as the number of known asteroids increases fast it becomes more and more difficult to obtain robust list of members of an asteroid family. To cope with these challenges we are proposing a new approach that may help to significantly reduce presence of interlopers among the family members. This method should be particularly useful once additional information become available, including primarily spectro-photometric data. This is exactly the kind of information that will be provided by Gaia. Metodology: Families (and their members) have been commonly identified by analysing the distribution of asteroids in the space of proper orbital elements, using the Hierarchical Clustering Method (HCM) [1]. A well-known drawback of the HCM based on the single linkage rule is the so-called chaining phenomenon: first concentrations naturally tend to incorporate nearby groups, forming a kind of 'chain'. Thus, any family membership obtained by the pure HCM must unavoidably include some interlopers. The method we are proposing here could be used to identify these interlopers, with its main advantage being an ability to significantly reduce the chaining effect. The method consists of three main steps. First we determine an asteroid family members by applying the HCM to the catalogue of proper elements obtained

  7. Asteroid Ida - Five Frame Mosaic

    Science.gov (United States)

    1993-01-01

    This view of the asteroid 243 Ida is a mosaic of five image frames acquired by the Galileo spacecraft's solid-state imaging system at ranges of 3,057 to 3,821 kilometers (1,900 to 2,375 miles) on August 28, 1993, about 3-1/2 minutes before the spacecraft made its closest approach to the asteroid. Galileo flew about 2,400 kilometers (1,500 miles) from Ida at a relative velocity of 12.4 km/sec (28,000 mph). Asteroid and spacecraft were 441 million kilometers (274 million miles) from the Sun. Ida is the second asteroid ever encountered by a spacecraft. It appears to be about 52 kilometers (32 miles) in length, more than twice as large as Gaspra, the first asteroid observed by Galileo in October 1991. Ida is an irregularly shaped asteroid placed by scientists in the S class (believed to be like stony or stony iron meteorites). It is a member of the Koronis family, presumed fragments left from the breakup of a precursor asteroid in a catastrophic collision. This view shows numerous craters, including many degraded craters larger than any seen on Gaspra. The extensive cratering seems to dispel theories about Ida's surface being geologically youthful. This view also seems to rule out the idea that Ida is a double body. The south pole is believed to be in the darkside near the middle of the asteroid. The camera's clear filter was used to produce this extremely sharp picture. Spatial resolution is 31 to 38 meters (roughly 100 feet) per pixel. A 30-frame mosaic was taken to assure capturing Ida; its position was somewhat uncertain before the Galileo encounter. Galileo shuttered and recorded a total of 150 images in order to capture Ida 21 different times during a five hour period (about one rotation of the asteroid). Color filters were used at many of these times to allow reconstruction of color images. Playback to Earth of the remaining images is planned for April through June 1994. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995

  8. Developing an Asteroid Rotational Theory

    Science.gov (United States)

    Geis, Gena; Williams, Miguel; Linder, Tyler; Pakey, Donald

    2018-01-01

    The goal of this project is to develop a theoretical asteroid rotational theory from first principles. Starting at first principles provides a firm foundation for computer simulations which can be used to analyze multiple variables at once such as size, rotation period, tensile strength, and density. The initial theory will be presented along with early models of applying the theory to the asteroid population. Early results confirm previous work by Pravec et al. (2002) that show the majority of the asteroids larger than 200m have negligible tensile strength and have spin rates close to their critical breakup point. Additionally, results show that an object with zero tensile strength has a maximum rotational rate determined by the object’s density, not size. Therefore, an iron asteroid with a density of 8000 kg/m^3 would have a minimum spin period of 1.16h if the only forces were gravitational and centrifugal. The short-term goal is to include material forces in the simulations to determine what tensile strength will allow the high spin rates of asteroids smaller than 150m.

  9. ASTEROID OCCULTATIONS V6.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid occultation events as well as asteroid occultation axes derived from those timings by...

  10. ASTEROID OCCULTATIONS V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid occultation events through Mar. 1, 2004, as well as asteroid occultation axes derived...

  11. ASTEROID PHOTOMETRIC CATALOG V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Photometric Catalog (3rd update), Lagerkvist, et.al., 1993 [LAGERKVISTETAL1993], is a compilation of all asteroid lightcurve photometry published up to...

  12. ASTEROID FAMILY IDENTIFICATIONS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a compilation of the family memberships of numbered asteroids in five different asteroid family analyses. These include the analyses of Zappala et al.,...

  13. ASTEROID PHOTOMETRIC CATALOG V1.1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Photometric Catalog (3rd update), Lagerkvist, et.al., 1993 [LAGERKVISTETAL1993], is a compilation of all asteroid lightcurve photometry published up to...

  14. ASTEROID OCCULTATIONS V4.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid occultation events through Apr. 11, 2006, as well as asteroid occultation axes derived...

  15. ASTEROID POLARIMETRIC DATABASE V6.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko and S.V. Vasiliev of Karazin Kharkiv National...

  16. ASTEROID POLARIMETRIC DATABASE V5.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko of Karazin Kharkiv National University, Ukraine....

  17. ASTEROID POLARIMETRIC DATABASE V8.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko of Karazin Kharkiv National University, Ukraine....

  18. ASTEROID POLARIMETRIC DATABASE V7.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko and S.V. Vasiliev of Karazin Kharkiv National...

  19. Impact of a pharmacist led diabetes mellitus intervention on HbA1c, medication adherence and quality of life: A randomised controlled study.

    Science.gov (United States)

    Butt, Mubashra; Mhd Ali, Adliah; Bakry, Mohd Makmor; Mustafa, Norlaila

    2016-01-01

    Malaysia is situated in Western Pacific region which bears 36.17% of total diabetes mellitus population. Pharmacist led diabetes interventions have been shown to improve the clinical outcomes amongst diabetes patients in various parts of the world. Despite high prevalence of disease in this region there is a lack of reported intervention outcomes from this region. The aim of this study was to evaluate the impact of a pharmacist led intervention on HbA1c, medication adherence, quality of life and other secondary outcomes amongst type 2 diabetes patients. Type 2 diabetes mellitus patients (n = 73) attending endocrine clinic at Universiti Kebangsaan Malaysia Medical Centre (UKMMC) were randomised to either control (n = 36) or intervention group (n = 37) after screening. Patients in the intervention group received an intervention from a pharmacist during the enrolment, after three and six months of the enrolment. Outcome measures such as HbA1c, BMI, lipid profile, Morisky scores and quality of life (QoL) scores were assessed at the enrolment and after 6 months of the study in both groups. Patients in the control group did not undergo intervention or educational module other than the standard care at UKMMC. HbA1c values reduced significantly from 9.66% to 8.47% (P = 0.001) in the intervention group. However, no significant changes were noted in the control group (9.64-9.26%, P = 0.14). BMI values showed significant reduction in the intervention group (29.34-28.92 kg/m(2); P = 0.03) and lipid profiles were unchanged in both groups. Morisky adherence scores significantly increased from 5.83 to 6.77 (P = 0.02) in the intervention group; however, no significant change was observed in the control group (5.95-5.98, P = 0.85). QoL profiles produced mixed results. This randomised controlled study provides evidence about favourable impact of a pharmacist led diabetes intervention programme on HbA1c, medication adherence and QoL scores amongst type 2 diabetes

  20. Can Asteroid Airbursts Cause Dangerous Tsunami?.

    Energy Technology Data Exchange (ETDEWEB)

    Boslough, Mark B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    I have performed a series of high-resolution hydrocode simulations to generate “source functions” for tsunami simulations as part of a proof-of-principle effort to determine whether or not the downward momentum from an asteroid airburst can couple energy into a dangerous tsunami in deep water. My new CTH simulations show enhanced momentum multiplication relative to a nuclear explosion of the same yield. Extensive sensitivity and convergence analyses demonstrate that results are robust and repeatable for simulations with sufficiently high resolution using adaptive mesh refinement. I have provided surface overpressure and wind velocity fields to tsunami modelers to use as time-dependent boundary conditions and to test the hypothesis that this mechanism can enhance the strength of the resulting shallow-water wave. The enhanced momentum result suggests that coupling from an over-water plume-forming airburst could be a more efficient tsunami source mechanism than a collapsing impact cavity or direct air blast alone, but not necessarily due to the originally-proposed mechanism. This result has significant implications for asteroid impact risk assessment and airburst-generated tsunami will be the focus of a NASA-sponsored workshop at the Ames Research Center next summer, with follow-on funding expected.

  1. Discovery of a Satellite around a Near-Earth Asteroid

    Science.gov (United States)

    1997-07-01

    the data necessary for these determinations, observations will be continued during the present period of good visibility that lasts until September-October 1997. For this reason the discoverers have initiated an international observation campaign devoted to the study of this intriguing object and now involving astronomers from many countries. How common are such satellites? Satellites in orbit around small bodies in the solar system - asteroids and cometary nuclei - have been predicted on theoretical grounds for a long time, even though there is no consensus among planetary scientists about the actual numbers of such systems. Hints about the existence of asteroid satellites also come from the presence of double impact craters on the Moon and other planetary surfaces. This suggests that the projectiles forming these craters were `double' asteroids. Moreover, measurements obtained when an asteroid passes in front of a relatively bright star (a so-called `occultation') have on a few occasions shown features which could be interpreted as due to the presence of a satellite. However, because of the difficult nature of such measurements, it has never been possible to draw unambiguous conclusions. The existence of double asteroids was invoked earlier by Petr Pravec and Gerhard Hahn to explain the unusual features observed in the lightcurves of two other Earth-approaching asteroids 1991 VH and 1994 AW1 . In the case of Dionysus , however, it is possible to predict eclipse events and to confirm them by subsequent measurements. There is therefore mounting evidence that asteroid binary systems might be comparatively common. Observational programmes like the present one by the DLR and Ondrejov groups will help to verify this possibility. Where to find additional information Detailed and up-to-date information about (3671) Dionysus can be found in the Web at the following URL: http://earn.dlr.de/dionysus. Notes: [1] This institute and its parent organisation are known in Germany as

  2. New active asteroid 313P/Gibbs

    Energy Technology Data Exchange (ETDEWEB)

    Jewitt, David; Hui, Man-To; Li, Jing [Department of Earth, Planetary and Space Sciences, UCLA, 595 Charles Young Drive East, Los Angeles, CA 90095-1567 (United States); Agarwal, Jessica [Max Planck Institute for Solar System Research, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau (Germany); Peixinho, Nuno [Unidad de Astronomía, Fac. de Ciencias Básicas, Universidad de Antofagasta, Avda. U. de Antofagasta 02800, Antofagasta (Chile); Weaver, Harold [The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland, MD 20723 (United States); Mutchler, Max [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Larson, Stephen, E-mail: jewitt@ucla.edu [Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd. Tucson AZ 85721-0092 (United States)

    2015-02-01

    We present initial observations of the newly discovered active asteroid 313P/Gibbs (formerly P/2014 S4), taken to characterize its nucleus and comet-like activity. The central object has a radius ∼0.5 km (geometric albedo 0.05 assumed). We find no evidence for secondary nuclei and set (with qualifications) an upper limit to the radii of such objects near 20 m, assuming the same albedo. Both aperture photometry and a morphological analysis of the ejected dust show that mass-loss is continuous at rates ∼0.2–0.4 kg s{sup −1}, inconsistent with an impact origin. Large dust particles, with radii ∼50–100 μm, dominate the optical appearance. At 2.4 AU from the Sun, the surface equilibrium temperatures are too low for thermal or desiccation stresses to be responsible for the ejection of dust. No gas is spectroscopically detected (limiting the gas mass-loss rate to <1.8 kg s{sup −1}). However, the protracted emission of dust seen in our data and the detection of another episode of dust release near perihelion, in archival observations from 2003, are highly suggestive of an origin by the sublimation of ice. Coincidentally, the orbit of 313P/Gibbs is similar to those of several active asteroids independently suspected to be ice sublimators, including P/2012 T1, 238P/Read, and 133P/Elst–Pizarro, suggesting that ice is abundant in the outer asteroid belt.

  3. Project RAMA: Reconstructing Asteroids Into Mechanical Automata

    Science.gov (United States)

    Dunn, Jason; Fagin, Max; Snyder, Michael; Joyce, Eric

    2017-01-01

    Many interesting ideas have been conceived for building space-based infrastructure in cislunar space. From O'Neill's space colonies, to solar power satellite farms, and even prospecting retrieved near earth asteroids. In all the scenarios, one thing remained fixed - the need for space resources at the outpost. To satisfy this need, O'Neill suggested an electromagnetic railgun to deliver resources from the lunar surface, while NASA's Asteroid Redirect Mission called for a solar electric tug to deliver asteroid materials from interplanetary space. At Made In Space, we propose an entirely new concept. One which is scalable, cost effective, and ensures that the abundant material wealth of the inner solar system becomes readily available to humankind in a nearly automated fashion. We propose the RAMA architecture, which turns asteroids into self-contained spacecraft capable of moving themselves back to cislunar space. The RAMA architecture is just as capable of transporting conventional-sized asteroids on the 10-meter length scale as transporting asteroids 100 meters or larger, making it the most versatile asteroid retrieval architecture in terms of retrieved-mass capability. This report describes the results of the Phase I study funded by the NASA NIAC program for Made In Space to establish the concept feasibility of using space manufacturing to convert asteroids into autonomous, mechanical spacecraft. Project RAMA, Reconstituting Asteroids into Mechanical Automata, is designed to leverage the future advances of additive manufacturing (AM), in-situ resource utilization (ISRU) and in-situ manufacturing (ISM) to realize enormous efficiencies in repeated asteroid redirect missions. A team of engineers at Made In Space performed the study work with consultation from the asteroid mining industry, academia, and NASA. Previous studies for asteroid retrieval have been constrained to studying only asteroids that are both large enough to be discovered, and small enough to be

  4. Asteroid Models from Sparse Photometry

    OpenAIRE

    Hanuš, Josef

    2013-01-01

    We investigate the photometric accuracy of the sparse data from astrometric surveys available on AstDyS. We use data from seven surveys with the best accu- racy in combination with relative lightcurves in the lightcurve inversion method to derive ∼300 new asteroid physical models (i.e., convex shapes and rotational states). We introduce several reliability tests that we use on all new asteroid mod- els. We investigate rotational properties of our MBAs sample (∼450 models here or previously de...

  5. Spin states of asteroids in the Eos collisional family

    Science.gov (United States)

    Hanuš, J.; Delbo', M.; Alí-Lagoa, V.; Bolin, B.; Jedicke, R.; Ďurech, J.; Cibulková, H.; Pravec, P.; Kušnirák, P.; Behrend, R.; Marchis, F.; Antonini, P.; Arnold, L.; Audejean, M.; Bachschmidt, M.; Bernasconi, L.; Brunetto, L.; Casulli, S.; Dymock, R.; Esseiva, N.; Esteban, M.; Gerteis, O.; de Groot, H.; Gully, H.; Hamanowa, Hiroko; Hamanowa, Hiromi; Krafft, P.; Lehký, M.; Manzini, F.; Michelet, J.; Morelle, E.; Oey, J.; Pilcher, F.; Reignier, F.; Roy, R.; Salom, P. A.; Warner, B. D.

    2018-01-01

    Eos family was created during a catastrophic impact about 1.3 Gyr ago. Rotation states of individual family members contain information about the history of the whole population. We aim to increase the number of asteroid shape models and rotation states within the Eos collision family, as well as to revise previously published shape models from the literature. Such results can be used to constrain theoretical collisional and evolution models of the family, or to estimate other physical parameters by a thermophysical modeling of the thermal infrared data. We use all available disk-integrated optical data (i.e., classical dense-in-time photometry obtained from public databases and through a large collaboration network as well as sparse-in-time individual measurements from a few sky surveys) as input for the convex inversion method, and derive 3D shape models of asteroids together with their rotation periods and orientations of rotation axes. We present updated shape models for 15 asteroids and new shape model determinations for 16 asteroids. Together with the already published models from the publicly available DAMIT database, we compiled a sample of 56 Eos family members with known shape models that we used in our analysis of physical properties within the family. Rotation states of asteroids smaller than ∼ 20 km are heavily influenced by the YORP effect, whilst the large objects more or less retained their rotation state properties since the family creation. Moreover, we also present a shape model and bulk density of asteroid (423) Diotima, an interloper in the Eos family, based on the disk-resolved data obtained by the Near InfraRed Camera (Nirc2) mounted on the W.M. Keck II telescope.

  6. Explaining the impact of a women's group led community mobilisation intervention on maternal and newborn health outcomes: the Ekjut trial process evaluation

    Directory of Open Access Journals (Sweden)

    Sinha Rajesh

    2010-10-01

    Full Text Available Abstract Background Few large and rigorous evaluations of participatory interventions systematically describe their context and implementation, or attempt to explain the mechanisms behind their impact. This study reports process evaluation data from the Ekjut cluster-randomised controlled trial of a participatory learning and action cycle with women's groups to improve maternal and newborn health outcomes in Jharkhand and Orissa, eastern India (2005-2008. The study demonstrated a 45% reduction in neonatal mortality in the last two years of the intervention, largely driven by improvements in safe practices for home deliveries. Methods A participatory learning and action cycle with 244 women's groups was implemented in 18 intervention clusters covering an estimated population of 114 141. We describe the context, content, and implementation of this intervention, identify potential mechanisms behind its impact, and report challenges experienced in the field. Methods included a review of intervention documents, qualitative structured discussions with group members and non-group members, meeting observations, as well as descriptive statistical analysis of data on meeting attendance, activities, and characteristics of group attendees. Results Six broad, interrelated factors influenced the intervention's impact: (1 acceptability; (2 a participatory approach to the development of knowledge, skills and 'critical consciousness'; (3 community involvement beyond the groups; (4 a focus on marginalized communities; (5 the active recruitment of newly pregnant women into groups; (6 high population coverage. We hypothesize that these factors were responsible for the increase in safe delivery and care practices that led to the reduction in neonatal mortality demonstrated in the Ekjut trial. Conclusions Participatory interventions with community groups can influence maternal and child health outcomes if key intervention characteristics are preserved and tailored to

  7. Two cubesat mission to study the Didymos asteroid system

    Science.gov (United States)

    Wahlund, J.-E.; Vinterhav, E.; Trigo-Rodríguez, J. M.; Hallmann, M.; Barabash, S.; Ivchenko, N.

    2015-10-01

    Among the growing interest about asteroid impact hazard mitigation in our community the Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to use a kinetic impactor to demonstrate its capability as reliable deflection system [1]. As a part of the AIDA mission, we have proposed a set of two three-axis stabilized 3U CubeSats (with up to 5 science sensors) to simultaneously rendezvous at close range (camera (NAC) and a Video Emission Spectrometer (VES) with a diffraction grating for allowing a sequential chemical study of the emission spectra associated with the impact flare and the expanding plume. Consequently, the different envisioned instruments onboard the CubeSats can provide significant insight into the complex response of asteroid materials during impacts that has been theoretically studied using different techniques [2]. The two CubeSats will remain stowed in CubeSat dispensers aboard the main AIM spacecraft. They will be deployed and commissioned before the AIM impactor reaches the secondary and record the impact event from a closer vantage point than the main spacecraft. The two CubeSats are equipped with relative navigation systems capable of estimating the spacecraft position relative to the asteroids and propulsion system that allow them to operate close to the asteroid bodies. The two CubeSats will rely on mapping data relayed via the AIM main spacecraft but operate autonomously and individually based on schedules and navigation maps uploaded from ground. AIDA's target is the binary Apollo asteroid 65803 Didymos that is also catalogued as Potentially Hazardous Asteroid (PHA) because it experiences close approaches to Earth. Didymos' primary has a diameter of ˜800 meters and the secondary is ˜150 m across. Both bodies are separated about 1.1 km [3]. The rotation period and asymmetry of the secondary object is unknown, and it might be tidally locked to the larger primary body. At least the primary body is expected

  8. A Martian origin for the Mars Trojan asteroids

    Science.gov (United States)

    Polishook, D.; Jacobson, S. A.; Morbidelli, A.; Aharonson, O.

    2017-08-01

    Seven of the nine known Mars Trojan asteroids belong to an orbital cluster1,2 named after its largest member, (5261) Eureka. Eureka is probably the progenitor of the whole cluster, which formed at least 1 Gyr ago3. It has been suggested3 that the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect spun up Eureka, resulting in fragments being ejected by the rotational-fission mechanism. Eureka's spectrum exhibits a broad and deep absorption band around 1 μm, indicating an olivine-rich composition4. Here we show evidence that the Trojan Eureka cluster progenitor could have originated as impact debris excavated from the Martian mantle. We present new near-infrared observations of two Trojans ((311999) 2007 NS2 and (385250) 2001 DH47) and find that both exhibit an olivine-rich reflectance spectrum similar to Eureka's. These measurements confirm that the progenitor of the cluster has an achondritic composition4. Olivine-rich reflectance spectra are rare amongst asteroids5 but are seen around the largest basins on Mars6. They are also consistent with some Martian meteorites (for example, Chassigny7) and with the material comprising much of the Martian mantle8,9. Using numerical simulations, we show that the Mars Trojans are more likely to be impact ejecta from Mars than captured olivine-rich asteroids transported from the main belt. This result directly links specific asteroids to debris from the forming planets.

  9. Simultaneous Mass Determination for Gravitationally Coupled Asteroids

    Energy Technology Data Exchange (ETDEWEB)

    Baer, James [Private address, 3210 Apache Road, Pittsburgh, PA 15241 (United States); Chesley, Steven R., E-mail: jimbaer1@earthlink.net [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2017-08-01

    The conventional least-squares asteroid mass determination algorithm allows us to solve for the mass of a large subject asteroid that is perturbing the trajectory of a smaller test asteroid. However, this algorithm is necessarily a first approximation, ignoring the possibility that the subject asteroid may itself be perturbed by the test asteroid, or that the encounter’s precise geometry may be entangled with encounters involving other asteroids. After reviewing the conventional algorithm, we use it to calculate the masses of 30 main-belt asteroids. Compared to our previous results, we find new mass estimates for eight asteroids (11 Parthenope, 27 Euterpe, 51 Neimausa, 76 Freia, 121 Hermione, 324 Bamberga, 476 Hedwig, and 532 Herculina) and significantly more precise estimates for six others (2 Pallas, 3 Juno, 4 Vesta, 9 Metis, 16 Psyche, and 88 Thisbe). However, we also find that the conventional algorithm yields questionable results in several gravitationally coupled cases. To address such cases, we describe a new algorithm that allows the epoch state vectors of the subject asteroids to be included as solve-for parameters, allowing for the simultaneous solution of the masses and epoch state vectors of multiple subject and test asteroids. We then apply this algorithm to the same 30 main-belt asteroids and conclude that mass determinations resulting from current and future high-precision astrometric sources (such as Gaia ) should conduct a thorough search for possible gravitational couplings and account for their effects.

  10. Asteroid Lightcurves from Etscorn Observatory

    Science.gov (United States)

    Klinglesmith, Daniel A., III; Hendrickx, Sebastian

    2018-01-01

    During 2017 August and September, we observed five spin-shape asteroids: 418 Alemannia, 1095 Tulipa, 2648 Owa, 3122 Florence, and 5040 Rabinowitz. The selections were by listed by Warner et al. (2017) in their regular MPB paper featuring photometric opportunities for the upcoming quarter.

  11. The empty primordial asteroid belt.

    Science.gov (United States)

    Raymond, Sean N; Izidoro, Andre

    2017-09-01

    The asteroid belt contains less than a thousandth of Earth's mass and is radially segregated, with S-types dominating the inner belt and C-types the outer belt. It is generally assumed that the belt formed with far more mass and was later strongly depleted. We show that the present-day asteroid belt is consistent with having formed empty, without any planetesimals between Mars and Jupiter's present-day orbits. This is consistent with models in which drifting dust is concentrated into an isolated annulus of terrestrial planetesimals. Gravitational scattering during terrestrial planet formation causes radial spreading, transporting planetesimals from inside 1 to 1.5 astronomical units out to the belt. Several times the total current mass in S-types is implanted, with a preference for the inner main belt. C-types are implanted from the outside, as the giant planets' gas accretion destabilizes nearby planetesimals and injects a fraction into the asteroid belt, preferentially in the outer main belt. These implantation mechanisms are simple by-products of terrestrial and giant planet formation. The asteroid belt may thus represent a repository for planetary leftovers that accreted across the solar system but not in the belt itself.

  12. NASA's Asteroid Redirect Mission (ARM)

    Science.gov (United States)

    Abell, Paul; Mazanek, Dan; Reeves, David; Naasz, Bo; Cichy, Benjamin

    2015-11-01

    The National Aeronautics and Space Administration (NASA) is developing a robotic mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, and redirect it into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts will explore the boulder and return to Earth with samples. This Asteroid Redirect Mission (ARM) is part of NASA’s plan to advance the technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Subsequent human and robotic missions to the asteroidal material would also be facilitated by its return to cislunar space. Although ARM is primarily a capability demonstration mission (i.e., technologies and associated operations), there exist significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, asteroidal resources and in-situ resource utilization (ISRU), and capability and technology demonstrations. In order to maximize the knowledge return from the mission, NASA is organizing an ARM Investigation Team, which is being preceded by the Formulation Assessment and Support Team. These teams will be comprised of scientists, technologists, and other qualified and interested individuals to help plan the implementation and execution of ARM. An overview of robotic and crewed segments of ARM, including the mission requirements, NEA targets, and mission operations, will be provided along with a discussion of the potential opportunities associated with the mission.

  13. Heavy Metal - Exploring a magnetised metallic asteroid

    Science.gov (United States)

    Wahlund, Jan-Erik; Andrews, David; Futaana, Yoshifumi; Masters, Adam; Thomas, Nicolas; De Sanctis, Maria Cristina; Herique, Alain; Retherford, Kurt; Tortora, Paolo; Trigo-Rodriguez, Joseph; Ivchenko, Nickolay; Simon, Sven

    2017-04-01

    We propose a spacecraft mission (Heavy Metal) to orbit and explore (16) Psyche - the largest M-class metallic asteroid in the main belt. Recent estimates of the shape, 279×232×189 km and mass, 2.7×10(19) kg make it one of the largest and densest of asteroids, and together with the high surface radar reflectivity and the spectral data measured from Earth it is consistent with a bulk composition rich in iron-nickel. The M5 mission Heavy Metal will investigate if (16) Psyche is the exposed metallic core of a planetesimal, formed early enough to melt and differentiate. High-resolution mapping of the surface in optical, IR, UV and radar wavebands, along with the determination of the shape and gravity field will be used to address the formation and subsequent evolution of (16) Psyche, determining the origin of metallic asteroids. It is conceivable that a cataclysmic collision with a second body led to the ejection of all or part of the differentiated core of the parent body. Measurements at (16) Psyche therefore provide a possibility to directly examine an iron-rich planetary core, similar to that expected at the center of all the major planets including Earth. A short-lived dynamo producing a magnetic field early in the life of (16) Psyche could have led to a remnant field (of tens of micro Tesla) being preserved in the body today. (16) Psyche is embedded in the variable flow of the solar wind. Whereas planetary magnetospheres and induced magnetospheres are the result of intense dynamo fields and dense conductive ionospheres presenting obstacles to the solar wind, (16) Psyche may show an entirely new 'class' of interaction as a consequence of its lack of a significant atmosphere, the extremely high bulk electrical conductivity of the asteroid, and the possible presence of intense magnetic fields retained in iron-rich material. The small characteristic scale of (16) Psyche ( 200 km) firmly places any solar wind interaction in the "sub-MHD" scale, in which kinetic

  14. OSIRIS-REx Asteroid Sample Return Mission

    Science.gov (United States)

    Drake, M. J.; Lauretta, D. S.; Team, O.

    2011-12-01

    OSIRIS-REx is an asteroid sample return mission to organic-rich asteroid (101955) 1999 RQ36. The mission seeks to address deep questions: where did we come from; what is our destiny? Earth sterilized itself during its formation, yet here we are today. Where did the organics come from? To do so, we will return at least 60g of pristine, uncontaminated, organic-rich regolith for study on Earth by advanced analytical equipment. Because it is relatively easy for us to get the RQ36, it is relatively easy for it to get to us, making I the most potentially hazardous asteroid know to humanity with a 1:1800 probability of impacting the Earth in 2180. We will study the Yarkovsky effect, thermal forces that cause small objects to deviate from keplerian orbits, with the goal of understanding how to mitigate against a civilization-ending or species-ending impact catastrophe. The mission launches in September, 2016, arrives at RQ36 in November of 2019, and spends about a year conducting detailed studies of RQ36 in order to select the best sampling site. Sampling is achieved by approaching the surface ay 10 cm/sec and agitating the regolith with nitrogen gas on contact. The agitated regolith is collected in a sample head, which is stowed in the Sample return capsule for return to Earth at the UTTR Test range in Utah in September 2023. Two years of funded studies are carried out by the U.S. and world community before end of mission in 2025, after which samples will still be available through the NASA-JSC Curation Facility. OSIRIS-REx will return samples never before available for study on Earth, probably using some instruments yet to be invented. In addition, OSIRIS-REx will provide "ground truth" for telescope observations of airless bodies by returning a pristine sample of the surface of RQ36. OSIRIS-REx will evaluate resources available to future human missions, both materials and technologies such as proximity operations. And we will learn how to mitigate against impact

  15. The Miniaturized Moessbauer Spectrometer MIMOS II for the Asteroid Redirect Mission(ARM): Quantative Iron Mineralogy And Oxidation States

    Science.gov (United States)

    Schroeder, C.; Klingelhoefer, G; Morris, R. V.; Yen, A. S.; Renz, F.; Graff, T. G.

    2016-01-01

    The miniaturized Moessbauer spectrometer MIMOS II is an off-the-shelf instrument with proven flight heritage. It has been successfully deployed during NASA’s Mars Exploration Rover (MER) mission and was on-board the UK-led Beagle 2 Mars lander and the Russian Phobos-Grunt sample return mission. A Moessbauer spectrometer has been suggested for ASTEX, a DLR Near-Earth Asteroid (NEA) mission study, and the potential payload to be hosted by the Asteroid Redirect Mission (ARM). Here we make the case for in situ asteroid characterization with Moessbauer spectroscopy on the ARM employing one of three available fully-qualified flight-spare Moessbauer instruments.

  16. Impact of a nurse-led home and clinic-based secondary prevention programme to prevent progressive cardiac dysfunction in high-risk individuals: the Nurse-led Intervention for Less Chronic Heart Failure (NIL-CHF) randomized controlled study.

    Science.gov (United States)

    Stewart, Simon; Chan, Yih-Kai; Wong, Chiew; Jennings, Garry; Scuffham, Paul; Esterman, Adrian; Carrington, Melinda

    2015-06-01

    The aim of this study was to determine the effectiveness of a long-term, nurse-led, multidisciplinary programme of home/clinic visits in preventing progressive cardiac dysfunction in individuals at risk of developing de novo chronic heart failure (CHF). A pragmatic, single-centre (tertiary-referral hospital with specialist cardiological services), open-label, randomized controlled trial with blinded endpoint adjudication was carried out. In total, 624 cardiac inpatients (66 ± 11 years, 71% male, and 70% with CAD) were randomly allocated (1:1) to standard care or the study intervention. The intention-to-treat cohort comprised 310 standard care and 301 intervention participants. During 51.0 ± 8.2 months follow-up, 38/310 (12%) standard care [mean event-free survival 1865 days, 95% confidence interval (CI) 1817-1913 days] vs. 41/301 (14%) intervention participants (1855 days, 95% CI 1804-1906 days) experienced the primary composite endpoint of de novo CHF hospitalization or all-cause mortality (P = 0.574). Although there were no statistically significant differences in the rate of cardiovascular-related and emergency hospitalizations, the NIL-CHF (Nurse-led Intervention for Less Chronic Heart Failure) group accumulated 478 (0.214 ± 0.70 vs. 0.095 ± 0.284 days/participant/month; P = 0.052) and 1097 fewer days of hospital stay (0.391 ± 1.80 vs. 0.199 ± 0.47 days/participant/month; P = 0.023), respectively, compared with standard care. The intervention group also showed better cardiac recovery on echocardiography at 3 years [81/226 (35.8%) vs. 56/225 (24.9%), odds ratio 1.44, 95% CI 1.08-1.92, P = 0.011]. Relative to a high level of standard care, the NIL-CHF intervention was ineffective in preventing CHF and rehospitalization. On the other hand, it was associated with reduced hospital stay and improved cardiac function over the long term. Australian New Zealand Clinical Trials Registry (No. 12608000022369). © 2015 The Authors. European Journal of Heart Failure

  17. Arecibo Radar Observations of Near-Earth Asteroids

    Science.gov (United States)

    Rivera-Valentin, Edgard G.; Taylor, Patrick A.; Virkki, Anne; Saran Bhiravarasu, Sriram; Venditti, Flaviane; Zambrano-Marin, Luisa Fernanda; Aponte-Hernandez, Betzaida

    2017-10-01

    The Arecibo S-Band (2.38 GHz, 12.6 cm; 1 MW) planetary radar system at the 305-m William E. Gordon Telescope in Arecibo, Puerto Rico is the most active, most powerful, and most sensitive planetary radar facility in the world. As such, Arecibo is vital for post-discovery characterization and orbital refinement of near-Earth asteroids. Since August 2016, the program has observed 100 near-Earth asteroids (NEAs), of which 38 are classified as potentially hazardous to Earth and 31 are compliant with the NASA Near-Earth Object Human Space Flight Accessible Targets Study (NHATS). Arecibo observations are critical for identifying NEAs that may be on a collision course with Earth in addition to providing detailed physical characterization of the objects themselves in terms of size, shape, spin, and surface properties, which are valuable for assessing impact mitigation strategies. Here, we will present a sampling of the asteroid zoo observed by Arecibo, including press-noted asteroids 2014 JO25 and the (163693) Atira binary system.

  18. Asteroids. Prospective energy and material resources

    Energy Technology Data Exchange (ETDEWEB)

    Badescu, Viorel (ed.) [Bucharest Polytechnic Univ. (Romania). Candida Oancea Institute

    2013-11-01

    Recent research on Prospective Energy and Material Resources on Asteroids. Carefully edited book dedicated to Asteroids prospective energy and material resources. Written by leading experts in the field. The Earth has limited material and energy resources while these resources in space are virtually unlimited. Further development of humanity will require going beyond our planet and exploring of extraterrestrial resources and sources of unlimited power. Thus far, all missions to asteroids have been motivated by scientific exploration. However, given recent advancements in various space technologies, mining asteroids for resources is becoming ever more feasible. A significant portion of asteroids value is derived from their location; the required resources do not need to be lifted at a great expense from the surface of the Earth. Resources derived from Asteroid not only can be brought back to Earth but could also be used to sustain human exploration of space and permanent settlements in space. This book investigates asteroids' prospective energy and material resources. It is a collection of topics related to asteroid exploration, and utilization. It presents past and future technologies and solutions to old problems that could become reality in our life time. The book therefore is a great source of condensed information for specialists involved in current and impending asteroid-related activities and a good starting point for space researchers, inventors, technologists and potential investors. Written for researchers, engineers, and businessmen interested in asteroids' exploration and exploitation.

  19. Maturation of the Asteroid Threat Assessment Project

    Science.gov (United States)

    Arnold, J. O..; Burkhard, C. D.

    2017-01-01

    As described at IPPW 12 [1], NASA initiated a new research activity focused on Planetary Defense (PD) on October 1, 2014. The overarching function of the Asteroid Threat Assessment Project (ATAP) is to provide capabilities to assess impact damage of any Near-Earth Object (NEO) that could inflict on the Earth. The activity includes four interrelated efforts: Initial Conditions (at the atmospheric entry interface); Entry Modeling (energy deposition in the atmosphere); Hazards (on the surface including winds, over pressures, thermal exposures, craters, tsunami and earthquakes) and Risk (physics-based). This paper outlines progress by ATAP and highlights achievements that are complimentary to activities of interest to the International Planetary Probe community. The ATAPs work is sponsored by NASAs Planetary Defense Coordination Office (PDCO), a part of the agency's Science Mission Directorate [1] Arnold, J. O., et. al., Overview of a New NASA Activity Focused on Planetary Defense, IPPW 12 Cologne Germany, June 15-19. 2015.

  20. LEDs for greenhouse lighting

    OpenAIRE

    Nederhoff, E.M.

    2010-01-01

    Light Emitting Diodes (LED's) are a promising technology for greenhouse lighting with their efficiency to activate plant photosynthesis potentially higher in red LEDs than in HPS lamps. Due to their particular light colour, LEDs can initiate special effects in plants or steer plant processes and plant balance

  1. LEDs for greenhouse lighting

    NARCIS (Netherlands)

    Nederhoff, E.M.

    2010-01-01

    Light Emitting Diodes (LED's) are a promising technology for greenhouse lighting with their efficiency to activate plant photosynthesis potentially higher in red LEDs than in HPS lamps. Due to their particular light colour, LEDs can initiate special effects in plants or steer plant processes and

  2. The asteroid 2014 JO25

    Science.gov (United States)

    Vodniza, Alberto; Pereira, Mario

    2017-10-01

    The asteroid 2014 JO25 was discovered by A. D. Grauer at the Mt. Lemmon Survey on May 2014, and Joe Masiero used observations from the NEOWISE in 2014 to estimate a diameter of 650 meters [1]. However, using the radio telescope at Arecibo-Puerto Rico, astronomers obtained radar images on April 17-2017 and Edgar Rivera Valentín (scientist at Arecibo) said: “We found 2014 JO25 is a contact binary asteroid, two space rocks that were originally separate bodies, and each segment is about 640 meters and 670 meters, for a total of about 1.3 km long. Its rotation is of 3.5 hours” [2]. This asteroid flew past Earth on April 19 at a distance of about 4.6 lunar distances from the Earth. This was the closest approach by an asteroid since 4179 Toutatis. Toutatis flew past Earth on September 2004 at a distance of about 4 lunar distances from the Earth [3]. In April 12-2020 the asteroid will be at a minimum possible distance of 0.1617280 A.U from Earth [4]. From our observatory, located in Pasto-Colombia, we obtained a lot of pictures. Our data was published by the Minor Planet Center [5] and also appears at the web page of NEODyS [6]. Astrometry and photometry were carried out, and we calculated the orbital elements. We obtained the following orbital parameters: eccentricity=0.88454+/-0.00152, semi-major axis= 2.0573+/- 0.0216 A.U, orbital inclination=25.22+/-0.10 deg, longitude of the ascending node =30.6530+/-0.0032 deg, argument of perihelion=49.586+/-0.012 deg, mean motion = 0.33402+/-0.00527 deg/d, perihelion distance=0.237524+/-0.000644 A.U, aphelion distance=3.8770+/-0.0449 A.U, absolute magnitude =18.1. The parameters were calculated based on 164 observations. Dates: 2017 April: 22 to 24 with mean residual=0.22 arcseconds.The asteroid has an orbital period of 2.95 years.[1] https://echo.jpl.nasa.gov/asteroids/2014JO25/2014JO25_planning.html[2] http://earthsky.org/astronomy-essentials/large-asteroid-2014-jo25-close-april-19-2017-how-to-see[3] https

  3. Colorimetry and magnitudes of asteroids

    Science.gov (United States)

    Bowell, E.; Lumme, K.

    1979-01-01

    In the present paper, 1500 UBV observations are analyzed by a new rather general multiple scattering theory which provided clear insight into previously poorly-recognized optical nature of asteroid surfaces. Thus, phase curves are shown to consist of a surface-texture controlled component, due to singly scattered light, and a component due to multiple scattering. Phase curve shapes can be characterized by a single parameter, the multiple scattering factor, Q. As Q increases, the relative importance of the opposition effect diminishes. Asteroid surfaces are particulate and strikingly similar to texture, being moderately porous and moderately rough on a scale greater than the wavelength of light. In concequence, Q (and also the phase coefficient) correlate well with geometric albedo, and there exists a purely photometric means of determining albedos and diameters.

  4. GRASPING THE NATURE OF POTENTIALLY HAZARDOUS ASTEROIDS

    Energy Technology Data Exchange (ETDEWEB)

    Perna, D.; Barucci, M. A.; Fornasier, S.; Deshapriya, J. D. P. [LESIA—Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France); Dotto, E.; Ieva, S.; Epifani, E. Mazzotta [INAF—Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Roma) (Italy); Bernardi, F. [SpaceDyS, via Mario Giuntini 63, I-56023 Cascina (Pisa) (Italy); Luise, F. De [INAF—Osservatorio Astronomico di Teramo, via Mentore Maggini snd, I-64100 Teramo (Italy); Perozzi, E. [Deimos Space, Strada Buchesti 75-77, Bucharest (Romania); Rossi, A. [IFAC—CNR, via Madonna del Piano 10, I-50019 Sesto Fiorentino (Firenze) (Italy); Micheli, M., E-mail: davide.perna@obspm.fr [ESA—NEOCC, ESRIN, via Galileo Galilei 64, I-00044 Frascati (Rome) (Italy)

    2016-01-15

    Through their delivery of water and organics, near-Earth objects (NEOs) played an important role in the emergence of life on our planet.  However, they also pose a hazard to the Earth, as asteroid impacts could significantly affect our civilization. Potentially hazardous asteroids (PHAs) are those that, in principle, could possibly impact the Earth within the next century, producing major damage. About 1600 PHAs are currently known, from an estimated population of 4700 ± 1450. However, a comprehensive characterization of the PHA physical properties is still missing. Here we present spectroscopic observations of 14 PHAs, which we have used to derive their taxonomy, meteorite analogs, and mineralogy. Combining our results with the literature, we investigated how PHAs are distributed as a function of their dynamical and physical properties. In general, the “carbonaceous” PHAs seem to be particularly threatening, because of their high porosity (limiting the effectiveness of the main deflection techniques that could be used in space) and low inclination and minimum orbit intersection distance (MOID) with the Earth (favoring more frequent close approaches). V-type PHAs also present low MOID values, which can produce frequent close approaches (as confirmed by the recent discovery of a limited space weathering on their surfaces). We also identified those specific objects that deserve particular attention because of their extreme rotational properties, internal strength, or possible cometary nature. For PHAs and NEOs in general, we identified a possible anti-correlation between the elongation and the rotational period, in the range of P{sub rot} ≈ 5–80 hr. This would be compatible with the behavior of gravity-dominated aggregates in rotational equilibrium. For periods ≳80–90 hr, such a trend stops, possibly under the influence of the YORP effect and collisions. However, the statistics is very low, and further observational and theoretical work is required

  5. Asteroids prospective energy and material resources

    CERN Document Server

    2013-01-01

    The Earth has limited material and energy resources while these resources in space are virtually unlimited. Further development of humanity will require going beyond our planet and exploring of extraterrestrial resources and sources of unlimited power.   Thus far, all missions to asteroids have been motivated by scientific exploration. However, given recent advancements in various space technologies, mining asteroids for resources is becoming ever more feasible. A significant portion of asteroids value is derived from their location; the required resources do not need to be lifted at a great expense from the surface of the Earth.   Resources derived from Asteroid not only can be brought back to Earth but could also be used to sustain human exploration of space and permanent settlements in space.   This book investigates asteroids' prospective energy and material resources. It is a collection of topics related to asteroid exploration, and utilization. It presents past and future technologies and solutions t...

  6. Comparison of Asteroids Observed in the SDSS with a Catalog of Known Asteroids

    OpenAIRE

    Juric, M.; Ivezic, Z.; Lupton, H. R.; Quinn, T.; Tabachnik, S.

    2002-01-01

    We positionally correlate asteroids from existing catalogs with a sample of $\\about$18,000 asteroids detected by the Sloan Digital Sky Survey (SDSS, Ivezi\\'{c} {\\em et al.} 2001). We find 2641 unique matches, which represent the largest sample of asteroids with both accurate multi-color photometry and known orbital parameters. The matched objects are predominantly bright, and demonstrate that the SDSS photometric pipeline recovers \\about90% of the known asteroids in the observed region. For t...

  7. Modern Asteroid Occultation Observing Methods

    Science.gov (United States)

    Lucas, G. A.

    2004-05-01

    This presentation reviews current working methods for asteroid occultations developed by the International Occultation Timing Association (IOTA). Reduc- tion of multiple tracks or "chords" observed during stellar occultations pro- vides valuable measures of the relative sizes and shapes of asteroids. Tradi- tionally, predictions for asteroid occultations were prepared by regional IOTA computors, distributed annually in "hard copy" format to IOTA subscrib- ers and in publications such as Sky & Telescope magazine and the annual RASC Observers Handbook. IOTA - like many other organizations - is now using worldwide internet services and e-mail to distribute frequently-updated pre- dictions based upon the latest astrometry. The IOTA web pages provide an easily accessible, centralized source of information on lunar and solar sys- tem occultation events. IOTA's web pages feature a variety of articles on current activities, plans for observing campaigns and expeditions, and "how to do it" information on the latest technology and techniques. The latest up- dated predictions for asteroid events are made available as they are pro- duced, providing more accurate observing tracks and efficient coordination of observers. The IOTA e-mail list provides a dynamic forum for the exchange of technical information and com-munication of observing plans in a timely man- ner. Individuals may now generate customized occultation predictions using the WinOccult software package. The author presents some examples of recent occultation events, showing the benefits of coordinated observations. Also described are some of the latest innovations, featuring low-cost video camera equipment, devices for time insertion based on Global Positioning Satellite (GPS) technology, and a new approach using unattended secondary field station equipment to multiply the number of tracks observed.

  8. LED-roulette : LED's vervangen balletje

    NARCIS (Netherlands)

    Goossens, P.

    2007-01-01

    Iedereen waagt wel eens een gokje, in een loterij of misschien ook in een casino. Wie droomt er immers niet van om op een gemakkelijke manier rijk te worden? Met de hier beschreven LED-roulette valt weliswaar weinig te winnen, maar het is wel een uitstekende manier om het roulettespel thuis te

  9. Figure of Merit for Asteroid Regolith Simulants

    Science.gov (United States)

    Metzger, P.; Britt, D.; Covey, S.; Lewis, J. S.

    2017-09-01

    High fidelity asteroid simulant has been developed, closely matching the mineral and elemental abundances of reference meteorites representing the target asteroid classes. The first simulant is a CI class based upon the Orgueil meteorite, and several other simulants are being developed. They will enable asteroid mining and water extraction tests, helping mature the technologies for space resource utilization for both commercial and scientific/exploration activities in space.

  10. Asteroid Evolution: Role of Geotechnical Properties

    Science.gov (United States)

    Sánchez, Paul

    2016-01-01

    This paper presents a brief review and latest results of the work that has been carried out by the Planetary Science community in order to understand the role of the geotechnical properties of granular asteroids (commonly known as ``rubble-pile'' asteroids) in their formation, evolution and possible disruption. As such, we will touch in aspects of the theoretical and numerical tools that have been used with this objective and how the obtained results compare to the observed asteroids.

  11. Anchoring a lander on an asteroid using foam stabilization Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has proposed several missions to land a craft on an asteroid and potentially to return samples from it. While large asteroids in the asteroid belt can exhibit a...

  12. ASTEROID DYNAMICAL FAMILIES V3.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset contains the asteroid dynamical family classifications contained in Zappala, et al. (1995) [ZAPPALAETAL1995]. These are based on the heirarchical...

  13. Geotechnical Tests on Asteroid Simulant Orgueil

    Science.gov (United States)

    Garcia, Alexander D'marco

    2017-01-01

    In the last 100 years, the global population has more than quadrupled to over seven billion people. At the same time, the demand for food and standard of living has been increasing which has amplified the global water use by nearly eight times from approximately 500 to 4000 cu km per yr from 1900 to 2010. With the increasing concern to sustain the growing population on Earth it is necessary to seek other approaches to ensure that our planet will have resources for generations to come. In recent years, the advancement of space travel and technology has allowed the idea of mining asteroids with resources closer to becoming a reality. During the duration of the internship at NASA Kennedy Space Center, several geotechnical tests were conducted on BP-1 lunar simulant and asteroid simulant Orgueil. The tests that were conducted on BP-1 was to practice utilizing the equipment that will be used on the asteroid simulant and the data from those tests will be omitted from report. Understanding the soil mechanics of asteroid simulant Orgueil will help provide basis for future technological advances and prepare scientists for the conditions they may encounter when mining asteroids becomes reality in the distant future. Distinct tests were conducted to determine grain size distribution, unconsolidated density, and maximum density. Once the basic properties are known, the asteroid simulant will be altered to different levels of compaction using a vibrator table to see how compaction affects the density. After different intervals of vibration compaction, a miniature vane shear test will be conducted. Laboratory vane shear testing is a reliable tool to investigate strength anisotropy in the vertical and horizontal directions of a very soft to stiff saturated fine-grained clayey soil. This test will provide us with a rapid determination of the shear strength on the undisturbed compacted regolith. The results of these tests will shed light on how much torque is necessary to drill

  14. A reduced estimate of the number of kilometre-sized near-Earth asteroids.

    Science.gov (United States)

    Rabinowitz, D; Helin, E; Lawrence, K; Pravdo, S

    2000-01-13

    Near-Earth asteroids are small (diameters 1 km has been estimated to be in the range 1,000-2,000, which translates to an approximately 1% chance of a catastrophic collision with the Earth in the next millennium. These numbers are, however, poorly constrained because of the limitations of previous searches using photographic plates. (One kilometre is below the size of a body whose impact on the Earth would produce global effects.) Here we report an analysis of our survey for near-Earth asteroids that uses improved detection technologies. We find that the total number of asteroids with diameters > 1 km is about half the earlier estimates. At the current rate of discovery of near-Earth asteroids, 90% will probably have been detected within the next 20 years.

  15. Itokawa dust particles: a direct link between S-type asteroids and ordinary chondrites.

    Science.gov (United States)

    Nakamura, Tomoki; Noguchi, Takaaki; Tanaka, Masahiko; Zolensky, Michael E; Kimura, Makoto; Tsuchiyama, Akira; Nakato, Aiko; Ogami, Toshihiro; Ishida, Hatsumi; Uesugi, Masayuki; Yada, Toru; Shirai, Kei; Fujimura, Akio; Okazaki, Ryuji; Sandford, Scott A; Ishibashi, Yukihiro; Abe, Masanao; Okada, Tatsuaki; Ueno, Munetaka; Mukai, Toshifumi; Yoshikawa, Makoto; Kawaguchi, Junichiro

    2011-08-26

    The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission and scanning electron microscope analyses indicate that the mineralogy and mineral chemistry of the Itokawa dust particles are identical to those of thermally metamorphosed LL chondrites, consistent with spectroscopic observations made from Earth and by the Hayabusa spacecraft. Our results directly demonstrate that ordinary chondrites, the most abundant meteorites found on Earth, come from S-type asteroids. Mineral chemistry indicates that the majority of regolith surface particles suffered long-term thermal annealing and subsequent impact shock, suggesting that Itokawa is an asteroid made of reassembled pieces of the interior portions of a once larger asteroid.

  16. Cruise status of Hayabusa2: Round trip mission to asteroid 162173 Ryugu

    Science.gov (United States)

    Tsuda, Yuichi; Watanabe, Sei-ichiro; Saiki, Takanao; Yoshikawa, Makoto; Nakazawa, Satoru

    2017-07-01

    The Japan Aerospace Exploration Agency launched an asteroid sample return spacecraft "Hayabusa2" on December 3, 2014 by the Japanese H2A launch vehicle. Hayabusa2 aims at the round trip mission to the asteroid 162173 Ryugu. Hayabusa2 successfully conducted the Earth gravity assist on December 3, 2015, and now the spacecraft is flying toward Ryugu with the microwave discharge ion engine as the means of propulsion. As of September 2016, 1346 h of the ion engine operation has been achieved as planned. Three touch downs/sample collections, one kinetic impact/crater generation, four surface rovers deployment and many other in-situ observations are planned in the asteroid proximity phase. The operation team will perform extensive operation practice/rehearsal using a hardware-in-the-loop simulator in the year 2017 to be ready for the asteroid arrival in the summer 2018.

  17. Asteroid Families: Myth or Reality?

    Science.gov (United States)

    Bus, S. J.; Binzel, R. P.; Burbine, T. H.

    1996-09-01

    Dynamical families among the asteroids are thought to result from the collisional disruption of larger parent bodies. Even with recent improvements in the calculation of proper elements and the use of better clustering algorithms, a grouping in orbital element space is not sufficient proof of a genetic association. Proof of a genetic link between these objects is possible only through physical studies of the individual family members. In the course of the Small Main-Belt Asteroid Spectroscopic Survey (SMASS), we have measured the spectral reflectance properties of more than 250 asteroids whose semi-major axes are between 2.7 and 2.82 AU. This region of the main-belt has been chosen for study due to the diversity of asteroid spectral types present, and for the number of dynamical families that have been identified (e.g., Williams 1992, Icarus 96, 251 and Zappala et al. 1994, Astron. J. 107, 772). We have focused our efforts on 10 families defined by Zappala et al. (1995, Icarus 116, 291) (Astrid, Ceres, Chloris, Dora, Henan, Hoffmeister, Liberatrix, Lydia, Merxia, Nemesis) and on the proposed high inclination Pallas family (e.g., Lemaitre and Morbidelli 1994, Cel. Mech. Dynam. Astron. 60, 29). Observations were obtained with a CCD spectrograph attached to the 2.4-m Hiltner telescope of the Michigan-Dartmouth-MIT Observatory and cover the wavelength range of 4400-9200 Angstroms. Of the >250 objects observed, approximately one-half are identified as family members while the other half are non-family members, where the latter are used to define the background population. For each of the eleven families studied, strong similarities are seen in the reflectance properties between the individual family members. This is in significant contrast to the relatively random distribution of C-type and S-type asteroids seen in the background population. Interlopers are found, but usually appear to be at the periphery of a family, highlighting the difficulty of establishing

  18. Ground-based astrometry calibrated by Gaia DR1: new perspectives in asteroid orbit determination

    Science.gov (United States)

    Spoto, F.; Tanga, P.; Bouquillon, S.; Desmars, J.; Hestroffer, D.; Mignard, F.; Altmann, M.; Herald, D.; Marchant, J.; Barache, C.; Carlucci, T.; Lister, T.; Taris, F.

    2017-10-01

    Context. The Gaia Data Release 1 (GDR1) is a first, important step on the path of evolution of astrometric accuracy towards a much improved situation. Although asteroids are not present in GDR1, this intermediate release already impacts asteroid astrometry. Aims: Our goal is to investigate how the GDR1 can change the approach to a few typical problems, including the determination of orbits from short-arc astrometry, the exploitation of stellar occultations, and the impact risk assessment. Methods: We employ optimised asteroid orbit determination tools, and study the resulting orbit accuracy and post-fit residuals. For this goal, we use selected ground-based asteroid astrometry, and occultation events observed in the past. All measurements are calibrated by using GDR1 stars. Results: We show that, by adopting GDR1, very short measurement arcs can already provide interesting orbital solutions, capable of correctly identifying near-Earth asteroids (NEAs) and providing a much more accurate risk rating. We also demonstrate that occultations, previously used to derive asteroid size and shapes, now reach a new level of accuracy at which they can be fruitfully used to obtain astrometry at the level of accuracy of Gaia star positions.

  19. Detecting stars, galaxies, and asteroids with Gaia

    Science.gov (United States)

    de Bruijne, J. H. J.; Allen, M.; Azaz, S.; Krone-Martins, A.; Prod'homme, T.; Hestroffer, D.

    2015-04-01

    stars with ΔG> 0 mag, larger separations are required. We find that, whereas the optimised rejection parameters have no significant impact on the detectability of pure de Vaucouleurs profiles, they do significantly improve the detection of pure exponential-disk profiles, and hence also the detection of unresolved external galaxies with intermediate profiles. We also find that the optimised rejection parameters provide detection gains for asteroids fainter than 20 mag and for fast-moving near-Earth objects fainter than 18 mag, although this gain comes at the expense of a modest detection-probability loss for bright, fast-moving near-Earth objects. The major side effect of the optimised parameters is that spurious ghosts in the wings of bright stars essentially pass unfiltered.

  20. Petrogenesis of Miller Range 07273, a new type of anomalous melt breccia: Implications for impact effects on the H chondrite asteroid

    Science.gov (United States)

    Ruzicka, Alex M.; Hutson, Melinda; Friedrich, Jon M.; Rivers, Mark L.; Weisberg, Michael K.; Ebel, Denton S.; Ziegler, Karen; Rumble, Douglas; Dolan, Alyssa A.

    2017-09-01

    Miller Range 07273 is a chondritic melt breccia that contains clasts of equilibrated ordinary chondrite set in a fine-grained (shapes for coarse metal grains, unusual internal textures and compositions for coarse metal, a matrix composed chiefly of clinoenstatite and omphacitic pigeonite, and troilite veining most common in coarse olivine and orthopyroxene. These features can be explained by a model involving impact into a porous target that produced brief but intense heating at high pressure, a sudden pressure drop, and a slower drop in temperature. Olivine and orthopyroxene in chondrule clasts were the least melted and the most deformed, whereas matrix and troilite melted completely and crystallized to nearly strain-free minerals. Coarse metal was largely but incompletely liquefied, and matrix silicates formed by the breakdown during melting of albitic feldspar and some olivine to form pyroxene at high pressure (>3 GPa, possibly to 15-19 GPa) and temperature (>1350 °C, possibly to ≥2000 °C). The higher pressures and temperatures would have involved back-reaction of high-pressure polymorphs to pyroxene and olivine upon cooling. Silicates outside of melt matrix have compositions that were relatively unchanged owing to brief heating duration.

  1. Eccentricity distribution in the main asteroid belt

    Science.gov (United States)

    Malhotra, Renu; Wang, Xianyu

    2017-03-01

    The observationally complete sample of the main belt asteroids now spans more than two orders of magnitude in size and numbers more than 64 000 (excluding collisional family members). We undertook an analysis of asteroids' eccentricities and their interpretation with simple physical models. We find that a century old conclusion that the asteroids' eccentricities follow a Rayleigh distribution holds for the osculating eccentricities of large asteroids, but the proper eccentricities deviate from a Rayleigh distribution; there is a deficit of eccentricities smaller than ∼0.1 and an excess of larger eccentricities. We further find that the proper eccentricities do not depend significantly on asteroid size but have strong dependence on heliocentric distance; the outer asteroid belt follows a Rayleigh distribution, but the inner belt is strikingly different. Eccentricities in the inner belt can be modelled as a vector sum of a primordial eccentricity vector of random orientation and magnitude drawn from a Rayleigh distribution of parameter ∼0.06, and an excitation of random phase and magnitude ∼0.13. These results imply that when a late dynamical excitation of the asteroids occurred, it was independent of asteroid size and was stronger in the inner belt than in the outer belt. We discuss implications for the primordial asteroid belt and suggest that the observationally complete sample size of main belt asteroids is large enough that more sophisticated model-fitting of the eccentricities is warranted and could serve to test alternative theoretical models of the dynamical excitation history of asteroids and its links to the migration history of the giant planets.

  2. Broadband Radiometric LED Measurements.

    Science.gov (United States)

    Eppeldauer, G P; Cooksey, C C; Yoon, H W; Hanssen, L M; Podobedov, V B; Vest, R E; Arp, U; Miller, C C

    2016-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

  3. Broadband Radiometric LED Measurements

    Science.gov (United States)

    Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

    2017-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed. PMID:28649167

  4. Asteroid Ida - Limb at Closest Approach

    Science.gov (United States)

    1994-01-01

    The Galileo imaging system captured this picture of the limb of the asteroid 243 Ida about 46 seconds after its closest approach on August 28, 1993, from a range of only 2480 kilometers. It is the highest-resolution image of an asteroid's surface ever captured and shows detail at a scale of about 25 meters per pixel. This image is one frame of a mosaic of 15 frames shuttered near Galileo's closest approach to Ida. Since the exact location of Ida in space was not well-known prior to the Galileo flyby, this mosaic was estimated to have only about a 50 percent chance of capturing Ida. Fortunately, this single frame did successfully image a part of the sunlit side of Ida. The area seen in this frame shows some of the same territory seen in a slightly lower resolution full disk mosaic of Ida returned from the spacecraft in September, 1993, but from a different perspective. Prominent in this view is a 2 kilometer deep 'valley' seen in profile on the limb. This limb profile and the stereoscopic effect between this image and the full disk mosaic will permit detailed refinement of Ida's shape in this region. This high resolution view shows many small craters and some grooves on the surface of Ida, which give clues to understanding the history of this heavily impacted object. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory.

  5. Cooling rates of LL, L and H chondrites and constraints on the duration of peak thermal conditions: Diffusion kinetic modeling and implications for fragmentation of asteroids and impact resetting of petrologic types

    Science.gov (United States)

    Ganguly, Jibamitra; Tirone, Massimiliano; Domanik, Kenneth

    2016-11-01

    We have carried out detailed thermometric and cooling history studies of several LL-, L- and H-chondrites of petrologic types 5 and 6. Among the selected samples, the low-temperature cooling of St. Séverin (LL6) has been constrained in an earlier study by thermochronological data to an average rate of ∼2.6 °C/My below 500 °C. However, numerical simulations of the development of Fe-Mg profiles in Opx-Cpx pairs using this cooling rate grossly misfit the measured compositional profiles. Satisfactory simulation of the latter and low temperature thermochronological constraints requires a two-stage cooling model with a cooling rate of ∼50-200 °C/ky from the peak metamorphic temperature of ∼875 °C down to 450 °C, and then transitioning to very slow cooling with an average rate of ∼2.6 °C/My. Similar rapid high temperature cooling rates (200-600 °C/ky) are also required to successfully model the compositional profiles in the Opx-Cpx pairs in the other samples of L5, L6 chondrites. For the H-chondrite samples, the low temperature cooling rates were determined earlier to be 10-20 °C/My by metallographic method. As in St. Séverin, these cooling rates grossly misfit the compositional profiles in the Opx-Cpx pairs. Modeling of these profiles requires very rapid cooling, ∼200-400 °C/ky, from the peak temperatures (∼810-830 °C), transitioning to the metallographic rates at ∼450-500 °C. We interpret the rapid high temperature cooling rates to the exposure of the samples to surface or near surface conditions as a result of fragmentation of the parent body by asteroidal impacts. Using the thermochronological data, the timing of the presumed impact is constrained to be ∼4555-4560 My before present for St. Séverin. We also deduced similar two stage cooling models in earlier studies of H-chondrites and mesosiderites that could be explained, using the available geochronological data, by impact induced fragmentation at around the same time. Diffusion kinetic

  6. Spitzer Survey of the Karin Cluster Asteroids

    NARCIS (Netherlands)

    Harris, Alan W.; Mueller, M.; Lisse, C.; Cheng, A.; Osip, D.

    2007-01-01

    The Karin cluster is one of the youngest known families of main-belt asteroids, dating back to a collisional event only 5.8 Myr ago. Using the Spitzer Space Telescope we have sampled the thermal continua of 17 Karin cluster asteroids, down to the smallest members discovered so far, in order to

  7. [Asteroid hyalopathy (benson's disease): about a case].

    Science.gov (United States)

    Bienvenu, Yogolelo Asani; Angel, Musau Nkola; Leon, Kabamba Ngombe; Socrate, Kapalu Mwangala; Bruno, Iye Ombamba Kayimba; Gaby, Chenge Borasisi

    2017-01-01

    We here report a case of a 58 year-old diabetic male patient with asteroid hyalopathy, an affection rarely described in the literature. This study can help focus the attention of scientists on the pathologies of the vitreous disorders in diabetic patients as well as on other systemic diseases asteroid hyalopathy may be associated with.

  8. Asteroid-Deepsky Appulses in 2018

    Science.gov (United States)

    Warner, Brian D.

    2018-01-01

    The following list is a very small subset of the results of a search for asteroid-deepsky appulses for 2018, presenting only the highlights for the year based on close approaches of brighter asteroids to brighter DSOs. The complete set of predictions is available at http://www.minorplanet.info/ObsGuides/Appulses/DSOAppulses.htm

  9. EXTREME AO OBSERVATIONS OF TWO TRIPLE ASTEROID SYSTEMS WITH SPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B.; Wahhaj, Z.; Dumas, C.; Marsset, M. [European Southern Observatory, Santiago (Chile); Beauvalet, L. [National Observatory, Rio de Janeiro (Brazil); Marchis, F.; Nielsen, E. L. [Carl Sagan Center at the SETI Institute, Mountain View, CA (United States); Vachier, F., E-mail: byang@eso.org [Institut de Mécanique Céleste et de Calcul des Éphémérides, Paris (France)

    2016-04-01

    We present the discovery of a new satellite of asteroid (130) Elektra—S/2014 (130) 1—in differential imaging and in integral field spectroscopy data over multiple epochs obtained with Spectro-Polarimetric High-contrast Exoplanet Research/Very Large Telescope. This new (second) moonlet of Elektra is about 2 km across, on an eccentric orbit, and about 500 km away from the primary. For a comparative study, we also observed another triple asteroid system, (93) Minerva. For both systems, component-resolved reflectance spectra of the satellites and primary were obtained simultaneously. No significant spectral difference was observed between the satellites and the primary for either triple system. We find that the moonlets in both systems are more likely to have been created by sub-disruptive impacts as opposed to having been captured.

  10. Dansk LED - Museumsbelysning

    DEFF Research Database (Denmark)

    Poulsen, Peter Behrensdorff; Dam-Hansen, Carsten; Thorseth, Anders

    Projektet har til formål at anvende dansk forskning inden for optik og lys til at realisere innovative energieffektive LED lyssystemer til museumsbranchen.......Projektet har til formål at anvende dansk forskning inden for optik og lys til at realisere innovative energieffektive LED lyssystemer til museumsbranchen....

  11. Lightcurve Photometry of Six Asteroids

    Science.gov (United States)

    Ferrero, Andrea

    2012-07-01

    Observations from 2012 January to March lead to the determination of the rotation periods for six main-belt asteroids: 33 Polyhymnia, P = 18.604 ± 0.004 h; 467 Laura, P = 37.4 ± 0.1 h; 825 Tanina, P = 6.940 ± 0.001 h; 1421 Esperanto, P = 21.982 ± 0.005 h; 3481 Xianglupeak, P = 5.137 ± 0.003 h; and 4350 Shibecha, which had two possible solutions, P = 2.890 ± 0.001 h and P = 5.778 ± 0.002 h.

  12. Measurement of Cohesion in Asteroid Regolith Materials

    Science.gov (United States)

    Kleinhenz, Julie; Gaier, James; Waters, Deborah; Harvey, Ralph; Zeszut, Zoe; Carreno, Brandon; Shober, Patrick

    2017-01-01

    There is increasing evidence that a large fraction of asteroids, and even Phobos, have such low densities (asteroids are thought to be made up of unconsolidated smaller particles of varying size referred to as rubble piles. Images of the asteroid Itokawa reinforce this hypothesis. What holds the rubble piles together? Gravitational forces alone are not strong enough to hold together rubble pile asteroids, at least not those that are rapidly spinning Van der Waals forces and or Electrostatic forces must therefore be responsible for holding them together. Previous work suggests that electrostatic forces, which are orders of magnitude stronger are far more likely. Charge build-up is a likely consequence of the interaction of airless bodies with the solar wind plasma, analogous to what has been proposed to occur on the moon. Objective: Experimentally measure cohesive forces relevant to those holding rubble pile asteroids together

  13. The Impact of a Student-Led Pedometer Intervention Incorporating Cognitive-Behavioral Strategies on Step Count and Self-Efficacy

    Science.gov (United States)

    Raedeke, Thomas D.; Focht, Brian C.; King, Jenna S.

    2010-01-01

    This study evaluated the effectiveness of a student-led physical activity intervention that incorporated pedometers and cognitive-behavioral strategies. Undergraduate students (N = 117) enrolled in upper division exercise and sport science courses recruited participants. Participants in the cognitive-behavioral intervention condition received…

  14. Growth of asteroids, planetary embryos, and Kuiper belt objects by chondrule accretion.

    Science.gov (United States)

    Johansen, Anders; Low, Mordecai-Mark Mac; Lacerda, Pedro; Bizzarro, Martin

    2015-04-01

    Chondrules are millimeter-sized spherules that dominate primitive meteorites (chondrites) originating from the asteroid belt. The incorporation of chondrules into asteroidal bodies must be an important step in planet formation, but the mechanism is not understood. We show that the main growth of asteroids can result from gas drag-assisted accretion of chondrules. The largest planetesimals of a population with a characteristic radius of 100 km undergo runaway accretion of chondrules within ~3 My, forming planetary embryos up to Mars's size along with smaller asteroids whose size distribution matches that of main belt asteroids. The aerodynamical accretion leads to size sorting of chondrules consistent with chondrites. Accretion of millimeter-sized chondrules and ice particles drives the growth of planetesimals beyond the ice line as well, but the growth time increases above the disc lifetime outside of 25 AU. The contribution of direct planetesimal accretion to the growth of both asteroids and Kuiper belt objects is minor. In contrast, planetesimal accretion and chondrule accretion play more equal roles in the formation of Moon-sized embryos in the terrestrial planet formation region. These embryos are isolated from each other and accrete planetesimals only at a low rate. However, the continued accretion of chondrules destabilizes the oligarchic configuration and leads to the formation of Mars-sized embryos and terrestrial planets by a combination of direct chondrule accretion and giant impacts.

  15. Looking into the evolution of granular asteroids in the Solar System

    Directory of Open Access Journals (Sweden)

    Sánchez Paul

    2017-01-01

    Full Text Available By now it has been accepted that most of the small asteroids in the Solar System are granular aggregates kept together by gravitational and possibly, cohesive forces. These aggregates can form, deform and disrupt over millennia subjected to different internal and external factors that would ultimately determine how they evolve over time. Parameters such as porosity, cohesive and tensile strength, angles of friction, particle size distributions, stress states, heterogeneity and yield criteria among others, determine how these granular systems will react when subjected to different, changing, external factors. These external factors include solar photon momentum, gravitational tides, micro- and macro-impacts and are believed to have produced and shaped the current asteroid population. In our research we use a combination of Soil Mechanics theory, Soft-Sphere Discrete Element Method (SSDEM Simulations and Orbital Mechanics in order to understand how simulated, homogeneous and heterogeneous, ellipsoidal and spherical gravitational aggregates, a crude but useful representation of an asteroid, evolve when rotated to the point of disruption. Then, we compare our results to the shapes of observed asteroids as well as to the disruption patterns of a few active asteroids. Our results lead us to believe that the different shapes of observed asteroids as well as their unique disruption patterns could give us clues about their internal structure, strength and geophysical properties in general.

  16. Spacecraft Mission Design for the Mitigation of the 2017 PDC Hypothetical Asteroid Threat

    Science.gov (United States)

    Barbee, Brent W.; Sarli, Bruno V.; Lyzhoft, Josh; Chodas, Paul W.; Englander, Jacob A.

    2017-01-01

    This paper presents a detailed mission design analysis results for the 2017 Planetary Defense Conference (PDC) Hypothetical Asteroid Impact Scenario, documented at https:cneos.jpl.nasa.govpdcspdc17. The mission design includes campaigns for both reconnaissance (flyby or rendezvous) of the asteroid (to characterize it and the nature of the threat it poses to Earth) and mitigation of the asteroid, via kinetic impactor deflection, nuclear explosive device (NED) deflection, or NED disruption. Relevant scenario parameters are varied to assess the sensitivity of the design outcome, such as asteroid bulk density, asteroid diameter, momentum enhancement factor, spacecraft launch vehicle, and mitigation system type. Different trajectory types are evaluated in the mission design process from purely ballistic to those involving optimal midcourse maneuvers, planetary gravity assists, and/or low-thrust solar electric propulsion. The trajectory optimization is targeted around peak deflection points that were found through a novel linear numerical technique method. The optimization process includes constrain parameters, such as Earth departure date, launch declination, spacecraft, asteroid relative velocity and solar phase angle, spacecraft dry mass, minimum/maximum spacecraft distances from Sun and Earth, and Earth-spacecraft communications line of sight. Results show that one of the best options for the 2017 PDC deflection is solar electric propelled rendezvous mission with a single spacecraft using NED for the deflection.

  17. Growth of asteroids, planetary embryos, and Kuiper belt objects by chondrule accretion

    Science.gov (United States)

    Johansen, Anders; Low, Mordecai-Mark Mac; Lacerda, Pedro; Bizzarro, Martin

    2015-01-01

    Chondrules are millimeter-sized spherules that dominate primitive meteorites (chondrites) originating from the asteroid belt. The incorporation of chondrules into asteroidal bodies must be an important step in planet formation, but the mechanism is not understood. We show that the main growth of asteroids can result from gas drag–assisted accretion of chondrules. The largest planetesimals of a population with a characteristic radius of 100 km undergo runaway accretion of chondrules within ~3 My, forming planetary embryos up to Mars’s size along with smaller asteroids whose size distribution matches that of main belt asteroids. The aerodynamical accretion leads to size sorting of chondrules consistent with chondrites. Accretion of millimeter-sized chondrules and ice particles drives the growth of planetesimals beyond the ice line as well, but the growth time increases above the disc lifetime outside of 25 AU. The contribution of direct planetesimal accretion to the growth of both asteroids and Kuiper belt objects is minor. In contrast, planetesimal accretion and chondrule accretion play more equal roles in the formation of Moon-sized embryos in the terrestrial planet formation region. These embryos are isolated from each other and accrete planetesimals only at a low rate. However, the continued accretion of chondrules destabilizes the oligarchic configuration and leads to the formation of Mars-sized embryos and terrestrial planets by a combination of direct chondrule accretion and giant impacts. PMID:26601169

  18. Looking into the evolution of granular asteroids in the Solar System

    Science.gov (United States)

    Sánchez, Paul; Scheeres, Daniel; Hirabayashi, Masatoshi; Tardivel, Simon

    2017-06-01

    By now it has been accepted that most of the small asteroids in the Solar System are granular aggregates kept together by gravitational and possibly, cohesive forces. These aggregates can form, deform and disrupt over millennia subjected to different internal and external factors that would ultimately determine how they evolve over time. Parameters such as porosity, cohesive and tensile strength, angles of friction, particle size distributions, stress states, heterogeneity and yield criteria among others, determine how these granular systems will react when subjected to different, changing, external factors. These external factors include solar photon momentum, gravitational tides, micro- and macro-impacts and are believed to have produced and shaped the current asteroid population. In our research we use a combination of Soil Mechanics theory, Soft-Sphere Discrete Element Method (SSDEM) Simulations and Orbital Mechanics in order to understand how simulated, homogeneous and heterogeneous, ellipsoidal and spherical gravitational aggregates, a crude but useful representation of an asteroid, evolve when rotated to the point of disruption. Then, we compare our results to the shapes of observed asteroids as well as to the disruption patterns of a few active asteroids. Our results lead us to believe that the different shapes of observed asteroids as well as their unique disruption patterns could give us clues about their internal structure, strength and geophysical properties in general.

  19. Large area LED package

    Science.gov (United States)

    Goullon, L.; Jordan, R.; Braun, T.; Bauer, J.; Becker, F.; Hutter, M.; Schneider-Ramelow, M.; Lang, K.-D.

    2015-03-01

    Solid state lighting using LED-dies is a rapidly growing market. LED-dies with the needed increasing luminous flux per chip area produce a lot of heat. Therefore an appropriate thermal management is required for general lighting with LEDdies. One way to avoid overheating and shorter lifetime is the use of many small LED-dies on a large area heat sink (down to 70 μm edge length), so that heat can spread into a large area while at the same time light also appears on a larger area. The handling with such small LED-dies is very difficult because they are too small to be picked with common equipment. Therefore a new concept called collective transfer bonding using a temporary carrier chip was developed. A further benefit of this new technology is the high precision assembly as well as the plane parallel assembly of the LED-dies which is necessary for wire bonding. It has been shown that hundred functional LED-dies were transferred and soldered at the same time. After the assembly a cost effective established PCB-technology was applied to produce a large-area light source consisting of many small LED-dies and electrically connected on a PCB-substrate. The top contacts of the LED-dies were realized by laminating an adhesive copper sheet followed by LDI structuring as known from PCB-via-technology. This assembly can be completed by adding converting and light forming optical elements. In summary two technologies based on standard SMD and PCB technology have been developed for panel level LED packaging up to 610x 457 mm2 area size.

  20. Polarimetric observations of Hungaria asteroids

    Science.gov (United States)

    Gil-Hutton, R.; Lazzaro, D.; Benavidez, P.

    2007-06-01

    Aims:We present the results of a polarimetric program at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina. The aim of this campaign is to estimate the polarimetric properties of asteroids belonging to the Hungaria dynamical group. Methods: The data were obtained with the Casprof polarimeter at the 2.15 m telescope. The Casprof polarimeter is a two-hole aperture polarimeter with rapid modulation. The campaign began in 2000, and data on a sample of 24 members of the Hungaria group were obtained. We use the slope - albedo or P_min - albedo relationships to get polarimetric albedos for 18 of these objects. Results: Only two Xe-type objects, 434 Hungaria and 3447 Burkhalter, shown a polarimetric behavior compatible with a high albedo object. The A-type asteroid 1600 Vyssotsky has a polarimetric behavior similar to what was observed by Fornasier et al. (2006) for 863 Benkolea, and four objects show P_min values consistent with dark surfaces. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

  1. Rosetta spacecraft meets asteroid Steins

    Science.gov (United States)

    2008-08-01

    Steins is Rosetta’s first nominal scientific target. The spacecraft will rendezvous with the asteroid in the course of its first incursion into the asteroid belt located between the orbits of Mars and Jupiter, while on its way to comet 67/P Churyumov-Gerasimenko. The study of asteroids is extremely important as they represent a sample of Solar System material at different stages of evolution - key to understanding the origin of our own planet and of our planetary neighbourhood. The closest approach to Steins is due to take place on 5 September at 20:58 CEST (Central European Summer Time), from a distance of 800 km, during which the spacecraft will not be communicating with Earth. First ground contact with the spacecraft and announcement of successful fly-by will take place at 22:23 CEST. The first data and images collected by Rosetta will be sent to Earth throughout the night of 5 to 6 September and will undergo preliminary processing in the morning of 6 September. The first images will be made available for broadcasters via a special satellite feed on Saturday 6 September (details will be given on http://television.esa.int). To register for the events, please use the attached form. The press conference on 6 September will also be streamed on the ESA web: at http://www.esa.int/rosetta. Rosetta Steins Fly-By Doors open to the media 5 September 2008, 18:00, Building K ESA-ESOC Robert-Bosch Strasse 5, 64293 Darmstadt, Germany 18:00 - Doors open 18:00 - 19:00 Interview opportunities 19:00 - 20:15 Buffet dinner 20:15 - 20:30 The Steins Fly-By, Introduction by Paolo Ferri, Head of Solar and Planetary Missions Division (Mission Operations Dept.), ESA The crucial role of Flight Dynamics, by Trevor Morley, Rosetta Flight Dynamics Team, ESA 20:30 - 21:00 Live from Rosetta’s control room (loss of telemetry signal at 20:47) 22:23 - First telemetry on ground: signal of successful fly-by 23:00 - End of event Rosetta Steins Fly-By Press Conference 6 September 2008, 12

  2. NASA Double Asteroid Redirection Test (DART) Trajectory Validation and Robutness

    Science.gov (United States)

    Sarli, Bruno V.; Ozimek, Martin T.; Atchison, Justin A.; Englander, Jacob A.; Barbee, Brent W.

    2017-01-01

    The Double Asteroid Redirection Test (DART) mission will be the first to test the concept of a kinetic impactor. Several studies have been made on asteroid redirection and impact mitigation, however, to this date no mission tested the proposed concepts. An impact study on a representative body allows the measurement of the effects on the target's orbit and physical structure. With this goal, DART's objective is to verify the effectiveness of the kinetic impact concept for planetary defense. The spacecraft uses solar electric propulsion to escape Earth, fly by (138971) 2001 CB21 for impact rehearsal, and impact Didymos-B, the secondary body of the binary (65803) Didymos system. This work focuses on the heliocentric transfer design part of the mission with the validation of the baseline trajectory, performance comparison to other mission objectives, and assessment of the baseline robustness to missed thrust events. Results show a good performance of the selected trajectory for different mission objectives: latest possible escape date, maximum kinetic energy on impact, shortest possible time of flight, and use of an Earth swing-by. The baseline trajectory was shown to be robust to a missed thrust with 1% of fuel margin being enough to recover the mission for failures of more than 14 days.

  3. LED roadway luminaires evaluation.

    Science.gov (United States)

    2012-02-01

    This research explores whether LED roadway luminaire technologies are a viable future solution to providing roadway lighting. Roadway lighting : enhances highway safety and traffic flow during limited lighting conditions. The purpose of this evaluati...

  4. Multicolor LED sensor

    Science.gov (United States)

    Lange, Volker; Ribeiro, Felipe; Tews, Walter; Kühlke, Dietrich

    2008-04-01

    We present a compact and cheap sensor device based on the combination of a standard RGB-LED with a luminescence material. The multicolor LED acts as the exciting light source, the luminescence light detector and simultaneously as an optical filter. As luminescence material various phosphor materials or crystals can be used, depending on the physical property to be sensed. Possible applications will be discussed.

  5. System Reliability for LED-Based Products

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J Lynn; Mills, Karmann; Lamvik, Michael; Yaga, Robert; Shepherd, Sarah D; Bittle, James; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy; Johnson, Cortina; Evans, Amy

    2014-04-07

    Results from accelerated life tests (ALT) on mass-produced commercially available 6” downlights are reported along with results from commercial LEDs. The luminaires capture many of the design features found in modern luminaires. In general, a systems perspective is required to understand the reliability of these devices since LED failure is rare. In contrast, components such as drivers, lenses, and reflector are more likely to impact luminaire reliability than LEDs.

  6. Asteroid Redirection Mission Evaluation Using Multiple Landers

    Science.gov (United States)

    Bazzocchi, Michael C. F.; Emami, M. Reza

    2018-01-01

    In this paper, a low-thrust tugboat redirection method is assessed using multiple spacecraft for a target range of small near-Earth asteroids. The benefits of a landed configuration of tugboat spacecraft in formation are examined for the redirection of a near-Earth asteroid. The tugboat method uses a gimballed thruster with a highly collimated ion beam to generate a thrust on the asteroid. The target asteroid range focuses on near-Earth asteroids smaller than 150 m in diameter, and carbonaceous (C-type) asteroids, due to the volatiles available for in-situ utilization. The assessment focuses primarily on the three key parameters, i.e., the asteroid mass redirected, the timeframe for redirection, and the overall system cost. An evaluation methodology for each parameter is discussed in detail, and the parameters are employed to determine the expected return and feasibility of the redirection mission. The number of spacecraft employed is optimized along with the electrical power needed for each spacecraft to ensure the highest possible return on investment. A discussion of the optimization results and the benefits of spacecraft formation for the tugboat method are presented.

  7. Mission Design and Optimal Asteroid Deflection for Planetary Defense

    Science.gov (United States)

    Sarli, Bruno V.; Knittel, Jeremy M.; Englander, Jacob A.; Barbee, Brent W.

    2017-01-01

    Planetary defense is a topic of increasing interest for many reasons, which has been mentioned in "Vision and Voyages for Planetary Science in the Decade 2013-2022". However, perhaps one of the most significant rationales for asteroid studies is the number of close approaches that have been documented recently. A space mission with a planetary defense objective aims to deflect the threatening body as far as possible from Earth. The design of a mission that optimally deflects an asteroid has different challenges: speed, precision, and system trade-off. This work addresses such issues and develops a fast transcription of the problem that can be implemented into an optimization tool, which allows for a broader trade study of different mission concepts with a medium fidelity. Such work is suitable for a mission's preliminary study. It is shown, using the fictitious asteroid impact scenario 2017 PDC, that the complete tool is able to account for the orbit sensitivity to small perturbations and quickly optimize a deflection trajectory. The speed in which the tool operates allows for a trade study between the available hardware. As a result, key deflection dates and mission strategies are identified for the 2017 PDC.

  8. OSIRIS-REx: Sample Return from Asteroid (101955) Bennu

    Science.gov (United States)

    Lauretta, D. S.; Balram-Knutson, S. S.; Beshore, E.; Boynton, W. V.; Drouet d'Aubigny, C.; DellaGiustina, D. N.; Enos, H. L.; Golish, D. R.; Hergenrother, C. W.; Howell, E. S.; Bennett, C. A.; Morton, E. T.; Nolan, M. C.; Rizk, B.; Roper, H. L.; Bartels, A. E.; Bos, B. J.; Dworkin, J. P.; Highsmith, D. E.; Lorenz, D. A.; Lim, L. F.; Mink, R.; Moreau, M. C.; Nuth, J. A.; Reuter, D. C.; Simon, A. A.; Bierhaus, E. B.; Bryan, B. H.; Ballouz, R.; Barnouin, O. S.; Binzel, R. P.; Bottke, W. F.; Hamilton, V. E.; Walsh, K. J.; Chesley, S. R.; Christensen, P. R.; Clark, B. E.; Connolly, H. C.; Crombie, M. K.; Daly, M. G.; Emery, J. P.; McCoy, T. J.; McMahon, J. W.; Scheeres, D. J.; Messenger, S.; Nakamura-Messenger, K.; Righter, K.; Sandford, S. A.

    2017-10-01

    In May of 2011, NASA selected the Origins, Spectral Interpretation, Resource Identification, and Security- Regolith Explorer (OSIRIS-REx) asteroid sample return mission as the third mission in the New Frontiers program. The other two New Frontiers missions are New Horizons, which explored Pluto during a flyby in July 2015 and is on its way for a flyby of Kuiper Belt object 2014 MU69 on January 1, 2019, and Juno, an orbiting mission that is studying the origin, evolution, and internal structure of Jupiter. The spacecraft departed for near-Earth asteroid (101955) Bennu aboard an United Launch Alliance Atlas V 411 evolved expendable launch vehicle at 7:05 p.m. EDT on September 8, 2016, on a seven-year journey to return samples from Bennu. The spacecraft is on an outbound-cruise trajectory that will result in a rendezvous with Bennu in November 2018. The science instruments on the spacecraft will survey Bennu to measure its physical, geological, and chemical properties, and the team will use these data to select a site on the surface to collect at least 60 g of asteroid regolith. The team will also analyze the remote-sensing data to perform a detailed study of the sample site for context, assess Bennu's resource potential, refine estimates of its impact probability with Earth, and provide ground-truth data for the extensive astronomical data set collected on this asteroid. The spacecraft will leave Bennu in 2021 and return the sample to the Utah Test and Training Range (UTTR) on September 24, 2023.

  9. The OSIRIS-REx Asteroid Sample Return Mission Operations Design

    Science.gov (United States)

    Gal-Edd, Jonathan S.; Cheuvront, Allan

    2015-01-01

    OSIRIS-REx is an acronym that captures the scientific objectives: Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer. OSIRIS-REx will thoroughly characterize near-Earth asteroid Bennu (Previously known as 1019551999 RQ36). The OSIRIS-REx Asteroid Sample Return Mission delivers its science using five instruments and radio science along with the Touch-And-Go Sample Acquisition Mechanism (TAGSAM). All of the instruments and data analysis techniques have direct heritage from flown planetary missions. The OSIRIS-REx mission employs a methodical, phased approach to ensure success in meeting the mission's science requirements. OSIRIS-REx launches in September 2016, with a backup launch period occurring one year later. Sampling occurs in 2019. The departure burn from Bennu occurs in March 2021. On September 24, 2023, the Sample Return Capsule (SRC) lands at the Utah Test and Training Range (UTTR). Stardust heritage procedures are followed to transport the SRC to Johnson Space Center, where the samples are removed and delivered to the OSIRIS-REx curation facility. After a six-month preliminary examination period the mission will produce a catalog of the returned sample, allowing the worldwide community to request samples for detailed analysis. Traveling and returning a sample from an Asteroid that has not been explored before requires unique operations consideration. The Design Reference Mission (DRM) ties together spacecraft, instrument and operations scenarios. Asteroid Touch and Go (TAG) has various options varying from ground only to fully automated (natural feature tracking). Spacecraft constraints such as thermo and high gain antenna pointing impact the timeline. The mission is sensitive to navigation errors, so a late command update has been implemented. The project implemented lessons learned from other "small body" missions. The key lesson learned was 'expect the unexpected' and implement planning tools early in the lifecycle

  10. Evidence of Collisional Histories of Asteroids, Comets and Meteorites: Comparisons with Shocked Minerals

    Science.gov (United States)

    Lederer, Susan M.; Jensen, Elizabeth; Smith, Douglas; Fane, Michael; Whizin, Akbar; Landsman, Zoe A.; Wooden, Diane H.; Lindsay, Sean S.; Cintala, Mark; Keller, Lindsay P.; hide

    2017-01-01

    Evidence of the collisional history of comets and asteroids has been emerging from analyses of cometary forsterite and enstatite returned from Comet Wild 2 by the Stardust mission (Keller et al.Geochim. Cosmochim. Acta 72, 2008; Tomeoka et al. MAPS 43, 2008; Jacobs et al. MAPS 44, 2009). Likewise, shock metamorphism is observed in many meteoritic forsterites and enstatites (McCausland et al. AGU, 2010), suggesting similar collisional histories for asteroids. Further exploration of the effects of collisions is slated for the upcoming Asteroid Impact Mission/Double Asteroid Redirection Test (AIM/DART) mission, expected for launch in 2020. DART will impact Didymoon, the companion of the larger 65803 Didymos (1996 G2) asteroid, and AIM will use its instrumentation to characterize the impact. A suite of relevant impact experiments have been carried out in the Experimental Impact Laboratory at the NASA Johnson Space Center at velocities ranging from approx. 2.0 - 2.8 km/s and temperatures from 25 C to -100 C. Targets include a suite of minerals typically found in cometary dust and in asteroids and meteorites: Mg-rich forsterite (olivine), enstatite (orthopyroxene), diopside (clinopyroxene), magnesite (Mg-rich carbonate), and serpentine (phyllosilicate). Transmission Electron Microscope (TEM) imaging indicates evidence of shock similar to that seen in forsterite and enstatite from Comet Wild 2. Fourier Transform Infrared (FTIR) Spectroscopy will also be used for comparisons with meteorite spectra. A quantitative analysis of the shock pressures required to induce planar dislocations and spectral effects with respect to wavelength will also be presented.

  11. Evidence of Collisional Histories of Asteroids, Comets and Meteorites: Comparisons with Shocked Minerals

    Science.gov (United States)

    Lederer, Susan M.; Jensen, Elizabeth; Smith, Douglas; Fane, Michael; Whizin, Akbar; Landsman, Zoe A.; Wooden, Diane H.; Lindsay, Sean S.; Cintala, Mark; Keller, Lindsay P.; Zolensky, Michael

    2017-10-01

    Evidence of the collisional history of comets and asteroids has been emerging from analyses of cometary forsterite and enstatite returned from Comet Wild 2 by the Stardust mission (Keller et al.Geochim. Cosmochim. Acta 72, 2008; Tomeoka et al. MAPS 43, 2008; Jacobs et al. MAPS 44, 2009). Likewise, shock metamorphism is observed in many meteoritic forsterites and enstatites (McCausland et al. AGU, 2010), suggesting similar collisional histories for asteroids. Further exploration of the effects of collisions is slated for the upcoming Asteroid Impact Mission/Double Asteroid Redirection Test (AIM/DART) mission, expected for launch in 2020. DART will impact Didymoon, the companion of the larger 65803 Didymos (1996 G2) asteroid, and AIM will use its instrumentation to characterize the impact.A suite of relevant impact experiments have been carried out in the Experimental Impact Laboratory at the NASA Johnson Space Center at velocities ranging from ~2.0 - 2.8 km s-1 and temperatures from 25°C to -100°C. Targets include a suite of minerals typically found in cometary dust and in asteroids and meteorites: Mg-rich forsterite (olivine), enstatite (orthopyroxene), diopside (clinopyroxene), magnesite (Mg-rich carbonate), and serpentine (phyllosilicate). Transmission Electron Microscope (TEM) imaging indicates evidence of shock similar to that seen in forsterite and enstatite from Comet Wild 2. Fourier Transform Infrared (FTIR) Spectroscopy will also be used for comparisons with meteorite spectra. A quantitative analysis of the shock pressures required to induce planar dislocations and spectral effects with respect to wavelength will also be presented.Funding provided by the NASA PG&G grant 09-PGG09-0115, NSF grant AST-1010012. Special thanks to NASA EIL staff, F. Cardenas and R. Montes.

  12. Exploration of the Moon and Asteroids by Secondary Students (ExMASS): An Authentic, Open-Inquiry Research Experience for High School Students

    Science.gov (United States)

    Shaner, A. J.; Allen, J. S.; Shipp, S. S.; Kramer, G. Y.; Nahm, A.; Balazs, L.; Fuller, J.; Newland, J.; Snyder, R. D.; Kring, D. A.

    2014-12-01

    The National Research Council (2012) has expressed a need for participatory science experiences for students. Opportunities are needed for students which 1) allow them to understand how scientific knowledge develops and 2) can heighten their curiosity, capture their interest, and motivate their continued study of science. Studies (e.g., Aydeniz et al., 2011) have also recommend educators provide students with opportunities to do science through extracurricular work with scientists. In addition to being given the opportunity to fully participate in the scientific enterprise, students must also be explicitly guided in their attempts to develop a more appropriate understanding of the nature of the scientific enterprise (McDonald, 2010; Rudge & Howe, 2010; Yacoubian & BouJaoude, 2010). Exploration of the Moon and Asteroids by Secondary Students, or ExMASS, provides such an opportunity for students. The ExMASS program is an education effort managed by the LPI/NASA JSC-led Center for Lunar Science and Exploration (CLSE), one of nine teams comprising NASA's Solar System Exploration Research Virtual Institute (SSERVI). Over the course of one academic year, teams of high school students conduct their own scientific investigations of either Earth's Moon or asteroids, with guidance from a scientist mentor. The program includes two elements: 1) a guided inquiry introductory research activity that builds student knowledge of current lunar/asteroid science and lunar/asteroid data, and 2) an open inquiry research project in which the students apply their knowledge to a self-defined project. Evaluation data collected during the predecessor program to ExMASS revealed many successes, but also room for improvement. In response, an Advisory Group consisting of past teachers and mentors was formed to address the gaps revealed in the evaluation data. The ExMASS program will continue to collect similar evaluation data including assessment of changes in students' lunar/asteroid content

  13. Migration of Asteroidal Dust Particles

    Science.gov (United States)

    Ipatov, S. I.; Mather, J. C.; Taylor, P. A.

    2003-08-01

    We numerically investigated the migration of dust particles with initial velocities and positions same as those of the numbered asteroids using the Bulirsh-Stoer method of integration and took into account the gravitational influence of 8 planets, radiation pressure, Poynting-Robertson drag and solar wind drag, for values of the ratio between the radiation pressure force and the gravitational force β equal to 0.01, 0.05, 0.1, 0.25, and 0.4. For silicate particles such values of β correspond to diameters of 40, 9, 4, 1.6, and 1 microns, respectively. For each β >= 0.05 we considered N=500 particles (N=250 for β =0.01). In our runs, planets were considered as material points, but, based on orbital elements obtained with a step of probability of a collision of a particle with a terrestrial planet during the lifetime of the particle. For smaller particles, the ratio of the number of particles that collided with the Sun to the total number of simulated particles and the probability of collisions of particles with the terrestrial planets are smaller. The probability of a collision of a migrating dust particle with the Earth for β =0.01 is greater by a factor of 220 than for β =0.4. The mean time ta during which an asteroidal dust particle had a semi-major axis 'a' in intervals with a fixed width is greater for smaller β (for the same initial number of particles) at a3.5 AU than at 'a' between 1 and 3 AU, and are usually maximum at 'a' about 2.3 AU. For β =0.01 the local maxima of ta corresponding to the 5:6, 6:7, 3:4, and 2:3 resonances with the Earth are greater than the maximum at 2.4 AU. The peaks in distribution of migrating asteroidal dust particles with semi-major axis corresponding to the n/(n+1) resonances with Earth and Venus and the gaps associated with the 1:1 resonances with these planets are more pronounced for larger particles. The spatial density of a simulated dust cloud and its luminosity (as seen from outside) were greater for smaller distance

  14. Spectroscopy of near-Earth asteroids

    DEFF Research Database (Denmark)

    Michelsen, René; Nathues, Andreas; Lagerkvist, Claes-Ingvar

    2006-01-01

    We present spectra and taxonomic classifications of 12 Near-Earth Asteroids (NEAs) and 2 inner Main Belt asteroids. The observations were carried out with the ESO 3.5 m NTT and the Danish 1.54 m telescope at La Silla, Chile. Eleven of the investigated NEAs belong to the S class while only one C......-type has been identified. Two NEAs were observed at phase angles larger than 60 degrees introducing significant phase reddening. In order to allow for comparisons between spectra of asteroids observed at different phase angles we make attempts to correct for this effect. However, it turned out...

  15. PRIMitive Asteroids Spectroscopic Survey - PRIMASS: Current Status

    Science.gov (United States)

    Pinilla-Alonso, Noemí; de León, Julia; Morate, David; de Prá, Mario; Lorenzi, Vania; Licandro, Javier; Campins, Humberto; Ali-Lagoa, Victor

    2017-10-01

    Primitive asteroids contain the most pristine material that gave birth to the rocky planets. Interest in spectral data from primitive asteroids that could be the source of the primitive near-Earth asteroids (NEAs) has increased in anticipation of the two sample-return missions that will reach their targets in the next four years and bring samples to the Earth within five years. Concurrently, the discovery of water ice on the surfaces of two primitive asteroids (24 Themis and 65 Cybele) placed the focus on the outer-belt (orbits with semi-major axis larger than 2.82 AU), where more asteroids could harbor water ice on, or below the surface.In 2010 we started a survey, called the PRIMitive Asteroids Spectroscopic Survey (PRIMASS), to collect spectra of primitive asteroids all through the Solar System. Up to now, PRIMASS library (PRIMASS-L) contains more than 530 spectra (0.4 - 2.5 μm) of primitive asteroids (> 90% of the asteroids had no spectroscopic data before) in the inner and outer belt. The aim of this survey is to provide the community with a comprehensive collection of data that enable us to study the surface composition of primitive asteroids by means of visible and near-infrared spectroscopy.Our plans for the close future include making PRIMASS-L publicly available in proper timing to be used by the teams of the OSIRIS-REx (NASA) and Hayabusa 2 (JAXA) missions. These missions will characterize two primitive near-Earth asteroids in detail, and the Earth-based libraries, as PRIMASS-L, will establish the broader framework and maximize the value of the spacecraft results. PRIMASS-L will also serve as a quality-check database for the Gaia spectroscopic products that will be published in its final release, by the end of the nominal mission in 2019.In parallel, we plan to continue observing at least for four more semesters (up to semester 2019A). After almost 10 years of data acquisition, the PRIMASS database will contain about 700 spectra of primitive asteroids

  16. NASA Double Asteroid Redirection Test (Dart) Trajectory Validation and Robustness

    Science.gov (United States)

    Sarli, Bruno V.; Ozimek, Martin T.; Atchison, Justin A.; Englander, Jacob A.; Barbee, Brent W.

    2017-01-01

    The Double Asteroid Redirection Test (DART) mission will be the first to test the concept of a kinetic impactor. Several studies have been made on asteroid redirection and impact mitigation, however, to this date no mission tested the proposed concepts. An impact study on a representative body allows the measurement of the effects on the target's orbit and physical structure. With this goal, DART's objective is to verify the effectiveness of the kinetic impact concept for planetary defense. The spacecraft uses solar electric propulsion to escape Earth, flyby (138971) 2001 CB21 for impart rehearsal, and impact the secondary body of the (65803) Didymos system. This work focuses on the interplanetary trajectory design part of the mission with the validation of the baseline trajectory, performance comparison to other mission objectives, and assessment of the baseline robustness to missed thrust events. Results show a good performance of the selected trajectory for different mission objectives: latest possible escape date, maximum kinetic energy on impact, shortest possible time of flight, and use of an Earth swing-by. The baseline trajectory was shown to be robust to a missed thrust with 1% of fuel margin being enough to recover the mission for failures of more than 14 days.

  17. Light Emitting Diode (LED)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  18. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  19. Led-sukellusvalaisin

    OpenAIRE

    Saarelainen, Mikko

    2012-01-01

    Opinnäytetyön aiheena on LED ja sen käyttö sukellusvalaisimissa. Työn tarkoitus oli tutkia miten LED toimii ja miten se soveltuu käytettäväksi sukellusvalaisimessa, sekä syventää omaa tietoutta valosta, mitä se on ja miten sitä mitataan. Työssä käydään läpi LEDin ominaisuuksia ja miten se eroaa muista sukellusvalaisimissa käytetyistä lampuista. Työ on toteutettu tutustumalla LEDiin ja valoon käyttämällä erilaisia lähteitä ja päivittämällä nykyinen sukellusvalaisimeni LED-sukellusvalaisime...

  20. Developing the future Indigenous health workforce: The feasibility and impact of a student-led placement programme in remote Indigenous communities.

    Science.gov (United States)

    Warren, Johanna M; Irish, Georgina L; Purbrick, Brydie; Li, Joule J; Li, Xi; Fitzpatrick, Danielle J; Faull, Randall J

    2016-10-01

    To describe and evaluate a programme where medical students designed and implemented Indigenous health placements for students with an interest in rural/Indigenous health. In 2011, a student-led programme at the University of Adelaide was set up to give medical students the opportunity to undertake outreach trips and clinical placements in remote Indigenous communities. Twenty-four medical students attended trips to remote communities between 2012 and 2014. Here we evaluate our programme using a single-arm experimental design. Responses to questionnaire items before and after attending an outreach placement, scored on 6-point Likert scales. Following their remote Indigenous health placement, participants expressed a significantly higher mean likelihood of working in an Indigenous community in the future (3.17 (2.69-3.64) versus 4.00 (3.65-4.35); P health. Implementation of this student-led model in other medical schools may encourage nationwide development of the Indigenous health workforce. © 2016 National Rural Health Alliance Inc.

  1. ASTEROID OCCULTATIONS V13.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid, planet, and planetary satellite occultation events as well as occultation axes...

  2. ASTEROID OCCULTATIONS V10.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid, planet, and planetary satellite occultation events as well as occultation axes...

  3. ASTEROID RADAR V10.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all published groundbased asteroid radar detections. The entries were collected by Steven J. Ostro, and selected data have been...

  4. Asteroid Occultations V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid, planet, and planetary satellite occultation events as well as occultation axes...

  5. ASTEROID RADAR V5.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all groundbased asteroid radar detections. These entries were collected by Steven J. Ostro (1989) [OSTRO1989] and selected data...

  6. ASTEROID RADAR V13.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all published groundbased asteroid radar detections. The entries were collected by Steven J. Ostro, and selected data have been...

  7. ASTEROID RADAR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset is intended to include all asteroid radar detections. An entry for each detection reports radar cross-section and circular polarization, if known, as...

  8. ASTEROID MASSES V3.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This collection of asteroid masses and densities was compiled from the published literature by Jim Baer, Steve Chesley, and Dan Britt. Size and shape information are...

  9. ASTEROID OCCULTATIONS V14.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all reported timings of observed asteroid, planet, and planetary satellite occultation events as well as occultation axes...

  10. ASTEROID RADAR V14.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is intended to include all published groundbased asteroid radar detections. The entries were collected by Steven J. Ostro, and selected data have been...

  11. SAWYER ASTEROID SPECTRA V1.1

    Data.gov (United States)

    National Aeronautics and Space Administration — Partial spectral data for the plots presented in S. Sawyer's PhD Thesis, 'A High Resolution Spectroscopic Survey of Low Albedo Main Belt Asteroids', 1991.

  12. Radar detection of mini-asteroids

    OpenAIRE

    Chernogor, Leonid F.

    2013-01-01

    Estimates of the possible early detection of decameter-size space bodies (mini-asteroids) by using the existing non-dedicated and dedicated (space surveillance) radars and also the upcoming radars are presented.

  13. Chelyabinsk: Portrait of an asteroid airburst

    Energy Technology Data Exchange (ETDEWEB)

    Kring, David A.; Boslough, Mark

    2014-09-01

    Video and audio from hundreds of smartphones and dashboard cameras combined with seismic, acoustic, and satellite measurements provide the first precise documentation of a 10 000-ton asteroid explosion.

  14. Shaping asteroid models using genetic evolution (SAGE)

    Science.gov (United States)

    Bartczak, P.; Dudziński, G.

    2018-02-01

    In this work, we present SAGE (shaping asteroid models using genetic evolution), an asteroid modelling algorithm based solely on photometric lightcurve data. It produces non-convex shapes, orientations of the rotation axes and rotational periods of asteroids. The main concept behind a genetic evolution algorithm is to produce random populations of shapes and spin-axis orientations by mutating a seed shape and iterating the process until it converges to a stable global minimum. We tested SAGE on five artificial shapes. We also modelled asteroids 433 Eros and 9 Metis, since ground truth observations for them exist, allowing us to validate the models. We compared the derived shape of Eros with the NEAR Shoemaker model and that of Metis with adaptive optics and stellar occultation observations since other models from various inversion methods were available for Metis.

  15. VILAS ASTEROID SPECTRA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains 85 published spectra of asteroids obtained by Faith Vilas during the years 1982 - 1992. These appeared in the following papers:...

  16. LEDS GP Success Story: Fostering Coordinated LEDS Support in Kenya (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2014-03-01

    The LEDS Global Partnership (LEDS GP) strives to advance climate-resilient, low-emission development through catalyzing collaboration, information exchange, and action on the ground. The Government of Kenya is a key LEDS GP member and offers an inspiring example of how LEDS GP is having an impact globally. The 2012 LEDS Collaboration in Action workshop in London provided an interactive space for members to share experiences on cross-ministerial LEDS leadership and to learn about concrete development impacts of LEDS around the world. Inspired by these stories, the Kenya's Ministry of State for Planning, National Development and Vision 2030 (MPND) began to collaborate closely with the Ministry of Environment and Mineral Resources to create strong links between climate change action and development in the country, culminating in the integration of Kenya's National Climate Change Action Plan and the country's Medium Term Development Plan.

  17. The impact and process of a community-led intervention on reducing environmental inequalities related to physical activity and healthy eating - a pilot study.

    Science.gov (United States)

    Davey, Rachel C; Hurst, Gemma L; Smith, Graham R; Grogan, Sarah C; Kurth, Judy

    2011-09-12

    There is growing recognition that a sedentary lifestyle is being driven, at least in part, by environmental factors that affect individuals' physical activity choices and health behaviours. In other words, the environments in which we live, and with which we interact, have become ones that encourage lifestyle choices that decrease physical activity and encourage over-consumption of foods. However, evidence from community-led interventions to change local neighbourhood environments to support physical activity and healthy eating is lacking. This article summarises the research protocol developed to evaluate a community-led intervention "My Health Matters" aimed at reducing health inequalities relating to increasing physical activity and healthy eating as defined by community members themselves. This study includes three of the most deprived electoral wards in Stoke-on-Trent. In each of these areas, environmental factors including proximity of physical activity spaces, greenspace and leisure facilities, neighbourhood connectivity and walkability, land-use-mix and population density, traffic, safety and crime, and food outlets will be mapped using Geographical Information Systems (GIS). A community postal survey of randomly selected addresses assessing environmental characteristics relating to physical activity, perceived health status, social capital, fruit and vegetable consumption and levels of physical activity will be undertaken (baseline and at 2 year follow-up). Based on baseline findings an intervention will be designed and implemented over a 2 year period that includes the following; use of community participatory research to build effective community partnerships; use of partnership consensus to identify, prioritise and design intervention(s) related to specific health disparities; recruitment of local residents to help with the delivery and sustainability of target intervention(s); and the development of local systems for ongoing monitoring and evaluation

  18. The impact and process of a community-led intervention on reducing environmental inequalities related to physical activity and healthy eating - a pilot study

    Directory of Open Access Journals (Sweden)

    Grogan Sarah C

    2011-09-01

    Full Text Available Abstract Background There is growing recognition that a sedentary lifestyle is being driven, at least in part, by environmental factors that affect individuals' physical activity choices and health behaviours. In other words, the environments in which we live, and with which we interact, have become ones that encourage lifestyle choices that decrease physical activity and encourage over-consumption of foods. However, evidence from community-led interventions to change local neighbourhood environments to support physical activity and healthy eating is lacking. This article summarises the research protocol developed to evaluate a community-led intervention "My Health Matters" aimed at reducing health inequalities relating to increasing physical activity and healthy eating as defined by community members themselves. Methods/Design This study includes three of the most deprived electoral wards in Stoke-on-Trent. In each of these areas, environmental factors including proximity of physical activity spaces, greenspace and leisure facilities, neighbourhood connectivity and walkability, land-use-mix and population density, traffic, safety and crime, and food outlets will be mapped using Geographical Information Systems (GIS. A community postal survey of randomly selected addresses assessing environmental characteristics relating to physical activity, perceived health status, social capital, fruit and vegetable consumption and levels of physical activity will be undertaken (baseline and at 2 year follow-up. Based on baseline findings an intervention will be designed and implemented over a 2 year period that includes the following; use of community participatory research to build effective community partnerships; use of partnership consensus to identify, prioritise and design intervention(s related to specific health disparities; recruitment of local residents to help with the delivery and sustainability of target intervention(s; and the development of

  19. Volatile Characterization on Near Earth Asteroids

    Science.gov (United States)

    McGraw, Lauren; Emery, Joshua P.; Thomas, Cristina A.; Rivkin, Andrew S.; Wigton, Nathanael R.

    2017-10-01

    Near Earth Asteroids (NEAs) are excellent laboratories for processes that affect the surfaces of airless bodies. Most NEAs are not expected to contain surface volatiles such as OH/H2O since they formed in the anhydrous regions of the solar system and since their surface temperatures are high enough to evaporate such volatiles. However, OH/H2O has been discovered on other seemingly dry bodies in the inner solar system, such as the Moon and Vesta. Possible sources for OH/H2O on these bodies include carbonaceous chondrite impacts and interactions with protons implanted by solar wind. NEAs should be subjected to the same processes as other “dry” bodies in the inner solar system so are hypothesized to also contain OH/H2O on their surfaces. We observed NEAs using SpeX on NASA’s Infrared Telescope Facility on Mauna Kea, Hawaii. Spectra were collected using both prism (0.7-2.52 µm) and LXD_short (1.67-4.2 µm) modes in order to accurately characterize asteroid type and the 3-µm region, where the OH/H2O signature is present. We have made 19 observations of 13 NEAs as part of this ongoing project, with five more observations scheduled for this Fall. Of those, at least 3 NEAs exhibit an absorption feature in the 3-µm region: (433) Eros, (1036) Ganymed, and (3122) Florence. Eros and Ganymed have both been observed multiple times and by multiple observers (e.g., Rivkin et al. 2017), including two observations of Eros in Fall 2016, and Florence will be observed again in early September. Of the other 10 NEAs studied, eight do not exhibit a 3-µm spectral feature. The spectra for 1998 XB and 2014 JO25 are too noisy to definitively determine the presence of volatiles. Characterizing the shape of the 3-µm absorption feature can yield information on the source of the OH/H2O on the surface. Shallow features that gradually slope upward towards the continuum, such as is present in the spectra of Eros and Ganymed, indicate the presence of OH, which is inferred to have formed

  20. Asteroids Lightcurves Analysis: 2016 November - 2017 June

    Science.gov (United States)

    Carbognani, Albino; Bacci, Paolo; Buzzi, Luca

    2018-01-01

    Twelve near-Earth asteroids were observed from 2016 November through 2017 June to find the synodic rotation period and lightcurve amplitudes for each asteroid. Results are reported for 2329 Orthos, (138846) 2000 VJ61, (326683) 2002 WP, (489337) 2006 UM, (494706) 2005 GL9, 2005 TF, 2017 BJ30, 2017 BQ6, 2017 CS, 2017 DC36, 2017 GK4, and 2017 JA2.

  1. Nurse-led discharge.

    Science.gov (United States)

    Page, Carole

    2010-12-01

    Delayed discharges have financial implications for hospital trusts and cause dissatisfaction for patients and their families. This article looks at nurse-led discharge pathways at Milton Keynes Hospital's ambulatory care unit. It explains how giving nurses the responsibility to discharge has improved the patient experience, made nurses more accountable and saved money for the trust.

  2. LED system reliability

    NARCIS (Netherlands)

    Driel, W.D. van; Yuan, C.A.; Koh, S.; Zhang, G.Q.

    2011-01-01

    This paper presents our effort to predict the system reliability of Solid State Lighting (SSL) applications. A SSL system is composed of a LED engine with micro-electronic driver(s) that supplies power to the optic design. Knowledge of system level reliability is not only a challenging scientific

  3. The impact of the Affordable Care Act on hospital-led community health evaluation in the U.S. Appalachian Ohio region.

    Science.gov (United States)

    Franz, Berkeley; Skinner, Daniel; Kelleher, Kelly

    2017-08-01

    In recent years, policy developments in the United States have dramatically changed how nonprofit hospitals interact with surrounding communities. However, despite the importance of these changes encoded in Internal Revenue Service regulations, little is known about how these requirements have affected how nonprofit hospitals are approaching community health evaluation. We present qualitative findings from interviews with hospital employees and consultants overseeing preliminary rounds of community health needs assessments, as required by the Affordable Care Act. The sample comes from the Appalachian region of Ohio, an area targeted because of significant health challenges. Our findings suggest that the Affordable Care Act has led hospitals to formalize their processes, focus on developing an evidence base, cultivate local partnerships, and reflect on the role of the hospital in public health. © 2017 John Wiley & Sons, Ltd.

  4. The impact of pharmacist-led medication therapy management on medication adherence in patients with type 2 diabetes mellitus: a randomized controlled study

    Directory of Open Access Journals (Sweden)

    Erku DA

    2017-09-01

    Full Text Available Background: Poor adherence to antidiabetic medications leads to a higher rate of hospital admissions and adverse health outcomes in type 2 diabetes mellitus patients. Objective: This study aims to evaluate whether a pharmacist-led medication therapy management, compared to the usual care, could enhance medication adherence and reduce hospital admission in patients with type 2 diabetes mellitus. Methods: A prospective randomized controlled study was conducted in patients with type 2 diabetes mellitus from February 1 to July 30, 2016. Patients in the control group (n=65 received the usual care while patients in the intervention group (n=62 received a personalized pharmacotherapeutic care plan and diabetes education. The two groups were compared by repeated measure ANOVA at 3 and 6‐months with medication adherence (using Morisky medication adherence scale and number of hospital admissions as the main outcome variables. Results: A total of 127 patients were included in the study. A marked and statistically significant increase in medication adherence from baseline to 3 and 6 months were noted in the intervention group (increased from 9.2% at baseline to 61% at 6 month compared with the control group (increased from 13.2% at baseline (to 30.2% at 6 month; p-value<0.01. Furthermore, at the 6-month follow-up, only 23 patients in MTM group with poorly controlled blood glucose levels resulted in hospital admissions compared to 48 patients in non-MTM group, resulting in a 52.1% fewer hospital admissions (p< 0.001. Conclusions: The findings of this study implied that pharmacist-led medication therapy management might improve medication adherence and reduce number of hospitalizations in patients with type 2 diabetes mellitus. Hence, policies and guidelines should be in place in order for clinical pharmacists to fully engage in patient care and improve the medication therapy outcomes.

  5. Asteroid hyalosis--current state of knowledge.

    Science.gov (United States)

    Jabłońska, Anna; Ciszewska, Joanna; Kęcik, Dariusz

    2014-01-01

    The search query into the Cochrane Library, Medline, Web of Science, Embase, Scopus and ScienceDirect enabled selection of research papers addressing the issue of asteroid hyalosis published in English between 1963 and January 2014. Asteroid hyalosis is a degenerative condition of the vitreous in which small, creamy or white, spherical particles (asteroid bodies) are randomly diffused within the vitreous. They consist mainly of calcium and phosphorus and have a structure of hydroxy lapatite. In 80.2-92.0% of cases the condition affects one eye only and it occurs in 0.36-1.96% of population, mostly in patients over 50 years of age and in males. Hypercholesterolemia and hypertension are systemic risk factors, but asteroid hyalosis is postulated to occur more often in retinitis pigmentosa and Leber amaurosis caused by mutations in lecithin retinol acyltransferase gene. Asteroid hyalosis also causes calcification of some intraocular lenses--mostly silicone ones. Vitreous of patients with asteroid hyalosis shows reduced gel liquefaction and anomalous vitreoretinal adhesion.

  6. Formation of asteroid pairs by rotational fission.

    Science.gov (United States)

    Pravec, P; Vokrouhlický, D; Polishook, D; Scheeres, D J; Harris, A W; Galád, A; Vaduvescu, O; Pozo, F; Barr, A; Longa, P; Vachier, F; Colas, F; Pray, D P; Pollock, J; Reichart, D; Ivarsen, K; Haislip, J; Lacluyze, A; Kusnirák, P; Henych, T; Marchis, F; Macomber, B; Jacobson, S A; Krugly, Yu N; Sergeev, A V; Leroy, A

    2010-08-26

    Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their formation-critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs, revealing that the primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero, requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system, which subsequently disrupts under its own internal system dynamics soon after formation.

  7. Asteroid 'Bites the Dust' Around Dead Star

    Science.gov (United States)

    2009-01-01

    NASA's Spitzer Space Telescope set its infrared eyes upon the dusty remains of shredded asteroids around several dead stars. This artist's concept illustrates one such dead star, or 'white dwarf,' surrounded by the bits and pieces of a disintegrating asteroid. These observations help astronomers better understand what rocky planets are made of around other stars. Asteroids are leftover scraps of planetary material. They form early on in a star's history when planets are forming out of collisions between rocky bodies. When a star like our sun dies, shrinking down to a skeleton of its former self called a white dwarf, its asteroids get jostled about. If one of these asteroids gets too close to the white dwarf, the white dwarf's gravity will chew the asteroid up, leaving a cloud of dust. Spitzer's infrared detectors can see these dusty clouds and their various constituents. So far, the telescope has identified silicate minerals in the clouds polluting eight white dwarfs. Because silicates are common in our Earth's crust, the results suggest that planets similar to ours might be common around other stars.

  8. Exploring Extreme Retro-reflection by Asteroids Using Las Cumbres Observatory Robotic Telescope Observations

    Science.gov (United States)

    Goguen, Jay D.; Bauer, James M.

    2017-10-01

    exploration, impact hazard assessment, and fundamental asteroid science.

  9. Effect of Giant Planet Formation on the Compositional Mixture of the Asteroid Belt

    Science.gov (United States)

    Kretke, Katherine A.; Bottke, William; Kring, David A.; Levison, Harold F.

    2017-06-01

    The asteroid belt is observed to be a mixture of objects with different compositions, with volatile-poor asteroids (mostly S-complex) dominant in the inner asteroid belt while volatile-rich (mostly C-complex) asteroids dominate the outer asteroid belt. While this general compositional stratification was originally thought to be an indicator of the primordial temperature gradient in the protoplanetary disk, the very distinct properties of these populations suggest that they must represent two completely decoupled reservoirs, not a simple gradient (e.g., Warren 2011). It is possible to create this general stratification (as well as the observed mixing) as the implantation of outer Solar System material into the asteroid belt by the early migration of the giant planets (e.g. the Grand Tack, Walsh et al. 2011). However, this presupposes that the inner and outer Solar System materials were still sorted in their primordial locations prior to any migration of the planets. The lack of a fully dynamically self-consistent model of giant planet core formation has prevented the study of how the core formation process itself may result in dynamical mixing in the early Solar System's history. Recently, pebble accretion, the process by which planetesimals can grow to giant planet cores via the accretion of small, rapidly drifting sub-meter-sized bodies known as ``pebbles,'' (Lambrechts & Johansen 2012, Levison, Kretke & Duncan 2015) finally offers such a model. Here we show how the process of giant planet formation will impact the surrounding planetesimal population, possibly resulting in the observed compositional mixture of the asteroid belt, without requiring a dramatic migration of the giant planets. For example, preliminary runs suggest planetesimals from the Jupiter-formation zone can be implanted in the outer main belt via interactions with scattered Jupiter-zone protoplanets. This could potentially provide an alternative non-Grand Tack solution to the origin of many C

  10. Asteroids, Comets, Meteors, and their Interrelations, Part I: Editorial review

    Science.gov (United States)

    Muinonen, Karri; Granvik, Mikael; Penttilä, Antti; Gritsevich, Maria

    2015-12-01

    It is widely agreed that the small Solar System bodies are a key to understanding the formation and evolution of the Solar System, carrying signals from pre-solar times. Unveiling the evolution of the Solar System helps research on the evolution of extrasolar planetary systems. Societally, small bodies will be important future resources of minerals. The near-Earth population of small bodies continues to pose an impact hazard, whether it be small pieces of falling meteorites or larger asteroids or cometary nuclei capable of causing global environmental effects.

  11. LSST’s Projected Near-Earth Asteroid Discovery Performance

    Science.gov (United States)

    Chesley, Steven R.; Vereš, Peter

    2015-11-01

    The Large Synoptic Survey Telescope (LSST) is an ambitious project that has the potential to make major advances in Near-Earth Asteroid search efforts. With construction already underway and major optical elements complete, first light is set for 2020, followed by two years of commissioning. Once regular survey operations begin in 2022, LSST will systematically survey the observable sky over a ten-year period from its site on Cerro Pachon, Chile. With an 8.4 m aperture (6.5 m effective), 9.6 square degree field of view, and a 3.2-Gigapixel camera, LSST represents the most capable asteroid survey instrument ever built.LSST will be able cover over 6000 square degrees of sky per clear night with single visit exposures of 30 s, reaching a faint limit of 24.5 mag in the r band. However the cadence of survey operations is a critical factor for the near-Earth asteroid search performance, and there are multiple science drivers with different cadence objectives that are competing to shape the final survey strategy. We examine the NEA search performance of various LSST search strategies, paying particular attention to the challenges of linking large numbers asteroid detections in the presence of noise.Our approach is to derive lists of synthetic detections for a given instantiation of the LSST survey, based on an assumed model for the populations of solar system objects from the main asteroid belt inwards to the near-Earth population. These detection lists are combined with false detection lists that model both random noise and non-random artifacts resulting from image differencing algorithms. These large detection lists are fed to the Moving Object Processing System (MOPS), which attempts to link the synthetic detections correctly without becoming confused or overwhelmed by the false detections.The LSST baseline survey cadence relies primarily on single night pairs of detections, with roughly 30-60 min separating elements of the pair. The strategy of using pairs is an

  12. LSST's Projected Near-Earth Asteroid Discovery Performance

    Science.gov (United States)

    Chesley, Steven R.; Veres, Peter

    2016-10-01

    The Large Synoptic Survey Telescope (LSST) is an ambitious project that has the potential to make major advances in Near-Earth Asteroid search efforts. With construction already underway and major optical elements complete, first light is set for 2020, followed by two years of commissioning. Once regular survey operations begin in 2022, LSST will systematically survey the observable sky over a ten-year period from its site on Cerro Pachon, Chile. With an 8.4 m aperture (6.5 m effective), 9.6 square degree field of view, and a 3.2-Gigapixel camera, LSST represents the most capable asteroid survey instrument ever built. LSST will be able cover over 6000 square degrees of sky per clear night with single visit exposures of 30 s, reaching a faint limit of 24.5 mag in the r band. However the cadence of survey operations is a critical factor for the near-Earth asteroid search performance, and there are multiple science drivers with different cadence objectives that are competing to shape the final survey strategy. We examine the NEA search performance of various LSST search strategies, paying particular attention to the challenges of linking large numbers asteroid detections in the presence of noise. Our approach is to derive lists of synthetic detections for a given instantiation of the LSST survey, based on an assumed model for the populations of solar system objects from the main asteroid belt inwards to the near-Earth population. These detection lists are combined with false detection lists that model both random noise and non-random artifacts resulting from image differencing algorithms. These large detection lists are fed to the Moving Object Processing System (MOPS), which attempts to link the synthetic detections correctly without becoming confused or overwhelmed by the false detections. The LSST baseline survey cadence relies primarily on single night pairs of detections, with roughly 30-60 min separating elements of the pair. The strategy of using pairs is an

  13. A Spectroscopic and Mineralogical Study of Multiple Asteroid Systems

    Science.gov (United States)

    Lindsay, Sean S.; Emery, J. P.; Marchis, F.; Enriquez, J.; Assafin, M.

    2013-10-01

    There are currently ~200 identified multiple asteroid systems (MASs). These systems display a large diversity in heliocentric distance, size/mass ratio, system angular momentum, mutual orbital parameters, and taxonomic class. These characteristics are simplified under the nomenclature of Descamps and Marchis (2008), which divides MASs into four types: Type-1 - large asteroids with small satellites; Type-2 - similar size double asteroids; Type-3 - small asynchronous systems; and Type-4 - contact-binary asteroids. The large MAS diversity suggests multiple formation mechanisms are required to understand their origins. There are currently three broad formation scenarios: 1) ejecta from impacts; 2) catastrophic disruption followed by rotational fission; and 3) tidal disruption. The taxonomic class and mineralogy of the MASs coupled with the average density and system angular momentum provide a potential means to discriminate between proposed formation mechanisms. We present visible and near-infrared (NIR) spectra spanning 0.45 - 2.45 μm for 23 Main Belt MASs. The data were primarily obtained using the Southern Astrophysical Research Telescope (SOAR) Goodman High Throughput Spectrograph (August 2011 - July 2012) for the visible data and the InfraRed Telescope Facility (IRTF) SpeX Spectrograph (August 2008 - May 2013) for the IR data. Our data were supplemented using previously published data when necessary. The asteroids' Bus-DeMeo taxonomic classes are determined using the MIT SMASS online classification routines. Our sample includes 3 C-types, 1 X-type, 1 K-type, 1 L-type, 4 V-types, 10 S-types, 2 Sq- or Q-types, and 1 ambiguous classification. We calculate the 1- and 2-μm band centers, depths, and areas to determine the pyroxene mineralogy (molar Fs and Wo) of the surfaces using empirically derived equations. The NIR band analysis allows us to determine the S-type subclasses, S(I) - S(VII), which roughly tracks olivine-pyroxene chemistry. A comparison of the orbital

  14. Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft.

    Science.gov (United States)

    Nakamura, Eizo; Makishima, Akio; Moriguti, Takuya; Kobayashi, Katsura; Tanaka, Ryoji; Kunihiro, Tak; Tsujimori, Tatsuki; Sakaguchi, Chie; Kitagawa, Hiroshi; Ota, Tsutomu; Yachi, Yusuke; Yada, Toru; Abe, Masanao; Fujimura, Akio; Ueno, Munetaka; Mukai, Toshifumi; Yoshikawa, Makoto; Kawaguchi, Jun'ichiro

    2012-03-13

    Records of micrometeorite collisions at down to submicron scales were discovered on dust grains recovered from near-Earth asteroid 25143 (Itokawa). Because the grains were sampled from very near the surface of the asteroid, by the Hayabusa spacecraft, their surfaces reflect the low-gravity space environment influencing the physical nature of the asteroid exterior. The space environment was examined by description of grain surfaces and asteroidal scenes were reconstructed. Chemical and O isotope compositions of five lithic grains, with diameters near 50 μm, indicate that the uppermost layer of the rubble-pile-textured Itokawa is largely composed of equilibrated LL-ordinary-chondrite-like material with superimposed effects of collisions. The surfaces of the grains are dominated by fractures, and the fracture planes contain not only sub-μm-sized craters but also a large number of sub-μm- to several-μm-sized adhered particles, some of the latter composed of glass. The size distribution and chemical compositions of the adhered particles, together with the occurrences of the sub-μm-sized craters, suggest formation by hypervelocity collisions of micrometeorites at down to nm scales, a process expected in the physically hostile environment at an asteroid's surface. We describe impact-related phenomena, ranging in scale from 10(-9) to 10(4) meters, demonstrating the central role played by impact processes in the long-term evolution of planetary bodies. Impact appears to be an important process shaping the exteriors of not only large planetary bodies, such as the moon, but also low-gravity bodies such as asteroids.

  15. Near Earth Asteroids- Prospection, Orbit Modification and Mining

    Science.gov (United States)

    Grandl, W.; Bazso, A.

    2014-04-01

    The number of known Near Earth Asteroids (NEAs) has increased continuously during the last decades. Now we understand the role of asteroid impacts for the evolution of life on Earth. To ensure that mankind will survive in the long run, we have to face the "asteroid threat" seriously. On one hand we will have to develop methods of detection and deflection for Hazardous Asteroids, on the other hand we can use these methods to modify their orbits and exploit their resources. Rare-earth elements, rare metals like platinum group elements, etc. may be extracted more easily from NEAs than from terrestrial soil, without environmental pollution or political and social problems. In a first step NEAs, which are expected to contain resources like nickel-iron, platinum group metals or rare-earth elements, will be prospected by robotic probes. Then a number of asteroids with a minimum bulk density of 2 g/cm^3 and a diameter of 150 to 500 m will be selected for mining. Given the long duration of an individual mission time of 10-20 years, the authors propose a "pipeline" concept. While the observation of NEAs can be done in parallel, the precursor missions of the the next phase can be launched in short intervals, giving time for technical corrections and upgrades. In this way a continuous data flow is established and there are no idle times. For our purpose Potentially Hazardous Asteroids (PHAs) seem to be a favorable choice for the following reasons: They have frequent closeencounters to Earth, their minimum orbit intersection distance is less than 0.05 AU (Astronomic Units) and they have diameters exceeding 150 meters. The necessary velocity change (delta V) for a spaceship is below 12 km/s to reach the PHA. The authors propose to modify the orbits of the chosen PHAs by orbital maneuvers from solar orbits to stable Earth orbits beyond the Moon. To change the orbits of these celestial bodies it is necessary to develop advanced propulsion systems. They must be able to deliver high

  16. Seven Near-Earth Asteroids at Asteroids Observers (OBAS) - MMPD: 2017 Jan-May

    Science.gov (United States)

    Fornas, Gonzalo; Carreño, Alfonso; Arce, Enrique; Flores, Angel; Mas, Vincente; Rodrigo, Onofre; Brines, Pedro; Fornas, Alvaro; Herrero, David; Lozano, Juan

    2018-01-01

    We report on the photometric analysis result of seven near-Earth asteroids (NEA) by Asteroides Observers (OBAS). This work is part of the Minor Planet Photometric Database effort that was initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

  17. International CJMT-1 Workshop on Asteroidal Science

    Science.gov (United States)

    Ip, Wing-Huen

    2014-03-01

    An international workshop on asteroidal science was held between October 16 and 17, 2012, at the Macau University of Science and Technology gathering together experts on asteroidal study in China, Japan, Macao and Taiwan. For this reason, we have called it CJMT-1 Workshop. Though small in sizes, the asteroids orbiting mainly between the orbit of Mars and of Jupiter have important influence on the evolution of the planetary bodies. Topics ranging from killer asteroids to space resources are frequently mentioned in news reports with prominence similar to the search for water on Mars. This also means that the study of asteroids is very useful in exciting the imagination and interest in science of the general public. Several Asian countries have therefore developed long-term programs integrating ground-based observations and space exploration with Japan being the most advanced and ambitious as demonstrated by the very successful Hayabusa mission to asteroid 25143 Itokawa. In this volume we will find descriptions of the mission planning of Hayabusa II to the C-type near-Earth asteroid, 1999 JU3. Not to be outdone, China's Chang-E 2 spacecraft was re-routed to a flyby encounter with asteroid 4179 Toutatis in December 2012. It is planned that in the next CJMT workshop, we will have the opportunity to learn more about the in-depth data analysis of the Toutatis observations and the progress reports on the Hayabusa II mission which launch date is set to be July 2014. Last but not least, the presentations on the ground-based facilities as described in this volume will pave the way for coordinated observations of asteroidal families and Trojan asteroids - across Asia from Taiwan to Uzbekistan. Such international projects will serve as an important symbol of good will and peaceful cooperation among the key members of this group. Finally, I want to thank the Space Science Institute, Macao University of Science and Technology, for generous support, and its staff members

  18. Testing the inversion of the Gaia asteroid photometry combined with groundbased observations

    Science.gov (United States)

    Santana-Ros, T.; Bartczak, P.; Michalowski, T.; Tanga, P.; Cellino, A.

    2014-07-01

    that have been obtained by means of several random variations during a ''genetic mutation''. This solution is more efficient in terms of CPU time and its capability to derive the "correct" inversion solution have been shown in some experiments with Gaia simulated observations and also with real data collected during the ESA Hipparcos mission (Cellino et al. 2009). On the other hand, adding existing groundbased observations for a given asteroid is not speeding up the performance of this method (in fact the inversion become slower with the increasing number of data points) and whether such observations can improve or not this method performance is a topic that needs to be studied. Now that all the parameters of the Gaia scanning law are fixed, we are able to predict exactly the observation sequence for solar-system objects. This means that we can plan to observe from the ground at the same time as Gaia. For example, we can very easily add a full rotational (dense) lightcurve around (or very close to) an isolated observation by Gaia. The link between the two data sets would then be very strong, as a single Gaia measurement provides a very precise absolute magnitude that can be used to calibrate the ground-based light curve. The question is: how many such lightcurves do we need (per object) to obtain a substantial improvement of the inversion? Maybe a single one? Or more? Therefore, our work is thought to address such questions and lay the foundations for a collaboration involving coordinated observations from the ground. Moreover, we focus on assessing the reliability of the solutions derived with the Gaia inversion method under all the possible coordinates for the rotation pole, different rotation periods and checking the impact of "realistic" asteroids using simulations with nonconvex shape models. Such work is necessary to correctly analyze the results that will be generated at the end of Gaia's mission, when photometric observations of asteroids will be available.

  19. Thermal management for LED applications

    CERN Document Server

    Poppe, András

    2014-01-01

    Thermal Management for LED Applications provides state-of-the-art information on recent developments in thermal management as it relates to LEDs and LED-based systems and their applications. Coverage begins with an overview of the basics of thermal management including thermal design for LEDs, thermal characterization and testing of LEDs, and issues related to failure mechanisms and reliability and performance in harsh environments. Advances and recent developments in thermal management round out the book with discussions on advances in TIMs (thermal interface materials) for LED applications, advances in forced convection cooling of LEDs, and advances in heat sinks for LED assemblies. This book also: Presents a comprehensive overview of the basics of thermal management as it relates to LEDs and LED-based systems Discusses both design and thermal management considerations when manufacturing LEDs and LED-based systems Covers reliability and performance of LEDs in harsh environments Has a hands-on applications a...

  20. Numerical analysis of space-weathering effects on light scattering by asteroid surfaces

    Science.gov (United States)

    Markkanen, J.; Martikainen, J.; Penttilä, A.; Muinonen, K.

    2017-09-01

    We have developed a novel radiative transfer (RT) / geometric optics (GO) numerical approach which allows us to model space-weathering effects on light scattering by planetary surfaces. Our analysis show that the space weathering has a major impact on light-scattering features of asteroids at the visible wavelengths.

  1. The January 7, 2015, superbolide over Romania and structural diversity of meter-sized asteroids

    Czech Academy of Sciences Publication Activity Database

    Borovička, Jiří; Spurný, Pavel; Grigore, V.I.; Svoreň, J.

    2017-01-01

    Roč. 143, SI (2017), s. 147-158 ISSN 0032-0633 R&D Projects: GA ČR(CZ) GA16-00761S Institutional support: RVO:67985815 Keywords : meteor * meteoroid * asteroid Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.892, year: 2016

  2. Water ice and organics on the surface of the asteroid 24 Themis.

    Science.gov (United States)

    Campins, Humberto; Hargrove, Kelsey; Pinilla-Alonso, Noemi; Howell, Ellen S; Kelley, Michael S; Licandro, Javier; Mothé-Diniz, T; Fernández, Y; Ziffer, Julie

    2010-04-29

    It has been suggested that Earth's current supply of water was delivered by asteroids, some time after the collision that produced the Moon (which would have vaporized any of the pre-existing water). So far, no measurements of water ice on asteroids have been made, but its presence has been inferred from the comet-like activity of several small asteroids, including two members of the Themis dynamical family. Here we report infrared spectra of the asteroid 24 Themis which show that ice and organic compounds are not only present on its surface but also prevalent. Infrared spectral differences between it and other asteroids make 24 Themis unique so far, and our identification of ice and organics agrees with independent results that rule out other compounds as possible sources of the observed spectral structure. The widespread presence of surface ice on 24 Themis is somewhat unexpected because of the relatively short lifetime of exposed ice at this distance ( approximately 3.2 au) from the Sun. Nevertheless, there are several plausible sources, such as a subsurface reservoir that brings water to the surface through 'impact gardening' and/or sublimation.

  3. Escape of asteroids from the main belt

    Science.gov (United States)

    Granvik, Mikael; Morbidelli, Alessandro; Vokrouhlický, David; Bottke, William F.; Nesvorný, David; Jedicke, Robert

    2017-02-01

    Aims: We locate escape routes from the main asteroid belt, particularly into the near-Earth-object (NEO) region, and estimate the relative fluxes for different escape routes as a function of object size under the influence of the Yarkovsky semimajor-axis drift. Methods: We integrated the orbits of 78 355 known and 14 094 cloned main-belt objects and Cybele and Hilda asteroids (hereafter collectively called MBOs) for 100 Myr and recorded the characteristics of the escaping objects. The selected sample of MBOs with perihelion distance q > 1.3 au and semimajor axis a random spin obliquities (either 0 deg or 180 deg) for each test asteroid. Results: We find more than ten obvious escape routes from the asteroid belt to the NEO region, and they typically coincide with low-order mean-motion resonances with Jupiter and secular resonances. The locations of the escape routes are independent of the semimajor-axis drift rate and thus are also independent of the asteroid diameter. The locations of the escape routes are likewise unaffected when we added a model for Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) cycles coupled with secular evolution of the rotation pole as a result of the solar gravitational torque. A Yarkovsky-only model predicts a flux of asteroids entering the NEO region that is too high compared to the observationally constrained flux, and the discrepancy grows larger for smaller asteroids. A combined Yarkovsky and YORP model predicts a flux of small NEOs that is approximately a factor of 5 too low compared to an observationally constrained estimate. This suggests that the characteristic timescale of the YORP cycle is longer than our canonical YORP model predicts.

  4. Mycetoma by Nocardia asteroides: a 9 year folow-up Micetoma por Nocardia asteroides: acompanhamento de 9 anos

    Directory of Open Access Journals (Sweden)

    Giani de Oliveira Saraça

    1993-04-01

    Full Text Available An extensive and severe actinomycetoma by Nocardia asteroides, a rare etiologic agent of this infection in Brazil, observed during a 9 year follow-up is reported. Unsuitable social and financial conditions led to amputation as the only possible solution for this case, no signs of infection relapse having been observed in three years after his surgery.É relatado um caso de micetoma actinomicótico por Nocardia asteroides, raro agente desta infecção no Brasil, acompanhado ao longo de 9 anos de evolução, com lesões extensas e profundas. As precárias condições sócio-econômicas do paciente tornaram a amputação a única solução viável para este caso, não tendo sido observados sinais de reci-diva da infecção em três anos após a cirurgia.

  5. The impact of pharmacist-led medication therapy management on medication adherence in patients with type 2 diabetes mellitus: a randomized controlled study.

    Science.gov (United States)

    Erku, Daniel A; Ayele, Asnakew A; Mekuria, Abebe B; Belachew, Sewunet A; Hailemeskel, Bisrat; Tegegn, Henok G

    2017-01-01

    Poor adherence to antidiabetic medications leads to a higher rate of hospital admissions and adverse health outcomes in type 2 diabetes mellitus patients. This study aims to evaluate whether a pharmacist-led medication therapy management, compared to the usual care, could enhance medication adherence and reduce hospital admission in patients with type 2 diabetes mellitus. A prospective randomized controlled study was conducted in patients with type 2 diabetes mellitus from February 1 to July 30, 2016. Patients in the control group (n=65) received the usual care while patients in the intervention group (n=62) received a personalized pharmacotherapeutic care plan and diabetes education. The two groups were compared by repeated measure ANOVA at 3 and 6-months with medication adherence (using Morisky medication adherence scale) and number of hospital admissions as the main outcome variables. A total of 127 patients were included in the study. A marked and statistically significant increase in medication adherence from baseline to 3 and 6 months were noted in the intervention group (increased from 9.2% at baseline to 61% at 6 month) compared with the control group (increased from 13.2% at baseline (to 30.2% at 6 month; p-value23 patients in MTM group with poorly controlled blood glucose levels resulted in hospital admissions compared to 48 patients in non-MTM group, resulting in a 52.1% fewer hospital admissions (pmedication therapy management might improve medication adherence and reduce number of hospitalizations in patients with type 2 diabetes mellitus. Hence, policies and guidelines should be in place in order for clinical pharmacists to fully engage in patient care and improve the medication therapy outcomes.

  6. Asteroid mass estimation using Markov-chain Monte Carlo

    Science.gov (United States)

    Siltala, Lauri; Granvik, Mikael

    2017-11-01

    Estimates for asteroid masses are based on their gravitational perturbations on the orbits of other objects such as Mars, spacecraft, or other asteroids and/or their satellites. In the case of asteroid-asteroid perturbations, this leads to an inverse problem in at least 13 dimensions where the aim is to derive the mass of the perturbing asteroid(s) and six orbital elements for both the perturbing asteroid(s) and the test asteroid(s) based on astrometric observations. We have developed and implemented three different mass estimation algorithms utilizing asteroid-asteroid perturbations: the very rough 'marching' approximation, in which the asteroids' orbital elements are not fitted, thereby reducing the problem to a one-dimensional estimation of the mass, an implementation of the Nelder-Mead simplex method, and most significantly, a Markov-chain Monte Carlo (MCMC) approach. We describe each of these algorithms with particular focus on the MCMC algorithm, and present example results using both synthetic and real data. Our results agree with the published mass estimates, but suggest that the published uncertainties may be misleading as a consequence of using linearized mass-estimation methods. Finally, we discuss remaining challenges with the algorithms as well as future plans.

  7. Standard Triaxial Ellipsoid Asteroids from AO Observations

    Science.gov (United States)

    Drummond, Jack D.; Merline, W. J.; Conrad, A.; Dumas, C.; Carry, B.

    2008-09-01

    As part of our study of resolved asteroids using adaptive optics (AO) on large telescopes (>8; m), we have identified several that can serve as Standard Triaxial Ellipsoid Asteroids (STEAs), suitable for radar and thermo-physical calibration. These objects are modeled well as triaxial ellipsoids, having: 1) small uncertainties on their three dimensions as determined with AO; 2) rotational poles well determined from both lightcurves and AO; and 3) good sidereal periods from lightcurves. Although AO allows the opportunity to find an asteroid's dimensions and rotational pole in one night, we have developed a method to combine AO observations from different oppositions to pool into a global solution. The apparent orientation and sizes of STEAs can be predicted to within a few degrees and a few km over decades. Currently, we consider 511 Davida, 52 Europa, 2 Pallas, and 15 Eunomia as STEAs. Asteroids that are not well modeled as ellipsoids, clearly showing departures from ellipsoid figures in AO images, include 129 Antigone and 41 Daphne. We will show movies of images and models of these asteroids.

  8. SDSS-BASED ASTEROID TAXONOMY V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains Sloan Digital Sky Survey (SDSS) asteroid photometric observations classified according to the SDSS-based Asteroid Taxonomy, as developed by...

  9. Human Robotic Systems (HRS): Robotic Technologies for Asteroid Missions Element

    Data.gov (United States)

    National Aeronautics and Space Administration — During 2014, the Robotic Technologies for Asteroid Missions activity has four tasks:Asteroid Retrieval Capture Mechanism Development and Testbed;Mission Operations...

  10. SMALL MAIN-BELT ASTEROID SPECTROSCOPIC SURVEY, PHASE II

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains visible-wavelength (0.435-0.925 micron) spectra for 1341 main-belt asteroids observed during the second phase of the Small Main-belt Asteroid...

  11. Asteroid 2008 TC3 Breakup and Meteorite Fractions

    Science.gov (United States)

    Goodrich, C.; Jenniskens, P.; Shaddad, M. H.; Zolensky, M. E.; Fioretti, A. M.

    2017-01-01

    The recovery of meteorites from the impact of asteroid 2008 TC3 in the Nubian Desert of Sudan on October 7, 2008, marked the first time meteorites were collected from an asteroid observed in space by astronomical techniques before impacting. Search teams from the University of Khartoum traced the location of the strewn field and collected about 660 meteorites in four expeditions to the fall region, all of which have known fall coordinates. Upon further study, the Almahata Sitta meteorites proved to be a mixed bag of mostly ureilites (course grained, fine grained, and sulfide-metal assemblages), enstatite chondrites (EL3-6, EH3, EH5, breccias) and ordinary chondrites (H5-6, L4-5). One bencubbinite-like carbonaceous chondrite was identified, as well as one unique Rumuruti-like chondrite and an Enstatite achondrite. New analysis: The analysed meteorites so far suggest a high 30-40 percent fraction of non-ureilites among the recovered samples, but that high fraction does not appear to be in agreement with the meteorites in the University of Khartoum (UoK) collection. Ureilites dominate the meteorites that were recovered by the Sudanese teams. To better understand the fraction of recovered materials that fell to Earth, a program has been initiated to type the meteorites in the UoK collection in defined search areas. At this meeting, we will present some preliminary results from that investigation.

  12. Incoming asteroid! what could we do about it?

    CERN Document Server

    Lunan, Duncan

    2014-01-01

    Lately there have been more and more news stories on objects from space – such as asteroids, comets, and meteors – whizzing past Earth. One even exploded in the atmosphere over a Russian city in 2012, causing real damage and injuries. Impacts are not uncommon in our Solar System, even on Earth, and people are beginning to realize that we must prepare for such an event here on Earth.   What if we knew there was going to be an impact in 10 years’ time? What could we do? It’s not so far in the future that we can ignore the threat, and not so soon that nothing could be done. The author and his colleagues set out to explore how they could turn aside a rock asteroid, one kilometer in diameter, within this 10-year timescale.   Having set themselves this challenge, they identified the steps that might be taken, using technologies that are currently under development or proposed. They considered an unmanned mission, a follow-up manned mission, and a range of final options, along with ways to reduce the worst...

  13. Constraints on Exposure Ages of Lunar and Asteroidal Regolith Particles

    Science.gov (United States)

    Berger, Eve L.; Keller, Lindsay P

    2014-01-01

    Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Exposure to the solar wind results in implantation effects that are preserved in the rims of grains (typically the outermost 100 nm), while impact processes result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. These processes are collectively referred to as space weathering. A critical element in the study of these processes is to determine the rate at which these effects accumulate in the grains during their space exposure. For small particulate samples, one can use the density of solar flare particle tracks to infer the length of time the particle was at the regolith surface (i.e., its exposure age). We have developed a new technique that enables more accurate determination of solar flare particle track densities in mineral grains <50 micron in size that utilizes focused ion beam (FIB) sample preparation combined with transmission electron microscopy (TEM) imaging. We have applied this technique to lunar soil grains from the Apollo 16 site (soil 64501) and most recently to samples from asteroid 25143 Itokawa returned by the Hayabusa mission. Our preliminary results show that the Hayabusa grains have shorter exposure ages compared to typical lunar soil grains. We will use these techniques to re-examine the track density-exposure age calibration from lunar samples reported by Blanford et al. (1975).

  14. Integrated science and engineering for the OSIRIS-REx asteroid sample return mission

    Science.gov (United States)

    Lauretta, D.

    2014-07-01

    Introduction: The Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) asteroid sample return mission will survey near-Earth asteroid (101955) Bennu to understand its physical, mineralogical, and chemical properties, assess its resource potential, refine the impact hazard, and return a sample of this body to the Earth [1]. This mission is scheduled for launch in 2016 and will rendezvous with the asteroid in 2018. Sample return to the Earth follows in 2023. The OSIRIS-REx mission has the challenge of visiting asteroid Bennu, characterizing it at global and local scales, then selecting the best site on the asteroid surface to acquire a sample for return to the Earth. Minimizing the risk of exploring an unknown world requires a tight integration of science and engineering to inform flight system and mission design. Defining the Asteroid Environment: We have performed an extensive astronomical campaign in support of OSIRIS-REx. Lightcurve and phase function observations were obtained with UA Observatories telescopes located in southeastern Arizona during the 2005--2006 and 2011--2012 apparitions [2]. We observed Bennu using the 12.6-cm radar at the Arecibo Observatory in 1999, 2005, and 2011 and the 3.5-cm radar at the Goldstone tracking station in 1999 and 2005 [3]. We conducted near-infrared measurements using the NASA Infrared Telescope Facility at the Mauna Kea Observatory in Hawaii in September 2005 [4]. Additional spectral observations were obtained in July 2011 and May 2012 with the Magellan 6.5-m telescope [5]. We used the Spitzer space telescope to observe Bennu in May 2007 [6]. The extensive knowledge gained as a result of our telescopic characterization of Bennu was critical in the selection of this object as the OSIRIS-REx mission target. In addition, we use these data, combined with models of the asteroid, to constrain over 100 different asteroid parameters covering orbital, bulk, rotational, radar

  15. Harvesting Near Earth Asteroid Resources Using Solar Sail Technology

    OpenAIRE

    McInnes, Colin

    2017-01-01

    Near Earth asteroids represent a wealth of material resources to support future space ventures. These resources include water from C-type asteroids for crew logistic support; liquid propellants electrolytically cracked from water to fuel crewed vehicles and commercial platforms; and metals from M-type asteroids to support in-situ manufacturing. In this paper the role of solar sail technology will be investigated to support the future harvesting of near Earth asteroid resources. This will incl...

  16. Use of Natural Light vs. Cold LED Lighting in Installations for the Recovery of Victims of Gender Violence: Impact on Energy Consumption and Victims’ Recovery

    Directory of Open Access Journals (Sweden)

    Raquel Amorim

    2017-04-01

    Full Text Available The efficiency of lighting installations is a major challenge concerning Governments, productive sectors and individuals. However, the importance of accurate lighting in some areas, especially those related to Health and Wellbeing is so critical that the constraints of energy efficiency and sustainability are not always a priority. This situation has become more critical with the current boom in the application of non-visual effects of light to these areas. In this study, the effects oftwo different kinds of lighting on femalevictims of gender violence are compared and analyzed in terms of positive results and impact on energy consumption and sustainability. The lighting technologies used are integrated in facilities where these women carry out different activities aimed at their integration into daily life after their traumatic experiences. The results are expected to become a tool for professionals working with these collectives and for installation designers. In spite of the well-known effects of cold light, especially for tasks involving arousal, sleepiness and other critical variables, it is demonstrated that daylight, which is obviously cheaper from productive and environmental perspectives, is better for this application.

  17. Asteroidal and cometary dust flux in the inner solar system

    Science.gov (United States)

    Borin, P.; Cremonese, G.; Marzari, F.; Lucchetti, A.

    2017-09-01

    Context. Meteoroids impacting terrestrial planets at high speed may have different effects. On bodies without atmospheres, such as the Moon and Mercury, they form impact craters and contribute to the gardening process through which the surface material is constantly mixed. The interaction of high-speed meteoroids with the atmosphere of Venus, the Earth, and Mars, may lead to the deposition in the ionosphere of species such as neutral Mg or Fe and their ionized atoms, caused by ablation processes during the entry. Aims: In this work we estimate and compare the flux and impact speeds onto the planets of the inner solar system by numerically integrating the orbital evolution of putative dust particles of asteroidal and cometary origin. Methods: The trajectories of dust particles of different sizes are computed with a numerical code that accounts for the gravitational forces due to all planets, the Poynting-Robertson drag and the solar wind drag. The flux of dust grains on each planet is estimated by calibrating the outcome of our model with the flux on the Earth reported previously. Results: We obtain new estimates of the flux and impact velocities for both asteroidal and cometary dust particles on Venus and Mars. For Venus we find that cometary grains enter the planet atmosphere at higher speeds, possibly contributing to the upper layers, while asteroidal grains would be relevant for the lower layers, possibly leading to a compositional gradient. This effect is also present for Mars, but it is less marked. We also find that analytical predictions, not taking radiative forces into account, of both flux and average impact speed are reliable for Mars but fail for Venus because of the complex dynamical evolution of grains in the inner solar system. Conclusions: Our results on the velocity distributions and fluxes of micrometeoroids on the terrestrial planets can be used to put stringent contraints on models that estimate either the superficial material mixing that is due

  18. Rock legends the asteroids and their discoverers

    CERN Document Server

    Murdin, Paul

    2016-01-01

    This book relates the history of asteroid discoveries and christenings, from those of the early pioneering giants of Hersehel and Piazzi to modern-day amateurs. Moving from history and anecdotal information to science, the book's structure is provided by the names of the asteroids, including one named after the author. Free from a need to conform to scientific naming conventions, the names evidence hero-worship, sycophancy, avarice, vanity, whimsy, erudition and wit, revealing the human side of astronomers, especially where controversy has followed the christening. Murdin draws from extensive historical records to explore the debate over these names. Each age reveals its own biases and preferences in the naming process. < Originally regarded as “vermin of the skies,” asteroids are minor planets, rocky scraps left over from the formation of the larger planets, or broken fragments of worlds that have collided. Their scientific classification as “minor” planets makes them seem unimportant, but over th...

  19. 78 FR 31977 - NASA Asteroid Initiative Call for Ideas

    Science.gov (United States)

    2013-05-28

    ... SPACE ADMINISTRATION NASA Asteroid Initiative Call for Ideas AGENCY: National Aeronautics and Space... announces a public forum to provide a status on the agency's asteroid initiative planning and to encourage...: This meeting will be streamed live online. Viewing options will be posted at www.nasa.gov/asteroid...

  20. Dormant Comets in the Near-Earth Asteroid Population

    NARCIS (Netherlands)

    Mommert, Michael; Harris, Alan W.; Mueller, Michael; Hora, Joseph L.; Trilling, David E.; Knight, Matthew; Bottke, William F.; Thomas, Cristina; Delbo', Marco; Emery, Josh P.; Fazio, Giovanni; Smith, Howard A.

    2015-01-01

    The population of near-Earth objects comprises active comets and asteroids, covering a wide range of dynamical parameters and physical properties. Dormant (or extinct) comets, masquerading as asteroids, have long been suspected of supplementing the near-Earth asteroid (NEA) population. We present a

  1. Determination of pole orientations and shapes of asteroids

    Science.gov (United States)

    Magnusson, Per; Barucci, M. Antonietta; Drummond, Jack D.; Lumme, Kari; Ostro, Steven J.

    1989-01-01

    The principles of asteroid light-curve inversion are discussed together with basic principles involved in approaches for deriving asteroid pole and shape parameters from photometry data. The merits of various pole determination techniques are described and compared. Results obtained so far on the pole orientations and shapes of asteroids are presented.

  2. Shape and spin determination of Barbarian asteroids

    Science.gov (United States)

    Devogèle, M.; Tanga, P.; Bendjoya, P.; Rivet, J. P.; Surdej, J.; Hanuš, J.; Abe, L.; Antonini, P.; Artola, R. A.; Audejean, M.; Behrend, R.; Berski, F.; Bosch, J. G.; Bronikowska, M.; Carbognani, A.; Char, F.; Kim, M.-J.; Choi, Y.-J.; Colazo, C. A.; Coloma, J.; Coward, D.; Durkee, R.; Erece, O.; Forne, E.; Hickson, P.; Hirsch, R.; Horbowicz, J.; Kamiński, K.; Kankiewicz, P.; Kaplan, M.; Kwiatkowski, T.; Konstanciak, I.; Kruszewki, A.; Kudak, V.; Manzini, F.; Moon, H.-K.; Marciniak, A.; Murawiecka, M.; Nadolny, J.; Ogłoza, W.; Ortiz, J. L.; Oszkiewicz, D.; Pallares, H.; Peixinho, N.; Poncy, R.; Reyes, F.; de los Reyes, J. A.; Santana-Ros, T.; Sobkowiak, K.; Pastor, S.; Pilcher, F.; Quiñones, M. C.; Trela, P.; Vernet, D.

    2017-11-01

    Context. The so-called Barbarian asteroids share peculiar, but common polarimetric properties, probably related to both their shape and composition. They are named after (234) Barbara, the first on which such properties were identified. As has been suggested, large scale topographic features could play a role in the polarimetric response, if the shapes of Barbarians are particularly irregular and present a variety of scattering/incidence angles. This idea is supported by the shape of (234) Barbara, that appears to be deeply excavated by wide concave areas revealed by photometry and stellar occultations. Aims: With these motivations, we started an observation campaign to characterise the shape and rotation properties of Small Main-Belt Asteroid Spectroscopic Survey (SMASS) type L and Ld asteroids. As many of them show long rotation periods, we activated a worldwide network of observers to obtain a dense temporal coverage. Methods: We used light-curve inversion technique in order to determine the sidereal rotation periods of 15 asteroids and the convergence to a stable shape and pole coordinates for 8 of them. By using available data from occultations, we are able to scale some shapes to an absolute size. We also study the rotation periods of our sample looking for confirmation of the suspected abundance of asteroids with long rotation periods. Results: Our results show that the shape models of our sample do not seem to have peculiar properties with respect to asteroids with similar size, while an excess of slow rotators is most probably confirmed. The light curves are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/607/A119

  3. NEOCAM: Near Earth Object Chemical Analysis Mission: Bridging the Gulf between Telescopic Observations and the Chemical and Mineralogical Compositions of Asteroids or Diogenes A: Diagnostic Observation of the Geology of Near Earth Spectrally-Classified Asteroids

    Science.gov (United States)

    Nuth, Joseph A.

    2009-01-01

    Studies of meteorites have yielded a wealth of scientific information based on highly detailed chemical and isotopic studies possible only in sophisticated terrestrial laboratories. Telescopic studies have revealed an enormous (greater than 10(exp 5)) number of physical objects ranging in size from a few tens of meters to several hundred kilometers, orbiting not only in the traditional asteroid belt between Mars and Jupiter but also throughout the inner solar system. Many of the largest asteroids are classed into taxonomic groups based on their observed spectral properties and are designated as C, D. X, S or V types (as well as a wide range in sub-types). These objects are certainly the sources far the meteorites in our laboratories, but which asteroids are the sources for which meteorites? Spectral classes are nominally correlated to the chemical composition and physical characteristics of the asteroid itself based on studies of the spectral changes induced in meteorites due to exposure to a simulated space environment. While laboratory studies have produced some notable successes (e.g. the identification of the asteroid Vesta as the source of the H, E and D meteorite classes), it is unlikely that we have samples of each asteroidal spectral type in our meteorite collection. The correlation of spectral type and composition for many objects will therefore remain uncertain until we can return samples of specific asteroid types to Earth for analyses. The best candidates for sample return are asteroids that already come close to the Earth. Asteroids in orbit near 1 A.U. have been classified into three groups (Aten, Apollo & Amor) based on their orbital characteristics. These Near Earth Objects (NEOs) contain representatives of virtually all spectral types and sub-types of the asteroid population identified to date. Because of their close proximity to Earth, NEOs are prime targets for asteroid missions such as the NEAR-Shoemaker NASA Discovery Mission to Eros and the

  4. Gravitational Capture of Asteroids by Gas Drag

    Directory of Open Access Journals (Sweden)

    E. Vieira Neto

    2009-01-01

    captured by the planet got its velocity reduced and could been trapped as an irregular satellite. It is well known that, depending on the time scale of the gas envelope, an asteroid will spiral and collide with the planet. So, we simulate the passage of the asteroid in the gas envelope with its density decreasing along the time. Using this approach, we found effective captures, and have a better understanding of the whole process. Finally, we conclude that the origin of the irregular satellites cannot be attributed to the gas drag capture mechanism alone.

  5. Manuel′s asteroid disruption technique

    Directory of Open Access Journals (Sweden)

    Manuel John

    2015-01-01

    Full Text Available A seventy-year-old male presented with dense asteroid hyalosis in both eyes. He had undergone cataract extraction in one eye 3 years ago, and the other eye had immature cataract. Both the autorefractor and dilated streak retinoscopy did not give readings and subjective visual improvement could not be achieved. Immediately following YAG posterior capsulotomy and anterior vitreous asteroid disruption, the vision improved to 20/20 with recordable auto refractor and streak retinoscopy values. Our initial experience indicates that the treatment is simple, safe and effective but needs controlled and prospective studies to confirm its long-term safety.

  6. Asteroidal Quadruples in non Rooted Path Graphs

    Directory of Open Access Journals (Sweden)

    Gutierrez Marisa

    2015-11-01

    Full Text Available A directed path graph is the intersection graph of a family of directed subpaths of a directed tree. A rooted path graph is the intersection graph of a family of directed subpaths of a rooted tree. Rooted path graphs are directed path graphs. Several characterizations are known for directed path graphs: one by forbidden induced subgraphs and one by forbidden asteroids. It is an open problem to find such characterizations for rooted path graphs. For this purpose, we are studying in this paper directed path graphs that are non rooted path graphs. We prove that such graphs always contain an asteroidal quadruple.

  7. A Fragment-Cloud Model for Breakup of Asteroids with Varied Internal Structures

    Science.gov (United States)

    Wheeler, Lorien; Mathias, Donovan; Stokan, Ed; Brown, Peter

    2016-01-01

    As an asteroid descends toward Earth, it deposits energy in the atmosphere through aerodynamic drag and ablation. Asteroid impact risk assessments rely on energy deposition estimates to predict blast overpressures and ground damage that may result from an airburst, such as the one that occurred over Chelyabinsk, Russia in 2013. The rates and altitudes at which energy is deposited along the entry trajectory depend upon how the bolide fragments, which in turn depends upon its internal structure and composition. In this work, we have developed an analytic asteroid fragmentation model to assess the atmospheric energy deposition of asteroids with a range of structures and compositions. The modeling approach combines successive fragmentation of larger independent pieces with aggregate debris clouds released with each fragmentation event. The model can vary the number and masses of fragments produced, the amount of mass released as debris clouds, the size-strength scaling used to increase the robustness of smaller fragments, and other parameters. The initial asteroid body can be seeded with a distribution of independent fragment sizes amid a remaining debris mass to represent loose rubble pile conglomerations, can be given an outer regolith later, or can be defined as a coherent or fractured monolith. This approach enables the model to represent a range of breakup behaviors and reproduce detailed energy deposition features such as multiple flares due to successive burst events, high-altitude regolith blow-off, or initial disruption of rubble piles followed by more energetic breakup of the constituent boulders. These capabilities provide a means to investigate sensitivities of ground damage to potential variations in asteroid structure.

  8. Detection of Yarkovsky effect and solar radiation pressure on Near-Earth Asteroids

    Science.gov (United States)

    Faggioli, Laura; Del Vigna, Alessio; Milani, Andrea; Spoto, Federica; Valsecchi, Giovanni B.

    2016-10-01

    The orbit of small-sized asteroids can be affected by non-gravitational perturbations. When this happens, non-gravitational forces need to be taken into account since they are as important as collisions and gravitational perturbations for the overall understanding of the asteroid orbital evolution.The Yarkovsky effect and the Solar Radiation Pressure (SRP) are non-gravitational perturbations that can be modelled knowing the physical properties of asteroids, and whose consequences of the motions can be measured from accurate astrometry.The knowledge of the physical properties of asteroids is usually not sufficient to produce the thermophysical models needed for the computation of the Yarkovsky acceleration. Nevertheless, it can often be measured as a semimajor axis drift if the astrometric dataset contains extremely accurate observations (e.g. radar data), or if the observations span a sufficiently long time interval.Farnocchia et al. 2013 list 21 NEAs with a measurable semimajor-axis drift. Since 2013, the number of asteroids for which it is possible to detect the Yarkovsky effect has grown. This is due to the increased quality and time span of the observations, and to new radar measurements that have since become available. We are able to detect the Yarkovsky effect for more than 40 NEAs, employing a high precision dynamical model, including the Newtonian attraction of 16 massive asteroids and the planetary relativistic terms, and a suitable astrometric data treatment. We present a list of objects with a significant detection of Yarkovksy effect and a value compatible with the Yarkovsky mechanism.The computed non-gravitational perturbations will be added to the web portal of the ESA SSA-NEO Coordination Centre, highlighting the fact that the orbit has been computed taking the Yarkovsky effect or the SRP into account. The inclusion of non-gravitational perturbations can also affect the results of the impact monitoring, as in the case of (410777) 2009 FD, (29075

  9. Contextual Student Learning through Authentic Asteroid Research Projects using a Robotic Telescope Network

    Science.gov (United States)

    Hoette, Vivian L.; Puckett, Andrew W.; Linder, Tyler R.; Heatherly, Sue Ann; Rector, Travis A.; Haislip, Joshua B.; Meredith, Kate; Caughey, Austin L.; Brown, Johnny E.; McCarty, Cameron B.; Whitmore, Kevin T.

    2015-11-01

    Skynet is a worldwide robotic telescope network operated by the University of North Carolina at Chapel Hill with active observing sites on 3 continents. The queue-based observation request system is simple enough to be used by middle school students, but powerful enough to supply data for research scientists. The Skynet Junior Scholars program, funded by the NSF, has teamed up with professional astronomers to engage students from middle school to undergraduates in authentic research projects, from target selection through image analysis and publication of results. Asteroid research is a particularly fruitful area for youth collaboration that reinforces STEM education standards and can allow students to make real contributions to scientific knowledge, e.g., orbit refinement through astrometric submissions to the Minor Planet Center. We have created a set of projects for youth to: 1. Image an asteroid, make a movie, and post it to a gallery; 2. Measure the asteroid’s apparent motion using the Afterglow online image processor; and 3. Image asteroids from two or more telescopes simultaneously to demonstrate parallax. The apparent motion and parallax projects allow students to estimate the distance to their asteroid, as if they were the discoverer of a brand new object in the solar system. Older students may take on advanced projects, such as analyzing uncertainties in asteroid orbital parameters; studying impact probabilities of known objects; observing time-sensitive targets such as Near Earth Asteroids; and even discovering brand new objects in the solar system.Images are acquired from among seven Skynet telescopes in North Carolina, California, Wisconsin, Canada, Australia, and Chile, as well as collaborating observatories such as WestRock in Columbus, Georgia; Stone Edge in El Verano, California; and Astronomical Research Institute in Westfield, Illinois.

  10. NASA's Asteroid Redirect Mission: Overview and Status

    Science.gov (United States)

    Abell, Paul; Gates, Michele; Johnson, Lindley; Chodas, Paul; Brophy, John; Mazanek, Dan; Muirhead, Brian

    A major element of the National Aeronautics and Space Administration’s (NASA) new Asteroid Initiative is the Asteroid Redirect Mission (ARM). This concept was first proposed in 2011 during a feasibility study at the Keck Institute for Space Studies (KISS)[1] and is under consideration for implementation by NASA. The ARM involves sending a high-efficiency (ISP 3000 s), high-power (40 kW) solar electric propulsion (SEP) robotic vehicle that leverages technology developed by NASA’s Space Technology Mission Directorate (STMD) to rendezvous with a near-Earth asteroid (NEA) and return asteroidal material to a stable lunar distant retrograde orbit (LDRO)[2]. There are two mission concepts currently under study, one that captures an entire 7 - 10 meter mean diameter NEA[3], and another that retrieves a 1 - 10 meter mean diameter boulder from a 100+ meter class NEA[4]. Once the retrieved asteroidal material is placed into the LDRO, a two person crew would launch aboard an Orion capsule to rendezvous and dock with the robotic SEP vehicle. After docking, the crew would conduct two extra-vehicular activities (EVA) to collect asteroid samples and deploy instruments prior to Earth return. The crewed portion of the mission is expected to last approximately 25 days and would represent the first human exploration mission beyond low-Earth orbit (LEO) since the Apollo program. The ARM concept leverages NASA’s activities in Human Exploration, Space Technology, and Planetary Defense to accomplish three primary objectives and several secondary objectives. The primary objective relevant to Human Exploration is to gain operational experience with vehicles, systems, and components that will be utilized for future deep space exploration. In regard to Space Technology, the ARM utilizes advanced SEP technology that has high power and long duration capabilities that enable future missions to deep space destinations, such as the Martian system. With respect to Planetary Defense, the ARM

  11. RAGE Hydrocode Modeling of Asteroid Mitigation: new simulations with parametric studies for uncertainty quantification

    Science.gov (United States)

    Weaver, R.; Plesko, C. S.; Gisler, G. R.

    2013-12-01

    obtain an "optimal stand-off" distance from detailed radiation transport-hydrodynamic simulations from generic explosion properties. The initial results of these two studies will also be presented. References [1] Gitting, Weaver et al 'The RAGE radiation-hydrodynamics Code,' Comp. Sci. Disc. 1 (2008) 015005 November 21, 2008 [2] Huebner, W.F. et al, 'The Engagement Space for Countermeasures Against Potentially Hazardous Objects (PHOs),' International Conference in Asteroid and Comet Hazards, 2009 held at the Russian Academy of Sciences, St. Petersburg 21-25-September 2009. [3] Gisler, Weaver, Mader, & Gittings, Two and three dimensional asteroid impact simulations, Computing in Science & Engineering, 6, 38 (2004). [4] NASA geometry courtesy of S.J. Osto et al. (2002) in Asteroids Book 3 [5] Itokawa image courtesy of JAXA: http://www.isas.jaxa.jp/e/snews/2005/1102.shtml#pic001 [6] Plesko, C et al "Looking Before we Leap: Recent Results from an Ongoing, Quantitative Investigation of Asteroid and Comet Impact Hazard Mitigation" Division of Planetary Sciences 2010. [7] Plesko, C et. al. "Numerical Models of Asteroid and Comet Impact Hazard Mitigation by Nuclear Stand-Off Burst." Planetary Defense Conference 2011.

  12. Sensitivity of the Asteroid Redirect Robotic Mission (ARRM) to Launch Date and Asteroid Stay Time

    Science.gov (United States)

    Mcguire, Melissa L.; Burke, Laura M.; McCarty, Steven L.; Strange, Nathan J.; Qu, Min; Shen, Haijun; Vavrina, Matthew A.

    2017-01-01

    National Aeronautics and Space Administrations (NASAs) proposed Asteroid Redirect Mission (ARM) is being designed to robotically capture and then redirect an asteroidal boulder mass into a stable orbit in the vicinity of the moon, where astronauts would be able to visit and study it. The current reference trajectory for the robotic portion, ARRM, assumes a launch on a Delta IV H in the end of the calendar year 2021, with a return for astronaut operations in cislunar space in 2026. The current baseline design allocates 245 days of stay time at the asteroid for operations and boulder collection. This paper outlines analysis completed by the ARRM mission design team to understand the sensitivity of the reference trajectory to launch date and asteroid stay time.

  13. DETECTION OF ROTATIONAL SPECTRAL VARIATION ON THE M-TYPE ASTEROID (16) PSYCHE

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Juan A.; Thomas, Cristina [Planetary Science Institute, Tucson, AZ 85719 (United States); Reddy, Vishnu [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Shepard, Michael K. [Bloomsburg University, Bloomsburg, PA 17815 (United States); Cloutis, Edward A.; Kiddell, Cain; Applin, Daniel [Department of Geography, University of Winnipeg, Winnipeg, Manitoba (Canada); Takir, Driss [Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001 (United States); Conrad, Albert, E-mail: jsanchez@psi.edu [LBT Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2017-01-01

    The asteroid (16) Psyche is of scientific interest because it contains ∼1% of the total mass of the asteroid belt and is thought to be the remnant metallic core of a protoplanet. Radar observations have indicated the significant presence of metal on the surface with a small percentage of silicates. Prior ground-based observations showed rotational variations in the near-infrared (NIR) spectra and radar albedo of this asteroid. However, no comprehensive study that combines multi-wavelength data has been conducted so far. Here we present rotationally resolved NIR spectra (0.7–2.5 μ m) of (16) Psyche obtained with the NASA Infrared Telescope Facility. These data have been combined with shape models of the asteroid for each rotation phase. Spectral band parameters extracted from the NIR spectra show that the pyroxene band center varies from ∼0.92 to 0.94 μ m. Band center values were used to calculate the pyroxene chemistry of the asteroid, whose average value was found to be Fs{sub 30}En{sub 65}Wo{sub 5}. Variations in the band depth (BD) were also observed, with values ranging from 1.0% to 1.5%. Using a new laboratory spectral calibration method, we estimated an average orthopyroxene content of 6% ± 1%. The mass-deficit region of Psyche, which exhibits the highest radar albedo, also shows the highest value for the spectral slope and the minimum BD. The spectral characteristics of Psyche suggest that its parent body did not have the typical structure expected for a differentiated body or that the sequence of events that led to its current state was more complex than previously thought.

  14. Development of a Landing Mechanism for Asteroids with Soft Surface

    Directory of Open Access Journals (Sweden)

    Zhijun Zhao

    2013-01-01

    Full Text Available A landing mechanism to an asteroid with soft surface is developed. It consists of three landing feet, landing legs, cardan element, damping element, equipment base, anchoring system, and so on. Static structural analysis and modal analysis are carried out to check the strength and natural frequency of the landing mechanism with FEA. Testing platform for the anchoring system is introduced, and then the penetrating and anchoring tests of the anchoring system are carried out in different media. It shows that cohesion of the media has large influence on the penetrating and anchoring performance of the anchoring system. Landing tests of the landing mechanism with different velocities under simulated microgravity environment are carried out on the air-floating platform, and the impact accelerations are measured by the sensors on the landing mechanism. At the same time, these impact accelerations are processed by spectrum analysis to find the natural frequency of the landing mechanism.

  15. Twenty-one Asteroid Lightcurves at Asteroids Observers (OBAS) - MPPD: Nov 2016 - May 2017

    Science.gov (United States)

    Mas, Vicente; Fornas, G.; Lozano, Juan; Rodrigo, Onofre; Fornas, A.; Carreño, A.; Arce, Enrique; Brines, Pedro; Herrero, David

    2018-01-01

    We report on the analysis of photometric observations of 21 main-belt asteroids (MBA) done by Asteroids Observers (OBAS). This work is part of the Minor Planet Photometric Database task that was initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

  16. MarcoPolo-R near earth asteroid sample return mission

    Science.gov (United States)

    Barucci, Maria Antonietta; Cheng, A. F.; Michel, P.; Benner, L. A. M.; Binzel, R. P.; Bland, P. A.; Böhnhardt, H.; Brucato, J. R.; Campo Bagatin, A.; Cerroni, P.; Dotto, E.; Fitzsimmons, A.; Franchi, I. A.; Green, S. F.; Lara, L.-M.; Licandro, J.; Marty, B.; Muinonen, K.; Nathues, A.; Oberst, J.; Rivkin, A. S.; Robert, F.; Saladino, R.; Trigo-Rodriguez, J. M.; Ulamec, S.; Zolensky, M.

    2012-04-01

    MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) proposed in collaboration with NASA. It will rendezvous with a primitive NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. MarcoPolo-R will return bulk samples (up to 2 kg) from an organic-rich binary asteroid to Earth for laboratory analyses, allowing us to: explore the origin of planetary materials and initial stages of habitable planet formation; identify and characterize the organics and volatiles in a primitive asteroid; understand the unique geomorphology, dynamics and evolution of a binary NEA. This project is based on the previous Marco Polo mission study, which was selected for the Assessment Phase of the first round of Cosmic Vision. Its scientific rationale was highly ranked by ESA committees and it was not selected only because the estimated cost was higher than the allotted amount for an M class mission. The cost of MarcoPolo-R will be reduced to within the ESA medium mission budget by collaboration with APL (John Hopkins University) and JPL in the NASA program for coordination with ESA's Cosmic Vision Call. The baseline target is a binary asteroid (175706) 1996 FG3, which offers a very efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of this target will allow new investigations to be performed more easily than at a single object, and also enables investigations of the fascinating geology and geophysics of asteroids that are impossible at a single object. Several launch windows have been identified in the time-span 2020-2024. A number of other possible primitive single targets of high scientific interest have been identified covering a wide range of possible launch dates. The baseline mission scenario of MarcoPolo-R to 1996 FG3 is as follows: a single primary spacecraft provided by ESA, carrying

  17. MarcoPolo-R: Asteroid Sample Return Mission

    Science.gov (United States)

    Brucato, John Robert

    2012-07-01

    MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) selected for the assessment study in the framework of ESA Cosmic Vision 2015-25 program. MarcoPolo-R is an European-led mission with a proposed NASA contribution. MarcoPolo-R will rendezvous with a primitive carbon-rich NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. The baseline target is a binary asteroid (175706) 1996 FG3, which offers a very efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of this target will allow new investigations to be performed more easily than at a single object, and also enables investigations of the fascinating geology and geophysics of asteroids that are impossible at a single object. Several launch windows have been identified in the time-span 2020-2024. The baseline mission scenario of MarcoPolo-R to 1996 FG3 foresees a single primary spacecraft, carrying the Earth re-entry capsule and sample acquisition and transfer system, launched by a Soyuz-Fregat rocket from Kourou. The scientific payload includes state-of-the-art instruments, e.g. a camera system for high resolution imaging from orbit and on the surface, spectrometers covering visible, near-infrared and mid-infrared wavelengths, a neutral-particle analyser, a radio science experiment and optional laser altimeter. If resources are available, an optional Lander will be added to perform in-situ characterization close to the sampling site, and internal structure investigations. MarcoPolo-R will allow us to study the most primitive materials available to investigate early solar system formation processes. The main goal of the MarcoPolo-R mission is to return unaltered NEA material for detailed analysis in ground-based laboratories. Only in the laboratory can instruments with the necessary precision and sensitivity be

  18. Detection of ice and organics on an asteroidal surface.

    Science.gov (United States)

    Rivkin, Andrew S; Emery, Joshua P

    2010-04-29

    Recent observations, including the discovery in typical asteroidal orbits of objects with cometary characteristics (main-belt comets, or MBCs), have blurred the line between comets and asteroids, although so far neither ice nor organic material has been detected on the surface of an asteroid or directly proven to be an asteroidal constituent. Here we report the spectroscopic detection of water ice and organic material on the asteroid 24 Themis, a detection that has been independently confirmed. 24 Themis belongs to the same dynamical family as three of the five known MBCs, and the presence of ice on 24 Themis is strong evidence that it also is present in the MBCs. We conclude that water ice is more common on asteroids than was previously thought and may be widespread in asteroidal interiors at much smaller heliocentric distances than was previously expected.

  19. Asteroid modeling for testing spacecraft approach and landing.

    Science.gov (United States)

    Martin, Iain; Parkes, Steve; Dunstan, Martin; Rowell, Nick

    2014-01-01

    Spacecraft exploration of asteroids presents autonomous-navigation challenges that can be aided by virtual models to test and develop guidance and hazard-avoidance systems. Researchers have extended and applied graphics techniques to create high-resolution asteroid models to simulate cameras and other spacecraft sensors approaching and descending toward asteroids. A scalable model structure with evenly spaced vertices simplifies terrain modeling, avoids distortion at the poles, and enables triangle-strip definition for efficient rendering. To create the base asteroid models, this approach uses two-phase Poisson faulting and Perlin noise. It creates realistic asteroid surfaces by adding both crater models adapted from lunar terrain simulation and multiresolution boulders. The researchers evaluated the virtual asteroids by comparing them with real asteroid images, examining the slope distributions, and applying a surface-relative feature-tracking algorithm to the models.

  20. Formation of the wide asynchronous binary asteroid population

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Seth A. [Department of Astrophysical and Planetary Science, UCB 391, University of Colorado, Boulder, CO 80309 (United States); Scheeres, Daniel J.; McMahon, Jay [Department of Aerospace Engineering Sciences, UCB 429, University of Colorado, Boulder, CO 80309 (United States)

    2014-01-01

    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semimajor axes relative to most near-Earth and main belt asteroid systems. Confirmed members have rapidly rotating primaries and satellites that are not tidally locked. Previously suggested formation mechanisms from impact ejecta, from planetary flybys, and directly from rotational fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (1) these systems are formed from rotational fission, (2) their satellites are tidally locked, (3) their orbits are expanded by the binary Yarkovsky-O'Keefe-Radzievskii-Paddack (BYORP) effect, (4) their satellites desynchronize as a result of the adiabatic invariance between the libration of the secondary and the mutual orbit, and (5) the secondary avoids resynchronization because of the YORP effect. This seemingly complex chain of events is a natural pathway for binaries with satellites that have particular shapes, which define the BYORP effect torque that acts on the system. After detailing the theory, we analyze each of the wide asynchronous binary members and candidates to assess their most likely formation mechanism. Finally, we suggest possible future observations to check and constrain our hypothesis.

  1. Split Active Asteroid P/2016 J1 (PANSTARRS)

    Science.gov (United States)

    Hui, Man-To; Jewitt, David; Du, Xinnan

    2017-10-01

    We present a photometric and astrometric study of the split active asteroid P/2016 J1 (PANSTARRS). Separation occurred either in 2012 May to June, or 2010 April, with a separation speed Vsep = 0.70 ± 0.02 m s-1 for the former scenario and 0.83 ± 0.06 m s-1 for the latter. The two fragments (hereafter J1-A and J1-B) have similar, Sun-like colors that are comparable to the colors of primitive C- and G-type asteroids. With a nominal comet-like albedo, pR = 0.04, the effective, dust-contaminated cross sections are estimated to be 2.4 km2 (J1-A) and 0.5 km2 (J1-B). We estimate that the nucleus radii lie in the range 140 impact, and that sublimation torques then rapidly drove the body to breakup. Further disintegration events are anticipated owing to the rotational instability. Reference: Hui, M.-T., Jewitt, D. and Du, X., 2017. AJ, 153(4), p.141.

  2. 133P/Elst-Pizarro: A Comet Amongst the Asteroids

    Science.gov (United States)

    Hsieh, H. H.; Jewitt, D. C.; Fernandez, Y. R.

    2003-05-01

    We present a new investigation of the comet-asteroid transition object 133P/(7968) Elst-Pizarro. As in 1996, when this object's comet-like activity first came to notice, observations in 2002 show a long, narrow dust trail in the projected orbit of the object. Observations over several months reveal changes in the structure and brightness of this trail, showing that it is actively generated over long periods of time. Finson-Probstein modeling is used to constrain the parameters of the dust trail. We find low ejection velocities (=0.69) and rapid rotation (P=3.471+/- 0.001 hrs). This rapid rotation may be a significant factor in mass loss from the body. The 1996 trail has been previously explained as debris released by a chance impact, but our recent trail detection casts doubt upon this interpretation. Instead, our data suggest that Elst-Pizarro is a barely active comet that has somehow evolved into an asteroid-like orbit. A paper describing this work has been submitted for publication in The Astronomical Journal.

  3. Galahad: medium class asteroid sample return mission

    Science.gov (United States)

    Cheng, Andrew; Rivkin, Andrew; Adler, Mark

    The Galahad asteroid sample return mission proposal to the NASA New Frontiers solicitation met all of the objectives for the Asteroid Rover/Sample Return mission as defined in that announcement. Galahad is in many ways similar to the Marco Polo and the OSIRIS-Rex proposals. All three missions plan bulk sample returns from primitive, C or B class Near Earth asteroids. Galahad in particular will rendezvous with and orbit the binary C-asteroid 1996 FG3, making extensive orbital measurements. It will then land and collect over 60 g of well-documented samples with geologic context for return to Earth. The samples are expected to provide abundant materials from the early solar system, including chondrules and CAIs, as well as a primitive assemblage of organics, presolar grains and probably hydrated minerals. Analyses of these samples will yield new understanding of the early solar system, planetary accretion, and the nature and origins of prebiotic organic material. We will discuss scientific and technical approaches to characterization of, landing on, and sample collection from small primitive bodies.

  4. Asteroid thermal modeling: recent developments and applications

    NARCIS (Netherlands)

    Harris, A. W.; Mueller, M.

    2006-01-01

    A variety of thermal models are used for the derivation of asteroid physical parameters from thermal-infrared observations Simple models based on spherical geometry are often adequate for obtaining sizes and albedos when very little information about an object is available However sophisticated

  5. Spectral analyses of asteroids' linear features

    Science.gov (United States)

    Longobardo, A.; Palomba, E.; Scully, J. E. C.; De Sanctis, M. C.; Capaccioni, F.; Tosi, F.; Zinzi, A.; Galiano, A.; Ammannito, E.; Filacchione, G.; Ciarniello, M.; Raponi, A.; Zambon, F.; Capria, M. T.; Erard, S.; Bockelee-Morvan, D.; Leyrat, C.; Dirri, F.; Nardi, L.; Raymond, C. A.

    2017-09-01

    Linear features are commonly found on small bodies and can have a geomorphic or tectonic origin. Generally, these features are studied by means of morphological analyses. Here we propose a spectroscopic analyses of linear features of different asteroids visited by space missions, in order to search for correspondence between spectral properties and origin of linear features.

  6. Rotation Properties of Small Jovian Trojan Asteroids

    Science.gov (United States)

    French, Linda M.; Stephens, Robert D.; James, David; Coley, Daniel R.; Warner, Brian D.; Rohl, Derrick

    2016-10-01

    Jovian Trojan asteroids are of interest both as objects in their own right (we have no spectral analogs among meteorite samples) and as possible relics of Solar System formation. Asteroid lightcurves can give information about processes that have affected a group of asteroids; they can also give information about the density of the objects when enough lightcurves have been collected. We have been carrying out a survey of Trojan lightcurve properties for comparison with small asteroids and with comets. In a recent paper (French et al. 2015) we presented evidence that a significant number of Trojans have rotation periods greater than 24 hours. We will report our latest results and compare them with results of sparsely-sampled lightcurves from the Palomar Transient Factory (Waszczak et al. 2015). LF, RS, and DR were visiting astronomers at Cerro Tololo Interamerican Observatory, operated by AURA under contract with the NSF, and with the SMARTS Consortium at CTIO. This research was sponsored by NSF Planetary Astronomy grant 1212115.ReferencesFrench, L.M. et al. 2015. Icarus 254, pp. 1-17.Waszczak, A. et al. 2015. A.J. 150, Issue 3, I.D. 35.

  7. Space Weathering in Olivine and the Mineralogy of (Some) M-Class Asteroids

    Science.gov (United States)

    Britt, Daniel; Kohout, Tomas; Schelling, Patrick; Consolmagno, Guy J.

    2014-11-01

    One aspect of space weathering of airless bodies is the production of nanophase iron (npFe0) from Fe bearing silicate minerals. The combined effects of low oxygen fugacity and solar-wind implanted H tend to result in strongly-reduced surfaces that can be chemically activated by heating due to micrometeorite impacts. The mineral kinetics of olivine makes it particularly vulnerable to reduction, decomposition, and npFe0 production. Kohout et al. has recently developed a new method of controlled npFe0 production on olivine powder grains that mimics the essential features of this weathering process and was developed to quantitatively evaluate spectral changes related to space weathering and presence of npFe0. Compared to fresh olivine the treated samples exhibit spectral characteristics of space weathering including spectral darkening, shallowing and attenuation of 1 µm olivine absorption band, and reddening. The attenuation of the 1 µm band significantly shrinks the band FWHM and shifts the much reduced band center to shorter wavelengths around 0.95 µm. These spectral changes are related to increasing amounts of npFe0 and the disruption of the crystal structure of the parent olivine. Significantly, the darkened, reddened, and band attenuated olivine spectra are a close match to a number of M-class asteroids. What is particularly interesting is the match with the weak absorption band near 0.95 µm seen in many M-class asteroids (i.e. 16 Psyche, 22 Kalliope, 55 Pandora to name a few). One of the major issues in asteroid science is the relative scarcity of olivine asteroids (the ”Great Dunite Shortage” coined by Bell et al in Asteroids II). One possibility worth further study is that asteroidal olivine may be hidden by the relative ease with which it weathers. The surface chemical and micrometeorite environment in the asteroid belt may produce over time a spectrum for an olivine-rich surface that is remarkably similar to that of an M-class asteroid.

  8. Advances in LEDs for automotive applications

    Science.gov (United States)

    Bhardwaj, Jy; Peddada, Rao; Spinger, Benno

    2016-03-01

    High power LEDs were introduced in automotive headlights in 2006-2007, for example as full LED headlights in the Audi R8 or low beam in Lexus. Since then, LED headlighting has become established in premium and volume automotive segments and beginning to enable new compact form factors such as distributed low beam and new functions such as adaptive driving beam. New generations of highly versatile high power LEDs are emerging to meet these application needs. In this paper, we will detail ongoing advances in LED technology that enable revolutionary styling, performance and adaptive control in automotive headlights. As the standards which govern the necessary lumens on the road are well established, increasing luminance enables not only more design freedom but also headlight cost reduction with space and weight saving through more compact optics. Adaptive headlighting is based on LED pixelation and requires high contrast, high luminance, smaller LEDs with high-packing density for pixelated Matrix Lighting sources. Matrix applications require an extremely tight tolerance on not only the X, Y placement accuracy, but also on the Z height of the LEDs given the precision optics used to image the LEDs onto the road. A new generation of chip scale packaged (CSP) LEDs based on Wafer Level Packaging (WLP) have been developed to meet these needs, offering a form factor less than 20% increase over the LED emitter surface footprint. These miniature LEDs are surface mount devices compatible with automated tools for L2 board direct attach (without the need for an interposer or L1 substrate), meeting the high position accuracy as well as the optical and thermal performance. To illustrate the versatility of the CSP LEDs, we will show the results of, firstly, a reflector-based distributed low beam using multiple individual cavities each with only 20mm height and secondly 3x4 to 3x28 Matrix arrays for adaptive full beam. Also a few key trends in rear lighting and impact on LED light

  9. Study of the Asteroid 2009 DL46

    Science.gov (United States)

    Vodniza, Alberto Quijano

    2017-06-01

    2009 DL46 was discovered by the Catalina Sky Survey on 2009-February 28. This asteroid has a diameter of about 194 meters (119 to 268 meters) [1], and Brian Warner has obtained a rotation period of at least 10 hours [2]. The asteroid 2009 DL46 flew past Earth on May 24/2016 at a distance of about 6.2 lunar distances (0.0158293668567628 A.U) [3]. The NEOWISE mission had a great likelihood to observing this asteroid in early May. Radiotelescopes of Goldstone and Arecibo had planned to make observations of 2009 DL46. “Using the Goldstone facility, we had planned to make radar observations of 2009 DL46” said Landis, Rob R. (HQ-DG000). This asteroid is on list for possible human mission targets. From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during several hours during three days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS [4]. The pictures and data of the asteroid were captured with the following equipment: CGE PRO 1400 CELESTRON (f/11 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera.. Astrometry was carried out, and we calculated the orbital elements. Summary and conclusions: We obtained the following orbital parameters: eccentricity = 0.30731 +/- 0.00025, semi-major axis = 1.460279 +/- 0.000532 A.U, orbital inclination = 7.9503 +/- 0.0048 deg, longitude of the ascending node = 63.45053 +/- 0.00034 deg, argument of perihelion = 159.8804 +/- 0.0024 deg, mean motion = 0.558535 +/- 0.000305 deg/d, perihelion distance = 1.01151363 +/- 3.39e-6 A.U, aphelion distance = 1.90904 +/- 0.00106 A.U, absolute magnitude = 22.5. The parameters were calculated based on 83 observations. Dates: 2016 May: 18 to 21 with mean residual = 0.29 arcseconds. The asteroid has an orbital period of 1.76 years (644.53 days).[1] http://newton.dm.unipi.it/neodys/index.php?pc=1.1.9&n=2009DL46.[2] http://echo.jpl.nasa.gov/asteroids/2009DL46/2009DL46_planning.html[3] http

  10. OSIRIS-REx, Returning the Asteroid Sample

    Science.gov (United States)

    Ajluni, Thomas, M.; Everett, David F.; Linn, Timothy; Mink, Ronald; Willcockson, William; Wood, Joshua

    2015-01-01

    This paper addresses the technical aspects of the sample return system for the upcoming Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) asteroid sample return mission. The overall mission design and current implementation are presented as an overview to establish a context for the technical description of the reentry and landing segment of the mission.The prime objective of the OSIRIS-REx mission is to sample a primitive, carbonaceous asteroid and to return that sample to Earth in pristine condition for detailed laboratory analysis. Targeting the near-Earth asteroid Bennu, the mission launches in September 2016 with an Earth reentry date of September 24, 2023.OSIRIS-REx will thoroughly characterize asteroid Bennu providing knowledge of the nature of near-Earth asteroids that is fundamental to understanding planet formation and the origin of life. The return to Earth of pristine samples with known geologic context will enable precise analyses that cannot be duplicated by spacecraft-based instruments, revolutionizing our understanding of the early Solar System. Bennu is both the most accessible carbonaceous asteroid and one of the most potentially Earth-hazardous asteroids known. Study of Bennu addresses multiple NASA objectives to understand the origin of the Solar System and the origin of life and will provide a greater understanding of both the hazards and resources in near-Earth space, serving as a precursor to future human missions to asteroids.This paper focuses on the technical aspects of the Sample Return Capsule (SRC) design and concept of operations, including trajectory design and reentry retrieval. Highlights of the mission are included below.The OSIRIS-REx spacecraft provides the essential functions for an asteroid characterization and sample return mission: attitude control propulsion power thermal control telecommunications command and data handling structural support to ensure successful

  11. High Power UV LED Industrial Curing Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karlicek, Robert, F., Jr; Sargent, Robert

    2012-05-14

    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  12. Asteroid Redirect Mission: Update on Planetary Defense Demonstration and Small Bodies Benefits and Community Interaction

    Science.gov (United States)

    Reeves, D.; Mazanek, D. D.; Abell, P. A.; Brophy, J. R.; Chodas, P. W.; Cichy, B. D.

    2016-12-01

    The National Aeronautics and Space Administration (NASA) is developing the Asteroid Redirect Mission (ARM) to robotically visit a large near-Earth asteroid (NEA), collect a multi-ton boulder and regolith samples from its surface, demonstrate the enhanced gravity tractor (EGT) planetary defense technique, return the asteroidal material to a stable orbit around the Moon, and explore the returned material with a crewed mission in the mid-2020s. Recent analysis of the EGT has led to a change in the robotic baseline operations from a halo orbit, to an in-line stand-off. This study took into account the uncertainties in size and mass of the current reference target (2008 EV5), the desire to be able to perform the EGT operations with the collected boulder augmenting the spacecraft mass or with the spacecraft alone, the assumed capability of the ARM solar electric propulsion (SEP) system, and the extensibility to future planetary defense missions. This presentation will cover the findings that led to this change in the baseline, as well as the benefits that this EGT demonstration will provide. ARM is a capability and technology demonstration mission, which will also benefit our understanding of small bodies in the areas of science, planetary defense, and asteroidal resources and in-situ resource utilization (ISRU). The synergistic benefits of both the robotic and crewed segments will be discussed in addition to describing ARM's interaction with communities that are interested in small bodies, including: the Formulation Assessment and Support Team (FAST) effort, the Small Bodies Assessment Group (SBAG) Special Action Team (SAT) effort, and the upcoming Investigation Team (IT). The IT, which is expected to be announced in the spring of 2017, will assist the ARM project in the definition, design, development, and operations phases of the ARRM with the goal of maximizing the probability of mission success and the knowledge return from the mission.

  13. Near Earth Asteroid Scout Solar Sail Thrust and Torque Model

    Science.gov (United States)

    Heaton, Andy; Ahmad, Naeem; Miller, Kyle

    2017-01-01

    The Near Earth Asteroid (NEA) Scout is a solar sail mission whose objective is to scout at least one Near Earth Asteroid to help prepare for human missions to Near Earth Asteroids. NEA Scout will launch as a secondary payload on the first SLS-Orion mission. NEA Scout will perform a small trim maneuver shortly after deploy from the spent SLS upper stage using a cold gas propulsion system, but from that point on will depend entirely on the solar sail for thrust. As such, it is important to accurately characterize the thrust of the sail in order to achieve mission success. Additionally, the solar sail creates a relatively large solar disturbance torque that must be mitigated. For early mission design studies a flat plate model of the solar sail with a fixed center of pressure was adequate, but as mission concepts and the sail design matured, greater fidelity was required. Here we discuss the progress to a three-dimensional sail model that includes the effects of tension and thermal deformation that has been derived from a large structural Finite Element Model (FEM) developed by the Langley Research Center. We have found that the deformed sail membrane affects torque relatively much more than thrust; a flat plate model could potentially model thrust well enough to close mission design studies, but a three-dimensional solar sail is essential to control system design. The three-dimensional solar sail model revealed that thermal deformations of unshielded booms would create unacceptably large solar disturbance torques. The original large FEM model was used in control and mission simulations, but was resulted in simulations with prohibitive run times. This led us to adapt the Generalized Sail Model (GSM) of Rios-Reyes. A design reference sail model has been baselined for NEA Scout and has been used to design the mission and control system for the sailcraft. Additionally, since NEA Scout uses reaction wheels for attitude pointing and control, the solar torque model is

  14. Enhanced Gravity Tractor Derived from the Asteroid Redirect Mission for Deflecting Hypothetical Asteroid 2017 PDC

    Science.gov (United States)

    Mazanek, Daniel D.; Reeves, David M.; Abell, Paul A.; Shen, Haijun; Qu, Min

    2017-01-01

    The Asteroid Redirect Mission (ARM) concept would robotically visit a hazardous-size near-Earth asteroid (NEA) with a rendezvous spacecraft, collect a multi-ton boulder and regolith samples from its surface, demonstrate an innovative planetary defense technique known as the Enhanced Gravity Tractor (EGT), and return the asteroidal material to a stable orbit around the Moon, allowing astronauts to explore the returned material in the mid-2020s. Launch of the robotic vehicle to rendezvous with the ARM reference target, NEA (341843) 2008 EV5, would occur in late 2021 [1,2]. The robotic segment of the ARM concept uses a 40 kW Solar Electric Propulsion (SEP) system with a specific impulse (Isp) of 2600 s, and would provide the first ever demonstration of the EGT technique on a hazardous-size asteroid and validate one method of collecting mass in-situ. The power, propellant, and thrust capability of the ARM robotic spacecraft can be scaled from a 40 kW system to 150 kW and 300 kW, which represent a likely future power level progression. The gravity tractor technique uses the gravitational attraction of a station-keeping spacecraft with the asteroid to provide a velocity change and gradually alter the trajectory of the asteroid. EGT utilizes a spacecraft with a high-efficiency propulsion system, such as Solar Electric Propulsion (SEP), along with mass collected in-situ to augment the mass of the spacecraft, thereby increasing the gravitational force between the objects [3]. As long as the spacecraft has sufficient thrust and propellant capability, the EGT force is only limited by the amount of in-situ mass collected and can be increased several orders of magnitude compared to the traditional gravity tractor technique in which only the spacecraft mass is used to generate the gravitational attraction force. This increase in available force greatly reduces the required deflection time. The collected material can be a single boulder, multiple boulders, regolith, or a

  15. MASCOT2, a Lander to Characterize the Target of an Asteroid Kinetic Impactor Deflection Test (AIM) Mission

    Science.gov (United States)

    Biele, J.; Ulamec, S.; Krause, C.; Cozzoni, B.; Lange, C.; Grundmann, J. T.; Grimm, C.; Ho, T.-M.; Herique, A.; Plettemeier, D.; Grott, M.; Auster, H.-U.; Hercik, D.; Carnelli, I.; Galvez, A.; Philippe, C.; Küppers, M.; Grieger, B.; Gil Fernandez, J.; Grygorczuk, J.

    2017-09-01

    In the course of the AIDA/AIM mission studies [1,2] a lander, MASCOT2, has been studied to be deployed on the moon of the binary Near-Earth Asteroid system, (65803) Didymos. The AIDA technology demonstration mission, composed of a kinetic impactor, DART, and an observing spacecraft, AIM, has been designed to deliver vital data to determine the momentum transfer efficiency of the kinetic impact and key physical properties of the target asteroid. This will enable derivation of the impact response of the object as a function of its physical properties, a crucial quantitative point besides the qualitative proof that the asteroid has been deflected at all. A landed asset on the target asteroid greatly supports analyzing its dynamical state, mass, geophysical properties, surface and subsurface structure. The lander's main instrument is a bistatic, low frequency radar (LFR) [3a,b] to sound the interior structure of the asteroid. It is supported by a camera (MasCAM) [4], a radiometer (MARA)[5], an accelerometer (DACC [9]), and, optionally regarding the science case, also a magnetometer (MasMAG)[6].

  16. The Physical Properties of Near-Earth Asteroids Associated With Meteoroid Streams

    Science.gov (United States)

    Kelley, Michael; Campins, Humberto; Fernandez, Yan; Jenniskens, Peter; Reach, William; Vaubaillon, Jeremie

    2008-03-01

    The recent Near-Earth asteroid surveys have discovered a number of bodies now identified as parents of our meteor showers. We propose a 7.5 hr Spitzer program to study the physical properties and meteoroid streams of 4 near-Earth asteroids. We will assess the size, albedo, surface composition, and thermal inertia of all 4 targets with 7-14 micron IRS spectra. We also propose MIPS 24 micron maps to measure each targets' meteoroid stream and assess their recent cometary activity. We expect that NEAs associated with meteor showers are all primitive in nature, i.e., they are derived from primitive main belt asteroids, or extinct Jupiter-family comets. We will compare the physical parameters of our targets to NEAs not associated with meteor showers, and to primitive asteroids, in the Spitzer archive. It is important to study NEAs in order to: 1) determine the sources of the current NEA population, 2) characterize the sources of meteorites, meteor showers, and interplanetary dust particles accumulated by the Earth, 3) characterize the properties of Earth impact hazards, and 4) find interesting targets of future robotic and human space exploration missions (e.g., Marco Polo and OSIRIS, two proposed sample return missions). Meteor showers also have a wide public appeal and Spitzer observations of these objects are likely to attract much attention whenever a new call for meteor shower observations is issued to the public.

  17. VizieR Online Data Catalog: Close encounters of asteroids 2003-2020 (Fienga+, 2003)

    Science.gov (United States)

    Fienga, A.; Bange, J. F.; Bec-Borsenberger, A.; Thuillot, W.

    2003-04-01

    Selection have been made of asteroids-asteroids close encounters inducing perturbations large enough to deduce masses of perturbing objects. In tablea1.dat, and tablea3.dat, the epoch of encounters is given as well as the impact parameter, the relative distance and the criterion of maximum deflection (see section 2). The epoch of encounters is defined as the epoch when the relative distance or velocity between the two asteroids become minimum or the criterion of deflection becomes maximum. The (Δα,Δδ) given in tables are the maximum differences in right ascension and declination between the perturbed and the unperturbed orbits and the epoch of maximum (Δα,Δδ) is defined as the mean epoch for the maximum values of (Δα,Δδ). Finally, in tablea2.dat and tablea4.dat, we give the observability of each encounters. We give the periods when the asteroids have a mean solar elongation greater than 50 degrees and when the perturbations of the orbits induced by the Multiple Gravitational Event (MGE) are greater than 50 mas. Mean values of these perturbations in right ascension and declination computed over the corresponding periods are given in Columns 4 and 5. (4 data files).

  18. Early investigations of Ceres and the discovery of Pallas historical studies in asteroid research

    CERN Document Server

    Cunningham, Clifford

    2016-01-01

    An asteroid scholar, Cunningham in this book picks up where his Discovery of the First Asteroid, Ceres left off in telling the story of the impact created by the discovery of this new class of object in the early 1800s. The best and brightest minds of mathematics, science, and philosophy were fascinated by Ceres, and figures as diverse as Gauss, Herschel, Brougham, Kant, and Laplace all contributed something to the conversation. The first few chapters deal with the mathematical and philosophical aspects of the discovery, and the rivalry between Germany and France that so affected science and astronomy of that era. The jockeying for glory over the discovery of Ceres by both Piazzi and Bode is examined in detail, as is the reception given to Herschel’s use of the word 'asteroid.' Archival research that reveals the creator of the word 'asteroid' is presented in this book. Astronomy was a truly cosmopolitan field at the time, spanning across various disciplines, and the discovery of Pallas, a story completely t...

  19. Another Option for the Asteroid Sample of the Asteroid Redirect Mission

    Science.gov (United States)

    Hou, Xiyun; Tang, Jingshi; Liu, Lin; Xin, Xiaosheng

    2016-07-01

    The asteroid redirect mission (ARM) consists of two phases: the asteroid redirect robotic mission (ARRM) and the asteroid redirect crewed mission (ARCM). The ARRM phase aims at capturing a boulder from the surface of an asteroid of hundred meters in diameter and returning it back to the Earth-Moon system. Currently, the option for the orbit of the returned sample is a large lunar distant retrograde orbit (LDRO) around the Moon. After the sample is returned to this LDRO, then the ARCM phase will send astronauts to the sample. The total energy cost consists of two parts: (1) from the orbit of an near-Earth asteroid to the LDRO, here as part I; (2) from the parking low Earth orbit (LEO) to the LDRO, here as part II. In the authors' work for stable motions in the real Earth-Moon system, we found that there are stable motions around the triangular libration points (TLP). Theoretically, these orbits can also be used as candidate orbits to hold the returned sample. Our previous preliminary works show that the energy of sending a manned probe from the LEO to these orbits is comparable to the option of sending it from the LEO to the LDRO. Besides, it's also possible for the sample to be returned from the orbit of a near-Earth asteroid to these stable orbits, with very small delta-V corrections. In this work, we'll study the energy cost of this option (i.e., using the stable orbits around the TLP as the orbits for the asteroid sample) in detail and compare this option with the LDRO option.

  20. A photometric model for asteroid (21) Lutetia

    Science.gov (United States)

    Hasselmann, P.; Leyrat, C.; Fornasier, S.; Barucci, M.; Lazzaro, D.

    2014-07-01

    (21) Lutetia has been successfully observed (July 10, 2010) by the ESA Rosetta spacecraft during its journey toward the comet 67P/Churyumov-Gerasimenko (Sierks et al. 2011, Coradini et al. 2011). All the available data show intriguing characteristics with a complex surface composition interpretation (Barucci et al. 2012). The quite high mean density estimation (3.4±0.3, Pätzold et al. 2011) together with the unmatching density derived from the most probable surface compositions raise a hypothesis of (21) Lutetia having a metal core (Weiss et al 2012). The surface geology of (21) Lutetia is also highly complex with significant interactions between ancient and more recent structures (Thomas et al; 2012). The large craters and lineaments show that the object was heavily battered in the past, probably losing almost all of its crust in the process (Massironi et al 2012). If (21) Lutetia is a partially differentiated asteroid with an impact-stripped crust, a complete study of variegations might help in elucidating this event. Regions or strips of different albedo might indicate heavier- or lighter-battered surface histories. Albedo variations have been detected by Leyrat et al. (2012) in the visible wavelengths. In this work, we present a deeper analysis of the Lutetia photometric properties. For such analysis, a full set of pipelines was developed in the Python 2.7.6 language. Images obtained by the OSIRIS cameras, NAC and WAC, were used alongside the shape model provided by L. Jorda to derive for each facet the luminance angles and the correct I/F. The pipeline takes image pixels and matches with facets on different observational conditions. Facets are iteratively fitted by a phase function and a disk function. Several phase functions were tested as Akimov (1976), Kaasalainen (Kaasalainen et al. 2003), Schroder (Schroder et al; 2013) and polynomial and were implemented; for disk function, McEwen (1991), Akimov and Minnaert (1941) were used. The method can be also