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Sample records for asteroid impact led

  1. The Asteroid Impact Mission

    Science.gov (United States)

    Carnelli, Ian; Galvez, Andres; Mellab, Karim

    2016-04-01

    The Asteroid Impact Mission (AIM) is a small and innovative mission of opportunity, currently under study at ESA, intending to demonstrate new technologies for future deep-space missions while addressing planetary defense objectives and performing for the first time detailed investigations of a binary asteroid system. It leverages on a unique opportunity provided by asteroid 65803 Didymos, set for an Earth close-encounter in October 2022, to achieve a fast mission return in only two years after launch in October/November 2020. AIM is also ESA's contribution to an international cooperation between ESA and NASA called Asteroid Impact Deflection Assessment (AIDA), consisting of two mission elements: the NASA Double Asteroid Redirection Test (DART) mission and the AIM rendezvous spacecraft. The primary goals of AIDA are to test our ability to perform a spacecraft impact on a near-Earth asteroid and to measure and characterize the deflection caused by the impact. The two mission components of AIDA, DART and AIM, are each independently valuable but when combined they provide a greatly increased scientific return. The DART hypervelocity impact on the secondary asteroid will alter the binary orbit period, which will also be measured by means of lightcurves observations from Earth-based telescopes. AIM instead will perform before and after detailed characterization shedding light on the dependence of the momentum transfer on the asteroid's bulk density, porosity, surface and internal properties. AIM will gather data describing the fragmentation and restructuring processes as well as the ejection of material, and relate them to parameters that can only be available from ground-based observations. Collisional events are of great importance in the formation and evolution of planetary systems, own Solar System and planetary rings. The AIDA scenario will provide a unique opportunity to observe a collision event directly in space, and simultaneously from ground-based optical and

  2. Designing Asteroid Impact Scenario Trajectories

    Science.gov (United States)

    Chodas, Paul

    2016-05-01

    In order to study some of the technical and geopolitical issues of dealing with an asteroid on impact trajectory, a number of hypothetical impact scenarios have been presented over the last ten years or so. These have been used, for example, at several of the Planetary Defense Conferences (PDCs), as well as in tabletop exercises with the Federal Emergency Management Agency (FEMA), along with other government agencies. The exercise at the 2015 PDC involved most of the attendees, consisted of seven distinct steps (“injects”), and with all the presentations and discussions, took up nearly 10 hours of conference time. The trajectory for the PDC15 scenario was entirely realistic, and was posted ahead of the meeting. It was made available in the NEO Program’s Horizons ephemeris service so that users could , for example, design their own deflection missions. The simulated asteroid and trajectory had to meet numerous very exacting requirements: becoming observable on the very first day of the conference, yet remaining very difficult to observe for the following 7 years, and far enough away from Earth that it was out of reach of radar until just before impact. It had to be undetectable in the past, and yet provide multiple perihelion opportunities for deflection in the future. It had to impact in a very specific region of the Earth, a specific number of years after discovery. When observations of the asteroid are simulated to generate an uncertainty region, that entire region must impact the Earth along an axis that cuts across specific regions of the Earth, the “risk corridor”. This is important because asteroid deflections generally move an asteroid impact point along this corridor. One scenario had a requirement that the asteroid pass through a keyhole several years before impact. The PDC15 scenario had an additional constraint that multiple simulated kinetic impactor missions altered the trajectory at a deflection point midway between discovery and impact

  3. Asteroids: Their composition and impact threat

    OpenAIRE

    Burbine T H

    2002-01-01

    Impacts by near-Earth asteroids are serious threats to life as we know it. The energy of the impact will be a function of the mass of the asteroid and its impact velocity. The mass of an asteroid is very difficult to determine from Earth. One way to derive a near-Earth object's mass is by estimating the object's density from its surface composition. Reflectance spectra are the best way to determine an object's composition since many minerals (e.g. olivine, pyroxene, hydrated silicates) have c...

  4. Asteroid rotation excitation by subcatastrophic impacts

    Czech Academy of Sciences Publication Activity Database

    Henych, T.; Pravec, Petr

    2013-01-01

    Roč. 432, č. 2 (2013), s. 1623-1631. ISSN 0035-8711 Institutional support: RVO:67985815 Keywords : numerical methods * minor planets * general asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.226, year: 2013

  5. An Early Warning System for Asteroid Impact

    CERN Document Server

    Tonry, John L

    2010-01-01

    Earth is bombarded by meteors, occasionally by one large enough to cause a significant explosion and possible loss of life. Although the odds of a deadly asteroid strike in the next century are low, the most likely impact is by a relatively small asteroid, and we suggest that the best mitigation strategy in the near term is simply to move people out of the way. We describe an "early warning" system that could provide a week's notice of most sizable asteroids or comets on track to hit the Earth. This system, dubbed "Asteroid Terrestrial-impact Last Alert System" (ATLAS), comprises two observatories separated by about 100km that simultaneously scan the visible sky twice a night, and can be implemented immediately for relatively low cost. The sensitivity of ATLAS permits detection of 140m asteroids (100 Mton impact energy) three weeks before impact, and 50m asteroids a week before arrival. An ATLAS alarm, augmented by other observations, should result in a determination of impact location and time that is accura...

  6. 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.

  7. AIDA: the Asteroid Impact & Deflection Assessment mission

    Science.gov (United States)

    Vincent, Jean-Baptiste

    2016-07-01

    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 assess the possibility of deflecting an asteroid trajectory by using a kinetic impactor. The European Asteroid Impact Mission (AIM) is under Phase A/B1 study at ESA from March 2015 until summer 2016. AIM is set to rendez-vous with the asteroid system a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft to fully characterize the smaller of the two binary components. 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: AIM will release a set of CubeSats in deep space and a lander on the surface of the smaller asteroid and for the first time, deep-space inter-satellite linking will be demonstrated between the main spacecraft, the CubeSats, and the lander, and data will also be transmitted from interplanetary space to Earth by a laser communication system. The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Small asteroids are believed to result from collisions and other processes (e.g., spinup, shaking) that made them what they are now. Having direct information on their surface and internal properties will allow us to understand how these processes work and transform these small bodies as well as, for this particular case, how a binary system forms. So far, our understanding of the collisional process and the validation of numerical simulations of the impact process rely on impact experiments at laboratory scales. With DART, thanks to the characterization of the

  8. The detectability of asteroids and comets before earth impact

    Energy Technology Data Exchange (ETDEWEB)

    Hills, J.

    1996-09-01

    In this final report of a 1-y LDRD project at LANL, requirements were investigated for detecting asteroids and comets in the final years before they impact Earth. Equipment and strategies were determined for detecting impacting asteroids and comets in all their permitted orbits. When this information is combined with possible mechanisms for diverting asteroids, it will determine the degree of readiness and minimum capability of deflection mechanisms required to prevent impact of these objects with Earth.

  9. Deflection by kinetic impact: Sensitivity to asteroid properties

    Science.gov (United States)

    Bruck Syal, Megan; Michael Owen, J.; Miller, Paul L.

    2016-05-01

    Impacting an asteroid with a spacecraft traveling at high speed delivers an impulsive change in velocity to the body. In certain circumstances, this strategy could be used to deflect a hazardous asteroid, moving its orbital path off of an Earth-impacting course. However, the efficacy of momentum delivery to asteroids by hypervelocity impact is sensitive to both the impact conditions (particularly velocity) and specific characteristics of the target asteroid. Here we numerically model asteroid response to kinetic impactors under a wide range of initial conditions, using an Adaptive Smoothed Particle Hydrodynamics code. Impact velocities spanning 1-30 km/s were investigated, yielding, for a particular set of assumptions about the modeled target material, a power-law dependence consistent with a velocity-scaling exponent of μ = 0.44. Target characteristics including equation of state, strength model, porosity, rotational state, and shape were varied, and corresponding changes in asteroid response were documented. The kinetic-impact momentum-multiplication factor, β, decreases with increasing asteroid cohesion and increasing porosity. Although increased porosity lowers β, larger porosities result in greater deflection velocities, as a consequence of reduced target masses for asteroids of fixed size. Porosity also lowers disruption risk for kinetic impacts near the threshold of disruption. Including fast (P = 2.5 h) and very fast (P = 100 s) rotation did not significantly alter β but did affect the risk of disruption by the impact event. Asteroid shape is found to influence the efficiency of momentum delivery, as local slope conditions can change the orientation of the crater ejecta momentum vector. These results emphasize the need for asteroid characterization studies to bracket the range of target conditions expected at near-Earth asteroids while also highlighting some of the principal uncertainties associated with the kinetic-impact deflection strategy.

  10. Guided asteroid deflection by kinetic impact: Mapping keyholes to an asteroid's surface

    Science.gov (United States)

    Chesley, S.; Farnocchia, D.

    2014-07-01

    The kinetic impactor deflection approach is likely to be the optimal deflection strategy in most real-world cases, given the likelihood of decades of warning time provided by asteroid search programs and the probable small size of the next confirmed asteroid impact that would require deflection. However, despite its straightforward implementation, the kinetic impactor approach can have its effectiveness limited by the astrodynamics that govern the impactor spacecraft trajectory. First, the deflection from an impact is maximized when the asteroid is at perihelion, while an impact near perihelion can in some cases be energetically difficult to implement. Additionally, the asteroid change in velocity Δ V should aligned with the target's heliocentric velocity vector in order to maximize the deflection at a potential impact some years in the future. Thus the relative velocity should be aligned with or against the heliocentric velocity, which implies that the impactor and asteroid orbits should be tangent at the point of impact. However, for natural bodies such as meteorites colliding with the Earth, the relative velocity vectors tend to cluster near the sunward or anti- sunward directions, far from the desired direction. This is because there is generally a significant crossing angle between the orbits of the impactor and target and an impact at tangency is unusual. The point is that hitting the asteroid is not enough, but rather we desire to hit the asteroid at a point when the asteroid and spacecraft orbits are nearly tangent and when the asteroid is near perihelion. However, complicating the analysis is the fact that the impact of a spacecraft on an asteroid would create an ejecta plume that is roughly normal to the surface at the point of impact. This escaping ejecta provides additional momentum transfer that generally adds to the effectiveness of a kinetic deflection. The ratio β between the ejecta momentum and the total momentum (ejecta plus spacecraft) can

  11. Dust productivity and impact collision of the asteroid (596) Scheila

    Science.gov (United States)

    Neslusan, L.; Ivanova, O.; Husarik, M.; Svoren, J.; Krisandova, Z. Seman

    2016-06-01

    Photometric observations of asteroid (596) Scheila were obtained during and after its 2010 outburst. The estimated radius of the body (spherical approximation of the asteroidal body) was 51.2±3.0 km and 50.6±3.0 km for different methods. The ejected dust mass from the asteroid ranged from 2.5 ×107 to 3.4 ×107 kg for different methods. An impact mechanism for triggering Scheila's activity is discussed. A few days before the impact, Scheila passed through the corridors of two potential cometary streams.

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

    CERN Document Server

    Glikson, Andrew Y

    2013-01-01

    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 res

  13. 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.

  14. 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

  15. 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.

  16. 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.

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

    Science.gov (United States)

    Hills, J. G.

    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. 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

  19. ASTEROIDS

    OpenAIRE

    Željko Andreić

    2016-01-01

    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 overv...

  20. Simulations of impacts on rubble-pile asteroids

    Science.gov (United States)

    Deller, J.; Snodgrass, C.; Lowry, S.; Price, M.; Sierks, H.

    2014-07-01

    Rubble-pile asteroids can contain a high level of macroporosity. For some asteroids, porosities of 40 % or even more have been measured [1]. While little is known about the exact distribution of the voids inside rubble-pile asteroids, assumptions have to be made for the modeling of impact events on these bodies. Most hydrocodes do not distinguish between micro- and macroporosity, instead describing brittle material by a constitutive model as homogeneous. We developed a method to model rubble-pile structures in hypervelocity impact events explicitly. The formation of the asteroid is modelled as a gravitational aggregation of spherical `pebbles', that form the building blocks of our target. This aggregate is then converted into a high-resolution Smoothed Particle Hydrodynamics (SPH) model, which also accounts for macroporosity inside the pebbles. We present results of a study that quantifies the influence of our model parameters on the outcome of a typical impact event of two small main-belt asteroids. The existence of void space in our model increases the resistance against collisional disruption, a behavior observed before [2]. We show that for our model no a priori knowledge of the rubble-pile constituents in the asteroid is needed, as the choice of the corresponding parameters does not directly correlate with the impact outcome. The size distribution of the pebbles used as building blocks in the formation of an asteroid is only poorly constrained. As a starting point, we use a power law N(>r) ∝ r^α to describe the distribution of radii of the pebbles. Reasonable values for the slope α range around α=-2.5, as found in the size distribution of main-belt objects [3,4]. The cut-off values for pebbles, r_{min} and r_{max} are given by practical considerations: In the SPH formalism, properties are represented by weighted averages of particles within their smoothing length h, preventing the resolution of structures below that scale. Using spheres with radius in the

  1. Sensitivity to Uncertainty in Asteroid Impact Risk Assessment

    Science.gov (United States)

    Mathias, D.; Wheeler, L.; Prabhu, D. K.; Aftosmis, M.; Dotson, J.; Robertson, D. K.

    2015-12-01

    The Engineering Risk Assessment (ERA) team at NASA Ames Research Center is developing a physics-based impact risk model for probabilistically assessing threats from potential asteroid impacts on Earth. The model integrates probabilistic sampling of asteroid parameter ranges with physics-based analyses of entry, breakup, and impact to estimate damage areas and casualties from various impact scenarios. Assessing these threats is a highly coupled, dynamic problem involving significant uncertainties in the range of expected asteroid characteristics, how those characteristics may affect the level of damage, and the fidelity of various modeling approaches and assumptions. The presented model is used to explore the sensitivity of impact risk estimates to these uncertainties in order to gain insight into what additional data or modeling refinements are most important for producing effective, meaningful risk assessments. In the extreme cases of very small or very large impacts, the results are generally insensitive to many of the characterization and modeling assumptions. However, the nature of the sensitivity can change across moderate-sized impacts. Results will focus on the value of additional information in this critical, mid-size range, and how this additional data can support more robust mitigation decisions.

  2. Water delivery to the Moon by asteroidal and cometary impacts

    Science.gov (United States)

    Svetsov, V. V.; Shuvalov, V. V.

    2015-11-01

    Recent spacecraft missions detected presence of hydroxyl or water over large areas on the lunar surface. Several craters near the lunar poles have increased concentrations of hydrogen suggesting impact delivery of water. Using a numerical model, we have carried out computer simulations of the impacts of asteroids and comets in order to estimate the fate of water that can be contained in the projectiles. We find that at impact velocities below ~10 km/s a significant fraction of a stony projectile remains in the crater and is heated to temperatures below 1000 K. At these velocities hydrated minerals contained in carbonaceous projectiles decompose only partly. We conclude that the impacts of water-bearing carbonaceous asteroids could produce deposits of free and chemically bound water inside some lunar craters. The relative number of these craters may reach several percent. In contrast to asteroids, water from cometary impacts, even at low velocities, is vaporized, and vapor plume expands and disperses over the lunar surface.

  3. An Airborne Observing Campaign of an Announced Small Asteroid Impact for High Fidelity Impact Modeling Validation

    Science.gov (United States)

    Jenniskens, P. M. M.; Grinstead, J. H.

    2015-12-01

    High fidelity modeling of an asteroid impact requires a known size, mass, shape, entry orientation, entry speed, entry angle, time and location of entry, and material properties of the impacting asteroid. Much of that information can be gathered from small asteroids on an impact trajectory with Earth while they are on approach, given sufficient warning time. That makes small asteroid impacts uniquely suited for collecting data to validate such models. One-meter sized asteroids impact Earth about once a week, 4-meter sized asteroids impact once a year. So far, only asteroid 2008 TC3 was observed in space, characterized prior to impact, and then recovered in part as meteorites on the ground. The next TC3-like impact could provide more warming time to study the impact in detail. Close to 70 percent of all asteroid impacts on Earth occur over the ocean. Hence, small asteroid impact observations require an instrumented airborne platform to take a multi-disciplined research team to the right location at the right time. From a safe 100-km distance, the impact would be observed low enough in the sky to study the process of fragmentation that dictates at which altitude the kinetic energy is deposited that can cause an airburst. Constraints on radiative heating, ablation rate, and fragmentation processes can be obtained from measuring the air plasma emission escaping the shock, elemental atom line emissions and excitation conditions, pressure broadening, and deceleration in the plane of the known trajectory. It is also possible to measure wake, lightcurve and air plasma emission line intensities early in flight that can be used to evaluate the presence of regolith and the internal cohesion of asteroids. The main element abundance (asteroid composition) can be measured for individual fragments, while CN-band emission can point to the presence of organic matter. Such information will help constrain the meteorite type if no meteorites can be recovered in an over

  4. Modeling the onset of photosynthesis after the Chicxulub asteroid impact

    CERN Document Server

    Perez, Noel; Martin, Osmel; Rojas, Reinaldo

    2012-01-01

    We do a preliminary modelling of the photosynthetic rates of phytoplankton at the very beginning of the Paleogene, just after the impact of the Chicxulub asteroid, which decisively contributed to the last known mass extinction of the Phanerozoic eon. We assume the worst possible scenario from the photobiological point of view: an already clear atmosphere with no ozone, as the timescale for soot and dust settling (years) is smaller than that of the full ozone regeneration (decades). Even in these conditions we show that most phytoplankton species would have had reasonable potential for photosynthesis in all the three main optical ocean water types. This modelling could help explain why the recovery of phytoplankton was relatively rapid after the huge environmental stress of that asteroid impact. In a more general scope, it also reminds us of the great resilience of the unicellular biosphere against huge environmental perturbations.

  5. Analytical model of impact disruption of satellites and asteroids

    Science.gov (United States)

    Leliwa-Kopystyński, J.; Włodarczyk, I.; Burchell, M. J.

    2016-04-01

    A model of impact disruption of the bodies with sizes from the laboratory scale to that of an order of 100 km is developed. On the lowermost end of the target size the model is based on the numerous laboratory data related to the mass-velocity distribution of the impact produced fragments. On the minor-planets scale the model is supported by the data related to the largest observed craters on small icy satellites and on some asteroids (Leliwa-Kopystynski, J., Burchell, M.J., Lowen, D. [2008]. Icarus 195, 817-826). The model takes into account the target disruption and the dispersion of the impact produced fragments against the intermolecular forces acting on the surfaces of the contacts of the fragments and against self-gravitation of the target. The head-on collisions of non-rotating and non-porous targets and impactors are considered. The impactor delivers kinetic energy but its mass is neglected in comparison to mass of the target. For this simple case the analytical formulae for specific disruption energy as well as for specific energy of formation of the largest craters are found. They depend on a set of parameters. Of these the most important (i.e. with the greatest influence on the final result) are three rather weakly known parameters. They are: (i) The exponent γ in the distribution function of the fragments. (ii) The characteristic velocity v0 that appears in the velocity distribution of the ejected fragments. (iii) The exponent β in the mass-velocity distribution. The influence of the choice of the numerical values of these parameters on the final results has been studied. Another group of parameters contains the relevant material data. They are: (a) The energy σ of breaking of the intermolecular bonds of the target material per unit of the fragment surface and (b) the density ρ of the target. According to our calculations the transition between the strength regime and the gravitational regime is in the range of the target radius from ∼0.4 km to

  6. On the influence of impact effect modelling for global asteroid impact risk distribution

    CERN Document Server

    Rumpf, Clemens M; Atkinson, Peter M

    2016-01-01

    ESA and NASA maintain asteroid hazard lists that contain all known asteroids with a non zero chance of colliding with the Earth in the future. Some software tools exist that are, either, capable of calculating the impact points of those asteroids, or that can estimate the impact effects of a given impact incident. However, no single tool is available that combines both aspects and enables a comprehensive risk analysis. The question is, thus, whether tools that can calculate impact location may be used to obtain a qualitative understanding of the asteroid impact risk distribution. To answer this question, two impact risk distributions that control for impact effect modelling were generated and compared. The Asteroid Risk Mitigation Optimization and Research (ARMOR) tool, in conjunction with the freely available software OrbFit, was used to project the impact probabilities of listed asteroids with a minimum diameter of 30 m onto the surface of the Earth representing a random sample (15% of all objects) of the h...

  7. 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.

  8. On the influence of impact effect modelling for global asteroid impact risk distribution

    Science.gov (United States)

    Rumpf, Clemens; Lewis, Hugh G.; Atkinson, Peter M.

    2016-06-01

    The collision of an asteroid with Earth can potentially have significant consequences for the human population. The European and United States space agencies (ESA and NASA) maintain asteroid hazard lists that contain all known asteroids with a non-zero chance of colliding with the Earth in the future. Some software tools exist that are, either, capable of calculating the impact points of those asteroids, or that can estimate the impact effects of a given impact incident. However, no single tool is available that combines both aspects and enables a comprehensive risk analysis. The question is, thus, whether tools that can calculate impact location may be used to obtain a qualitative understanding of the asteroid impact risk distribution. To answer this question, two impact risk distributions that control for impact effect modelling were generated and compared. The Asteroid Risk Mitigation Optimisation and Research (ARMOR) tool, in conjunction with the freely available software OrbFit, was used to project the impact probabilities of listed asteroids with a minimum diameter of 30 m onto the surface of the Earth representing a random sample (15% of all objects) of the hazard list. The resulting 261 impact corridors were visualised on a global map. Furthermore, the impact corridors were combined with Earth population data to estimate the "simplified" risk (without impact effects) and "advanced" risk (with impact effects) associated with the direct asteroid impacts that each nation faces from present to 2100 based on this sample. The relationship between risk and population size was examined for the 40 most populous countries and it was apparent that population size is a good proxy for relative risk. The advanced and simplified risk distributions were compared and the alteration of the results based on the introduction of physical impact effects was discussed. Population remained a valid proxy for relative impact risk, but the inclusion of impact effects resulted in

  9. 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.

  10. 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

  11. 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.

    2015-04-01

    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.

  12. Impact risk assessment and planetary defense mission planning for asteroid 2015 PDC

    Science.gov (United States)

    Vardaxis, George; Sherman, Peter; Wie, Bong

    2016-05-01

    In this paper, an integrated utilization of analytic keyhole theory, B-plane mapping, and planetary encounter geometry, augmented by direct numerical simulation, is shown to be useful in determining the impact risk of an asteroid with the Earth on a given encounter, as well on potential future encounters via keyhole passages. The accurate estimation of the impact probability of hazardous asteroids is extremely important for planetary defense mission planning. Asteroids in Earth resonant orbits are particularly troublesome because of the continuous threat they pose in the future. Based on the trajectories of the asteroid and the Earth, feasible mission trajectories can be found to mitigate the impact threat of hazardous asteroids. In order to try to ensure mission success, trajectories are judged based on initial and final mission design parameters that would make the mission easier to complete. Given the potential of a short-warning time scenario, a disruption mission considered in this paper occurs approximately one year prior to the anticipated impact date. Expanding upon the established theory, a computational method is developed to estimate the impact probability of the hazardous asteroid, in order to assess the likelihood of an event, and then investigate the fragmentation of the asteroid due to a disruption mission and analyze its effects on the current and future encounters of the fragments with Earth. A fictional asteroid, designated as 2015 PDC - created as an example asteroid risk exercise for the 2015 Planetary Defence Conference, is used as a reference target asteroid to demonstrate the effectiveness and applicability of computational tools being developed for impact risk assessment and planetary defense mission planning for a hazardous asteroid or comet.

  13. The trajectory and atmospheric impact of asteroid 2014 AA

    Science.gov (United States)

    Farnocchia, Davide; Chesley, Steven R.; Brown, Peter G.; Chodas, Paul W.

    2016-08-01

    Near-Earth asteroid 2014 AA entered the Earth's atmosphere on 2014 January 2, only 21 h after being discovered by the Catalina Sky Survey. In this paper we compute the trajectory of 2014 AA by combining the available optical astrometry, seven ground-based observations over 69 min, and the International Monitoring System detection of the atmospheric impact infrasonic airwaves in a least-squares orbit estimation filter. The combination of these two sources of observations results in a tremendous improvement in the orbit uncertainties. The impact time is 3:05 UT with a 1σ uncertainty of 6 min, while the impact location corresponds to a west longitude of 44.2° and a latitude of 13.1° with a 1σ uncertainty of 140 km. The minimum impact energy estimated from the infrasound data and the impact velocity result in an estimated minimum mass of 22.6 t. By propagating the trajectory of 2014 AA backwards we find that the only window for finding precovery observations is for the three days before its discovery.

  14. The atmospheric impact trajectory of asteroid 2014 AA

    CERN Document Server

    Farnocchia, D; Brown, P G; Chodas, P W

    2016-01-01

    Near-Earth asteroid 2014 AA entered the Earth's atmosphere on 2014 January 2, only 21 hours after being discovered by the Catalina Sky Survey. In this paper we compute the trajectory of 2014 AA by combining the available optical astrometry, seven ground-based observations over 69 minutes, and the International Monitoring system detection of the atmospheric impact infrasonic airwaves in a least-squares orbit estimation filter. The combination of these two sources of observations results in a tremendous improvement in the orbit uncertainties. The impact time is 3:05 UT with a 1-sigma uncertainty of 6 min, while the impact location corresponds to a west longitude of 44.7 deg and a latitude of 13.1 deg with a 1-sigma uncertainty of 140 km. The minimum impact energy estimated from the infrasound data and the impact velocity result in an estimated minimum mass of 22.6 t. By propagating the trajectory of 2014 AA backwards we find that the only window for finding precovery observations is for the three days before it...

  15. 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.

  16. The impact imperative: Laser ablation for deflecting asteroids, meteoroids, and comets from impacting the earth

    International Nuclear Information System (INIS)

    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. This can be accomplished by irradiating the surface of an inbound rock with sufficiently intense pulses so that ablation occurs. This ablation acts as a small rocket incrementally changing the shape of the rock's orbit around the Sun. One-kilometer size rocks can be moved sufficiently in about a month while smaller rocks may be moved in a shorter time span

  17. The Lockne - Målingen doublet impacts, the result of a binary asteroid from the 470 Ma Main Asteroid Belt event

    Science.gov (United States)

    Sturkell, E. C.; Ormo, J.; Alwmark, C.; Melosh, H., IV

    2015-12-01

    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 (MAB), 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. The 600 m large Lockne asteroid was a binary and had a companion in space by a smaller 150 m satellite. The recent discovery of the nearby, 0.7-km diameter, synchronous Målingen crater suggests it to form a doublet impact structure together with the larger Lockne crater, and as we will show here, most likely by a binary, 'rubble pile' asteroid. Despite observational evidence that about 16% of the Near Earth Asteroids (NEA's) are binary, only a handful of the approximately 188 known craters on Earth have been suggested as potential doublets. The stratigraphic and geographic relationship with Lockne suggests the Lockne and Målingen craters to be the first described doublet impact structure by a binary asteroid into a marine-target setting. In addition, the precise dating of the Lockne-Målingen impact in relation to the MAB breakup event provides a hands-on reference for studies of the formation of binaries from asteroid breakup events.

  18. Asteroid 2007 WD5 will not impact Mars on January 30!

    CERN Document Server

    Krolikowska, Malgorzata

    2008-01-01

    The Monte Carlo method of the nominal orbit clonning was applied to the case of 2007 WD5, the asteroid from the Apollo group. Calculations based on 33 observations from the time interval of 2007 11 08 - 2008 01 02 showed that the asteroid will pass near planet Mars at the minimum distance of 10.9\\pm 2.9 R_{Mars}, what implies that probability that 2007 WD5 strike the planet decreased to the value of 0.03% from the value of about 3--4% previously announced by NASA. The additional observations taken on January 3--9 reduce further the asteroid's impact chances, effectively to nil: the asteroid will pass near planet Mars at the minimum distance of 8.4\\pm 1.1 R_{Mars}.

  19. 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, f

  20. The orbits of asteroids that impact earth and groundbased detection strategies

    Energy Technology Data Exchange (ETDEWEB)

    Hills, J.G.; Leonard, P.T.

    1995-12-31

    The danger of impacts by Earth-crossing asteroids (ECAs). Asteroids 60 meters in diameter and larger can destroy large cities by airblast, by 200 meters in diameter they produce substantial regional impact damage as well as tsunami that can devastate the shore lines of entire ocean basins and by 1 km in diameter they made. in addition, perturb the atmosphere enough to produce global mass extinctions. In this paper we examine strategies for detecting ECAs that may hit Earth within the next few years. We wish to detect asteroids down to 60 meters in diameter in sufficient time to allow them to be deflected or destroyed before Earth impact. A week is sufficient warning to allow a single rocket equipped with a nuclear explosive (using existing rocket boosters and nuclear explosives) to deflect from Earth impact an asteroid with a diameter up to 1--2 km if such a rocket were on standby for this purpose. To deflect a larger asteroid requires a lead time of months to years even if rockets to deflect it were on standby.

  1. Waves Generated by Asteroid Impacts and Their Hazard Consequences on The Shorelines

    Science.gov (United States)

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

    2014-12-01

    We have performed numerical simulations of a hypothetical asteroid impact onto the ocean in support of an emergency preparedness, planning, and management exercise. We addressed the scenario from asteroid entry; to ocean impact (splash rim); to wave generation, propagation, and interaction with the shoreline. For the analysis we used GEODYN, a hydrocode, to simulate the impact and generate the source wave for the large-scale shallow water wave program, SWWP. Using state-of-the-art, high-performance computing codes we simulated three impact areas — two are located on the West Coast near Los Angeles's shoreline and the San Francisco Bay, respectively, and the third is located in the Gulf of Mexico, with a possible impact location between Texas and Florida. On account of uncertainty in the exact impact location within the asteroid risk corridor, we examined multiple possibilities for impact points within each area. Uncertainty in the asteroid impact location was then convolved and represented as uncertainty in the shoreline flooding zones. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and partially funded by the Laboratory Directed Research and Development Program at LLNL under tracking code 12-ERD-005.

  2. The Impact Clan: A Disenchanted Look at Asteroid Impact Monitoring Science

    Science.gov (United States)

    D'Abramo, Germano

    2015-11-01

    Synopsis: How many times in the last decade have you heard announcements about asteroids with unusually high Earth-collision chances in the near future? Surely more than once, we guess. It is not difficult to find sentences like "this is one of most dangerous asteroids ever found" every now and then in the media. It is probably difficult for the man in the street to reconcile his (ordinary) perception of risk with something that, despite these continuous and alarming announcements, has never happened and is still not happening: how many people have been killed by these nasty asteroids in the history of mankind? Earthquakes, floods, and volcanic eruptions are known to be dangerous because they have already struck with a high death toll. This book is an informed and disenchanted review of the activity of the so-called "Impact Monitoring Systems", which were born in the late 90's. The author happened to be involved in this business right from the outset, when he started his research career. His critique addresses directly the merits of that science, providing the reader with scientific and rigorous arguments against the worth of such an activity, at least in the way in which it is currently being carried out. But this book also brings together the personal and human vicissitudes of the author, experienced during his 16 years spent in Astronomy and Astrophysics research, his views on Science, Life and Society. The book is non-fiction; it is accessible to any (curious) person with a high-school/college level education.

  3. 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

  4. Measurement requirements for a near-Earth asteroid impact mitigation demonstration mission

    CERN Document Server

    Wolters, Stephen D; Wells, Nigel; Saunders, Christopher; McBride, Neil

    2011-01-01

    A concept for an Impact Mitigation Preparation Mission, called Don Quijote, is to send two spacecraft to a Near-Earth Asteroid (NEA): an Orbiter and an Impactor. The Impactor collides with the asteroid while the Orbiter measures the resulting change in the asteroid's orbit, by means of a Radio Science Experiment (RSE) carried out before and after impact. Three parallel Phase A studies on Don Quijote were carried out for the European Space Agency: the research presented here reflects outcomes of the study by QinetiQ. We discuss the mission objectives with regards to the prioritisation of payload instruments, with emphasis on the interpretation of the impact. The Radio Science Experiment is described and it is examined how solar radiation pressure may increase the uncertainty in measuring the orbit of the target asteroid. It is determined that to measure the change in orbit accurately a thermal IR spectrometer is mandatory, to measure the Yarkovsky effect. The advantages of having a laser altimeter are discusse...

  5. 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

  6. 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.

  7. Images of an Activated Asteroid

    Science.gov (United States)

    Kohler, Susanna

    2016-08-01

    In late April of this year, asteroid P/2016 G1 (PANSTARRS) was discovered streaking through space, a tail of dust extending behind it. What caused this asteroids dust activity?Asteroid or Comet?Images of asteroid P/2016 G1 at three different times: late April, late May, and mid June. The arrow in the center panel points out an asymmetric feature that can be explained if the asteroid initially ejected material in a single direction, perhaps due to an impact. [Moreno et al. 2016]Asteroid P/2016 G1 is an interesting case: though it has the orbital elements of a main-belt asteroid it orbits at just under three times the EarthSun distance, with an eccentricity of e ~ 0.21 its appearance is closer to that of a comet, with a dust tail extending 20 behind it.To better understand the nature and cause of this unusual asteroids activity, a team led by Fernando Moreno (Institute of Astrophysics of Andalusia, in Spain) performed deep observations of P/2016 G1 shortly after its discovery. The team used the 10.4-meter Great Canary Telescope to image the asteroid over the span of roughly a month and a half.A Closer Look at P/2016 G1P/2016 G1 lies in the inner region of the main asteroid belt, so it is unlikely to have any ices that suddenly sublimated, causing the outburst. Instead, Moreno and collaborators suggest that the asteroids tail may have been caused by an impact that disrupted the parent body.To test this idea, the team used computer simulations to model their observations of P/2016 G1s dust tail. Based on their models, they demonstrate that the asteroid was likely activated on February 10 2016 roughly 350 days before it reached perihelion in its orbit and its activity was a short-duration event, lasting only ~24 days. The teams models indicate that over these 24 days, the asteroid lost around 20 million kilograms of dust, and at its maximum activity level, it was ejecting around 8 kg/s!Comparison of the observation from late May (panel a) and two models: one in which

  8. Experimental study on impact disruption of porous asteroids: Effects of oblique impact and multiple collisions on impact strength

    Science.gov (United States)

    Yasui, Minami; Takano, Shota; Matsue, Kazuma; Arakawa, Masahiko

    2015-08-01

    Most of asteroids would have pores and a plenty of pre-cracks in their interiors, and the pre-cracks could be formed by multiple impacts at various impact angles. Porosity and pre-cracks are important physical properties controlling the impact strength. Okamoto and Arakawa (2009) did impact experiments of porous gypsum spheres to obtain the impact strength of porous asteroids, but they carried out only single impact experiments on the same target at head-on. In this study, we conducted oblique impact and multiple impacts on porous gypsum and examined the effects of impact angle and pre-cracks on the impact strength.We carried out impact experiments by using the one-stage He gas gun and the two-stage H2 gas gun at Kobe University. The impact velocities were 3 km/s (high-vi). Targets were porous gypsum spheres with the porosity of 55% and the diameters of 7 or 12 cm. The projectiles were a porous gypsum sphere with the diameter of 2.5 cm at low-vi or a polycarbonate sphere with the diameter of 4.7 cm at high-vi. The impact angle changed from 15° to 90°, and the projectile was impacted on the same target for 2-15 times. The impact phenomena were observed by a high-speed digital video camera to measure the fragment velocities.The oblique impact experiments showed that the impact strength did not depend on the impact angle θ between 45° and 90°, and obtained to be ~2000 J/kg, while it drastically changed at the θ from 15° to 30°. We reanalyzed our results by using the effective energy density defined as Qsin2θ, where Q is the energy density, and found that most of the results were consistent with the results of head-on impacts. The multiple impacts showed that the impact strength of pre-impacted targets was larger than that of intact targets in the case of low-vi. This might be caused by the compaction of the target surface. In the case of high-vi, the impact strength of pre-impacted targets was smaller than that of intact targets. This is because many cracks

  9. 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.

  10. 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

  11. Assessment of the 2880 impact threat from asteroid (29075) 1950 DA

    CERN Document Server

    Farnocchia, D

    2013-01-01

    In this paper we perform an assessment of the 2880 Earth impact risk for asteroid (29075) 1950 DA. To obtain reliable predictions we analyze the contribution of the observational dataset and the astrometric treatment, the numerical error in the long-term integration, and the different accelerations acting on the asteroid. The main source of uncertainty is the Yarkovsky effect, which we statistically model starting from 1950 DA's available physical characterization, astrometry, and dynamical properties. This modeling suggests that 1950 DA has 98% likelihood of being a retrograde rotator. By using a 7-dimensional Monte Carlo sampling we map 1950 DA's uncertainty region to the 2880 close approach b-plane and find a 4x10^-4 impact probability.

  12. Impact trajectories of the asteroid Apophis in the 21st century

    Science.gov (United States)

    Sokolov, L. L.; Bashakov, A. A.; Borisova, T. P.; Petrov, N. A.; Pitjev, N. P.; Shaidulin, V. S.

    2012-07-01

    The asteroid Apophis is one of the most hazardous near-Earth asteroids. As a result of the scattering of Apophis' potential trajectories after its close approach in 2029, and its possible approach in 2036, there are many dangerous trajectories including impact trajectories after 2036. The purpose of this study is to identify and investigate these trajectories. We use the Everhart integrator; the DE405, DE423, and EPM2008 ephemerides; and two sets of initial data for Apophis (those collected by NASA in 2006 and by the IAA in 2010). More than 50 possible encounters in this century are presented, including 13 encounters between 2036 and 2050. The minimum geocentric distances obtained using a different ephemeris and initial conditions differ little between themselves. Analogous results in (Yeomans et al., 2009) are consistent with our results.

  13. 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

  14. The Hungaria Asteroids: resonances, close encounters and impacts with terrestrial planets

    CERN Document Server

    Galiazzo, Mattia Alvise; Dvorak, Rudolf

    2012-01-01

    The Hungaria asteroid family, which consists of more than 8000 members with semi-major axes between 1.78 and 2.03 AU, is regarded as one source for Near-Earth Asteroids. Named after (434) Hungaria these asteroids are relatively small (mean diameter $\\sim 1$ km) and have inclinations of the order of $20^\\circ$. They are mainly perturbed by Jupiter and Mars, and are ejected because of mean motion and secular resonances with these planets and then become Mars-crossers; later they may even cross the orbits of Earth and Venus. We are interested to analyse the close encounters and possible impacts with these planets. For 200 selected objects which are on the edge of the group we integrated their orbits over 100 million years in a simplified model of the planetary system (Mars to Saturn) subject to only gravitational forces. We picked out a sample of 11 objects (each with 50 clones) with large variations in semi-major axis and restarted the numerical integration in the model Venus to Saturn. Due to close encounters ...

  15. Asteroid Defense: Comparison of Kinetic-Impact and Nuclear Stand-Off Schemes

    Science.gov (United States)

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

    2014-12-01

    In this work we study the deflection of hazardous near-earth objects using either a kinetic impactor or a nuclear stand-off burst. If the object is known to be competent, the kinetic impactor is shown to be highly efficient. The momentum delivered to the object can be much greater than the momentum of the impactor because of the reaction force produced by ablation from the impact crater. We use an adaptive-mesh hydrocode to study the momentum-enhancement factor, or beta, varying the assumptions regarding the equation of state and the strength of the target. Spall from the back side of the asteroid, which partly counters the favorable effect of ablation, is also included in the calculations. For objects not known to be competent, the nuclear stand-off burst option may be preferable. In this case, crucial questions surround the optimum height of burst and the radiation characteristics of the burst. The same hydrocode, with radiation diffusion included, is used to study this case as well. Figures of merit from both these studies include the bulk momentum imparted to the asteroid and the degree to which the asteroid is disrupted. LA-UR-14-26234

  16. Asteroid thermophysical modeling

    CERN Document Server

    Delbo, Marco; 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 few-percent level by later spacecraft visits. We discuss how instrumentation advances now allow mid-infrared interferometric observations as well as high-accuracy spectro-photometry, posing their own set of thermal-modeling challenges.We present major breakthroughs achieved in studies of the thermal inertia, a sensitive indicator for the nature of asteroids soils, allowing us, for instance, to determine the grain size of asteroidal regoliths. Thermal inertia also governs non-gravitational effects on asteroid orbits, requir...

  17. The Dawn Mission & Asteroid Mappers: The Impact of Crowd-Sourced Crater Counting

    Science.gov (United States)

    Schmidt, B. E.; Scully, J. E.; Hart, R.; Russell, C. T.; Wise, J.; Cobb, W. H.; Ristvey, J.; Counley, J.; Hess, N.

    2012-12-01

    While the driving principle for a science investigation may be the pursuit of knowledge, the process of acquiring that knowledge that matters as much as the result. This process is known to many as the scientific method, a concept regularly taught in schools but that remains in many cases poorly tied to science outreach. But with the growth of the Citizen Science movement, we have entered a new era for both science and science outreach marked by the accessibility of tools that allow the public to experience science first hand in a manner previously unimagined. Gone are the days when a launch and a landing are all that are seen of a mission. Now, it's time to let the public in on the fun, and of course, all the work. In a time of large data returns and dwindling science budgets, citizen science may help scientists and educators with two fundamental problems: (1) increasing awareness and (2) accomplishing the key science investigations. The Dawn Mission has long been on the path towards involving the public in the process of science, and with the advent of the new Asteroid Mappers project, joint with CosmoQuest, the long-term goal of presenting the data to the public in a meaningful manner will be achieved. And in the long run, the public may also prove key to accomplishing mission science. Vesta is a unique body in the solar system, a likely a witness to the earliest stages of solar system formation and the environment within the main asteroid belt. Its impact history will be critical not only to understanding the initial population of the asteroid belt and thus impact hazards on the early Earth, but also the production of Vesta's impact family and the samples of Vesta, the HED meteorites, we have on Earth. Thus determining the impact crater population and distribution is a critical mission goal. Because craters are easily recognized and relatively straightforward to measure, a careful member of the public may be able to perform the same basic tasks as a scientist

  18. Impact craters at falling of large asteroids in Ukraine

    Science.gov (United States)

    Vidmachenko, A. P.

    2016-05-01

    Catastrophes of different scale that are associated with the fall of celestial bodies to the Earth - occurred repeatedly in its history. But direct evidence of such catastrophes has been discovered recently. Thus, in the late 1970s studies of terrestrial rocks showed that in layers of the earth's crust that corresponded to the period of 65 million years before the present, marked by the mass extinction of some species of living creatures, and the beginning of the rapid development of others. It was then - a large body crashed to Earth in the Gulf of Mexico in Central America. The consequence of this is the Chicxulub crater with a diameter of ~170 km on Yucatan Peninsula. Modern Earth's surface retains many traces of collisions with large cosmic bodies. To indicate the craters with a diameter of more than 2 km using the name "astrobleme". Today, it found more than 230. The largest astroblems sizes exceeding 200 km. Ukraine also has some own astroblems. In Ukraine, been found nine large impact craters. Ukrainian crystalline shield, because of its stability for a long time (more than 1.5 billion years), has the highest density of large astroblems on the Earth's surface. The largest of the Ukrainian astroblems is Manevytska. It has a diameter of 45 km. There are also Ilyinetskyi (7 km), Boltysh (25 km), Obolon' (20 km), Ternivka (12-15 km), Bilylivskyi (6 km), Rotmystrivka (3 km) craters. Zelenohayska astrobleme founded near the village Zelenyi Gay in Kirovograd region and consists of two craters: larger with diameter 2.5-3.5 km and smaller - with diameter of 800 m. The presence of graphite, which was the basis for the research of the impact diamond in astroblems of this region. As a result, the diamonds have been found in rocks of Ilyinetskyi crater; later it have been found in rocks in the Bilylivska, Obolon' and other impact structures. The most detailed was studied the geological structure and the presence of diamonds in Bilylivska astrobleme

  19. The Gao-Guenie impact melt breccia—Sampling a rapidly cooled impact melt dike on an H chondrite asteroid?

    Science.gov (United States)

    Schmieder, Martin; Kring, David A.; Swindle, Timothy D.; Bond, Jade C.; Moore, Carleton B.

    2016-04-01

    The Gao-Guenie H5 chondrite that fell on Burkina Faso (March 1960) has portions that were impact-melted on an H chondrite asteroid at ~300 Ma and, through later impact events in space, sent into an Earth-crossing orbit. This article presents a petrographic and electron microprobe analysis of a representative sample of the Gao-Guenie impact melt breccia consisting of a chondritic clast domain, quenched melt in contact with chondritic clasts, and an igneous-textured impact melt domain. Olivine is predominantly Fo80-82. The clast domain contains low-Ca pyroxene. Impact melt-grown pyroxene is commonly zoned from low-Ca pyroxene in cores to pigeonite and augite in rims. Metal-troilite orbs in the impact melt domain measure up to ~2 mm across. The cores of metal orbs in the impact melt domain contain ~7.9 wt% of Ni and are typically surrounded by taenite and Ni-rich troilite. The metallography of metal-troilite droplets suggest a stage I cooling rate of order 10 °C s-1 for the superheated impact melt. The subsolidus stage II cooling rate for the impact melt breccia could not be determined directly, but was presumably fast. An analogy between the Ni rim gradients in metal of the Gao-Guenie impact melt breccia and the impact-melted H6 chondrite Orvinio suggests similar cooling rates, probably on the order of ~5000-40,000 °C yr-1. A simple model of conductive heat transfer shows that the Gao-Guenie impact melt breccia may have formed in a melt injection dike ~0.5-5 m in width, generated during a sizeable impact event on the H chondrite parent asteroid.

  20. The Gao-Guenie impact melt breccia—Sampling a rapidly cooled impact melt dike on an H chondrite asteroid?

    Science.gov (United States)

    Schmieder, Martin; Kring, David A.; Swindle, Timothy D.; Bond, Jade C.; Moore, Carleton B.

    2016-06-01

    The Gao-Guenie H5 chondrite that fell on Burkina Faso (March 1960) has portions that were impact-melted on an H chondrite asteroid at ~300 Ma and, through later impact events in space, sent into an Earth-crossing orbit. This article presents a petrographic and electron microprobe analysis of a representative sample of the Gao-Guenie impact melt breccia consisting of a chondritic clast domain, quenched melt in contact with chondritic clasts, and an igneous-textured impact melt domain. Olivine is predominantly Fo80-82. The clast domain contains low-Ca pyroxene. Impact melt-grown pyroxene is commonly zoned from low-Ca pyroxene in cores to pigeonite and augite in rims. Metal-troilite orbs in the impact melt domain measure up to ~2 mm across. The cores of metal orbs in the impact melt domain contain ~7.9 wt% of Ni and are typically surrounded by taenite and Ni-rich troilite. The metallography of metal-troilite droplets suggest a stage I cooling rate of order 10 °C s-1 for the superheated impact melt. The subsolidus stage II cooling rate for the impact melt breccia could not be determined directly, but was presumably fast. An analogy between the Ni rim gradients in metal of the Gao-Guenie impact melt breccia and the impact-melted H6 chondrite Orvinio suggests similar cooling rates, probably on the order of ~5000-40,000 °C yr-1. A simple model of conductive heat transfer shows that the Gao-Guenie impact melt breccia may have formed in a melt injection dike ~0.5-5 m in width, generated during a sizeable impact event on the H chondrite parent asteroid.

  1. 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.

  2. 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

  3. OBSERVATIONAL EVIDENCE FOR AN IMPACT ON THE MAIN-BELT ASTEROID (596) SCHEILA

    International Nuclear Information System (INIS)

    An unexpected outburst was observed around (596) Scheila in 2010 December. We observed (596) Scheila soon after the impact using ground-based telescopes. We succeeded in the detection of a faint linear tail after 2011 February, which provides a clue to determine the dust ejection date. It is found that the dust particles ranging from 0.1-1 μm to 100 μm were ejected into the interplanetary space impulsively on December 3.5 ±1.0 day. The ejecta mass was estimated to be (1.5-4.9)x108 kg, suggesting that an equivalent mass of a 500-800 m diameter crater was excavated by the event. We also found that the shape of the light curve changed after the impact event probably because fresh material was excavated around the impact site. We conclude that a decameter-sized asteroid collided with (596) Scheila only eight days before the discovery.

  4. The Active Asteroids

    CERN Document Server

    Jewitt, David; Agarwal, Jessica

    2015-01-01

    Some asteroids eject dust, producing transient, comet-like comae and tails; these are the active asteroids. The causes of activity in this newly-identified population are many and varied. They include impact ejection and disruption, rotational instabilities, electrostatic repulsion, radiation pressure sweeping, dehydration stresses and thermal fracture, in addition to the sublimation of asteroidal ice. These processes were either unsuspected or thought to lie beyond the realm of observation before the discovery of asteroid activity. Scientific interest in the active asteroids lies in their promise to open new avenues into the direct study of asteroid destruction, the production of interplanetary debris, the abundance of asteroid ice and the origin of terrestrial planet volatiles.

  5. 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.

  6. 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.

  7. Effects of asteroid and comet impacts on thermal environment and atmopsheric erosion

    Science.gov (United States)

    Wallemacq, Quentin; Gillmann, Cedric; Karatekin, Ozgur; Dehant, Veronique

    2016-04-01

    Asteroid and comet impacts have implications on the atmospheric and thermal evolution of terrestrial planets and hence on their habitability. They can affect the planetary evolution by eroding the mass of the atmosphere and by depositing energy at the surface. These effects depend on impactor and surface parameters, including composition, size, density and impactor velocity. In this study, we investigate the effects of impactors of various sizes on the environment and on the evolution of the mantle and atmosphere of terrestrial planets with a special emphasis on Mars. Models with different levels of complexity are used to explore the thermal effects and the atmospheric erosion ; They vary from semi-analytical models to fully coupled subsurface/atmosphere numerical codes. While small impactors with relatively small velocities have only local and time-limited effects, large impactors can create a strong thermal anomaly affecting both the crust and the mantle, which can trigger a change in the dynamic patterns of the mantle.

  8. A preliminary assessment of asteroid shapes produced by impact disruption and re-creation: Application to the AIDA target.

    Science.gov (United States)

    Barnouin, Olivier; Michel, Patrick; Richardson, Derek

    2016-04-01

    In order to understand the origin of the 65803 Didymos, the target of the Asteroid Impact and Deflection Assessment mission, and gain insights on the origin and evolution of the asteroid's162173 Ryugu and 101955 Bennu, we investigate systematically the shapes of all re-accumulated fragments produced by the catastrophic disruption of a parent body that is 1 km in diameter or larger. These new fragments eventually become new asteroids of the size that current sample-return missions plan to explore. We choose a range of impact conditions by varying the parent bodies' strength, size and porosity, and the velocity and size of the projectile. Impact conditions range from near the catastrophic threshold, usually designated by Q*, where half of the target's mass escapes, to far greater values above this threshold. Our numerical investigations of the catastrophic disruption, which are undertaken using an SPH hydrocode, include a model of fragmentation for porous materials. The gravitationally dominated phase of reaccumulation of our asteroids is computed using the N-body code pkdgrav. At sufficiently slow impact speeds in the N-body model, particles are permitted to stick, forming irregular, competent pieces that can gather into non-idealized rubble piles as a result of re-accumulation. Shape and spin information of re-accumulated bodies are thus preserved. Due to numerical expense, this first study uses what we call a hard-sphere model, rather than a soft-sphere spring and dashpot model. This latter model is more commonly used in granular flow simulations for which detailed treatment of the multicontact physics is needed, which is not the case here, and comes at the expense of much smaller timesteps. With the hard-sphere model, there are three supported collision outcomes for bonded aggregates: sticking on contact (to grow the aggregate); bouncing (computed for these generally non-central impacts); and fragmentation (wherein the particles involved become detached from

  9. Ejecta Cloud from a Kinetic Impact on the Secondary of a Binary Asteroid: I. Mechanical Environment and Dynamic Model

    CERN Document Server

    Yu, Yang; Schwartz, Stephen R; Naidu, Shantanu P; Benner, Lance A M

    2016-01-01

    An understanding of the post-impact dynamics of ejecta clouds are crucial to the planning of a kinetic impact mission to an asteroid, and also has great implications for the history of planetary formation. The purpose of this article to track the evolution of ejecta produced by AIDA mission, which targets for kinetic impact the secondary of near-Earth binary asteroid 65803 Didymos on 2022, and to feedback essential informations to AIDA's ongoing phase-A study. We present a detailed dynamic model for the simulation of an ejecta cloud from a binary asteroid that synthesizes all relevant forces based on a previous analysis of the mechanical environment. We apply our method to gain insight into the expected response of Didymos to the AIDA impact, including the subsequent evolution of debris and dust. The crater scaling relations from laboratory experiments are employed to approximate the distributions of ejecta mass and launching speed. The size composition of fragments is modeled with a power law fitted from obs...

  10. How selection and weighting of astrometric observations influence the impact probability. Asteroid (99942) Apophis case

    CERN Document Server

    Krolikowska, Malgorzata; Soltan, Andrzej M

    2009-01-01

    The aim is to show that in case of low probability of asteroid collision with Earth, the appropriate selection and weighing of the data are crucial for the impact investigation, and to analyze the impact possibilities using extensive numerical simulations. By means of the Monte Carlo special method a large number of ``clone'' orbits have been generated. A full range of orbital elements in the 6-dimensional parameter space, e.g. in the entire confidence region allowed by the observational material has been examined. On the basis of 1000 astrometric observations of (99942) Apophis, the best solution for the geocentric encounter distance of 6.065\\pm 0.081 R_{Earth} were derived for the close encounter with the Earth on April 13, 2029. The present uncertainties allow for the special configurations (``keyholes'') during these encounter which may lead to the very close encounters in the future approaches of Apophis. Two groups of keyholes are connected with the close encounter with the Earth in 2036 (within the min...

  11. P/2010 A2 LINEAR. I. An impact in the asteroid main belt

    Science.gov (United States)

    Hainaut, O. R.; Kleyna, J.; Sarid, G.; Hermalyn, B.; Zenn, A.; Meech, K. J.; Schultz, P. H.; Hsieh, H.; Trancho, G.; Pittichová, J.; Yang, B.

    2012-01-01

    Comet P/2010 A2 LINEAR is an object on an asteroidal orbit within the inner main belt, therefore a good candidate for membership with the main belt comet family. It was observed with several telescopes (ESO New Technology Telescope, La Silla, Chile; Gemini North, Mauna Kea, Hawaii; University of Hawaii 2.2 m, Mauna Kea, Hawaii) from 14 Jan. until 19 Feb. 2010 in order to characterize and monitor it and its very unusual dust tail, which appears almost fully detached from the nucleus; the head of the tail includes two narrow arcs forming a cross. No evolution was observed during the span of the observations. Observations obtained during the Earth orbital plane crossing allowed an examination of the out-of-plane 3D structure of the tail. The immediate surroundings of the nucleus were found dust-free, which allowed an estimate of the nucleus radius of 80-90 m, assuming an albedo p = 0.11 and a phase correction with G = 0.15 (values typical for S-type asteroids). A model of the thermal evolution indicates that such a small nucleus could not maintain any ice content for more than a few million years on its current orbit, ruling out ice sublimation dust ejection mechanism. Rotational spin-up and electrostatic dust levitations were also rejected, leaving an impact with a smaller body as the favoured hypothesis. This is further supported by the analysis of the tail structure. Finston-Probstein dynamical dust modelling indicates the tail was produced by a single burst of dust emission. More advanced models (described in detail in a companion paper), independently indicate that this burst populated a hollow cone with a half-opening angle α ~ 40° and with an ejection velocity vmax ~ 0.2 m s-1, where the small dust grains fill the observed tail, while the arcs are foreshortened sections of the burst cone. The dust grains in the tail are measured to have radii between a = 1-20 mm, with a differential size distribution proportional to a-3.44 ± 0.08. The dust contained in the

  12. Design concepts and options for the Thermal Infrared Imager (TIRI) as part of ESA's Asteroid Impact Mission.

    Science.gov (United States)

    Bowles, Neil; Calcutt, Simon; Licandro, Javier; Reyes, Marcos; Delbo, Marco; Donaldson Hanna, Kerri; Arnold, Jessica; Howe, Chris

    2016-04-01

    ESA's Asteroid Impact Mission (AIM) is being studied as part of the joint ESA/NASA AIDA mission for launch in 2020. AIDA's primary mission is to investigate the effect of a kinetic impactor on the secondary component of the binary asteroid 65803 Didymos in late 2022. AIM will characterise the Didymos system and monitor the response of the binary system to the impact. A multi-spectral, thermal-infrared imaging instrument (TIRI) will be an essential component of AIM's remote sensing payload, as it will provide key information on the nature of the surfaces (e.g. presence or absence of materials, degree of compaction, and rock abundance of the regolith) of both components in the Didymos system. The temperature maps provided by TIRI will be important for navigation and spacecraft health and safety for proximity/lander operations. By measuring the asteroids' diurnal thermal responses (thermal inertia) and their surface compositions via spectral signatures, TIRI will provide information on the origin and evolution of the binary system. In this presentation we will discuss possible instrument design for TIRI, exploring options that include imaging spectroscopy to broadband imaging. By using thermal models and compositional analogues of the Didymos system we will show how the performance of each design option compares to the wider scientific goals of the AIDA/AIM mission.

  13. Threat Mitigation: The Asteroid Tugboat

    CERN Document Server

    Schweickart, R; Durda, D; Hut, P; Chapman, Clark; Durda, Dan; Hut, Piet; Schweickart, Russell

    2006-01-01

    The Asteroid Tugboat (AT) is a fully controlled asteroid deflection concept using a robotic spacecraft powered by a high efficiency, electric propulsion system (ion or plasma) which docks with and attaches to the asteroid, conducts preliminary operations, and then thrusts continuously parallel to the asteroid velocity vector until the desired velocity change is achieved. Based on early warning, provided by ground tracking and orbit prediction, it would be deployed a decade or more prior to a potential impact. On completion of the initial rendezvous with the near-Earth object (NEO) the AT would first reduce the uncertainty in the orbit of the asteroid via Earth tracking of its radio transponder while it is station keeping with the asteroid. If on analysis of tracking data a deflection is required the AT would execute a reconnaissance phase collecting and processing information about the physical characteristics of the asteroid to support subsequent operations. The AT would then dock at the appropriate pole (i....

  14. Asteroid 2007 WD5 will not impact Mars on January 30!

    OpenAIRE

    Krolikowska, Malgorzata; Sitarski, Grzegorz

    2008-01-01

    The Monte Carlo method of the nominal orbit clonning was applied to the case of 2007 WD5, the asteroid from the Apollo group. Calculations based on 33 observations from the time interval of 2007 11 08 - 2008 01 02 showed that the asteroid will pass near planet Mars at the minimum distance of 10.9\\pm 2.9 R_{Mars}, what implies that probability that 2007 WD5 strike the planet decreased to the value of 0.03% from the value of about 3--4% previously announced by NASA. The additional observations ...

  15. The small binary asteroid (939) Isberga

    Czech Academy of Sciences Publication Activity Database

    Carry, B.; Matter, A.; Scheirich, Peter; Pravec, Petr; Molnar, L.; Mottola, S.; Carbognani, A.; Jehin, E.; Marciniak, A.; Binzel, R. P.; DeMeo, E.F.; Birlan, M.; Delbó, M.; Barbotin, E.; Behrend, R.; Bonnardeau, M.; Colas, F.; Farissier, P.; Fauvaud, M.; Fauvaud, S.; Gillier, C.; Gillon, M.; Hellmich, S.; Hirsch, R.; Leroy, A.; Manfroid, J.; Montier, J.; Morelle, E.; Richard, F.; Sobkowiak, K.; Strajnic, J.; Vachier, F.

    2015-01-01

    Roč. 248, March (2015), s. 516-525. ISSN 0019-1035 Institutional support: RVO:67985815 Keywords : asteroids * dynamics * satellites of asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.038, year: 2014

  16. Dynamics of ejecta from a binary asteroid impact in the framework of the AIDA mission: a NEOShield-2 contribution

    Science.gov (United States)

    Yu, Y.; Schwartz, S. R.; Michel, P.; Benner, L. A. M.

    2015-10-01

    The dynamics of the ejecta cloud that results from a binary asteroid impact is one of the tasks of the NEOShield-2 project, funded by the European Commission in its program Horizon 2020. Results from such an investigation will have great relevance to the Phase-A study of the AIDA space mission, a collaborative effort between ESA and NASA, which aims to perform a kinetic impactor demonstration. Our study presents a multi-scale dynamical model of the ejecta cloud produced by a hypervelocity impact, which enables us to check the behaviors of the ejecta at different spatial and time scales. This model is applied to the impact into the small moon of the binary Near- Earth asteroid (65803) Didymos on October 2022 as considered by the AIDA mission. We attempt to model the process by including as much practical information as possible, e.g., the gravitational environment influenced by the non-spherical shapes of the bodies based on observed shape of the primary), the solar tides, and the solar radiation pressure. Our simulations show the general patterns of motion of the ejecta cloud, which we use to assess the potential hazard to an observing spacecraft. We also look into the grain-scale dynamics of the ejecta during this process, which has influence on the re-accumulation of particles orbiting in the vicinity.

  17. 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.

  18. Impact of photonic crystals on LED light extraction efficiency: approaches and limits to vertical structure designs

    International Nuclear Information System (INIS)

    The enhancement of the extraction efficiency in light emitting diodes (LEDs) through the use of photonic crystals (PhCs) requires a structure design that optimizes the interaction of the guided modes with the PhCs. The main optimization parameters are related to the vertical structure of the LED, such as the thickness of layers, depth of the PhCs, position of the quantum wells as well as the PhC period and fill factor. We review the impact of the vertical design of different approaches of PhC LEDs through a theoretical and experimental standpoint, assessing quantitatively the competing mechanisms that act over each guided mode. Three approaches are described to overcome the main limitation of LEDs with surface PhCs, i.e. the insufficient interaction of low order guided modes with the PhCs. The introduction of an AlGaN confining layer in such structure is shown to be effective in extracting a fraction of the optical energy of low order modes; however, this approach is limited by the growth of the lattice mismatched AlGaN layer on GaN. The second approach, based on thin-film LEDs with PhCs, is limited by the presence of an absorbing reflective metal layer close to the guided modes that plays a major role in the competition between PhC extraction and metal dissipation. Finally, we demonstrate both experimentally and theoretically the superior extraction of the guided light in embedded PhC LEDs due to the higher interaction between all optical modes and the PhCs, which resulted in a close to unity extraction efficiency for this device. The use of high-resolution angle-resolved measurements to experimentally determine the PhC extraction parameters was an essential tool for corroborating the theoretical models and quantifying the competing absorption and extraction mechanisms in LEDs.

  19. 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.

  20. Asteroid taxonomy

    Science.gov (United States)

    Tholen, David J.; Barucci, M. Antonietta

    1989-01-01

    The spectral reflectivity of asteroid surfaces over the wavelength range of 0.3 to 1.1 micron can be used to classify these objects into several broad groups with similar spectral characteristics. The three most recently developed taxonomies group the asteroids into 9, 11, or 14 different clases, depending on the technique used to perform the analysis. The distribution of the taxonomic classes shows that darker and redder objects become more dominant at larger heliocentric distances, while the rare asteroid types are found more frequently among the small objects of the planet-crossing population.

  1. Asteroid Kinetic Impactor Missions

    Science.gov (United States)

    Chesley, Steven

    2015-08-01

    Asteroid impact missions can be carried out as a relatively low-cost add-ons to most asteroid rendezvous missions and such impact experiments have tremendous potential, both scientifically and in the arena of planetary defense.The science returns from an impactor demonstration begin with the documentation of the global effects of the impact, such as changes in orbit and rotation state, the creation and dissipation of an ejecta plume and debris disk, and morphological changes across the body due to the transmission of seismic waves, which might induce landslides and toppling of boulders, etc. At a local level, an inspection of the impact crater and ejecta blanket reveals critical material strength information, as well as spectral differences between the surface and subsurface material.From the planetary defense perspective, an impact demonstration will prove humankind’s capacity to alter the orbit of a potentially threatening asteroid. This technological leap comes in two parts. First, terminal guidance systems that can deliver an impactor with small errors relative to the ~100-200 meter size of a likely impactor have yet to be demonstrated in a deep space environment. Second, the response of an asteroid to such an impact is only understood theoretically due to the potentially significant dependence on the momentum carried by escaping ejecta, which would tend to enhance the deflection by tens of percent and perhaps as much as a factor of a few. A lack of validated understanding of momentum enhancement is a significant obstacle in properly sizing a real-world impactor deflection mission.This presentation will describe the drivers for asteroid impact demonstrations and cover the range of such concepts, starting with ESA’s pioneering Don Quijote mission concept and leading to a brief description of concepts under study at the present time, including the OSIRIS-REx/ISIS, BASiX/KIX and AIM/DART (AIDA) concepts.

  2. 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.

  3. Ballistic transport in InGaN-based LEDs: impact on efficiency

    International Nuclear Information System (INIS)

    Heterojunction light-emitting diodes (LEDs) based on the InGaN/GaN system have improved considerably but still suffer from efficiency degradation at high injection levels which unless overcome would aggravate LED lighting. Although Auger recombination has been proposed as the genesis of the efficiency degradation, it appears that the premise of electron overflow and non-uniform distribution of carriers in the active region being the immediate impediment is gaining popularity. The lack of temperature sensitivity and sizeable impact of the barrier height provided by an electron blocking layer and the electron cooling layer prior to electron injection into the active region suggest that the new concept of hot electrons and ballistic/quasi-ballistic transport be invoked to account for the electron overflow. The electron overflow siphons off the electrons before they can participate in the recombination process. If the electrons are made to remain in the active region e.g. by cooling them prior to injection and/or blocking the overflow by an electron blocking layer, they would have to either recombine, radiatively or nonradiatively (e.g. Shockley–Read–Hall and Auger), or accumulate in the active region. The essence of the proposed overflow model is in good agreement with the experimental electroluminescence data obtained for m-plane and c-plane LEDs with/without electron blocking layers and with/without staircase electron injectors

  4. Low-speed Impact Simulations into Regolith in Support of Asteroid Sampling Mechanism Design I.: Comparison with 1-g Experiments

    CERN Document Server

    Schwartz, Stephen R; Richardson, Derek C; Yano, Hajime

    2014-01-01

    This study is carried out in the framework of sample-return missions to asteroids that use a low-speed projectile as the primary component of its sampling mechanism (e.g., JAXA's Hayabusa and Hayabusa2 missions). We perform numerical simulations of such impacts into granular materials using different projectile shapes under Earth's gravity. We then compare the amounts of ejected mass obtained in our simulations against what was found in experiments that used similar setups, which allows us to validate our numerical approach. For the targets, we consider 2 different monodisperse grain-diameter sizes: 5 mm and 3 mm. The impact speed of the projectile is 11 m s$^{-1}$ directed downward, perpendicular to the surface of the targets. Using an implementation of the soft-sphere discrete element method (SSDEM) in the $N$-Body gravity tree code PKDGRAV, previously validated in the context of low-speed impacts into sintered glass bead agglomerates, we find a noticeable dependence of the amount of ejected mass on the pro...

  5. Asteroid Lightcurve Photometry

    Science.gov (United States)

    Harris, A. W.

    2004-05-01

    With the advent of modestly priced CCD cameras and computer controller and reduction software, amateurs can now do photometry on fainter targets than was possible even from large observatories only a decade or so ago. This has led to an explosion of lightcurve data that in turn has yielded rich results. We now have rotation periods for more than 1500 asteroids, extending down to objects only tens of meters in diameter, and well determined shapes and pole orientations of more than 100 objects. Among smaller asteroids, the dispersion in rotation rates ranges from minutes to months, with the slower ones mostly "tumbling," or in states of non-principal axis rotation. The fastest ones must be monolithic, as centrifugal force exceeds their gravity. But among those larger than a few hundred meters diameter, there is a "rotation barrier" at the rate where gravity and centrifugal force match, suggesting that most asteroids this large or larger are "rubble piles." The broad dispersion in spin rates, almost a bimodal distribution, has long been a mystery, but now appears likely to be due to thermal radiation torques from the randomly asymmetric shapes of small asteroids. This is a major paradigm shift from the past, where mutual collisions were considered to be the dominant (or only) evolutionary process affecting spins. Amateur observations have already contributed a great deal leading to this new view, and much remains to be done, providing abundant opportunities for amateur-professional collaborations.

  6. Maskelynite in asteroidal, lunar and planetary basaltic meteorites: An indicator of shock pressure during impact ejection from their parent bodies

    Science.gov (United States)

    Rubin, Alan E.

    2015-09-01

    Maskelynite is a diaplectic glass that forms from plagioclase at shock pressures of ∼20-30 GPa, depending on the Ca concentration. The proportion of maskelynite-rich samples in a basaltic meteorite group correlates with the parent-body escape velocity and serves as a shock indicator of launching conditions. For eucrites (basalts widely presumed to be from Vesta; vesc = 0.36 km s-1), ∼5% of the samples are maskelynite rich. For the Moon (vesc = 2.38 km s-1), ∼30% of basaltic meteorites are maskelynite rich. For Mars (vesc = 5.03 km s-1), ∼93% of basaltic meteorites are maskelynite rich. In contrast, literature data show that maskelynite is rare (∼1%) among mare basalts and basaltic fragments in Apollo 11, 12, 15 and 17 soils (which were never ejected from the Moon). Angrites are unbrecciated basaltic meteorites that are maskelynite free; they were ejected at low-to-moderate shock pressures from an asteroid smaller than Vesta. Because most impacts that eject materials from a large (⩾100 km) parent body are barely energetic enough to do that, a collision that has little more than the threshold energy required to eject a sample from Vesta will not be able to eject identical samples from the Moon or Mars. There must have been relatively few impacts, if any, that launched eucrites off their parent body that also imparted shock pressures of ∼20-30 GPa in the ejected rocks. More-energetic impacts were required to launch basalts off the Moon and Mars. On average, Vesta ejecta were subjected to lower shock pressures than lunar ejecta, and lunar ejecta were subjected to lower shock pressures than martian ejecta. H and LL ordinary chondrites have low percentages of shock-stage S5 maskelynite-bearing samples (∼1% and ∼4%, respectively), probably reflecting shock processes experienced by these rocks on their parent asteroids. In contrast, L chondrites have a relatively high proportion of samples containing maskelynite (∼11%), most likely a result of

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

    OpenAIRE

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

    2014-01-01

    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 cra...

  8. Scenarios of atmospheric mass evolution on Mars influenced by asteroid and comet impacts since the late Noachian

    Science.gov (United States)

    Pham, L. B. S.; Karatekin, Ö.

    2016-06-01

    Early in its history, Mars probably had a denser atmosphere and higher surface temperatures to sustain the presence of stable liquid water or saline solution at the surface. Impacts by asteroids and comets could affect the atmospheric evolution of a planet, by removing part of its atmosphere and by delivering into it material and volatiles. In this study we investigate the atmospheric loss and delivery of volatiles between the end of the Noachian and present, with the help of a semi-analytic model. Our results suggest that impacts alone can hardly remove a significant amount of atmospheric mass over this period. Contribution of additional factors such as outgassing and non-thermal escape processes cannot explain neither the presence of surface pressure larger than few hundreds of mbars 3.9 Gyr ago, unless parameter values outside of their expected range are considered. Based on extreme case scenarios, maximum surface pressures at the end of the Noachian, could be as much as 0.25 bar or 1.9 bar, with and without CO2 storage into carbonate reservoirs, respectively.

  9. Asteroid Satellites

    Science.gov (United States)

    Merline, W. J.

    2001-11-01

    Discovery and study of small satellites of asteroids or double asteroids can yield valuable information about the intrinsic properties of asteroids themselves and about their history and evolution. Determination of the orbits of these moons can provide precise masses of the primaries, and hence reliable estimates of the fundamental property of bulk density. This reveals much about the composition and structure of the primary and will allow us to make comparisons between, for example, asteroid taxonomic type and our inventory of meteorites. The nature and prevalence of these systems will also give clues as to the collisional environment in which they formed, and have further implications for the role of collisions in shaping our solar system. A decade ago, binary asteroids were more of a theoretical curiosity. In 1993, the Galileo spacecraft allowed the first undeniable detection of an asteroid moon, with the discovery of Dactyl, a small moon of Ida. Since that time, and particularly in the last year, the number of known binaries has risen dramatically. Previously odd-shaped and lobate near-Earth asteroids, observed by radar, have given way to signatures indicating, almost certainly, that at least four NEAs are binary systems. The tell-tale lightcurves of several other NEAs reveal a high likelihood of being double. Indications are that among the NEAs, there may be a binary frequency of several tens of percent. Among the main-belt asteroids, we now know of 6 confirmed binary systems, although their overall frequency is likely to be low, perhaps a few percent. The detections have largely come about because of significant advances in adaptive optics systems on large telescopes, which can now reduce the blurring of the Earth's atmosphere to compete with the spatial resolution of space-based imaging (which itself, via HST, is now contributing valuable observations). Most of these binary systems have similarities, but there are important exceptions. Searches among other

  10. Earth-crossing asteroids - New discoveries

    Science.gov (United States)

    Helin, E. F.

    1982-01-01

    An earth-crossing asteroid is an asteroid whose orbit will intersect the orbit of the earth as a result of secular perturbations. Astronomical observations have led to the discovery of 43 earth-crossing asteroids during the last fifty years. Nearly sixty percent of these were found in the decade 1971-1981. Noteworthy results of the last decade are discussed, taking into account the Aten asteroids, accidental rediscoveries, asteroids of possible cometary origin, candidates for rendezvous and sample return missions, and populations and collision rates with earth. The observed earth-crossing asteroids are listed in a table, and the orbits of earth, Mars, and four Atens projected on ecliptic plane are shown.

  11. Asteroid impact vs. Deccan eruptions: The origin of low magnetic susceptibility beds below the Cretaceous-Paleogene boundary revisited

    Science.gov (United States)

    Abrajevitch, Alexandra; Font, Eric; Florindo, Fabio; Roberts, Andrew P.

    2015-11-01

    The respective roles of an asteroid impact and Deccan Traps eruptions in biotic changes at the Cretaceous-Paleogene (K-Pg) boundary are still debated. In many shallow marine sediments from around the world, the K-Pg boundary is marked by a distinct clay layer that is often underlain by a several decimeter-thick low susceptibility zone. A previous study of the Gubbio section, Italy (Lowrie et al., 1990), attributed low magnetization intensity in this interval to post-depositional dissolution of ferrimagnetic minerals. Dissolution was thought to be a consequence of downward infiltration of reducing waters that resulted from rapid accumulation of organic matter produced by mass extinctions after the K-Pg event. We compare the magnetic properties of sediments from the Gubbio section with those of the Bidart section in southern France. The two sections are similar in their carbonate lithology and the presence of a boundary clay and low susceptibility zone. When compared to background Cretaceous sediments, the low susceptibility zone in both sections is marked by an absence of biogenic magnetite, a decrease in total ferrimagnetic mineral content, and a preferential loss of magnetite with respect to hematite - features that are consistent with reductive dissolution. However, unlike the Gubbio section, where the low susceptibility zone starts immediately below the boundary clay, the low susceptibility zone and the clay layer at Bidart are separated by a ∼4-cm carbonate interval that contains abundant biogenic magnetite. Such separation casts doubt on a causal link between the impact and sediment bleaching. More likely, the low susceptibility layer marks a different environmental event that preceded the impact. An episode of increased atmospheric and oceanic acidity associated with Deccan Traps volcanism that occurred well before the K-Pg impact is argued here to account for the distinct magnetic properties of the low susceptibility intervals.

  12. 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, Elizabeth A.; Fane, Michael; Smith, Douglas C.; Holmes, Jacob; Keller, Lindsay P.; Lindsay, Sean S.; Wooden, Diane H.; Cintala, Mark J.; Zolensky, Michael E.

    2015-11-01

    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-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 as

  13. Impact of extinction coefficient of phosphor on thermal load of color conversion elements of phosphor converted LEDs

    Institute of Scientific and Technical Information of China (English)

    F.P. Wenzl; G. Langer; J. Nicolics; P. Fulmek; C. Sommer; S. Schweitzer; W. Nemitz; P. Hartmann; P. Pachler; H. Hoschopf; F. Schrank

    2014-01-01

    Besides their direct impact on the respective correlated color temperature, the extinction coefficient and the quantum effi-ciency of the phosphor also have tremendous impact on the thermal load of the color conversion elements of phosphor converted LEDs under operation. Because of the low thermal conductivity of the silicone matrix in which the phosphor particles are typically embedded, the by far highest temperatures within the LED assembly are reached within the color conversion element. Based on a combined optical and thermal simulation procedure we show that in particular a larger value for the extinction coefficient might have a beneficial impact on the resulting thermal load.

  14. Asteroid science by Gaia

    Science.gov (United States)

    Muinonen, Karri; Cellino, Alberto; Dell Oro, Aldo; Tanga, Paolo; Delbo, Marco; Mignard, Francois; Thuillot, William; Berthier, Jerome; Carry, Benoit; Hestroffer, Daniel; Granvik, Mikael; Fedorets, Grigori

    2016-07-01

    Since the start of its regular observing program in summer 2014, the Gaia mission has carried out systematic photometric, spectrometric, and astrometric observations of asteroids. In total, the unique capabilities of Gaia allow for the collection of an extensive and homogeneous data set of some 350,000 asteroids down to the limiting magnitude of G = 20.7 mag. The Gaia performance remains excellent over the entire available brightness range. Starting from 2003, a working group of European asteroid scientists has explored the main capabilities of the mission, defining the expected scientific impact on Solar System science. These results have served as a basis for developing the Gaia data reduction pipeline, within the framework of the Data Processing and Analysis Consortium (DPAC). We describe the distribution of the existing and forecoming Gaia observations in space and time for different categories of objects. We illustrate the peculiar properties of each single observation, as these properties will affect the subsequent exploitation of the mission data. We will review the expected performances of Gaia, basically as a function of magnitude and proper motion of the sources. We will further focus on the areas that will benefit from complementary observational campaigns to improve the scientific return of the mission, and on the involvement of the planetary science community as a whole in the exploitation of the Gaia survey. We will thus describe the current and future opportunities for ground-based observers and forthcoming changes brought by Gaia in some observational approaches, such as stellar occultations by transneptunian objects and asteroids. We will show first results from the daily, short-term processing of Gaia data, all the way from the onboard data acquisition to the ground-based processing. We illustrate the tools developed to compute predictions of asteroid observations, we discuss the procedures implemented by the daily processing, and we illustrate

  15. Scenario-Led Habitat Modelling of Land Use Change Impacts on Key Species.

    Directory of Open Access Journals (Sweden)

    Matthew Geary

    Full Text Available Accurate predictions of the impacts of future land use change on species of conservation concern can help to inform policy-makers and improve conservation measures. If predictions are spatially explicit, predicted consequences of likely land use changes could be accessible to land managers at a scale relevant to their working landscape. We introduce a method, based on open source software, which integrates habitat suitability modelling with scenario-building, and illustrate its use by investigating the effects of alternative land use change scenarios on landscape suitability for black grouse Tetrao tetrix. Expert opinion was used to construct five near-future (twenty years scenarios for the 800 km2 study site in upland Scotland. For each scenario, the cover of different land use types was altered by 5-30% from 20 random starting locations and changes in habitat suitability assessed by projecting a MaxEnt suitability model onto each simulated landscape. A scenario converting grazed land to moorland and open forestry was the most beneficial for black grouse, and 'increased grazing' (the opposite conversion the most detrimental. Positioning of new landscape blocks was shown to be important in some situations. Increasing the area of open-canopy forestry caused a proportional decrease in suitability, but suitability gains for the 'reduced grazing' scenario were nonlinear. 'Scenario-led' landscape simulation models can be applied in assessments of the impacts of land use change both on individual species and also on diversity and community measures, or ecosystem services. A next step would be to include landscape configuration more explicitly in the simulation models, both to make them more realistic, and to examine the effects of habitat placement more thoroughly. In this example, the recommended policy would be incentives on grazing reduction to benefit black grouse.

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

    International Nuclear Information System (INIS)

    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 at 30 km/sec demonstrate that from 12 to 15% of the bolide energy resides in the water. In the gravity field of the earth some 10 to 30 times the impactor mass of water is launched on trajectories which would take it to altitudes of 10 km or higher. This ejecta launched on trajectories which can achieve stratospheric heights is 101 to 102 projectile masses, similar to that resulting from impact of objects on an ocean-free silicate half-space (continent). Ejecta composed of impactor material, launched on trajectories which would carry it to stratospheric heights, matches the fraction (10-2 to 10-1) of bolide (extraterrestrial) material found in the platinum-metal-rich Cretaceous-Tertiary and Eocene-Oligocene boundary layers. Oceanic impact results in giant tsunamis initially having amplitudes of approx. 4 km, representing the solitary waterwave stability limit in the deep ocean, and containing 10-2 to 10-1 of the energy of the impact. Using the constraint of no observed turbidities in marine sediments in the Cretaceous-Tertiary and Eocene-Oligocene boundary materials (calculated maximum water-sediment interface particle velocity approx. 100 m/sec) implies a maximum impactor energy of approx. 1028 to approx. 1029 erg corresponding to a maximum diameter for a silicate impactor of approx. 2 km (at 11 km/sec). Minimal global tsunami run-up heights on the continents corresponding to impacts of this energy are 300-400 m. We speculate that such waves would inundate all low altitude continental areas. As a result, the terrestrial animal food chain would be seriously perturbed, which could have caused extinction of large terrestrial animals

  17. 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.

  18. Formation of the Treysa quintet and the main-group pallasites by impact-generated processes in the IIIAB asteroid

    Science.gov (United States)

    Wasson, John T.

    2016-04-01

    Treysa and Delegate have compositions closely similar to those of IIIAB irons but plot above the IIIAB field on Ir-Au diagrams; for this reason they are designated anomalous members of IIIAB. All refractory siderophiles share this anomaly. Wasson () interpreted the large spread on IIIAB Ir-Au diagrams to result from melt-trapping and generated solid and liquid fractional crystallization tracks; almost all IIIAB irons fall between the tracks. In contrast, Treysa, Delegate, and three other irons (the Treysa quintet) plot beyond the liquid track. Ideal fractional crystallization cannot account for compositions that plot outside the region between the tracks. Possible explanations for the anomalous compositions of the Treysa quintet are that (1) these meteorites did not form in the IIIAB magma or (2) they formed by the mixing of early crystallized solids with a late liquid. The weight of the evidence including cosmic-ray ages favor the second explanation. Although this explanation can account for positions plotting above the liquid track, it requires special circumstances. The infalling blocks must be assimilated and the resulting melt must crystallize quickly into pockets small enough (track with most main-group pallasites (PMG), which may have also originated in the IIIAB body. It appears that Treysa, its relatives, and the PMG were formed in one or more impact events that mixed olivine and solid metal formed near the core-mantle boundary with nearby magma. It is then necessary to cool the melt rapidly; the best way to achieve rapid cooling is by heat exchange with cooler solids. That the Treysa quintet and the PMG can be explained by the same processes operating on late IIIAB magma supports the conclusion that PMG formed on the IIIAB parent asteroid.

  19. Selecting asteroids for a targeted spectroscopic survey

    CERN Document Server

    Oszkiewicz, D A; Tomov, T; Birlan, M; Geier, S; Penttilä, A; Polińska, M

    2014-01-01

    Asteroid spectroscopy reflects surface mineralogy. There are few thousand asteroids whose surfaces have been observed spectrally. Determining the surface properties of those objects is important for many practical and scientific applications, such as for example developing impact deflection strategies or studying history and evolution of the Solar System and planet formation. The aim of this study is to develop a pre-selection method that can be utilized in searching for asteroids of any taxonomic complex. The method could then be utilized im multiple applications such as searching for the missing V-types or looking for primitive asteroids. We used the Bayes Naive Classifier combined with observations obtained in the course of the Sloan Digital Sky Survey and the Wide-field Infrared Survey Explorer surveys as well as a database of asteroid phase curves for asteroids with known taxonomic type. Using the new classification method we have selected a number of possible V-type candidates. Some of the candidates we...

  20. 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.

  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. PMID:25796389

  2. Binary asteroid population. 1. Angular momentum content

    Czech Academy of Sciences Publication Activity Database

    Pravec, Petr; Harris, A. W.

    2007-01-01

    Roč. 190, č. 1 (2007), s. 250-259. ISSN 0019-1035 R&D Projects: GA ČR(CZ) GA205/05/0604 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * satellites of asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.869, year: 2007

  3. Tektite origin by hypervelocity asteroidal or cometary impact: The quest for the source craters

    Science.gov (United States)

    Koeberl, Christian

    Tektites are natural glasses that are chemically homogeneous, often spherically symmetrical objects several centimeters in size, and occur in four known strewn fields on the surface of the Earth: the North American, moldavite (or Central European), Ivory Coast, and Australasian strewn fields. Tektites found within such strewn fields are related to each other with respect to their petrological, physical, and chemical properties as well as their age. A theory of tektite origin needs to explain the similarity of tektites in respect to age and certain aspects of isotopic and chemical composition within one strewn field, as well as the variety of tektite materials present in each strewn field. In addition to tektites on land, microtektites (which are generally less than 1 mm in diameter) have been found in deep-sea cores. Tektites are classified into three groups: (1) normal or splash-form tektites, (2) aerodynamically shaped tektites, and (3) Muong Nong-type tektites (sometimes also called layered tektites). The aerodynamic ablation results from partial remelting of glass during atmospheric passage after it was ejected outside the terrestrial atmosphere and quenched from a hot liquid. Aerodynamically shaped tektites are known mainly from the Australasian strewn field where they occur as flanged-button australites. The shapes of splash-form tektites (spheres, droplets, teardrops, dumbbells, etc., or fragments thereof) are the result of the solidification of rotating liquids in the air or vacuum. Mainly due to chemical studies, it is now commonly accepted that tektites are the product of melting and quenching of terrestrial rocks during hypervelocity impact on the Earth. The chemistry of tektites is in many respects identical to the composition of upper crustal material.

  4. 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

  5. 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…

  6. Experimental study on the impact-induced seismic wave propagating through granular materials: Implications for a future asteroid mission

    Science.gov (United States)

    Yasui, M.; Matsumoto, E.; Arakawa, M.; Matsue, K.; Kobayashi, N.

    2014-07-01

    Introduction: A seismic wave survey is a direct method to investigate the sub-surface structures of solid bodies, so we measured and analyzed these seismic waves propagating through these interiors. Earthquake and Moonquake are the only two phenomena that have been observed to explore these interiors until now, while the future surveys on the other bodies, (solid planets and/or asteroids) are now planned. To complete a seismic wave survey during the mission period, an artificial method that activates the seismic wave is necessary and one candidate is a projectile collision on the target body. However, to utilize the artificial seismic wave generated on the target body, the relationship between the impact energy and the amplitude and the decay process of the seismic wave should be examined. If these relationships are clarified, we can estimate the required sensitivity of seismometers installed on the target body and the possible distance from the seismic origin measurable for the seismometer. Furthermore, if we can estimate the impact energy from the observed seismic wave, we expect to be able to estimate the impact flux of impactors that collided on the target body. McGarr et al. (1969) did impact experiments by using the lexan projectile and two targets, quartz sand and sand bonded by epoxy cement, at 0.8-7 km/s. They found a difference of seismic wave properties between the two targets, and calculated the conversion efficiency to discuss the capability of detection of seismic waves on the Moon. However, they did not examine the excitation and propagation properties of the seismic waves in detail. In this study, we carried out impact experiments in the laboratory to observe the seismic waves by accelerometers, and examined the effects of projectile properties on the excitation and propagation properties of the seismic waves. Experimental methods: We made impact experiments by using a one-stage gas gun at Kobe University. Projectiles were a polycarbonate cylinder

  7. Physics of crustal fracturing and chert dike formation triggered by asteroid impact, ˜3.26 Ga, Barberton greenstone belt, South Africa

    Science.gov (United States)

    Sleep, Norman H.; Lowe, Donald R.

    2014-04-01

    asteroid impacts, reflected in the presence of spherule beds in the 3.2-3.5 Ga Barberton greenstone belt (BGB), South Africa, generated extreme seismic waves. Spherule bed S2 provides a field example. It locally lies at the contact between the Onverwacht and Fig Tree Groups in the BGB, which formed as a result of the impact of asteroid (possibly 50 km diameter). Scaling calculations indicate that very strong seismic waves traveled several crater diameters from the impact site, where they widely damaged Onverwacht rocks over much of the BGB. Lithified sediments near the top of the Onverwacht Group failed with opening-mode fractures. The underlying volcanic sequence then failed with normal faults and opening-mode fractures. Surficial unlithified sediments liquefied and behaved as a fluid. These liquefied sediments and some impact-produced spherules-filled near-surface fractures, today represented by swarms of chert dikes. Strong impact-related tsunamis then swept the seafloor. P waves and Rayleigh waves from the impact greatly exceeded the amplitudes of typical earthquake waves. The duration of extreme shaking was also far longer, probably hundreds of seconds, than that from strong earthquakes. Dynamic strains of ˜10-3 occurred from the surface and downward throughout the lithosphere. Shaking weakened the Onverwacht volcanic edifice and the surface layers locally moved downhill from gravity accommodated by faults and open-mode fractures. Coast-parallel opening-mode fractures on the fore-arc coast of Chile, formed as a result of megathrust events, are the closest modern analogs. It is even conceivable that dynamic stresses throughout the lithosphere initiated subduction beneath the Onverwacht rocks.

  8. Asteroid breakup linked to the Great Ordovician Biodiversification Event

    Science.gov (United States)

    Schmitz, Birger; Harper, David A. T.; Peucker-Ehrenbrink, Bernhard; Stouge, Svend; Alwmark, Carl; Cronholm, Anders; Bergström, Stig M.; Tassinari, Mario; Xiaofeng, Wang

    2008-01-01

    The rise and diversification of shelled invertebrate life in the early Phanerozoic eon occurred in two major stages. During the first stage (termed as the Cambrian explosion), a large number of new phyla appeared over a short time interval ~540Myrago. Biodiversity at the family, genus and species level, however, remained low until the second stage marked by the Great Ordovician Biodiversification Event in the Middle Ordovician period. Although this event represents the most intense phase of species radiation during the Palaeozoic era and led to irreversible changes in the biological make-up of Earth's seafloors, the causes of this event remain elusive. Here, we show that the onset of the major phase of biodiversification ~470Myrago coincides with the disruption in the asteroid belt of the L-chondrite parent body-the largest documented asteroid breakup event during the past few billion years. The precise coincidence between these two events is established by bed-by-bed records of extraterrestrial chromite, osmium isotopes and invertebrate fossils in Middle Ordovician strata in Baltoscandia and China. We argue that frequent impacts on Earth of kilometre-sized asteroids-supported by abundant Middle Ordovician fossil meteorites and impact craters-accelerated the biodiversification process.

  9. 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.

  10. Delivery of meteorites from the asteroid belt

    Science.gov (United States)

    Nolan, Michael Craig

    The process of the delivery of meteorites to the surface of the Earth from plausible source regions such as the asteroid belt is currently understood in general terms, but important uncertainties and conflicts remain to be resolved. Stochastic effects of the rare disruptions of large asteroids on the population of meteorite-sized Earth-crossing asteroids can change the flux and the proportions of compositional types in the infalling meteorite population. These changes can be significant in magnitude over timescales of 108 years. Changes of the order of 1 percent can be expected on timescales of 105-106 y, consistent with small differences between the Antarctic meteorites and modern falls. The magnitude of changes depends strongly on poorly-understood details of collisions. Asteroids 961 Gaspra and 243 Ida were recently imaged by the Galileo spacecraft. I use a numerical hydrocode model to examine the outcomes of various sire impacts into targets the sizes of these asteroids. A shock wave fractures the asteroid in advance of crater excavation flow; thus, for impactors larger than 100 m, impacting at 5.3 km s-1, tensile strength is unimportant in these bodies, whether they are initially intact or are 'rubble piles'. Because of the shock-induced fracture, impact results are controlled by gravity. Therefore these asteroids are much more resistant to catastrophic disruption than predicted by previous estimates, which had assumed that strength was controlling these processes for rock targets. Fracture of km-size asteroids is different from fracture in terrestrial experiments using few-cm targets. The composition distribution of delivered meteorites depends on the outcomes of such asteroid impacts.

  11. 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

  12. 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.

  13. Exploring future hydrogen development and the impact of policy: A novel investment-led approach

    International Nuclear Information System (INIS)

    It is generally recognised that the primary tools being utilised today for hydrogen energy forecasting and policy development take a least-cost approach. While useful for comparing the viability of different technologies from a cost perspective, it is argued that these models fail to capture the potential value contribution such technologies could offer companies and, in consequence, the likelihood of their receiving investment. The authors propose a novel model for forecasting the deployment of hydrogen energy systems based on a company value maximisation approach designed to assist governments in the development of appropriate policy instruments. In this paper a theoretical relationship between market sector valuations and investment activity is presented using 3 value metrics, namely net present value (NPV), earnings per share (EPS) and sum of the parts (SOP). It is shown that, as the electricity and transport fuel markets begin to converge, examination of the effects of different policy measures through the value-led model can highlight otherwise hidden counter incentives. The model further recognises that the propensity to invest in hydrogen differs according to the characteristics of the company looking to make the investment and the implications for policy-makers regarding levels of support are also discussed in the paper. - Research highlights: → A novel approach to forecasting energy market development is proposed. → Approach based on analysis of value contribution of investment opportunities. → Model applied to the potential hydrogen energy market in Scotland. → Reveals potential inadequacy of assessing market development based on levelised cost alone. → Highlights relevance of investor company performance in assessing market development.

  14. 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.

  15. Working Group Reports and Presentations: Asteroids

    Science.gov (United States)

    Lewis, John

    2006-01-01

    The study and utilization of asteroids will be an economical way to enable exploration of the solar system and extend human presence in space. There are thousands of near-earth objects (NEOs) that we will be able to reach. They offer resources, transportation, and exploration platforms, but also present a potential threat to civilization. Asteroids play a catastrophic role in the history of the Earth. Geological records indicate a regular history of massive impacts, which astronomical observations confirm is likely to continue with potentially devastating consequences. However, study and exploration of near earth asteroids can significantly increase advanced warning of an Earth impact, and potentially lead to the technology necessary to avert such a collision. Efforts to detect and prevent cataclysmic events would tend to foster and likely require international cooperation toward a unified goal of self-preservation. Exploration of asteroids will help us to understand our history and perhaps save our future. Besides the obvious and compelling scientific and security drivers for asteroid research and exploration, there are numerous engineering and industrial applications for near-term asteroid exploration. We have strong evidence that some asteroids are metal rich. Some are water and organic rich. They can be reached with a very low fuel cost compared to other solar system destinations. Once we reach them, there are efficient, simple extraction technologies available that would facilitate utilization. In addition, the costs of returning extracted resources from asteroids will be a fraction of the cost to return similar resources from the moon to Low Earth Orbit (LEO). These raw materials, extracted and shipped at relatively low cost, can be used to manufacture structures, fuel, and products which could be used to foster mankind s further exploration of the solar system. Asteroids also have the potential to offer transport to several destinations in the solar system

  16. Spectral investigation of two asteroidal fireballs

    Czech Academy of Sciences Publication Activity Database

    Borovička, Jiří

    2006-01-01

    Roč. 97, 3-4 (2006), s. 279-293. ISSN 0167-9295. [Asteroids, Comets, Meteors 2005. Búzios, 07.08.2005-12.08.2005] R&D Projects: GA ČR GA205/05/0543; GA ČR GA205/03/1404 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * meteors * spectroscopy Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.252, year: 2006

  17. 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.

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

    DEFF Research Database (Denmark)

    Bager, Palle

    2014-01-01

    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....... Budget impact analysis (BIA) and cost-effectiveness analysis (CEA) were done. Furthermore, the staff evaluated the process. Almost 30% (n = 474) of the total cohort was enrolled in the service. Eighty-seven per cent of the patients welcomed the phone service beforehand. After implementation, 94% 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...

  19. The Cratering History of Asteroid (21) Lutetia

    CERN Document Server

    Marchi, S; Vincent, J -B; Morbidelli, A; Mottola, S; Marzari, F; Kueppers, M; Besse, S; Thomas, N; Barbieri, C; Naletto, G; Sierks, H

    2011-01-01

    The European Space Agency's Rosetta spacecraft passed by the main belt asteroid (21) Lutetia the 10th July 2010. With its ~100km size, Lutetia is one of the largest asteroids ever imaged by a spacecraft. During the flyby, the on-board OSIRIS imaging system acquired spectacular images of Lutetia's northern hemisphere revealing a complex surface scarred by numerous impact craters, reaching the maximum dimension of about 55km. In this paper, we assess the cratering history of the asteroid. For this purpose, we apply current models describing the formation and evolution of main belt asteroids, that provide the rate and velocity distributions of impactors. These models, coupled with appropriate crater scaling laws, allow us to interpret the observed crater size-frequency distribution (SFD) and constrain the cratering history. Thanks to this approach, we derive the crater retention age of several regions on Lutetia, namely the time lapsed since their formation or global surface reset. We also investigate the influe...

  20. 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.

  1. An overview of the asteroids

    Science.gov (United States)

    Binzel, Richard P.

    1989-01-01

    An introductory overview of the field of asteroid science is presented, with emphasis placed on the accomplishments of the 1980s. Following the survey of known asteroids, attention is given to the observations of asteroids with the IRAS. Particular consideration is given to the origin and evolution of asteroids and their interrelations. Possible future directions of asteroid research are discussed together with the potential of the Hubble Space Telescope for providing new data on asteroid surface chemistry, geology, structure, and morphology.

  2. Near Earth Asteroid Characteristics for Asteroid Threat Assessment

    Science.gov (United States)

    Dotson, J.; Wooden, D. H.; Bryson, K.; Ostrowski, D. R.

    2015-12-01

    Information about the physical characteristics of Near Earth Asteroids (NEAs) is needed to model behavior during atmospheric entry, to assess the risk of an impact, and to model possible mitigation techniques. The intrinsic properties of interest to entry and mitigation modelers, however, rarely are directly measureable. Instead we measure other properties and infer the intrinsic physical properties, so determining the complete set of characteristics of interest is far from straightforward. In addition, 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. We will provide an assessment of the current state of knowledge about the physical characteristics of importance to asteroid threat assessment. In addition, an ongoing effort to collate NEA characteristics into a readily accessible database for use by the planetary defense community will be discussed.

  3. LED wireless

    OpenAIRE

    Pang, G.; Kwan, T.; Liu, H; Chan, CH

    2002-01-01

    High-brightness light-emitting diodes (LEDs) are getting more popular and are opening up a number of new applications. In this paper, the novel idea based on the fast switching of LEDs and the modulation of visible light is developed into a new kind of information system. A visible-LED audio system that makes use of visual-light rays to transmit audio messages to a remotely located receiver is described. Such a system made up of high-brightness visible LEDs can provide the function of open sp...

  4. Photometric geodesy of main-belt asteroids. III. Additional lightcurves

    International Nuclear Information System (INIS)

    A total of 107 complete or partial lightcurves are presented for 59 different asteroids over the 1982-1989 period. Unusual lightcurves with unequal minima and maxima at large amplitudes are preferentially seen for M-type asteroids. Some asteroids, such as 16 Psyche and 201 Penelope, exhibit lightcurves combining large amplitude with very unequal brightness for both maxima and both minima, even at small phase angles. An M-type asteroid is believed to consist of a metal core of a differentiated parent body that has had its rocky mantle completely removed by one or more large impacts. 39 refs

  5. Photometric geodesy of main-belt asteroids. III - Additional lightcurves

    Science.gov (United States)

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

    1990-01-01

    A total of 107 complete or partial lightcurves are presented for 59 different asteroids over the 1982-1989 period. Unusual lightcurves with unequal minima and maxima at large amplitudes are preferentially seen for M-type asteroids. Some asteroids, such as 16 Psyche and 201 Penelope, exhibit lightcurves combining large amplitude with very unequal brightness for both maxima and both minima, even at small phase angles. An M-type asteroid is believed to consist of a metal core of a differentiated parent body that has had its rocky mantle completely removed by one or more large impacts.

  6. Asteroid rotation and orbit control via laser ablation

    Science.gov (United States)

    Vetrisano, Massimo; Colombo, Camilla; Vasile, Massimiliano

    2016-04-01

    This paper presents an approach to control the rotational motion of an asteroid while a spacecraft is deflecting its trajectory through laser ablation. During the deflection, the proximity motion of the spacecraft is coupled with the orbital and rotational motion of the asteroid. The combination of the deflection acceleration, solar radiation pressure, gravity field and plume impingement will force the spacecraft to drift away from the asteroid. In turn, a variation of the motion of the spacecraft produces a change in the modulus and direction of the deflection action which modifies the rotational and orbital motion of the asteroid. An on-board state estimation and control algorithm is then presented that simultaneously provides an optimal proximity control and a control of the rotational motion of the asteroid. It will be shown that the simultaneous control of the rotational and proximity motions of asteroid and spacecraft has a significant impact on the required deflection time.

  7. The impact of aid chains: relations of dependence or supportive partnerships for community-led responses to HIV/AIDS?

    Science.gov (United States)

    Aveling, E L

    2010-01-01

    In the context of increasing global emphasis on partnerships between international, governmental and civil society organisations in the distribution of international aid, this paper examines the ways in which the resulting aid chains promote and undermine community-led responses to HIV/AIDS. The impact of the aid-granting system is examined using an ethnographic case study of an HIV/AIDS prevention programme with Cambodian military families. The case study draws on observations of stakeholder meetings and programme activities, interviews with stakeholders (the donor, NGOs and military community) and textual materials (programme guidelines, policies and reports). Campbell et al.'s interrelated concepts of relational, symbolic and material context are used to frame the analysis. The establishment of a relationship with a more powerful international NGO is shown to be beneficial to the military community and civil society groups. The international NGO uses its significant material and economic leverage to improve the community's relational context (by ensuring the support of the military high command), symbolic context (by strengthening the position of community and civil society partners in relation to government bodies) and material context (through increasing access to health services). However, material and symbolic asymmetries between partners in the aid chain persist, curtailing the community's involvement and leadership. At the material and relational levels, the hierarchical flow of aid encourages accountability to the demands of the donor while excluding grassroots groups from directly accessing funding. At the symbolic level, problem-focused representations of the military further reinforce the community's position as recipients of intervention, which undermines recognition for the community's knowledge, strengths and right to fully participate. Thus while aid chains can be supportive of community-led responses, this analysis highlights how the structures

  8. The thermal impact of phototherapy with concurrent super-pulsed lasers and red and infrared LEDs on human skin.

    Science.gov (United States)

    Grandinétti, Vanessa dos Santos; Miranda, Eduardo Foschini; Johnson, Douglas Scott; de Paiva, Paulo Roberto Vicente; Tomazoni, Shaiane Silva; Vanin, Adriane Aver; Albuquerque-Pontes, Gianna Móes; Frigo, Lucio; Marcos, Rodrigo Labat; de Carvalho, Paulo de Tarso Camillo; Leal-Junior, Ernesto Cesar Pinto

    2015-07-01

    From the very first reports describing the method of action of phototherapy, the effects have been considered to be the result of photochemical and photophysical interactions between the absorbed photons and tissue and not related to secondary changes in tissue or skin temperature. However, thermal effects have been recently reported in dark pigmented skin when irradiated with single wavelengths of 810 and 904 nm of low-level laser therapy (LLLT) devices even with doses that do not exceed those recommended by the World Association of Laser Therapy (WALT). The aim of this study was to evaluate the thermal impact during the concurrent use of pulsed red and infrared LEDs and super-pulsed lasers when applied to light, medium, and dark pigmented human skin with doses typically seen in clinical practice. The study evaluated the skin temperature of 42 healthy volunteers (males and females 18 years or older, who presented different pigmentations, stratified according to Von Luschan's chromatic scale) via the use of a thermographic camera. Active irradiation was performed with using the multi-diode phototherapy cluster containing four 905-nm super-pulsed laser diodes (frequency set to 250 Hz), four 875-nm infrared-emitting diodes, and four 640-nm LEDs (manufactured by Multi Radiance Medical™, Solon, OH, USA). Each of the four doses were tested on each subject: placebo, 0 J (60 s); 10 J (76 s); 30 J (228 s); and 50 J (380 s). Data were collected during the last 5 s of each dose of irradiation and continued for 1 min after the end of each irradiation. No significant skin temperature increases were observed among the different skin color groups (p > 0.05), age groups (p > 0.05), or gender groups (p > 0.05). Our results indicate that the concurrent use of super-pulsed lasers and pulsed red and infrared LEDs can be utilized in patients with all types of skin pigmentation without concern over safety or excessive tissue heating. Additionally, the doses

  9. 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

  10. Asteroid secular dynamics: Ceres' fingerprint identified

    CERN Document Server

    Novaković, Bojan; Tsirvoulis, Georgios; Knezević, Zoran

    2015-01-01

    Here we report on the significant role of a so far overlooked dynamical aspect, namely a secular resonance between the dwarf planet Ceres and other asteroids. We demonstrate that this type of secular resonance can be the dominant dynamical factor in certain regions of the main asteroid belt. Specifically, we performed a dynamical analysis of the asteroids belonging to the (1726) Hoffmeister family. To identify which dynamical mechanisms are actually at work in this part of the main asteroid belt, i.e. to isolate the main perturber(s), we study the evolution of this family in time. The study is accomplished using numerical integrations of test particles performed within different dynamical models. The obtained results reveal that the post-impact evolution of the Hoffmeister asteroid family is a direct consequence of the nodal secular resonance with Ceres. This leads us to the conclusion that similar effects must exist in other parts of the asteroid belt. In this respect, the obtained results shed light on an i...

  11. Modeling of Asteroid Shapes

    CERN Document Server

    Kokorev, Andrii

    2016-01-01

    In this article we consider different methods of modeling asteroid shapes, especially lightcurve inversion technique, and scattering laws used for it. We also introduce our program, which constructs lightcurves for a given asteroid shape model. It can be used to comparing shape model with observational data.

  12. Polarimetric properties of asteroids

    Science.gov (United States)

    Shestopalov, D. I.; Golubeva, L. F.

    2015-11-01

    Quite frequently astronomic polarimetric observations of different celestial bodies do not guarantee a proper phase angle coverage that is required for estimating all of the attributes of their polarization phase curves with a high accuracy. To approximate the phase dependences of polarization observed for particulate surfaces, we use a simple empiric formula recently suggested by Shestopalov (2004). The efficiency of the approximating function in a wide range of phase angles is illustrated with the use of the results of polarimetric measurements of lunar areas, lunar samples, and near-Earth asteroids. For asteroids of various types, we can reproduce their negative polarization branches with adequate accuracy and roughly estimate a probable value of the maximum polarization degree at an appropriate phase angle. From the polarimetric database available at NASA PDS [Asteroid Polarimetric Database V7.0 (2012)] we calculated the main parameters of 153 polarimetric curves of asteroids in various spectral bands with the accuracy comparable to the observation errors. One more purpose of our analysis was to find correlations between the polarimetric and photometric properties of asteroids. For C-, M-, S-, E-type asteroids, the characteristics of the negative branch of polarization curves turned out to correlate closely with the phase coefficient of the photometric function of asteroids and the photometric roughness of asteroid surfaces. This implies that the complex geometry of the surface microrelief affects the polarization properties of asteroids. In particular, the data scattering around regression lines on the plots of the albedo versus the depth of negative polarization branch and the slope of the polarimetric function at inversion angle strongly depends on the differences in the photometric roughness of asteroid surfaces.

  13. Geodynamic stability of the primary in the binary asteroid system 65803 Didymos

    Science.gov (United States)

    Barnouin, Olivier S.; Maurel, Clara; Richardson, Derek C.; Ballouz, Ronald-Louis; Schwartz, Stephen; Michel, Patrick

    2015-11-01

    The moon of the near-Earth binary asteroid 65803 Didymos is the target of the Asteroid Impact and Deflection Assessment (AIDA) mission. This mission is a joint concept between NASA and ESA to investigate the effectiveness of a kinetic impactor in deflecting an asteroid. The mission is composed of two components: the NASA-led Double Asteroid Redirect Test (DART) that will impact the Didymos moon, and the ESA-led Asteroid Impact Monitoring (AIM) mission that will characterize the Didymos system. In order to provide AIDA constraints on the physical character of the both objects in this binary system, we undertook preliminary numerical investigations to evaluate the stability of the shape of the primary using its rapid 2.26 h rotation. We modeled the primary as a rubble pile. Each model consisted of thousands of uniform rigid spheres collapsed together under their own gravity to form a spherical pile that was then carved to match the current radar-derived shape model of the primary, as well as other comparable shapes (e.g. asteroid 1999 KW4, spheres) that were scaled to match best estimates of the size of Didymos. Each model was given a starting rotation period of 6 h with the spin axis aligned to the pole. At each timestep the spin rate was increased by a small amount so that after about 1 million timesteps the spin would match the observed rotation of 2.26 h. We tested a range of bulk densities spanning the current observational uncertainty (mean 2.4 g/cc) using "gravel"-like material parameters that provide significant resistance to sliding and rolling. We find that at the upper range of the density uncertainty it is possible for Didymos to hold its shape and not lose mass at its nominal rotation period, without the need for cohesive forces. At lower densities or with smoother particles, significant shape change occurs and mass loss is possible. We conclude that based on the radar shape available at the time of this writing, Didymos is marginally stable as a rubble

  14. Small asteroid fragments in earth-crossing orbits

    Science.gov (United States)

    Duha, J.; Afonso, G. B.

    2014-10-01

    The meteorite that fell in Chelyabinsk, Russia, naturally made many people think it could be a smaller companion of the Asteroid 2012 DA14, which passed close to Earth on that same day. Some asteroid specialists discarded this hypothesis for two main reasons: The meteorite was too far away from the asteroid, because the collision happened sixteen hours before the asteroid passed close to Earth. Moreover, it was not traveling, similarly to asteroid DA14, from south to north. However the possibility of the meteorite being a companion of the Asteroid 2012 DA14 cannot be completely discarded. The Asteroid 2012 DA14, with a diameter of 45 meters, is very small. It can be considered an asteroids fragment, which is usually accompanied by other smaller fragments, scattered in space, practically in the same orbit and possibly being separated from each other by long distances. Assuming that 2012 DA14 is not an isolated asteroid, but the biggest remaining fragment from a previous impact, we developed a model to study the dynamics of an asteroid fragment, similar to DA14, and its companions, the smaller fragments. This dynamically interesting encounter with planet Earth is addressed and the orbital changes that could explain the Chelyabinsk event are discussed. As a result we find that, there could be a collision of a meteorite before, during, or after the Asteroid 2012 DA14 passing by, the same way that happens with meteorite showers, which can last several days. Therefore, it would be very interesting to look for asteroid fragments also, close to the larger fragments, more easily found.

  15. Asteroid Family Physical Properties

    CERN Document Server

    Masiero, Joseph; Kasuga, Toshihiro; Parker, Alex H

    2015-01-01

    An asteroid family is typically formed when a larger parent body undergoes a catastrophic collisional disruption, and as such family members are expected to show physical properties that closely trace the composition and mineralogical evolution of the parent. Recently a number of new datasets have been released that probe the physical properties of a large number of asteroids, many of which are members of identified families. We review these data sets and the composite properties of asteroid families derived from this plethora of new data. We also discuss the limitations of the current data, and the open questions in the field.

  16. 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

  17. LED lamp

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Asteroid Photometry: Tricky Business

    Science.gov (United States)

    Menke, J.

    2005-05-01

    Two nagging issues (among others) that tend to afflict asteroid photometrists (and others) are (1) concerns about just what a Flat is doing (and whether it makes things better or worse), and (2) how to handle those pesky stars that keep jumping into the path of the asteroid as it cruises across the field of view (FOV) using StarZap, a program written to subtract the offending stars. We'll discuss experiments done to get a handle on these two issues.

  19. 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.

  20. Impact of a Teacher-Led Intervention on Preference for Self-Regulated Learning, Finding Main Ideas in Expository Texts, and Reading Comprehension

    Science.gov (United States)

    Stoeger, Heidrun; Sontag, Christine; Ziegler, Albert

    2014-01-01

    We examined the impact of a teacher-led intervention, implemented during regular classroom instruction and homework, on fourth-grade students' preference for self-regulated learning, finding main ideas in expository texts, and reading comprehension. In our quasi-experimental study with intact classrooms, (a) students (n = 266, 12 classrooms) who…

  1. The 3.26-3.24 Ga Barberton asteroid impact cluster: Tests of tectonic and magmatic consequences, Pilbara Craton, Western Australia

    Science.gov (United States)

    Glikson, Andrew; Vickers, John

    2006-01-01

    The location in the Barberton Greenstone Belt (Kaapvaal Craton) of ∼3.26-3.24 Ga asteroid impact ejecta units at, and immediately above, a sharp break between a > 12 km-thick mafic-ultramafic volcanic crust (Onverwacht Group ∼3.55-3.26 Ga, including the ∼3.298 > 3.258 Ga Mendon Formation) and a turbidite-felsic volcanic rift-facies association (Fig Tree Group ∼3.258-3.225 Ga), potentially represents the first documented example of cause-effect relations between extraterrestrial bombardment and major tectonic and igneous events [D.R. Lowe, G.R. Byerly, F. Asaro, F.T. Kyte, Geological and geochemical record of 3400 Ma old terrestrial meteorite impacts, Science 245 (1989) 959-962; D.R. Lowe, G.R. Byerly, F.T. Kyte, A. Shukolyukov, F. Asaro, A. Krull, Spherule beds 3.47-3.34 Ga-old in the Barberton greenstone belt, South Africa: a record of large meteorite impacts and their influence on early crustal and biological evolution, Astrobiology 3 (2003) 7-48; A.Y. Glikson, The astronomical connection of terrestrial evolution: crustal effects of post-3.8 Ga mega-impact clusters and evidence for major 3.2 ± 0.1 Ga bombardment of the Earth-Moon system, J. Geodyn. 32 (2001) 205-229]. Here we correlate this boundary with a contemporaneous break and peak magmatic and faulting events in the Pilbara Craton, represented by the truncation of a 3.255-3.235 Ga-old volcanic sequence (Sulphur Springs Group-SSG) by a turbidite-banded iron formation-felsic volcanic association (Pincunah Hill Formation, basal Gorge Creek Group). These events are accompanied by ∼3.252-3.235 Ga granitoids (Cleland plutonic suite). The top of the komatiite-tholeiite-rhyolite sequence of the SSG is associated with a marker chert defined at 3.238 ± 3-3.235 ± 3 Ga, abruptly overlain by an olistostrome consisting of mega-clasts of felsic volcanics, chert and siltstone up to 250 × 150 m-large, intercalated with siliciclastic sedimentary rocks and felsic volcanics (Pincunah Hill Formation-basal Gorge

  2. Thermal and Impact History of the H Chondrite Parent Asteroid during Metamorphism: Constraints from Metallic Fe-Ni

    CERN Document Server

    Scott, Edward R D; Goldstein, Joseph I; Wakita, Shigeru

    2014-01-01

    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 Ar-Ar ages greater than 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 to 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, St...

  3. 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...

  4. Threat Mitigation: The Asteroid Tugboat

    OpenAIRE

    Schweickart, Russell; Chapman, Clark; Durda, Dan; Hut, Piet

    2006-01-01

    The Asteroid Tugboat (AT) is a fully controlled asteroid deflection concept using a robotic spacecraft powered by a high efficiency, electric propulsion system (ion or plasma) which docks with and attaches to the asteroid, conducts preliminary operations, and then thrusts continuously parallel to the asteroid velocity vector until the desired velocity change is achieved. Based on early warning, provided by ground tracking and orbit prediction, it would be deployed a decade or more prior to a ...

  5. Spectral study of the Eunomia asteroid family. I. Eunomia

    Science.gov (United States)

    Nathues, Andreas; Mottola, Stefano; Kaasalainen, Mikko; Neukum, Gerhard

    2005-06-01

    We present color ratio curves of the S-Asteroid 15 Eunomia, which have been extracted from high-precision photometric lightcurves obtained in three different VNIR wavelength bands at the Bochum Telescope, La Silla. The measured color ratio curves and near infrared spectra were used to derive a detailed surface composition model whose shape has been computed by V-lightcurve inversions. According to this analysis, the asteroid shows on one hemisphere a higher concentration of pyroxene, which causes an increased 440/700 nm and a reduced 940/700 nm reflectance ratio as well as a pronounced 2-μm absorption band. The remaining surface shows a higher concentration of olivine, leading to a reduced 440/700 nm and slightly increased 940/700 nm color ratio. In addition, we found that the maximum of the 440/700 nm color ratio curve coincide with the minimum of the 940/700 nm color ratio curve and vice versa. We demonstrate on the basis of USGS laboratory spectra that this anti-cyclical behavior can be explained by choosing Fe-rich olivine and a pyroxene with moderate Fe content as varying mineral phases. Furthermore, our observations confirm that 15 Eunomia is an irregular elongated and at least partially differentiated body. Previous spectral investigations of several smaller fragments of the Eunomia asteroid family revealed that the amount of fragments showing an increased pyroxene content exceeds the amount of pyroxene-poor fragments (Nathues, 2000, DLR Forschungsbericht, ISSN 1434-8454). This finding together with the observation that the major fraction of Eunomia's surface is enriched in olivine let us claim that a large fraction of the original pyroxene-enriched crust layer has been lost due to a major collision that created the Eunomia asteroid family. Significant spectral evidences, consistent with high concentrations of metals have been found neither in the rotational resolved spectra of 15 Eunomia nor in its fragments. This led to the conclusion that either no core

  6. 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.

  7. Eight billion asteroids in the Oort cloud

    CERN Document Server

    Shannon, Andrew; Veras, Dimitri; Wyatt, Mark

    2014-01-01

    The Oort cloud is usually thought of as a collection of icy comets inhabiting the outer reaches of the Solar system, but this picture is incomplete. We use simulations of the formation of the Oort cloud to show that ~4% of the small bodies in the Oort cloud should have formed within 2.5 au of the Sun, and hence be ice-free rock-iron bodies. If we assume these Oort cloud asteroids have the same size distribution as their cometary counterparts, the Large Synoptic Survey Telescope should find roughly a dozen Oort cloud asteroids during ten years of operations. Measurement of the asteroid fraction within the Oort cloud can serve as an excellent test of the Solar system's formation and dynamical history. Oort cloud asteroids could be of particular concern as impact hazards as their high mass density, high impact velocity, and low visibility make them both hard to detect and hard to divert or destroy. However, they should be a rare class of object, and we estimate globally catastrophic collisions should only occur ...

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

    OpenAIRE

    Chapman, S. J.; Glasbey, J. C. D.; Khatri, C.; Kelly, M.; Nepogodiev, D.; Bhangu, A; Fitzgerald, J. E. F.

    2015-01-01

    Background 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. Methods Participation in the national, clinical project was...

  9. Impact of Nurse-Led, Multidisciplinary Home-Based Intervention on Event-Free Survival Across the Spectrum of Chronic Heart Disease

    OpenAIRE

    Stewart, Simon; Wiley, Joshua F.; Ball, Jocasta; Chan, Yih-Kai; Ahamed, Yasmin; Thompson, David R; Carrington, Melinda J.

    2016-01-01

    Background— We sought to determine the overall impact of a nurse-led, multidisciplinary home-based intervention (HBI) adapted to hospitalized patients with chronic forms of heart disease of varying types. Methods and Results— Prospectively planned, combined, secondary analysis of 3 randomized trials (1226 patients) of HBI were compared with standard management. Hospitalized patients presenting with heart disease but not heart failure, atrial fibrillation but not heart failure, and heart failu...

  10. Peer-led sex education--characteristics of peer educators and their perceptions of the impact on them of participation in a peer education programme.

    Science.gov (United States)

    Strange, Vicki; Forrest, Simon; Oakley, Ann

    2002-06-01

    The RIPPLE study is a randomized controlled trial of peer-led sex education in English secondary schools. In 1997, 27 schools were recruited and randomly allocated to a programme of peer-led sex education or to act as control schools. In experimental schools peer educators in Year 12 (aged 16/17 years) were recruited in two successive cohorts and, having received a standardized training programme, delivered classroom-based sex education sessions to Year 9 students (aged 13/14 years). This paper is the first of two focusing on data gathered from these peer educators. Through analysis of pre-(n = 505) and post- (n = 331) programme questionnaire data, the paper describes the profile of peer educators and examines the impact on them of their involvement. Compared to the students receiving the peer-led sex education, more peer educators were female, white, high academic achievers and less socially disadvantaged. Peer educators reported positive changes in sexual knowledge and changes towards more liberal attitudes, and believed the programme would have a positive impact on their confidence in relationships and on their sexual behaviour. There was an increase in confidence about communication and interaction in groups. The paper discusses the methodological difficulties of assessing how involvement in such a programme impacts on peer educators. PMID:12120848

  11. Cosmic Roulette: Comets In The Main Belt Asteroid Region

    Science.gov (United States)

    Beech, Martin; Gauer, Kai

    2002-08-01

    We have produced top ten ranked lists of impact velocity, mainbelt asteroid region dwell times and impact probabilities for a selection of short period comets. The comet with the combined highest ranking with respect to impact probability and impact velocity is Comet C/1766 G1 Helfenzrieder. Since it is not clear that this comet still exists, the highest ranked, presently active, comet with respect to the likelihood of suffering impacts from meter-sized objects while in the main belt asteroid region is Comet 28P/Neujmin 1. We find no evidence to support the existence of a distinctive sub-set of the short period comets liable to show repeated outburst or splitting behavioursdue to small body, meter-sized, asteroid impacts.

  12. Seven Asteroids Studied from Modra Observatory in the Course of Binary Asteroid Photometric Campaign

    Czech Academy of Sciences Publication Activity Database

    Galád, Adrián; Pravec, Petr; Kornoš, L.; Gajdoš, Š.; Világi, J.

    2007-01-01

    Roč. 101, 1-2 (2007), s. 17-25. ISSN 0167-9295 R&D Projects: GA ČR(CZ) GA205/05/0604 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * photometry Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.558, year: 2007

  13. Small Near-Earth Asteroids as a Source of Meteorites

    OpenAIRE

    Borovička, Jiří; Spurný, Pavel; Brown, Peter

    2015-01-01

    Small asteroids intersecting Earth's orbit can deliver extraterrestrial rocks to the Earth, called meteorites. This process is accompanied by a luminous phenomena in the atmosphere, called bolides or fireballs. Observations of bolides provide pre-atmospheric orbits of meteorites, physical and chemical properties of small asteroids, and the flux (i.e. frequency of impacts) of bodies at the Earth in the centimeter to decameter size range. In this chapter we explain the processes occurring durin...

  14. A radar survey of M- and X-class asteroids

    Czech Academy of Sciences Publication Activity Database

    Shepard, M.K.; Clark, B. E.; Nolan, M. C.; Howell, E. S.; Magri, C.; Giorgini, J. D.; Benner, L. A. M.; Ostro, S. J.; Harris, A. W.; Warner, B. D.; Pray, D. P.; Pravec, Petr; Fauerbach, M.; Bennett, T.; Klotz, A.; Behrend, R.; Correia, H.; Coloma, J.M.; Casulli, S.; Rivkin, A. S.

    2008-01-01

    Roč. 195, č. 1 (2008), s. 184-205. ISSN 0019-1035 R&D Projects: GA ČR(CZ) GA205/05/0604 Grant ostatní: NSF(US) AST-0605903; NSF(US) AST-0606704; NSF(US) AST-0607505; NASA (US) NNG06GI32G Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * asteroids composition * surfaces Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.268, year: 2008

  15. On the maximum amplitude of harmonics of an asteroid lightcurve

    Czech Academy of Sciences Publication Activity Database

    Harris, A. W.; Pravec, Petr; Galád, Adrián; Skiff, B.A.; Warner, B. D.; Világi, J.; Gajdoš, Š.; Carbognani, A.; Hornoch, Kamil; Kušnirák, Peter; Cooney jr., W. R.; Gross, J.; Terrell, D.; Higgins, D.; Bowell, E.; Koehn, B.W.

    2014-01-01

    Roč. 235, June (2014), s. 55-59. ISSN 0019-1035 R&D Projects: GA ČR GAP209/12/0229 Grant ostatní: SAV(SK) Vega 1/0670/13; NASA (US) NNX13AP56G Institutional support: RVO:67985815 Keywords : asteroids * asteroids rotation * photometry Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.038, year: 2014

  16. 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

  17. Polyhedron tracking and gravity tractor asteroid deflection

    Science.gov (United States)

    Ummen, N.; Lappas, V.

    2014-11-01

    In the wake of the Chelyabinsk airburst, the defense against hazardous asteroids is becoming a topic of high interest. This work improves the gravity tractor asteroid deflection approach by tracking realistic small body shapes with tilted ion engines. An algorithm for polyhedron tracking was evaluated in a fictitious impact scenario. The simulations suggest a capability increase up to 38.2% with such improved tilting strategies. The long- and short-term effects within polyhedron tracking are illustrated. In particular, the orbital reorientation effect is influential when realistic asteroid shapes and rotations are accounted for. Also analyzed is the subject of altitude profiles, a way to tailor the gravity tractor performance, and to achieve a steering ability within the B-plane. A novel analytical solution for the classic gravity tractor is derived. It removes the simulation need for classic tractor designs to obtain comparable two body model Δv figures. This paper corroborates that the asteroid shape can be exploited for maximum performance. Even a single engine tilt adjustment at the beginning of deflection operations yields more deflection than a fixed preset tilt.

  18. Making an IMPACT: The Story of a Medical Student-Designed, Peer-Led Healthy Eating and Physical Activity Curriculum

    Directory of Open Access Journals (Sweden)

    Avik Chatterjee

    2015-01-01

    Full Text Available Despite the importance of healthful dietary choices in combating the childhood obesity epidemic, neither primary and secondary schools nor medical schools provide adequate nutrition education. In 2005, two medical students at the University of North Carolina started the Improving Meals and Physical Activity in Children and Teens (IMPACT program, which utilized a peer-educator model to engage medical students and high school students in teaching 4th graders about healthy eating and physical activity. Over the years, medical student leaders of IMPACT continued the program, orienting the curriculum around the 5-2-1-0 Let’s Go campaign, aligning the IMPACT curriculum with North Carolina state curricular objectives for 4th graders and engaging and training teams of health professional students to deliver the program. The IMPACT project demonstrates how medical and other health professional students can successfully promote nutrition and physical activity education for themselves and for children through community-based initiatives. Ongoing efforts are aimed at increasing family participation in the curriculum to maximize changes in eating and physical activity of IMPACT participants and ensuring sustainability of the organization by engaging health professional student participants in continuing to improve the program.

  19. Impact of different monochromatic LED light colours and bird age on the behavioural output and fear response in ducks

    Directory of Open Access Journals (Sweden)

    Shabiha Sultana

    2013-12-01

    Full Text Available This study was performed to observe the effect of monochromatic light emitting diode (LED light colour and bird age on the behaviour and fear response of ducks. A total of 200 1-day-old ducklings were used in the experiment (two replications, 25 ducklings/pen, and lighting was set up as follows: white (W, control, 400-770 nm, yellow (Y, 600 nm, green (G, 520 nm and blue (B, 460 nm LED lights. Ducks were subjected to 23L: 1D h lighting with 0.1 Watt/m2 light intensity. Video was recorded twice per day (2 h in the morning and 2 h in the afternoon and observed five consecutive days per week. Duration of feeding, drinking, sitting, walking, standing, preening, wing flapping, wing stretching, tail wagging, head shaking, body shaking, ground pecking, peck object, and social interaction behaviour were recorded. At 3 and 6 weeks of age, 10 birds per treatment were subjected to the tonic immobility (TI test (three times/duck. Ducks reared in Y and W light were more active, as expressed by more walking, ground pecking, drinking and social interaction activities than those of ducks under the B light treatment (P<0.05. Ducks showed more time sitting, standing, and preening under B light (P<0.05. Feeding, sitting, standing and drinking behaviours increased, and walking and social interaction behaviours decreased with age of the ducks (P<0.05. Differences in behaviours among different light colours were observed. In addition, the TI test results indicated that B and G light reduced the fear response of the ducks.

  20. 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…

  1. Formation of asteroid pairs by rotational fission

    Czech Academy of Sciences Publication Activity Database

    Pravec, Petr; Vokrouhlický, D.; Polishook, D.; Scheeres, D.J.; Harris, A. W.; Galád, Adrián; Vaduvescu, O.; Pozo, F.; Barr, A.; Longa, P.; Vachier, F.; Colas, F.; Pray, D. P.; Pollock, J.; Reichart, D. E.; Ivarsen, K.M.; Haislip, J.B.; LaCluyze, A.; Kušnirák, Peter; Henych, Tomáš; Marchis, F.; Macomber, B.; Jacobson, S.A.; Krugly, Yu. N.; Sergeev, A.V.; Leroy, A.

    2010-01-01

    Roč. 466, č. 7310 (2010), s. 1085-1088. ISSN 0028-0836 R&D Projects: GA ČR GA205/09/1107; GA ČR GD205/08/H005 Institutional research plan: CEZ:AV0Z10030501 Keywords : full 2-body problem * binary asteroids * stability Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 36.101, year: 2010

  2. Asteroids in the service of humanity

    CERN Document Server

    Crawford, Ian A

    2013-01-01

    There are at least three compelling reasons for the human race to initiate a major programme to explore and better understand the 'minor planets' of the Solar System: (1) Enhancing scientific knowledge; (2) Mitigating the impact hazard; and (3) Utilizing extraterrestrial resources. Strong synergies exist between all three. Moreover, all these activities would benefit from greater international cooperation in space exploration by the World's space agencies, and the recognition that asteroids are important targets for human and robotic exploration.

  3. Making an IMPACT: The Story of a Medical Student-Designed, Peer-Led Healthy Eating and Physical Activity Curriculum

    OpenAIRE

    Avik Chatterjee; Rusher, Thomas N.; Julia Nugent; Herring, Kenneth W.; Lindsey M. Rose; Dean Nehama; Muth, Natalie D.

    2015-01-01

    Despite the importance of healthful dietary choices in combating the childhood obesity epidemic, neither primary and secondary schools nor medical schools provide adequate nutrition education. In 2005, two medical students at the University of North Carolina started the Improving Meals and Physical Activity in Children and Teens (IMPACT) program, which utilized a peer-educator model to engage medical students and high school students in teaching 4th graders about healthy eating and physical a...

  4. Asteroid Evolution: Role of geotechnical properties

    Science.gov (United States)

    Sanchez Lana, Diego P.

    2015-08-01

    Over the last decade of Planetary research, the scientific community has made many advances in their understanding of the evolution of asteroids in the Solar System. One particular area of fruitful study started with the bold idea that these small planetary bodies could be gravitational aggregates and initially motivated by several different observations and early simulations.If we start with the idea that asteroids are aggregates of different sized components, and not singular monolithic bodies, it is possible to study them with some of the tools that have been used in the fields of Soil Mechanics and Granular Dynamics. In them, parameters such as porosity, cohesive and tensile strength, angles of friction and repose, 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 are believed to have produced and shaped the asteroids that now exist around us and include solar photon momentum, gravitational tides, micro- and macro-impacts and internal energy dissipation.In this presentation we will review what is known about the surface and interiors of rubble pile asteroids, how different theoretical, experimental and simulation tools have been used to study them, how space mission and ground-based observations have shaped our understanding of their physical reality, and what we expect to learn from future missions. The talk will also touch on some of the latest findings obtained by different groups. In particular we will discuss the rotational evolution of self-gravitating aggregates under the influence of the YORP effect and how their angles of friction, tensile strength, porosity, internal structure and density give rise to different disruption modes and the role they play in the formation of asteroids pairs, tumblers and binary systems.

  5. Constraints on the original ejection velocity fields of asteroid families

    CERN Document Server

    Carruba, Valerio

    2016-01-01

    Asteroid families form as a result of large-scale collisions among main belt asteroids. The orbital distribution of fragments after a family-forming impact could inform us about their ejection velocities. Unfortunately, however, orbits dynamically evolve by a number of effects, including the Yarkovsky drift, chaotic diffusion, and gravitational encounters with massive asteroids, such that it is difficult to infer the ejection velocities eons after each family's formation. Here we analyze the inclination distribution of asteroid families, because proper inclination can remain constant over long time intervals, and could help us to understand the distribution of the component of the ejection velocity that is perpendicular to the orbital plane ($v_{W}$). From modeling the initial breakup, we find that the distribution of $v_{W}$ of the fragments, which manage to escape the parent body's gravity, should be more peaked than a Gaussian distribution (i.e., be leptokurtic) even if the initial distribution was Gaussia...

  6. Small Near-Earth Asteroids as a Source of Meteorites

    CERN Document Server

    Borovička, Jiří; Brown, Peter

    2015-01-01

    Small asteroids intersecting Earth's orbit can deliver extraterrestrial rocks to the Earth, called meteorites. This process is accompanied by a luminous phenomena in the atmosphere, called bolides or fireballs. Observations of bolides provide pre-atmospheric orbits of meteorites, physical and chemical properties of small asteroids, and the flux (i.e. frequency of impacts) of bodies at the Earth in the centimeter to decameter size range. In this chapter we explain the processes occurring during the penetration of cosmic bodies through the atmosphere and review the methods of bolide observations. We compile available data on the fireballs associated with 22 instrumentally observed meteorite falls. Among them are the heterogeneous falls Almahata Sitta (2008 TC$_3$) and Bene\\v{s}ov, which revolutionized our view on the structure and composition of small asteroids, the P\\v{r}\\'{\\i}bram-Neuschwanstein orbital pair, carbonaceous chondrite meteorites with orbits on the asteroid-comet boundary, and the Chelyabinsk fal...

  7. Multiple origins of asteroid pairs

    Science.gov (United States)

    Jacobson, Seth A.

    2016-01-01

    Rotationally fissioned asteroids produce unbound asteroid pairs that have very similar heliocentric orbits. Backward integration of their current heliocentric orbits provides an age of closest proximity that can be used to date the rotational fission event. Most asteroid pairs follow a predicted theoretical relationship between the primary spin period and the mass ratio of the two pair members that is a direct consequence of the YORP-induced rotational fission hypothesis. If the progenitor asteroid has strength, asteroid pairs may have higher mass ratios or faster rotating primaries. However, the process of secondary fission leaves the originally predicted trend unaltered. We also describe the characteristics of pair members produced by four alternative routes from a rotational fission event to an asteroid pair. Unlike direct formation from the event itself, the age of closest proximity of these pairs cannot generally be used to date the rotational fission event since considerable time may have passed.

  8. Multiple origins of asteroid pairs

    CERN Document Server

    Jacobson, Seth A

    2015-01-01

    Rotationally fissioned asteroids produce unbound daughter asteroids that have very similar heliocentric orbits. Backward integration of their current heliocentric orbits provides an age of closest proximity that can be used to date the rotational fission event. Most asteroid pairs follow a predicted theoretical relationship between the primary spin period and the mass ratio of the two pair members that is a direct consequence of the YORP-induced rotational fission hypothesis. If the progenitor asteroid has strength, asteroid pairs may have high mass ratios with possibly fast rotating primaries. However, secondary fission leaves the originally predicted trend unaltered. We also describe the characteristics of pair members produced by four alternative routes from a rotational fission event to an asteroid pair. Unlike direct formation from the event itself, the age of closest proximity of these pairs cannot generally be used to date the rotational fission event since considerable time may have passed.

  9. Dynamical transport of asteroid fragments from the nu6 resonance

    CERN Document Server

    Ito, T; Ito, Takashi; Malhotra, Renu

    2006-01-01

    A large disruption in the main asteroid belt can cause a large flux, an "asteroid shower", on the terrestrial planets. We quantitatively examine the hypothesis that such an event was the cause of the lunar late heavy bombardment (LHB). We performed numerical integrations of about 20000 test particles starting in the vicinity of the nu6 secular resonance in the main asteroid belt. The purpose of these integrations is to calculate, for each of the terrestrial planets, the collision probability of asteroids coming from an asteroid break-up event in the inner part of the main belt. Compared with previous studies, we simulate nearly two orders of magnitude larger number of particles, and we include the orbital effects of the eight planets, Mercury to Neptune. We also examined in detail the orbital evolution of asteroid fragments once they enter the Earth's activity sphere, including the effect of the Earth-Moon orbit. We obtained the collision probability, the distributions of impact velocities, impact positions, ...

  10. 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

  11. Asteroid Surface Geophysics

    CERN Document Server

    Murdoch, Naomi; Schwartz, Stephen R; Miyamoto, Hideaki

    2015-01-01

    The regolith-covered surfaces of asteroids preserve records of geophysical processes that have occurred both at their surfaces and sometimes also in their interiors. As a result of the unique micro-gravity environment that these bodies posses, a complex and varied geophysics has given birth to fascinating features that we are just now beginning to understand. The processes that formed such features were first hypothesised through detailed spacecraft observations and have been further studied using theoretical, numerical and experimental methods that often combine several scientific disciplines. These multiple approaches are now merging towards a further understanding of the geophysical states of the surfaces of asteroids. In this chapter we provide a concise summary of what the scientific community has learned so far about the surfaces of these small planetary bodies and the processes that have shaped them. We also discuss the state of the art in terms of experimental techniques and numerical simulations that...

  12. New study reveals twice as many asteroids as previously believed

    Science.gov (United States)

    2002-05-01

    margin. Considering both the visible and infrared results, the 'best estimate' would be "1.2 million asteroids larger than 1 kilometre in the main belt, give or take 500,000," Tedesco says. The best strategy for finding the asteroid size distribution, according to this expert, is to combine near-simultaneous observations at infrared and visible light. "They provide different kinds of information and therefore play a complementary role in the search for the asteroid population's size distribution," he says. The 'impact hazard' A better knowledge of the number and size distribution of asteroids in the main belt is essential to understand the population of Near Earth Asteroids (NEAs), since most NEA are believed to be former main belt asteroids. In the main belt there are four 'special' regions where Jupiter's gravitational influence is especially disruptive; originally, most asteroids currently known as NEA suffered collisions which resulted in them ending up in one of those four key regions, and because of Jupiter's gravitational influence their orbits quickly evolved into Earth-crossing orbits. Therefore, by studying the asteroids near these so-called 'source regions' in the main belt astronomers can learn about NEA. About 500 NEAs have been found so far, and none of them pose any threat to Earth in this century. The generally accepted impact rate by objects larger than 1 kilometre in diameter is one every 100,000 to 300,000 years. The new 'best estimate' of about 1.2 million asteroids of 1 kilometre or larger in the main belt will not change the current estimates of impact hazard, the IDAS astronomers say; at least not yet. "IDAS has contributed to our knowledge of main belt asteroids. And, although we did not observe any NEAs, the ISO data will be used to improve our knowledge regarding asteroids currently near the NEA source regions. This, in turn, will allow us to better understand the population characteristics of the NEAs and so ultimately enable us to refine our

  13. 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.

  14. Asteroid Surface Geophysics

    OpenAIRE

    Murdoch, Naomi; Sanchez, Paul; Schwartz, Stephen R.; Miyamoto, Hideaki

    2015-01-01

    The regolith-covered surfaces of asteroids preserve records of geophysical processes that have occurred both at their surfaces and sometimes also in their interiors. As a result of the unique micro-gravity environment that these bodies posses, a complex and varied geophysics has given birth to fascinating features that we are just now beginning to understand. The processes that formed such features were first hypothesised through detailed spacecraft observations and have been further studied ...

  15. Comet or Asteroid?

    Science.gov (United States)

    1997-11-01

    When is a minor object in the solar system a comet? And when is it an asteroid? Until recently, there was little doubt. Any object that was found to display a tail or appeared diffuse was a comet of ice and dust grains, and any that didn't, was an asteroid of solid rock. Moreover, comets normally move in rather elongated orbits, while most asteroids follow near-circular orbits close to the main plane of the solar system in which the major planets move. However, astronomers have recently discovered some `intermediate' objects which seem to possess properties that are typical for both categories. For instance, a strange object (P/1996 N2 - Elst-Pizarro) was found last year at ESO ( ESO Press Photo 36/96 ) which showed a cometary tail, while moving in a typical asteroidal orbit. At about the same time, American scientists found another (1996 PW) that moved in a very elongated comet-type orbit but was completely devoid of a tail. Now, a group of European scientists, by means of observations carried out at the ESO La Silla observatory, have found yet another object that at first appeared to be one more comet/asteroid example. However, continued and more detailed observations aimed at revealing its true nature have shown that it is most probably a comet . Consequently, it has received the provisional cometary designation P/1997 T3 . The Uppsala-DLR Trojan Survey Some time ago, Claes-Ingvar Lagerkvist (Astronomical Observatory, Uppsala, Sweden), in collaboration with Gerhard Hahn, Stefano Mottola, Magnus Lundström and Uri Carsenty (DLR, Institute of Planetary Exploration, Berlin, Germany), started to study the distribution of asteroids near Jupiter. They were particularly interested in those that move in orbits similar to that of Jupiter and which are located `ahead' of Jupiter in the so-called `Jovian L4 Lagrangian point'. Together with those `behind' Jupiter, these asteroids have been given the names of Greek and Trojan Heroes who participated in the famous Trojan war

  16. Scientific mission to asteroid Phaethon

    Science.gov (United States)

    Padevet, V.; Lala, P.; Bumba, V.

    1986-10-01

    The asteroid 3200 Phaethon (previously 1983 TB) is being suggested for direct research by interplanetary probe. The asteroid, in an Apollo-type orbit, coincides with Geminid meteor stream and is so far the only body known to have features of an asteroid as well as a comet. A special program has been prepared for a desk computer to analyze interplanetary orbits with which the asteroid could be reached by the year 2000. Direct trajectories as well as trajectories with a gravitational maneuver near Venus have been tested.

  17. Self-reported Impacts of LED Lighting Technology Compared to Fuel-based Lighting on Night Market Business Prosperity in Kenya

    Energy Technology Data Exchange (ETDEWEB)

    Johnstone, Peter; Jacobson, Arne; Mills, Evan; Mumbi, Maina

    2009-02-11

    The notion of"productive use" is often invoked in discussions about whether new technologies improve productivity or otherwise enhance commerce in developing-country contexts. It an elusive concept,especially when quantitative measures are sought. Improved and more energy efficient illumination systems for off-gridapplication--the focus of the Lumina Project--provide a case in which a significant productivity benefit can be imagined, given the importance of light to the successful performance of many tasks, and the very low quality of baseline illumination provided by flame-based source. This Research Note summarizes self-reported quantitative and qualitative impacts of switching to LED lighting technology on the prosperity of night-market business owners and operators. The information was gathered in the context of our 2008 market testing field work in Kenya?s Rift Valley Province, which was performed in the towns of Maai Mahiu and Karagita by Arne Jacobson, Kristen Radecsky, Peter Johnstone, Maina Mumbi, and others. Maai Mahiu is a crossroads town; provision of services to travelers and freight carriers is a primary income source for the residents. In contrast, the primary income for Karagita's residents is from work in the large, factory style flower farms on the eastern shores of Lake Naivasha that specialize in producing cut flowers for export to the European market. According to residents, both towns had populations of 6,000 to 8,000 people in June 2008. We focused on quantifying the economics of fuel-based and LED lighting technology in the context of business use by night market vendors and shop keepers. Our research activities with the business owners and operators included baseline measurement of their fuel-based lighting use, an initial survey, offering for sale data logger equipped rechargeable LED lamps, monitoring the adoption of the LED lamps, and a follow-up survey.

  18. How to find metal-rich asteroids

    CERN Document Server

    Harris, Alan W

    2014-01-01

    The metal content of asteroids is of great interest, not only for theories of their origins and the evolution of the solar system but, in the case of near-Earth objects (NEOs), also for impact mitigation planning and endeavors in the field of planetary resources. However, since the reflection spectra of metallic asteroids are largely featureless, it is difficult to identify them and relatively few are known. We show how data from the Wide-field Infrared Survey Explorer (WISE)/NEOWISE thermal-infrared survey and similar surveys, fitted with a simple thermal model, can reveal objects likely to be metal rich. We provide a list of candidate metal-rich NEOs. Our results imply that future infrared surveys with the appropriate instrumentation could discover many more metal-rich asteroids, providing valuable data for assessment of the impact hazard and the potential of NEOs as reservoirs of vital materials for future interplanetary space activities and, eventually perhaps, for use on Earth.

  19. Rotational properties of asteroids: CCD observations of nine small asteroids

    Science.gov (United States)

    Birlan, M.; Barucci, M. A.; Angeli, C. A.; Doressoundiram, A.; De Sanctis, M. C.

    1996-06-01

    The observational programme on small asteroids (diameter less than about 50 km) is continued to enlarge the available dataset of small asteroids. The results are presented of CCD observations of nine small asteroids ( D≤23 km), performed in France with the 1.2 m telescope at Haute Provence Observatory and with the 2 m telescope at Pic du Midi Observatory. A total of 27 single night lightcurves for nine asteroids were obtained. All the objects were observed for the first time and rotational periods have been determined for all of the observed asteroids: 1992 Galvarino ( Psyn = 7 h.004), 2419 Moldavia ( Psyn = 2 h.412), 2921 Sophocles ( Psyn = 4 h.778), 3247 Di Martino ( Psyn = 5 h.445), 3623 Chaplin ( Psyn = 8 h.361), 3986 Rozhkovskij ( Psyn = 4 h.26), 4436 1983 EX ( Psyn = 6 h.656), 5046 1981 DQ ( Psyn = 6 h.050) and 1992 YG3 ( Psyn = 8 h.91).

  20. Establishing different size distributions in the asteroid belt

    Science.gov (United States)

    Jacobson, Seth A.; Morbidelli, Alessandro

    2016-05-01

    While gas is present in the protoplanetary disk, aerodynamic drag circularizes, equatorializes and shrinks planetesimal orbits. The strength of this effect is size-dependent effecting smaller planetesimals more severely. During planet formation debris from giant impacts amongst the growing terrestrial embryos can be transported to the asteroid belt via scattering events and secular resonances. The effectiveness of this transport is strongly size dependent due to the aforementioned gas drag. Thus transported debris in the asteroid belt can have a strong size sorting. Further processing due to collisions and YORP-induced rotational fission during the lifetime of the solar system must be taken into account before a model population of debris can be compared to suspected planetary debris in the asteroid belt, such as the A-type asteroids. Furthermore, scenarios such as the Grand Tack may establish size distributions since they predict that S-type asteroids are transported from an inner planetesimal disk while C-type asteroids are transporeted from an outer planetesimal disk.

  1. Asteroid and comet flux in the neighborhood of the earth

    International Nuclear Information System (INIS)

    Significant advances in the knowledge and understanding of the flux of large solid objects in the neighborhood of Earth have occurred. The best estimates of the collision rates with Earth of asteroids and comets and the corresponding production of impact craters are presented. Approximately 80 Earth-crossing asteroids were discovered through May 1988. Among 42 new Earth-crossing asteroids found in the last decade, two-thirds were discovered from observations at Palomar Observatory and 15 were discovered or independently detected in dedicated surveys with the Palomar Observatory and 15 were discovered or independently detected in dedicated surveys with the Palomar 46 cm Schmidt. Probabilities of collision with Earth have been calculated for about two-thirds of the known Earth-crossing asteroids. When multiplied by the estimated population of Earth-crossers, this yields an estimated present rate of collision about 65 pct higher than that previously reported. Spectrophotometric data obtained chiefly in the last decade show that the large majority of obvserved Earth-crossers are similar to asteroids found in the inner part of the main belt. The number of discovered Earth-crossing comets is more than 4 times greater than the number of known Earth-crossing asteroids, but reliable data on the sizes of comet nuclei are sparse. The flux of comets almost certainly was highly variable over late geologic time, owing to the random perturbation of the Oort comet cloud by stars in the solar neighborhood

  2. Preface: Advances in asteroid and space debris science and technology - Part 2

    Science.gov (United States)

    Vasile, Massimiliano

    2016-04-01

    Asteroids and space debris represent a significant hazard for space and terrestrial assets; at the same time asteroids represent also an opportunity. In recent years it has become clear that the increasing population of space debris could lead to catastrophic consequences in the near term. The Kessler syndrome (where the density of objects in orbit is high enough that collisions could set off a cascade) is more realistic than when it was first proposed in 1978. Although statistically less likely to occur, an asteroid impact would have devastating consequences for our planet. Although an impact with a large (∼10 km) to medium (∼300 m) sized, or diameter, asteroid is unlikely, still it is not negligible as the recent case of the asteroid Apophis has demonstrated. Furthermore impacts with smaller size objects, between 10 m and 100 m diameter, are expected to occur more frequently and hence are, proportionally, equally dangerous for humans and assets on Earth and in space.

  3. Max Wolf's Discovery of Near-Earth Asteroid 887 Alinda

    Science.gov (United States)

    Connors, Martin; Mandel, Holger; Demleitner, Markus; Heidelberg Digitized Astronomical Plates Project

    2016-01-01

    Max Wolf, director of the Heidelberg Observatory (Landessternwarte Königsstuhl), was the most prodigious discoverer of asteroids in the early twentieth century. He is now best known for the discovery of the Trojan asteroids associated with Jupiter in 1906, but was a pioneer in the application of photographic techniques to astronomy, particularly for conducting asteroid surveys. His attention to detail and perseverance also led to the discovery of the near-Earth asteroid 887 Alinda, which is the eponym of an orbital class in 3:1 resonance with Jupiter. Alinda class contains several potentially hazardous asteroids, and has been particularly instructive in development of theories of eccentricity increase for resonant asteroids. Alinda was discovered on January 3, 1918, on the very edge of one of two plates taken with the 40 cm aperture Bruce double astrograph. The inability to reduce a long trail going off the plate meant that only one month later could the object again be found with the Bruce telescope, and later observed with the follow-up instrument, the 72 cm aperture Waltz reflector. In what Wolf referred to as "the greatest embarrassment of my life", reflector observations had him conclude that Alinda had a satellite. At a time when plates had to be exposed for several hours, laboriously developed and analyzed, and in the case of high eccentricity objects like Alinda, predicted with inadequate theories, Wolf's persistence allowed it never to be lost. Despite this, its essential resonant nature was not determined until 1969, despite the pioneering work by Brown (1911) on resonance in the asteroid belt and the knowledge dating to the late nineteenth century work of Kirkwood that commensurabilities were important in its structure. The majority of Wolf's plates are available as online scans through the Heidelberg Digitized Astronomical Plates project of the German Astrophysical Virtual Observatory, but the Alinda discovery plate, which was broken, was scanned

  4. Joint lightcurve observations of 10 near-Earth asteroids from Modra and Ondřejov

    Czech Academy of Sciences Publication Activity Database

    Galád, Adrián; Pravec, Petr; Kušnirák, Peter; Gajdoš, Š.; Kornoš, L.; Világi, J.

    2005-01-01

    Roč. 97, 1-2 (2005), s. 147-163. ISSN 0167-9295 R&D Projects: GA ČR GA205/05/0604 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * near-Earth asteroids * photometry Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.975, year: 2005

  5. Evolutionary Pathways for Asteroid Satellites

    Science.gov (United States)

    Jacobson, Seth Andrew

    2015-08-01

    The YORP-induced rotational fission hypothesis is a proposed mechanism for the creation of small asteroid binaries, which make up approximately 1/6-th of the near-Earth asteroid and small Main Belt asteroid populations. The YORP effect is a radiative torque that rotationally accelerates asteroids on timescales of thousands to millions of years. As asteroids rotationally accelerate, centrifugal accelerations on material within the body can match gravitational accelerations holding that material in place. When this occurs, that material goes into orbit. Once in orbit that material coalesces into a companion that undergoes continued dynamical evolution.Observations with radar, photometric and direct imaging techniques reveal a diverse array of small asteroid satellites. These systems can be sorted into a number of morphologies according to size, multiplicity of members, dynamical orbit and spin states, and member shapes. For instance, singly synchronous binaries have short separation distances between the two members, rapidly rotating oblate primary members, and tidally locked prolate secondary members. Other confirmed binary morphologies include doubly synchronous, tight asynchronous and wide asynchronous binaries. Related to these binary morphologies are unbound paired asteroid systems and bi-lobate contact binaries.A critical test for the YORP-induced rotational fission hypothesis is whether the binary asteroids produced evolve to the observed binary and related systems. In this talk I will review how this evolution is believed to occur according to gravitational dynamics, mutual body tides and the binary YORP effect.

  6. New Paradigms For Asteroid Formation

    CERN Document Server

    Johansen, Anders; Cuzzi, Jeffrey N; Morbidelli, Alessandro; Gounelle, Matthieu

    2015-01-01

    Asteroids and meteorites provide key evidence on the formation of planetesimals in the Solar System. Asteroids are traditionally thought to form in a bottom-up process by coagulation within a population of initially km-scale planetesimals. However, new models challenge this idea by demonstrating that asteroids of sizes from 100 to 1000 km can form directly from the gravitational collapse of small particles which have organised themselves in dense filaments and clusters in the turbulent gas. Particles concentrate passively between eddies down to the smallest scales of the turbulent gas flow and inside large-scale pressure bumps and vortices. The streaming instability causes particles to take an active role in the concentration, by piling up in dense filaments whose friction on the gas reduces the radial drift compared to that of isolated particles. In this chapter we review new paradigms for asteroid formation and compare critically against the observed properties of asteroids as well as constraints from meteo...

  7. Asteroids and Comets

    CERN Document Server

    Fernandez, Yanga R; Howell, Ellen S; Woodney, Laura M

    2015-01-01

    Asteroids and comets are remnants from the era of Solar System formation over 4.5 billion years ago, and therefore allow us to address two fundamental questions in astronomy: what was the nature of our protoplanetary disk, and how did the process of planetary accretion occur? The objects we see today have suffered many geophysically-relevant processes in the intervening eons that have altered their surfaces, interiors, and compositions. In this chapter we review our understanding of the origins and evolution of these bodies, discuss the wealth of science returned from spacecraft missions, and motivate important questions to be addressed in the future.

  8. The Main Asteroid Belt: The Crossroads of the Solar System

    Science.gov (United States)

    Michel, Patrick

    2015-08-01

    Orbiting the Sun between Mars and Jupiter, main belt asteroids are leftover planetary building blocks that never accreted enough material to become planets. They are therefore keys to understanding how the Solar System formed and evolved. They may also provide clues to the origin of life, as similar bodies may have delivered organics and water to the early Earth.Strong associations between asteroids and meteorites emerged thanks to multi-technique observations, modeling, in situ and sample return analyses. Spacecraft images revolutionized our knowledge of these small worlds. Asteroids are stunning in their diversity in terms of physical properties. Their gravity varies by more orders of magnitude than its variation among the terrestrial planets, including the Moon. Each rendezvous with an asteroid thus turned our geological understanding on its head as each asteroid is affected in different ways by a variety of processes such as landslides, faulting, and impact cratering. Composition also varies, from ice-rich to lunar-like to chondritic.Nearly every asteroid we see today, whether of primitive or evolved compositions, is the product of a complex history involving accretion and one or more episodes of catastrophic disruption that sometimes resulted in families of smaller asteroids that have distinct and indicative petrogenic relationships. These families provide the best data to study the impact disruption process at scales far larger than those accessible in laboratory. Tens, perhaps hundreds, of early asteroids grew large enough to thermally differentiate. Their traces are scattered pieces of their metal-rich cores and, more rarely, their mantles and crusts.Asteroids represent stages on the rocky road to planet formation. They have great stories to tell about the formation and evolution of our Solar System as well as other planetary systems: asteroid belts seem common around Sun-like stars. We will review our current knowledge on their properties, their link to

  9. Active Near Earth Asteroids

    Science.gov (United States)

    Jenniskens, Peter

    2015-08-01

    Past activity from Near Earth Asteroids is recorded in the meteoroid streams that cause our meteor showers. Automated meteoroid orbit surveys by photographic, low-light video, specular radar, and head-echo radar reflections are providing the first maps of meteor shower activity at different particle sizes. There are distinct differences in particle size distributions among streams. The underlaying mechanisms that created these streams are illuminated: fragmentation from spin-up or thermal stresses, meteoroid ejection by water vapor drag, and ejection of icy particles by CO and CO2 sublimation. The distribution of the meteoroid orbital elements probe the subsequent evolution by planetary perturbations and sample the range of dynamical processes to which Near Earth Asteroids are exposed. The non-stream "sporadic" meteors probe early stages in the evolution from meteoroid streams into the zodiacal dust cloud. We see that the lifetime of large meteoroids is generally not limited by collisions. Results obtained by the CAMS video survey of meteoroid orbits are compared to those from other orbit surveys. Since October 2010, over 200,000 meteoroid orbits have been measured. First results from an expansion into the southern hemisphere are also presented, as are first results from the measurement of main element compositions. Among the many streams detected so far, the Geminid and Sextantid showers stand out by having a relatively high particle density and derive from parent bodies that appear to have originated in the main belt.

  10. Ion Beam Shepherd for Asteroid Deflection

    CERN Document Server

    Bombardelli, C

    2011-01-01

    We present a novel concept to impart a continuous thrust to an Earth threatening asteroid from a hovering spacecraft without need for physical attachment nor gravitational interaction with the asteroid. The concept involves an ion thruster placed at a distance of a few asteroid diameters directing a stream of quasi-neutral plasma against the asteroid surface resulting into a net transferred momentum. As the transmitted force is independent of the asteroid mass and size the method allows deflecting subkilometer asteroids with a spacecraft much lighter when compared to a gravity tractor spacecraft of equal deflection capability. The finding could make low-cost asteroid deflection missions possible in the coming years.

  11. The preventive destruction of a hazardous asteroid

    Science.gov (United States)

    Aleksandrova, A. G.; Galushina, T. Yu.; Prishchepenko, A. B.; Kholshevnikov, K. V.; Chechetkin, V. M.

    2016-06-01

    One means of countering a hazardous asteroid is discussed: destruction of the object using a nuclear charge. Explosion of such an asteroid shortly before its predicted collision would have catastrophic consequences, with numerous highly radioactive fragments falling onto the Earth. The possibility of exploding the asteroid several years before its impact is also considered. Such an approach is made feasible because the vast majority of hazardous objects pass by the Earth several times before colliding with it. Computations show that, in the 10 years following the explosion, only a negligible number of fragments fall onto the Earth, whose radioactivity has substantially reduced during this time. In most cases, none of these fragments collides with the Earth. Thus, this proposed method for eliminating a threat from space is reasonable in at least two cases: when it is not possible to undergo a soft removal of the object from the collisional path, and to destroy objects that are continually returning to near-Earth space and require multiple removals from hazardous orbits.

  12. New active asteroid 313P/Gibbs

    International Nuclear Information System (INIS)

    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−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−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.

  13. 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...

  14. Radar Observations and the Shape of Near-Earth Asteroid 2008 EV5

    CERN Document Server

    Busch, Michael W; Benner, Lance A M; Brozovic, Marina; Giorgini, Jon D; Jao, Joseph S; Scheeres, Daniel J; Magri, Christopher; Nolan, Michael C; Howell, Ellen S; Taylor, Patrick A; Margot, Jean-Luc; Brisken, Walter

    2011-01-01

    We observed the near-Earth asteroid 2008 EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array during December 2008. EV5 rotates retrograde and its overall shape is a 400 /pm 50 m oblate spheroid. The most prominent surface feature is a ridge parallel to the asteroid's equator that is broken by a concavity 150 m in diameter. Otherwise the asteroid's surface is notably smooth on decameter scales. EV5's radar and optical albedos are consistent with either rocky or stony-iron composition. The equatorial ridge is similar to structure seen on the rubble-pile near-Earth asteroid (66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid in the past. We interpret the concavity as an impact crater. Shaking during the impact and later regolith redistribution may have erased smaller features, explaining the general lack of decameter-scale surface structure.

  15. 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...

  16. Asteroid named after CAS scientist

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ An asteroid has been named after CAS astronomy historian XI Zezong with the approval of the International Minor Planet Nomenclature Committee (IMPNC), announced China's National Astronomical Observatories at CAS (NAOC) on 17 August.

  17. 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.

  18. 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 ostatní: 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

  19. Multi-wavelength observations of Asteroid 2100 Ra-Shalom

    Czech Academy of Sciences Publication Activity Database

    Shepard, M.K.; Clark, B. E.; Nolan, M. C.; Benner, L. A. M.; Ostro, S. J.; Giorgini, J. D.; Vilas, F.; Jarvis, K.; Lederer, S.; Lim, L.F.; McConnochie, T.; Bell, J.; Margot, J. L.; Rivkin, A. S.; Magrik, C.; Scheeres, D.J.; Pravec, Petr

    2008-01-01

    Roč. 193, č. 1 (2008), s. 20-38. ISSN 0019-1035 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids composition * radar observations Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.268, year: 2008

  20. 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 ostatní: 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

  1. Thermal infrared observations of asteroid (99942) Apophis with Herschel

    Czech Academy of Sciences Publication Activity Database

    Müller, T. G.; Kiss, C.; Scheirich, Peter; Pravec, Petr; O'Rourke, L.; Vilenius, E.; Altieri, B.

    2014-01-01

    Roč. 566, June (2014), A22/1-A22/10. ISSN 0004-6361 R&D Projects: GA ČR GAP209/12/0229; GA MŠk LG12001 Institutional support: RVO:67985815 Keywords : minor planets * asteroids: individual * radiation mechanisms Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

  2. Asteroids: up close and personal

    International Nuclear Information System (INIS)

    Think of our solar system. The Sun, the Moon and the nine planets come to mind first, followed by the moons of other planets and other small bodies like asteroids. In 1991, almost 30 years after planetary exploration began, an asteroid was visited by a passing spacecraft for the first time. Nearly another decade elapsed before the first dedicated asteroid mission went into orbit around Eros, a city-sized object some 34 km long. And earlier this year, the NEAR, Shoemaker spacecraft daringly descended to the surface of Eros and landed safely. Asteroids have been pushed to the tail-end of the itinerary of solar-system exploration because of their diminutive sizes. Indeed, the wealth of low-gravity phenomena associated with asteroids has captured the imagination of both researchers and the public alike. In the June issue of Physics World Clark R Chapman of the Southwest Research Institute, US, explains how the landing of a spacecraft on the asteroid Eros earlier this year has given space scientists the best view yet of small planetary bodies and has opened a new window on the solar system. (U.K.)

  3. Slowly increasing elongations of non-spherical asteroids caused by collisions

    Czech Academy of Sciences Publication Activity Database

    Henych, Tomáš; Pravec, Petr

    2015-01-01

    Roč. 454, č. 2 (2015), s. 1704-1710. ISSN 0035-8711 Institutional support: RVO:67985815 Keywords : numerical methods * minor planets * asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.107, year: 2014

  4. Looking a gift horse in the mouth: Evaluation of wide-field asteroid photometric surveys

    Czech Academy of Sciences Publication Activity Database

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

    2012-01-01

    Roč. 221, č. 1 (2012), s. 226-235. ISSN 0019-1035 Institutional support: RVO:67985815 Keywords : asteroids * rotation * photometry Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.161, year: 2012

  5. LED-LED portable oxygen gas sensor

    OpenAIRE

    Perez de Vargas Sansalvador, Isabel; Fay, Cormac; Fernandez-Ramos, M.D.; Diamond, Dermot; Benito-Lopez, Fernando; Capitan-Vallvey, L.F.

    2012-01-01

    A portable instrument for oxygen determination, based on the quenching of phosphorescent octaethylporphyrin by gaseous O2, has been developed using the fluorimetric paired emitter–detector diode technique (FPEDD). The instrument configuration used consists of two light emitting diodes (LEDs) facing each other including an interchangeable support containing a phosphorescent membrane in between, in which one of the LEDs is used as the light source (emitter LED) and the other working in reverse...

  6. Constraints on the original ejection velocity fields of asteroid families

    Science.gov (United States)

    Carruba, V.; Nesvorný, D.

    2016-04-01

    Asteroid families form as a result of large-scale collisions among main belt asteroids. The orbital distribution of fragments after a family-forming impact could inform us about their ejection velocities. Unfortunately, however, orbits dynamically evolve by a number of effects, including the Yarkovsky drift, chaotic diffusion, and gravitational encounters with massive asteroids, such that it is difficult to infer the ejection velocities eons after each family's formation. Here, we analyse the inclination distribution of asteroid families, because proper inclination can remain constant over long time intervals, and could help us to understand the distribution of the component of the ejection velocity that is perpendicular to the orbital plane (vW). From modelling the initial break up, we find that the distribution of vW of the fragments, which manage to escape the parent body's gravity, should be more peaked than a Gaussian distribution (i.e. be leptokurtic) even if the initial distribution was Gaussian. We surveyed known asteroid families for signs of a peaked distribution of vW using a statistical measure of the distribution peakedness or flatness known as kurtosis. We identified eight families whose vW distribution is significantly leptokurtic. These cases (e.g. the Koronis family) are located in dynamically quiet regions of the main belt, where, presumably, the initial distribution of vW was not modified by subsequent orbital evolution. We suggest that, in these cases, the inclination distribution can be used to obtain interesting information about the original ejection velocity field.

  7. The Explored Asteroids: Science and Exploration in the Space Age

    Science.gov (United States)

    Sears, D. W. G.

    2015-11-01

    Interest in asteroids is currently high in view of their scientific importance, the impact hazard, and the in situ resource opportunities they offer. They are also a case study of the intimate relationship between science and exploration. A detailed review of the twelve asteroids that have been visited by eight robotic spacecraft is presented here. While the twelve explored asteroids have many features in common, like their heavily cratered and regolith covered surfaces, they are a remarkably diverse group. Some have low-eccentricity orbits in the main belt, while some are potentially hazardous objects. They range from dwarf planets to primary planetesimals to fragments of larger precursor objects to tiny shards. One has a moon. Their surface compositions range from basaltic to various chondrite-like compositions. Here their properties are reviewed and what was confirmed and what was newly learned is discussed, and additionally the explored asteroids are compared with comets and meteorites. Several topics are developed. These topics are the internal structure of asteroids, water distribution in the inner solar system and its role in shaping surfaces, and the meteoritic links.

  8. Collisions, Cosmic Radiation and the Colors of the Trojan Asteroids

    CERN Document Server

    Melita, M D; Bar-Nun, A

    2009-01-01

    The Trojan asteroids orbit about the Lagrangian points of Jupiter and the residence times about their present location are very long for most of them. If these bodies originated in the outer Solar System, they should be mainly composed of water ice, but, in contrast with comets, all the volatiles close to the surface would have been lost long ago. Irrespective of the rotation period, and hence the surface temperature and ice sublimation rate, a dust layer exists always on the surface. We show that the timescale for resurfacing the entire surface of the Trojan asteroids is similar to that of the flattening of the red spectrum of the new dust by solar-proton irradiation. This, if the cut-off radius of the size distribution of the impacting objects is between 1mm and 1m and its slope is -3, for the entire size-range. Therefore, the surfaces of most Trojan asteroids should be composed mainly of unirradiated dust.

  9. Dynamics of asteroids and near-Earth objects from Gaia Astrometry

    CERN Document Server

    Bancelin, D; Thuillot, W

    2016-01-01

    Gaia is an astrometric mission that will be launched in spring 2013. There are many scientific outcomes from this mission and as far as our Solar System is concerned, the satellite will be able to map thousands of main belt asteroids (MBAs) and near-Earth objects (NEOs) down to magnitude < 20. The high precision astrometry (0.3-5 mas of accuracy) will allow orbital improvement, mass determination, and a better accuracy in the prediction and ephemerides of potentially hazardous asteroids (PHAs). We give in this paper some simulation tests to analyse the impact of Gaia data on known asteroids' orbit, and their value for the analysis of NEOs through the example of asteroid (99942) Apophis. We then present the need for a follow-up network for newly discovered asteroids by Gaia, insisting on the synergy of ground and space data for the orbital improvement.

  10. The Physical Characterization of the Potentially-Hazardous Asteroid 2004 BL86: A Fragment of a Differentiated Asteroid

    OpenAIRE

    Reddy, Vishnu; Gary, Bruce L.; Sanchez, Juan A; Takir, Driss; Thomas, Cristina A.; Hardersen, Paul S.; Ogmen, Yenal; Benni, Paul; Thomas G Kaye; Gregorio, Joao; Garlitz, Joe; Polishook, David; Corre, Lucille Le; Nathues, Andreas

    2015-01-01

    The physical characterization of potentially hazardous asteroids (PHAs) is important for impact hazard assessment and evaluating mitigation options. Close flybys of PHAs provide an opportunity to study their surface photometric and spectral properties that enable identification of their source regions in the main asteroid belt. We observed PHA (357439) 2004 BL86 during a close flyby of the Earth at a distance of 1.2 million km (0.0080 AU) on January 26, 2015, with an array of ground-based tel...

  11. 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.

  12. 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.

  13. 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

  14. Asteroid secular dynamics: Ceres' fingerprint identified

    OpenAIRE

    Novaković, Bojan; Maurel, Clara; Tsirvoulis, Georgios; Knezević, Zoran

    2015-01-01

    Here we report on the significant role of a so far overlooked dynamical aspect, namely a secular resonance between the dwarf planet Ceres and other asteroids. We demonstrate that this type of secular resonance can be the dominant dynamical factor in certain regions of the main asteroid belt. Specifically, we performed a dynamical analysis of the asteroids belonging to the (1726) Hoffmeister family. To identify which dynamical mechanisms are actually at work in this part of the main asteroid b...

  15. Asteroid Systems: Binaries, Triples, and Pairs

    CERN Document Server

    Margot, Jean-Luc; Taylor, Patrick; Carry, Benoît; Jacobson, Seth

    2015-01-01

    In the past decade, the number of known binary near-Earth asteroids has more than quadrupled and the number of known large main belt asteroids with satellites has doubled. Half a dozen triple asteroids have been discovered, and the previously unrecognized populations of asteroid pairs and small main belt binaries have been identified. The current observational evidence confirms that small (20 km) binaries with small satellites are most likely created during large collisions.

  16. 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.

  17. A Gravitational Tractor for Towing Asteroids

    CERN Document Server

    Lu, E T; Lu, Edward T.; Categories, Stanley G. Love

    2005-01-01

    We present a concept for a spacecraft that can controllably alter the trajectory of an Earth threatening asteroid using gravity as a towline. The spacecraft hovers near the asteroid with thrusters angled outward so the exhaust does not impinge on the surface. This deflection method is insensitive to the structure, surface properties, and rotation state of the asteroid.

  18. Reflectance spectroscopy and asteroid surface mineralogy

    Science.gov (United States)

    Gaffey, Michael J.; Bell, Jeffrey F.; Cruikshank, Dale P.

    1989-01-01

    Information available from reflectance spectroscopy on the surface mineralogy of asteroids is discussed. Current spectral interpretive procedures used in the investigations of asteroid mineralogy are described. Present understanding of the nature and history of asteroids is discussed together with some still unresolved issues such as the source of ordinary chondrites.

  19. Impact of Nurse-Led, Multidisciplinary Home-Based Intervention on Event-Free Survival Across the Spectrum of Chronic Heart Disease

    Science.gov (United States)

    Wiley, Joshua F.; Ball, Jocasta; Chan, Yih-Kai; Ahamed, Yasmin; Thompson, David R.; Carrington, Melinda J.

    2016-01-01

    Background— We sought to determine the overall impact of a nurse-led, multidisciplinary home-based intervention (HBI) adapted to hospitalized patients with chronic forms of heart disease of varying types. Methods and Results— Prospectively planned, combined, secondary analysis of 3 randomized trials (1226 patients) of HBI were compared with standard management. Hospitalized patients presenting with heart disease but not heart failure, atrial fibrillation but not heart failure, and heart failure, as well, were recruited. Overall, 612 and 614 patients, respectively, were allocated to a home visit 7 to 14 days postdischarge by a cardiac nurse with follow-up and multidisciplinary support according to clinical need or standard management. The primary outcome of days-alive and out-of-hospital was examined on an intention-to-treat basis. During 1371 days (interquartile range, 1112–1605) of follow-up, 218 patients died and 17 917 days of hospital stay were recorded. In comparison with standard management, HBI patients achieved significantly prolonged event-free survival (90.1% [95% confidence interval, 88.2–92.0] versus 87.2% [95% confidence interval, 85.1–89.3] days-alive and out-of-hospital; P=0.020). This reflected less all-cause mortality (adjusted hazard ratio, 0.67; 95% confidence interval, 0.50–0.88; P=0.005) and unplanned hospital stay (median, 0.22 [interquartile range, 0–1.3] versus 0.36 [0–2.1] days/100 days follow-up; P=0.011). Analyses of the differential impact of HBI on all-cause mortality showed significant interactions (characterized by U-shaped relationships) with age (P=0.005) and comorbidity (P=0.041); HBI was most effective for those aged 60 to 82 years (59%–65% of individual trial cohorts) and with a Charlson Comorbidity Index Score of 5 to 8 (36%–61%). Conclusions— These data provide further support for the application of postdischarge HBI across the full spectrum of patients being hospitalized for chronic forms of heart

  20. Thermal inertia of main belt asteroids smaller than 100 km from IRAS data

    CERN Document Server

    Delbo, Marco

    2008-01-01

    Recent works have shown that the thermal inertia of km-sized near-Earth asteroids (NEAs) is more than two orders of magnitude higher than that of main belt asteroids (MBAs) with sizes (diameters) between 200 and 1,000 km. This confirms the idea that large MBAs, over hundreds millions of years,have developed a fine and thick thermally insulating regolith layer, responsible for the low values of their thermal inertia, whereas km-sized asteroids, having collisional lifetimes of only some millions years, have less regolith, and consequently a larger surface thermal inertia. Because it is believed that regolith on asteroids forms as a result of impact processes, a better knowledge of asteroid thermal inertia values and its correlation with size, taxonomic type, and density can be used as an important constraintfor modeling of impact processes on asteroids. However, our knowledge of asteroids' thermal inertia values is still based on few data points with NEAs covering the size range 0.1-20 km and MBAs that >100 km....

  1. On the Astrid asteroid family

    CERN Document Server

    Carruba, V

    2016-01-01

    Among asteroid families, the Astrid family is peculiar because of its unusual inclination distribution. Objects at $a\\simeq$~2.764 au are quite dispersed in this orbital element, giving the family a "crab-like" appearance. Recent works showed that this feature is caused by the interaction of the family with the $s-s_C$ nodal secular resonance with Ceres, that spreads the inclination of asteroids near its separatrix. As a consequence, the currently observed distribution of the $v_W$ component of terminal ejection velocities obtained from inverting Gauss equation is quite leptokurtic, since this parameter mostly depends on the asteroids inclination. The peculiar orbital configuration of the Astrid family can be used to set constraints on key parameters describing the strength of the Yarkovsky force, such as the bulk and surface density and the thermal conductivity of surface material. By simulating various fictitious families with different values of these parameters, and by demanding that the current value of ...

  2. UV-LED photopolymerised monoliths

    Czech Academy of Sciences Publication Activity Database

    Abele, S.; Nie, F.; Foret, František; Paull, B.; Macka, M.

    2008-01-01

    Roč. 133, č. 7 (2008), s. 864-866. ISSN 0003-2654 R&D Projects: GA AV ČR KAN400310651 Institutional research plan: CEZ:AV0Z40310501 Keywords : photopolymerisation * UV- LED * polymethacrylate monolith Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.761, year: 2008

  3. Volcanism on differentiated asteroids (Invited)

    Science.gov (United States)

    Wilson, L.

    2013-12-01

    The Dawn spacecraft's investigation of 4 Vesta, best-preserved of the early-forming differentiated asteroids, prompts a reappraisal of factors controlling igneous activity on such bodies. Analogy with melt transfer in zones of partial melting on Earth implies that silicate melts moved efficiently within asteroid mantles in complex networks of veins and dikes, so that only a few percent of the mantle consisted of melt at any one time. Thus even in cases where large amounts of mantle melting occurred, the melts did not remain in the mantle to form "magma oceans", but instead migrated to shallow depths. The link between magma flow rate and the stresses needed to keep fractures open and allow flow fast enough to avoid excessive cooling implies that only within asteroids with radii more than ~190-250 km would continuous magma flow from mantle to surface be possible. In all smaller asteroids (including Vesta) magma must have accumulated in sills at the base of the lithosphere (the conductively controlled ~10 km thick thermal boundary layer) or in crustal magma reservoirs near its base. Magma would then have erupted intermittently to the surface from these steadily replenished reservoirs. The average rates of eruption to the surface (or shallow intrusion) should balance the magma production rate, but since magma could accumulate and erupt intermittently from these reservoirs, the instantaneous eruption rates could be hundreds to thousands of cubic m/s, comparable to historic basaltic eruption rates on Earth and very much greater than the average mantle melting rate. The absence of asteroid atmospheres makes explosive eruptions likely even if magmas are volatile-poor. On asteroids with radii less than ~100 km, gases and sub-mm pyroclastic melt droplets would have had speeds exceeding the escape speed assuming a few hundred ppm volatiles, and only cm sized or larger clasts would have been retained. On larger bodies almost all pyroclasts will have returned to the surface

  4. LED Color Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-01-01

    Color quality is an important consideration when evaluating LED-based products for general illumination. This fact sheet reviews the basics regarding light and color and summarizes the most important color issues related to white-light LED systems.

  5. Micro-meteoroid seismic uplift and regolith concentration on kilometric scale asteroids

    CERN Document Server

    Garcia, Raphael F; Mimoun, David

    2015-01-01

    Seismic shaking is an attractive mechanism to explain the destabilisation of regolith slopes and the regolith migration found on the surfaces of asteroids (Richardson et al. 2004; Miyamoto et al. 2007). Here, we use a continuum mechanics method to simulate the seismic wave propagation in an asteroid. Assuming that asteroids can be described by a cohesive core surrounded by a thin non-cohesive regolith layer, our numerical simulations of vibrations induced by micro-meteoroids suggest that the surface peak ground accelerations induced by micro-meteoroid impacts may have been previously under-estimated. Our lower bound estimate of vertical accelerations induced by seismic waves is about 50 times larger than previous estimates. It suggests that impact events triggering seismic activity are more frequent than previously assumed for asteroids in the kilometric and sub-kilometric size range. The regolith lofting is also estimated by a first order ballistic approximation. Vertical displacements are small, but lofting...

  6. AsteroidZoo: A New Zooniverse project to detect asteroids and improve asteroid detection algorithms

    Science.gov (United States)

    Beasley, M.; Lewicki, C. A.; Smith, A.; Lintott, C.; Christensen, E.

    2013-12-01

    We present a new citizen science project: AsteroidZoo. A collaboration between Planetary Resources, Inc., the Zooniverse Team, and the Catalina Sky Survey, we will bring the science of asteroid identification to the citizen scientist. Volunteer astronomers have proved to be a critical asset in identification and characterization of asteroids, especially potentially hazardous objects. These contributions, to date, have required that the volunteer possess a moderate telescope and the ability and willingness to be responsive to observing requests. Our new project will use data collected by the Catalina Sky Survey (CSS), currently the most productive asteroid survey, to be used by anyone with sufficient interest and an internet connection. As previous work by the Zooniverse has demonstrated, the capability of the citizen scientist is superb at classification of objects. Even the best automated searches require human intervention to identify new objects. These searches are optimized to reduce false positive rates and to prevent a single operator from being overloaded with requests. With access to the large number of people in Zooniverse, we will be able to avoid that problem and instead work to produce a complete detection list. Each frame from CSS will be searched in detail, generating a large number of new detections. We will be able to evaluate the completeness of the CSS data set and potentially provide improvements to the automated pipeline. The data corpus produced by AsteroidZoo will be used as a training environment for machine learning challenges in the future. Our goals include a more complete asteroid detection algorithm and a minimum computation program that skims the cream of the data suitable for implemention on small spacecraft. Our goal is to have the site become live in the Fall 2013.

  7. 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

  8. 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 pla

  9. 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.

  10. 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.

  11. Radar and optical observations and physical modeling of triple near-Earth Asteroid (136617) 1994 CC

    Czech Academy of Sciences Publication Activity Database

    Brozovic, M.; Benner, L. A. M.; Taylor, P.A.; Nolan, M. C.; Howell, E. S.; Magri, C.; Scheeres, D.J.; Giorgini, J. D.; Pollock, J.; Pravec, Petr; Galád, Adrián; Fang, J.; Margot, J. L.; Busch, M.W.; Shepard, M.K.; Reichart, D. E.; Ivarsen, K.M.; Haislip, J.B.; LaCluyze, A.; Jao, J.; Slade, M. A.; Lawrence, K. J.; Hicks, M. D.

    2011-01-01

    Roč. 216, č. 1 (2011), s. 241-256. ISSN 0019-1035 R&D Projects: GA ČR GA205/09/1107 Grant ostatní: SAV(SK) Vega 2/0016/09 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * radar observations * near-Earth objects * satellites of asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.385, year: 2011

  12. Footprints of a possible Ceres asteroid paleo-family

    CERN Document Server

    Carruba, V; Marchi, S; Aljbaae, S

    2016-01-01

    Ceres is the largest and most massive body in the asteroid main belt. Observational data from the Dawn spacecraft reveal the presence of at least two impact craters about 280~km in diameter on the Ceres surface, that could have expelled a significant number of fragments. Yet, standard techniques for identifying dynamical asteroid families have not detected any Ceres family. In this work, we argue that linear secular resonances with Ceres deplete the population of objects near Ceres. Also, because of the high escape velocity from Ceres, family members are expected to be very dispersed, with a considerable fraction of km-sized fragments that should be able to reach the pristine region of the main belt, the area between the 5J:-2A and 7J:-3A mean-motion resonances, where the observed number of asteroids is low. Rather than looking for possible Ceres family members near Ceres, here we propose to search in the pristine region. We identified 156 asteroids whose taxonomy, colors, albedo could be compatible with bein...

  13. Footprints of a possible Ceres asteroid paleo-family

    Science.gov (United States)

    Carruba, V.; Nesvorný, D.; Marchi, S.; Aljbaae, S.

    2016-05-01

    Ceres is the largest and most massive body in the asteroid main belt. Observational data from the Dawn spacecraft reveal the presence of at least two impact craters about 280 km in diameter on the Ceres surface, that could have expelled a significant number of fragments. Yet, standard techniques for identifying dynamical asteroid families have not detected any Ceres family. In this work, we argue that linear secular resonances with Ceres deplete the population of objects near Ceres. Also, because of the high escape velocity from Ceres, family members are expected to be very dispersed, with a considerable fraction of km-sized fragments that should be able to reach the pristine region of the main belt, the area between the 5J:-2A and 7J:-3A mean-motion resonances, where the observed number of asteroids is low. Rather than looking for possible Ceres family members near Ceres, here we propose to search in the pristine region. We identified 156 asteroids whose taxonomy, colours, albedo could be compatible with being fragments from Ceres. Remarkably, most of these objects have inclinations near that of Ceres itself.

  14. The Spherical Brazil Nut Effect and its Significance to Asteroids

    Science.gov (United States)

    Perera, Viranga; Jackson, Alan P.; Asphaug, Erik; Ballouz, Ronald-Louis

    2015-11-01

    Asteroids are intriguing remnant objects from the early solar system. They can inform us on how planets formed, they could possibly impact the earth in the future, and they likely contain precious metals; for those reasons, there will be future exploration and mining space missions to them. Telescopic observations and spacecraft data have helped us understand basic properties such as their size, mass, spin rate, orbital elements, and their surface properties. However, their interior structures have remained elusive. In order to fully characterize the interiors of these bodies, seismic data will be necessary. However, we can infer their interior structures by combining several key factors that we know about them: 1). Past work has shown that asteroids between 150 m to 10 km in size are rubble-piles that are a collection of particles held together by gravity and possibly cohesion. 2). Asteroid surfaces show cratering that suggests that past impacts would have seismically shaken these bodies. 3). Spacecraft images show that some asteroids have large protruding boulders on their surfaces. A rubble-pile object made of particles of different sizes and that undergoes seismic shaking will experience granular flow. Specifically, a size sorting effect known as the Brazil Nut Effect will lead larger particles to move towards the surface while smaller particles will move downwards. Previous work has suggested that this effect could possibly explain not only why there are large boulders on the surfaces of some asteroids but also might suggest that the interior particles of these bodies would be organized by size. Previous works have conducted computer simulations and lab experiments; however, all the particle configurations used have been either cylindrical or rectangular boxes. In this work we present a spherical configuration of self-gravitating particles that is a better representation of asteroids. Our results indicate that while friction is not necessary for the Brazil Nut

  15. Cyclical Regolith Processes on Hydrous Asteroids

    Science.gov (United States)

    Zolensky, M. E.

    1995-09-01

    Carbonaceous chondrites experienced and recorded a very wide range of chemical and physical processing in both nebular and asteroidal settings. Among the features arising from asteroidal processes are the following: (1) most of these meteorites are breccias; (2) some CV3s and CMs contain flattened chondrules and exhibit foliation; (3) veins are found in some CIs, CMs, CV3 dark inclusions; (4) CR2s, all CIs, some CR2s and CMs display weak alignment of matrix phyllosilicates, and (5) shearing (mylonitization) around lithic fragments. While these features have generally been assumed to have involved impact deformation in asteroidal regoliths, a process sometimes referred to as regolith or impact gardening, we suggest here that all of these particular features would have arisen naturally from cycles of wet-dry and freeze-thaw environmental conditions in asteroid regoliths. All of the extensively (Y82042, ALH 83100, Cold Bokkeveld, Y891198, EET 90047) and completely (ALH 88045, EET 83334, Kaidun CM1 lithology) altered CMs contain rounded to elliptical aggregates of phyllosilicates, carbonates, spinels (chromite and magnetite), Fe-Ni sulfides, and embayed olivines and pyroxenes, which we interpret as relict chondrules [1]; these sometimes define a definite foliation direction generally ascribed to impact shock [2&3]. We examined all available relict olivines from CMs showing the most pronounced chondrule flattening and foliation, and found only a few planar fractures in a single olivine grain in one sample (EET 90047), and no sign of shock effects in the others. We therefore suggest that static burial pressure was agent responsible for chondrule flattening in this case, and believe that the processes involved in burial compaction deserve more attention than they have hitherto received in the asteroid literature. It is probable that even in the wettest regions of an asteroid dry periods were experienced during the periodic breaching of an icy surficial rind [4], which

  16. 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 (continued science operation. The science sensors consist of a dual fluxgate magnetometer (MAG), one miniaturized volatile composition analyser (VCA), a narrow angle 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

  17. 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.

  18. Photometry of faint asteroids and satellites

    International Nuclear Information System (INIS)

    The smaller asteroids, having diameters of about 1 km, appear to rotate faster than do the larger asteroids (approximately 200 km diameter). Most of the bodies may be nearly spherical, probably due to a collisional erosion process in the Main Belt of asteroids. The distributions of diameter versus number were studied for low albedo (C, for carbonaceous) and high albedo (S, for silicaceous) type asteroids in the main belt, down to diameters of 25 km. Among the smaller bodies the S type asteroids are relatively more abundant, probably due to greater crushing strength for S type asteroids. This indicates that both optical types have also different properties in the interior of the body. Areas with slightly different reflectivity over the surface of an asteroid were detected; the rotational light variation of asteroid 4 (Vesta) was found to be caused by spots on its surface. Colorimetry and infrared radiometry of some Hilda asteroids, Trojans and the fainter satellites of Jupiter and Saturn, all having diameters between 100 and 200 km, show that a mixture of types exist. If some asteroids are nearly expended nuclei of comets that lost most of their volatile gaseous material, then their cometary activity is expected to be extinct or at least weak. (Auth.)

  19. Utilization of an H-reversal trajectory of a solar sail for asteroid deflection

    International Nuclear Information System (INIS)

    Near Earth Asteroids have a possibility of impacting the Earth and always represent a threat. This paper proposes a way of changing the orbit of the asteroid to avoid an impact. A solar sail evolving in an H-reversal trajectory is utilized for asteroid deflection. Firstly, the dynamics of the solar sail and the characteristics of the H-reversal trajectory are analyzed. Then, the attitude of the solar sail is optimized to guide the sail to impact the target asteroid along an H-reversal trajectory. The impact velocity depends on two important parameters: the minimum solar distance along the trajectory and lightness number of the solar sail. A larger lightness number and a smaller solar distance lead to a higher impact velocity. Finally, the deflection capability of a solar sail impacting the asteroid along the H-reversal trajectory is discussed. The results show that a 10 kg solar sail with a lead-time of one year can move Apophis out of a 600-m keyhole area in 2029 to eliminate the possibility of its resonant return in 2036. (editor's recommendation)

  20. Utilization of an H-reversal trajectory of a solar sail for asteroid deflection

    Institute of Scientific and Technical Information of China (English)

    Sheng-Ping Gong; Jun-Feng Li; Xiang-Yuan Zeng

    2011-01-01

    Near Earth Asteroids have a possibility of impacting the Earth and always represent a threat.This paper proposes a way of changing the orbit of the asteroid to avoid an impact.A solar sail evolving in an H-reversal trajectory is utilized for asteroid deflection.Firstly,the dynamics of the solar sail and the characteristics of the H-reversal trajectory are analyzed.Then,the attitude of the solar sail is optimized to guide the sail to impact the target asteroid along an H-reversal trajectory.The impact velocity depends on two important parameters:the minimum solar distance along the trajectory and lightness number of the solar sail.A larger lightness number and a smaller solar distance lead to a higher impact velocity.Finally,the deflection capability of a solar sail impacting the asteroid along the H-reversal trajectory is discussed.The results show that a 10 kg solar sail with a lead-time of one year can move Apophis out of a 600-m keyhole area in 2029 to eliminate the possibility of its resonant return in 2036.

  1. LED-roulette: LED's vervangen balletje

    OpenAIRE

    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 beoefenen op een eerlijke manier. Je kunt er namelijk niet mee valsspelen, de microcontroller die de LED’s aanstuurt is, onomkoopbaar.

  2. LED-valaisimien kuormitustaulukointi

    OpenAIRE

    Reinilä, Toni

    2015-01-01

    Opinnäytetyössä perehdyttiin virran käyttäytymiseen LED-valaisimen käynnistyessä. Työssä syvennyttiin LED-valaisimien teoriaan sekä teholähteiden ominaisuuksiin. Työ tehtiin Winled Oy:n pyynnöstä, koska yrityksellä oli tarve LED-valaisimien kuormitustaulukolle. Opinnäytetyön tavoite oli tuottaa lisää tietoa LED-valaisimista ja niiden ominaisuuksista. LED-valaisimen tiedetään ottavan suuria virtoja käynnistyessään. Työn tarkoitus oli laatia LED-valaisimien käynnistysvirroista kuormitustaulukko...

  3. 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…

  4. Led-valaistus liikerakennuksessa

    OpenAIRE

    Heikkilä, Juho

    2014-01-01

    Tässä insinöörityössä tutkittiin led-valaistuksen tuomia mahdollisuuksia liikerakennuksien valaistuksessa. Aihetta pohdittiin suunnittelijan näkökulmasta ja painotus oli liikerakennuksen eri tilojen valaistusmahdollisuuksissa. Liikerakennuksissa on tarvetta yleisvalaistukselle, kohdevalaistukselle, sosiaalitilojen sekä pysäköintipaikkojen valaistukselle. Näille tiloille pyrittiin suunnittelemaan optimaalinen valaistus led-valaisimilla. Led-valaisimet ovat korvaamassa valaisimia kaikilla näill...

  5. Photometric analysis of asteroids and comets from space observations

    OpenAIRE

    La Forgia, Fiorangela

    2014-01-01

    The European space mission Rosetta, during its still ongoing journey to the comet 67P/Churyumov-Gerasimenko, on 10 July 2010 made an intermediate stop flying close to the asteroid 21 Lutetia at a distance of less than 3200 km and observed it from a varying observing point, otherwise inaccessible from Earth. Less than four months later, on 4 November 2010, the EPOXI mission, extension of the NASA Deep Impact mission, offered another unexpected opportunity approaching the small hyperactive Jupi...

  6. SPH-based simulation of multi-material asteroid collisions

    CERN Document Server

    Maindl, Thomas I; Speith, Roland; Süli, Áron; Forgács-Dajka, Emese; Dvorak, Rudolf

    2013-01-01

    We give a brief introduction to smoothed particle hydrodynamics methods for continuum mechanics. Specifically, we present our 3D SPH code to simulate and analyze collisions of asteroids consisting of two types of material: basaltic rock and ice. We consider effects like brittle failure, fragmentation, and merging in different impact scenarios. After validating our code against previously published results we present first collision results based on measured values for the Weibull flaw distribution parameters of basalt.

  7. Grasping the Nature of Potentially Hazardous Asteroids

    Science.gov (United States)

    Perna, D.; Dotto, E.; Ieva, S.; Barucci, M. A.; Bernardi, F.; Fornasier, S.; De Luise, F.; Perozzi, E.; Rossi, A.; Mazzotta Epifani, E.; Micheli, M.; Deshapriya, J. D. P.

    2016-01-01

    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 Prot ≈ 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 to characterize

  8. Spitzer observations of two mission-accessible, tiny asteroids

    Science.gov (United States)

    Mommert, M.; Hora, J.; Farnocchia, D.; Chesley, S.; Vokrouhlicky, D.; Trilling, D.; Mueller, M.; Harris, A.; Smith, H.; Fazio, G.

    2014-07-01

    objects will be available at the time of the conference (Mommert et al., in preparation). 2009 BD and 2011 MD are the smallest asteroids for which physical properties have been constrained, providing unique insights into a population of asteroids that gives rise to frequent impacts on the Earth and the Moon. Furthermore, both asteroids are among the most easily accessible objects in space.

  9. 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...

  10. Migration of Near Earth Asteroid to Jovian-Crosser Asteroid:Case Study 3552 Don Quixote

    OpenAIRE

    Siregar, Suryadi

    2010-01-01

    It is generally recognized that main-belt asteroids (MBAs) and nuclei of extinct comets are the two main sources for the Near-Earth-Asteroids (NEAs). Theoretical studies of NEAs dynamics and numerical modelling of their orbital motions showed that the resonance mechanism for supplying NEAs is quite sufficient to sustain this population. Asteroid 1983 SA, also known as 3552 Don Quixote, is one of Near Earth Asteroids (NEAs) and the most probable candidates for NEAs of the cometary origin. In t...

  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...

  12. Families classification including multiopposition asteroids

    Science.gov (United States)

    Milani, Andrea; Spoto, Federica; Knežević, Zoran; Novaković, Bojan; Tsirvoulis, Georgios

    2016-01-01

    In this paper we present the results of our new classification of asteroid families, upgraded by using catalog with > 500,000 asteroids. We discuss the outcome of the most recent update of the family list and of their membership. We found enough evidence to perform 9 mergers of the previously independent families. By introducing an improved method of estimation of the expected family growth in the less populous regions (e.g. at high inclination) we were able to reliably decide on rejection of one tiny group as a probable statistical fluke. Thus we reduced our current list to 115 families. We also present newly determined ages for 6 families, including complex 135 and 221, improving also our understanding of the dynamical vs. collisional families relationship. We conclude with some recommendations for the future work and for the family name problem.

  13. 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....

  14. Asteroid Evolution: Role of Geotechnical Properties

    CERN Document Server

    Sánchez, Paul

    2015-01-01

    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 that 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.

  15. Stabilities of asteroid orbits in resonances

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A map of the asteroid motion is studied carefully. An exponential diffusion law in the chaotic sea and an algebraic law in the mixed region are observed. The effects of perturbations on diffusion are also discussed. The fixed points, their stabilities and the diffusion properties of the map give qualitative explanations of the distribution of asteroids, i.e. the depletion and accumulation of asteroids in the outer main belt, particularly in the first order mean motion resonances with Jupiter.

  16. Lay health worker led intervention for depressive and anxiety disorders in India: impact on clinical and disability outcomes over 12 months

    OpenAIRE

    Patel, Vikram; Weiss, Helen A; Chowdhary, Neerja; Naik, Smita; Pednekar, Sulochana; Chatterjee, Sudipto; Bhat, Bhargav; Araya, Ricardo; King, Michael; Simon, Gregory; Verdeli, Helena; Kirkwood, Betty R.

    2011-01-01

    This paper has been corrected post-publication in deviation from print and in accordance with a correction printed in the February 2012 issue of the Journal. Background Depressive and anxiety disorders (common mental disorders) are the most common psychiatric condition encountered in primary healthcare. Aims To test the effectiveness of an intervention led by lay health counsellors in primary care settings (the MANAS intervention) to improve the outcomes of people with common mental disorders...

  17. Composition of near-Earth asteroids

    Science.gov (United States)

    Lebofsky, Larry A.

    1992-01-01

    The continuing goal is to determine whether any of the near-Earth asteroids or the satellites of Mars contain hydrated phyllosilicate (clay) minerals. If these minerals are present, they would provide a ready source of water for propellant generation and use in life support systems. Many of the dark main belt asteroids have been shown to contain hydrated phyllosilicate minerals. Some of the near-Earth asteroids are also dark, but telescopic detection of water on these near-Earth asteroids is complicated because of the faintness of these small asteroids and because thermal emission masks the diagnostic spectral features beyond 3 microns due to water of hydration for objects within 2 AU of the Sun. New techniques for asteroid classification based on spectral reflectance and mineralogy will be necessary to determine whether the water absorption features are present on any of the near-Earth asteroids. This past year, better ways to classify 'wet' vs. 'dry' asteroids in the main belt were looked at. This new classification may allow us to determine the presence of water of hydration in the surface minerals of near-Earth asteroids even when we can only observe them at wavelengths that are not affected by thermal emission.

  18. Asteroid Models from Multiple Data Sources

    Science.gov (United States)

    Durech, J.; Carry, B.; Delbo, M.; Kaasalainen, M.; Viikinkoski, M.

    In the past decade, hundreds of asteroid shape models have been derived using the lightcurve inversion method. At the same time, a new framework of three-dimensional shape modeling based on the combined analysis of widely different data sources -- such as optical lightcurves, disk-resolved images, stellar occultation timings, mid-infrared thermal radiometry, optical interferometry, and radar delay-Doppler data -- has been developed. This multi-data approach allows the determination of most of the physical and surface properties of asteroids in a single, coherent inversion, with spectacular results. We review the main results of asteroid lightcurve inversion and also recent advances in multi-data modeling. We show that models based on remote sensing data were confirmed by spacecraft encounters with asteroids, and we discuss how the multiplication of highly detailed three-dimensional models will help to refine our general knowledge of the asteroid population. The physical and surface properties of asteroids, i.e., their spin, three-dimensional shape, density, thermal inertia, and surface roughness, are among the least known of all asteroid properties. Apart from the albedo and diameter, we have access to the whole picture for only a few hundreds of asteroids. These quantities are nevertheless very important to understand, as they affect the nongravitational Yarkovsky effect responsible for meteorite delivery to Earth, as well as the bulk composition and internal structure of asteroids.

  19. 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.

  20. LED-kasvivalaisin

    OpenAIRE

    Anttila, Toni

    2008-01-01

    LED-teknologian käyttö kasvihuonevalaistuksessa tulee lisääntymään. LED-valaistuksen etuja ovat mahdollisuudet energian säästöön, kasvatustilan vähentäminen ja mahdollisuudet kontrolloida kasvien kasvua. Tulevaisuudessa erityisvalaistuksen määrä kasvien kasvatuksessa tulee lisääntymään. Tässä työssä suunniteltiin ja rakennettiin LED-kasvivalaisin. Työssä käytiin läpi teoreettinen pohja kasvivalotukselle ja esiteltiin suunnittelun ja rakentamisen eri vaiheet ongelmineen ja erityispiirteine...

  1. Dealing with uncertainties in asteroid deflection demonstration missions: NEOTωIST

    Science.gov (United States)

    Eggl, Siegfried; Hestroffer, Daniel; Cano, Juan L.; Ávila, Javier Martín; Drube, Line; Harris, Alan W.; Falke, Albert; Johann, Ulrich; Engel, Kilian; Schwartz, Stephen R.; Michel, Patrick

    2016-01-01

    Deflection missions to near-Earth asteroids will encounter non-negligible uncertainties in the physical and orbital parameters of the target object. In order to reliably assess future impact threat mitigation operations such uncertainties have to be quantified and incorporated into the mission design. The implementation of deflection demonstration missions offers the great opportunity to test our current understanding of deflection relevant uncertainties and their consequences, e.g., regarding kinetic impacts on asteroid surfaces. In this contribution, we discuss the role of uncertainties in the NEOTωIST asteroid deflection demonstration concept, a low-cost kinetic impactor design elaborated in the framework of the NEOShield project. The aim of NEOTωIST is to change the spin state of a known and well characterized near-Earth object, in this case the asteroid (25143) Itokawa. Fast events such as the production of the impact crater and ejecta are studied via cube-sat chasers and a flyby vehicle. Long term changes, for instance, in the asteroid's spin and orbit, can be assessed using ground based observations. We find that such a mission can indeed provide valuable constraints on mitigation relevant parameters. Furthermore, the here proposed kinetic impact scenarios can be implemented within the next two decades without threatening Earth's safety.

  2. Spectroradiometry for LED characterization

    DEFF Research Database (Denmark)

    Dam-Hansen, Carsten

    Radiospectroscopy is the absolute measurement of electromagnetic radiation within a specific wavelength range. For characterization of LED components, light sources and lamps we are interested in absolute measurement of the spectral power distribution, SPD, in the visible and near infrared region....... Using integrating spheres for light collection setups for absolute total spectral flux is realized at the LED Light Lab at DTU Fotonik, Risø Campus. From these, both total radiant and luminous flux is determined and through electrical power measurement also the efficiency is determined. From the SPD...... colorimetric quantities like color coordinates, color temperature and color rendering indices are calculated. The facilities and special issues concerning LED measurements compared to traditional light sources are explained and examples from the “LED lighting quality program”, a project supported by the Danish...

  3. The Formation of the Wide Asynchronous Binary Asteroid Population

    CERN Document Server

    Jacobson, Seth A; McMahon, Jay

    2013-01-01

    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semi-major 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, planetary flybys and directly from rotational fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (i) these systems are formed from rotational fission, (ii) their satellites are tidally locked, (iii) their orbits are expanded by the BYORP effect, (iv) their satellites de-synchronize due to the adiabatic invariance between the libration of the secondary and the mutual orbit, and (v) the secondary avoids resynchronization due to the 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 torq...

  4. Prospects for LED lighting.

    Energy Technology Data Exchange (ETDEWEB)

    Tsao, Jeffrey Yeenien; Gee, James Martin; Simmons, Jerry Alvon

    2003-08-01

    Solid-state lighting using light-emitting diodes (LEDs) has the potential to reduce energy consumption for lighting by 50% while revolutionizing the way we illuminate our homes, work places, and public spaces. Nevertheless, substantial technical challenges remain in order for solid-state lighting to significantly displace the well-developed conventional lighting technologies. We review the potential of LED solid-state lighting to meet the long-term cost goals.

  5. RS-232 Led Board

    OpenAIRE

    Tskhvaradze, Vladimir

    2007-01-01

    This article demonstrates how to develop a Microchip PIC16F84 based device that supports RS-232 interface with PC. Circuit (LED Board) design and software development will be discussed. PicBasic Pro Compiler from microEngineering Labs, Inc. is used for PIC programming. Development of LED Board Control Console using C/C++ is also briefly discussed. The project requires basic work experience with Microchip PICs, serial communication and programming.

  6. LED facades in urbarchitecture

    OpenAIRE

    Cekić Nikola; Dačić Miloš; Kostić Aleksandra

    2012-01-01

    Rapid development of electronic technologies at the beginning of this century resulted in intensive changes in urbarchitectonic formation of façade planes and physical structures. Advent of LED lights and LED panels made possible that the physical structures in urban agglomerations worldwide, old or new, have opened a new chapter for strategic urbarchitectonic design and different cultural illumination diversity of houses in space. The user relationship towards activities in physical en...

  7. Surface plasmon enhanced LED

    OpenAIRE

    Vučković, Jelena; Lončar, Marko; Painter, Oskar; Scherer, Axel

    2000-01-01

    Summary form only given. We designed and fabricated an LED based on a thin semiconductor membrane (λ/2) with silver mirrors. A large spontaneous emission enhancement and a high modulation speed are obtainable due to the strong localization of the electromagnetic field in the microcavity. The coupling to surface plasmon modes which are subsequently scattered out by means of a grating is used to improve the extraction efficiency of the LED. The bottom mirror is thick and unpatterned. The top mi...

  8. Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey

    Science.gov (United States)

    Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; Ishihara, Daisuke; Kataza, Hirokazu; Takita, Satoshi; Oyabu, Shinki; Ueno, Munetaka; Matsuhara, Hideo; Onaka, Takashi

    2011-10-01

    We present the results of an unbiased asteroid survey in the mid-infrared wavelength region with the Infrared Camera (IRC) on board the Japanese infrared satellite AKARI. About 20% of the point source events recorded in the AKARI All-Sky Survey observations are not used for the IRC Point Source Catalog (IRC-PSC) in its production process because of a lack of multiple detection by position. Asteroids, which are moving objects on the celestial sphere, remain in these ``residual events''. We identify asteroids out of the residual events by matching them with the positions of known asteroids. For the identified asteroids, we calculate the size and albedo based on the Standard Thermal Model. Finally we have a new brand of asteroid catalog, named the Asteroid Catalog Using AKARI (AcuA), which contains 5120 objects, about twice as many as the IRAS asteroid catalog. The catalog objects comprise 4953 main belt asteroids, 58 near-Earth asteroids, and 109 Jovian Trojan asteroids. The catalog is publicly available via the Internet.

  9. Impact Evaluation of Training Natural Leaders during a Community-Led Total Sanitation Intervention: A Cluster-Randomized Field Trial in Ghana.

    Science.gov (United States)

    Crocker, Jonny; Abodoo, Elvis; Asamani, Daniel; Domapielle, William; Gyapong, Benedict; Bartram, Jamie

    2016-08-16

    We used a cluster-randomized field trial to evaluate training natural leaders (NLs) as an addition to a community-led total sanitation (CLTS) intervention in Ghana. NLs are motivated community members who influence their peers' behaviors during CLTS. The outcomes were latrine use and quality, which were assessed from surveys and direct observation. From October 2012, Plan International Ghana (Plan) implemented CLTS in 60 villages in three regions in Ghana. After 5 months, Plan trained eight NLs from a randomly selected half of the villages, then continued implementing CLTS in all villages for 12 more months. The NL training led to increased time spent on CLTS by community members, increased latrine construction, and a 19.9 percentage point reduction in open defecation (p sanitation projects, and may be most effective in socially cohesive villages. For both interventions, latrines built during CLTS were less likely to be constructed of durable materials than pre-existing latrines, but were equally clean, and more often had handwashing materials. CLTS with NL training contributes to three parts of Goal 6 of the Sustainable Development Goals: eliminating open defecation, expanding capacity-building, and strengthening community participation. PMID:27428399

  10. Migration of Near Earth Asteroid to Jovian-Crosser Asteroid:Case Study 3552 Don Quixote

    CERN Document Server

    Siregar, Suryadi

    2010-01-01

    It is generally recognized that main-belt asteroids (MBAs) and nuclei of extinct comets are the two main sources for the Near-Earth-Asteroids (NEAs). Theoretical studies of NEAs dynamics and numerical modelling of their orbital motions showed that the resonance mechanism for supplying NEAs is quite sufficient to sustain this population. Asteroid 1983 SA, also known as 3552 Don Quixote, is one of Near Earth Asteroids (NEAs) and the most probable candidates for NEAs of the cometary origin. In this work, an investigation on the evolution of the orbit is done by using the SWIFT subroutine package, where the gravitational perturbations of eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune are considered. Migration of asteroid 3552 Don Quixote from Near Earth Asteroids (NEAs) to Jovian-crosser asteroid is found.

  11. Asteroid Redirect Mission - Next Major stepping-stone to Human Exploration of NEOs and beyond

    Science.gov (United States)

    Sanchez, Natalia

    2016-07-01

    In response to NASA's Asteroid Initiative, an Asteroid Redirect and Robotic Mission (ARRM) is being studied by a NASA cohort, led by JPL, to enable the capture a multi-ton boulder from the surface of a Near-Earth Asteroid and return it to cislunar space for subsequent human and robotic exploration. The mission would boost our understanding of NEOs and develop technological capabilities for Planetary Defense, shall a NEO come up on a collision course. The benefits of this mission can extend our capabilities to explore farther into space, as well as create a new commercial sector in Space Mining, which would make materials in Space available for our use. ARRM would leverage and advance current knowledge of higher-efficiency propulsion systems with a new Solar Electric Propulsion demonstration (similar to that on the Dawn spacecraft) to be incorporated into future Mars Missions.

  12. Simulations of vibration-driven regolith segregation in the low-gravity asteroid environment

    Science.gov (United States)

    Maurel, C.; Richardson, D. C.; Ballouz, R.-L.; Michel, P.; Schwartz, S. R.

    2015-10-01

    Since the release of the first in situ images of asteroid surfaces by various space missions, several studies have attempted to understand the origin of visible evidence of possible regolith motion, accumulation, and segregation on asteroid surfaces (for example, boulders on the surface of asteroid Itokawa [1]). A plausible explanation for these phenomena that has recently been explored is that motion is caused by seismic waves, engendered by numerous micro-meteoroid impacts that asteroids undergo in their lifetime. In fact, vibrations induced by small impacts have already been considered in the study of regolith segregation, and more specifically in the case of the so-called Brazil nut effect (BNE) on asteroids [2, 3]. To further investigate this, we perform numerical simulations with an extension of the N-body code PKDGRAV [4] used by Matsumura et al. [2]. Our interest is in going beyond the classic BNE scheme (a single intruder of bigger size in a granular bed) and in looking into potential size and/or density segregation of regolith materials, and the dependency of the outcomes on material parameters. In order for our simulations to better represent actual asteroid surface conditions, we have introduced periodic boundary conditions, i.e., we have removed the simulated container of the granular bed, and at the same time, any artifacts that may arise by its presence. Preliminary results of our simulations will be presented. Going forward, we aim to establish scaling laws for regolith segregation in micro-gravity environments, which take into account material properties. To better apply our results in an asteroid-related context, we plan additionally to use realistic impact-generated seismic profiles (e.g., [5]) instead of the continuous sinusoidal shaking implemented until now.

  13. 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...

  14. Organic matter on asteroid 130 Elektra

    Science.gov (United States)

    Cruikshank, D. P.; Brown, R. H.

    1987-01-01

    Infrared absorption spectra of a low-albedo water-rich asteroid appear to show a weak 3.4-micrometer carbon-hydrogen stretching mode band, which suggests the presence of hydrocarbons on asteroid 130 Elektra. The organic extract from the primitive carbonaceous chondritic Murchison meteorite shows similar spectral bands.

  15. 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

  16. Scout: short-arc orbit analysis and hazard assessment for newly discovered asteroids

    Science.gov (United States)

    Farnocchia, Davide; Chesley, Steven R.; Micheli, Marco

    2016-05-01

    It typically takes a few days for a newly discovered asteroid to be officially recognized as a real object. This time is needed to collect additional data and make sure the observations belong to an actual asteroid rather than being an artifact or corresponding to an artificial object. However, asteroids could experience an Earth close approach or even an impact only a few days or less after the discovery observations, as in the cases of 2008 TC3 and 2014 AA, i.e., the only two asteroids discovered before an Earth impact. In such cases, a rapid identification of the close approach or impact dramatically improves the chances of securing the asteroid's trajectory with additional observations prior to impact. Scout is an automated system that provides an orbital and hazard assessment for new potential asteroid discoveries within minutes after the observations are available. Since the time interval covered by the observations is generally short, perhaps only a few hours or even less, there are severe degeneracies in the orbit estimation process. To overcome these degeneracies Scout relies on systematic ranging, a technique that scans the poorly constrained space of topocentric range and range rate, while the plane-of-sky position and motion are directly tied to the recorded observations. This scan allows us to identify the possible orbits and the regions corresponding to collision solutions, as well as potential impact times and locations. From the probability distribution of the observation errors, Scout derives a probability distribution in the orbital space and in turn estimates several metrics of interest, e.g., probability of an Earth impact, of a close approach to Earth, and of being a mission-accessible target.

  17. The Compositional Structure of the Asteroid Belt

    CERN Document Server

    DeMeo, Francesca E; Walsh, Kevin J; Chapman, Clark R; Binzel, Richard P

    2015-01-01

    The past decade has brought major improvements in large-scale asteroid discovery and characterization with over half a million known asteroids and over 100,000 with some measurement of physical characterization. This explosion of data has allowed us to create a new global picture of the Main Asteroid Belt. Put in context with meteorite measurements and dynamical models, a new and more complete picture of Solar System evolution has emerged. The question has changed from "What was the original compositional gradient of the Asteroid Belt?" to "What was the original compositional gradient of small bodies across the entire Solar System?" No longer is the leading theory that two belts of planetesimals are primordial, but instead those belts were formed and sculpted through evolutionary processes after Solar System formation. This article reviews the advancements on the fronts of asteroid compositional characterization, meteorite measurements, and dynamical theories in the context of the heliocentric distribution of...

  18. LEDS GP Success Story: Fostering Coordinated LEDS Support in Kenya (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. On the Astrid asteroid family

    Science.gov (United States)

    Carruba, V.

    2016-09-01

    Among asteroid families, the Astrid family is peculiar because of its unusual inclination distribution. Objects at a ≃ 2.764 au are quite dispersed in this orbital element, giving the family a `crab-like' appearance. Recent works showed that this feature is caused by the interaction of the family with the s - sC nodal secular resonance with Ceres, that spreads the inclination of asteroids near its separatrix. As a consequence, the currently observed distribution of the vW component of terminal ejection velocities obtained from inverting Gauss equation is quite leptokurtic, since this parameter mostly depends on the asteroids inclination. The peculiar orbital configuration of the Astrid family can be used to set constraints on key parameters describing the strength of the Yarkovsky force, such as the bulk and surface density and the thermal conductivity of surface material. By simulating various fictitious families with different values of these parameters, and by demanding that the current value of the kurtosis of the distribution in vW be reached over the estimated lifetime of the family, we obtained that the thermal conductivity of Astrid family members should be ≃0.001 W m-1 K-1, and that the surface and bulk density should be higher than 1000 kg m-3. Monte Carlo methods simulating Yarkovsky and stochastic Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) evolution of the Astrid family show its age to be T = 140 ± 30 Myr old, in good agreement with estimates from other groups. Its terminal ejection velocity parameter is in the range V_{EJ}= 5^{+17}_{-5} m s-1. Values of VEJ larger than 25 m s-1 are excluded from constraints from the current inclination distribution.

  20. The Asteroid 2015 KA122

    Science.gov (United States)

    Vodniza, Alberto Quijano; Pereira, Mario Rojas

    2015-11-01

    The Asteroid “2015 KA122” was discovered on May 25/2015 by the Catalina Sky Survey. This object is not well known. Its absolute magnitude, of 23.2, indicates a diameter of about 70 meters. The asteroid was at aproximately 3.3 lunar distances from the Earth, on June 6/2015. It has an orbital period of 2.11 years. From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during three days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS. Our observatory’s code at the MPC is “H78”. Pictures of the asteroid were captured with the following equipment: 14” LX200 GPS MEADE (f/10 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera. Astrometry was carried out, and we calculated the orbital elements. We obtained the following orbital parameters: eccentricity = 0.4089630 +/- 0.00189, semi-major axis = 1.64254884 +/- 0.00505 A.U, orbital inclination = 12.68490 +/- 0.039 deg, longitude of the ascending node = 73.14715 +/- 0.0013 deg, argument of perihelion = 214.82393 +/- 0.007 deg, orbital period = 2.11 years (768.90 days), mean motion = 0.46819485 +/- 0.00216 deg/d, perihelion distance = 0.97080706 +/- 0.000119 A.U, aphelion distance = 2.31429061 +/- 0.0103 A.U. The parameters were calculated based on 81 observations (2015 June 3-5) with mean residual = 0.343 arcseconds. Our videos appear in the following links:http://spaceweathergallery.com/indiv_upload.php?upload_id=113197http://spaceweathergallery.com/indiv_upload.php?upload_id=113238&PHPSESSID=f2lkigjogsfgcmi1rscc9jil36http://spaceweathergallery.com/indiv_upload.php?upload_id=113257

  1. A hypothesis on the origin of C-type asteroids and carbonaceous chondrites

    CERN Document Server

    Busarev, V V

    2012-01-01

    A hypothesis based on observational and theoretical results on the origin of C-type asteroids and carbonaceous chondrites is proposed. Asteroids of C-type and close BGF-types could form from hydrated silicate-organic matter accumulated in the cores of water-differentiated (due to 26Al and other short-lived isotopes decay) bodies existed in the growth zones of Jupiter. Gravitational scattering of such bodies by Jupiter at its final stage of formation to the main asteroid belt might have led to fragmentation and re-accretion of their primitive materials on the surfaces of many asteroids and/or asteroid parent bodies. The hypothesis makes clear a row of long-standing puzzling facts, the main of which are as follows. The low-albedo and carbonaceous-chondritic surface properties of (1) Ceres contradict to its probable differentiated structure and icy crust (e. g., Thomas et al., 2005, Nature 437: 224-226; Castillo-Rogez et al., 2010, Icarus 205, 443-459), but it could be explained by the process of primitive matte...

  2. 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.

  3. 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.

  4. Orbit Mechanics about Small Asteroids

    Science.gov (United States)

    Scheeres, D. J.

    2007-01-01

    Space missions to small solar system bodies must deal with multiple perturbations acting on the spacecraft. These include strong perturbations from the gravity field and solar tide, but for small bodies the most important perturbations may arise from solar radiation pressure (SRP) acting on the spacecraft. Previous research has generally investigated the effect of the gravity field, solar tide, and SRP acting on a spacecraft trajectory about an asteroid in isolation and has not considered their joint effect. In this paper a more general theoretical discussion of the joint effects of these forces is given.

  5. Semiconducting polymer LEDs

    Directory of Open Access Journals (Sweden)

    David Braun

    2002-06-01

    The field of semiconducting polymers has its root in the 1977 discovery of the semiconducting properties of polyacetylene1. This breakthrough earned Alan Heeger, Alan MacDiarmid, and Hideki Shirakawa the 2000 Nobel Prize in Chemistry for ‘the discovery and development of conductive polymers’2–5. Other review articles capture how more than two decades of developments in the physical and chemical understanding of these novel materials has led to new device applications as active and passive electronic and optoelectronic devices ranging from diodes and transistors to polymer LEDs, photodiodes, lasers, and solar cells6–11. Much interest in plastic devices derives from the opportunities to use clever control of polymer structure combined with relatively economical polymer synthesis and processing techniques to obtain simultaneous control over electronic, optical, chemical, and mechanical features5. This article focuses on the advances leading to polymer LEDs12–14.

  6. 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...

  7. Led-tievalaistus

    OpenAIRE

    Parviainen, Samuli

    2015-01-01

    Opinnäytetyön tavoitteena oli tehdä selvitystyö led-tievalaistuksesta. Työssä perehdytään Tiehallinnon vaatimuksiin tievalaistuksesta ja tievalaistuksesta. Työssä keskitytään tarkemmin led-valaistukseen ja sen hyötyihin. Työssä tarkastellaan myös Euroopan Unionin direktiivejä ja säädöksiä, jotka liittyvät valaistukseen ja energian säätämiseen julkisilla paikolla.

  8. LED-tekniikka elokuvavalaisussa

    OpenAIRE

    Laurila, Mika

    2016-01-01

    Opinnäytetyön tavoitteena oli luoda suomenkielinen katsaus led-tekniikan kehityksen tilanteesta vuonna 2016. Työtä varten haastateltiin viittä suomalaista elokuvavalaisijaa, ja siihen kerättiin kirjallista materiaalia sekä elokuva-alan kirjallisuudesta että internetistä. Työllä haluttiin tuoda esille led-tekniikan tuomia hyötyjä elokuvavalaisussa sekä toisaalta haluttiin paneutua myös ledien aiheuttamiin haasteisiin. Haastatteluiden pohjalta huomattiin ledien teknisen tason nousseen jo s...

  9. LED-valot rakentamisessa

    OpenAIRE

    Jokinen, Matti

    2011-01-01

    Tämä sähkövoimatekniikan opinnäytetyö tehtiin Rejlers Oy:lle.Vuonna 1942 perustettu Suomen Rejlers on osa pohjoismaista Rejlerkoncernen yhtiötä. Yhtiö tarjoaa suunnittelua, konsultointia ja turnkey-toimituksia teollisuuden, energian, rakentamisen ja kiinteistöjen sekä infran toimialoilla Suomessa, Ruotsissa, Virossa ja Norjassa. Opinnäytetyön tavoitteena oli tuoda esille LED-tekniikalla toteutettuja valojen käyttömahdollisuuksia rakentamisessa. Työssä tutustuttiin LED-valojen ominaisuuks...

  10. Lightcurve Analysis of Asteroids from Blue Mountains Observatory in 2014

    Science.gov (United States)

    Oey, Julian

    2016-01-01

    Photometric observations of a number of asteroids were done from Blue Mountains Observatory in 2014. The observations were made in support of the binary asteroid and asteroid pairs campaigns by Petr Pravec, and to obtain new data at favorable apparitions for asteroids with poorly defined lightcurves.

  11. Constraining the Bulk Density of 10m-Class Near-Earth Asteroid 2012 LA

    Science.gov (United States)

    Mommert, Michael; Hora, Joseph; Farnocchia, Davide; Trilling, David; Chesley, Steve; Harris, Alan; Mueller, Migo; Smith, Howard

    2016-08-01

    The physical properties of near-Earth asteroids (NEAs) provide important hints on their origin, as well as their past physical and orbital evolution. Recent observations seem to indicate that small asteroids are different than expected: instead of being monolithic bodies, some of them instead resemble loose conglomerates of smaller rocks, so called 'rubble piles'. This is surprising, since self-gravitation is practically absent in these bodies. Hence, bulk density measurements of small asteroids, from which their internal structure can be estimated, provide unique constraints on asteroid physical models, as well as models for asteroid evolution. We propose Spitzer Space Telescope observations of 10 m-sized NEA 2012 LA, which will allow us to constrain the diameter, albedo, bulk density, macroporosity, and mass of this object. We require 30 hrs of Spitzer time to detect our target with a minimum SNR of 3 in CH2. In order to interpret our observational results, we will use the same analysis technique that we used in our successful observations and analyses of tiny asteroids 2011 MD and 2009 BD. Our science goal, which is the derivation of the target's bulk density and its internal structure, can only be met with Spitzer. Our observations will produce only the third comprehensive physical characterization of an asteroid in the 10m size range (all of which have been carried out by our team, using Spitzer). Knowledge of the physical properties of small NEAs, some of which pose an impact threat to the Earth, is of importance for understanding their evolution and estimating the potential of destruction in case of an impact, as well as for potential manned missions to NEAs for either research or potential commercial uses.

  12. The spherical Brazil Nut Effect and its significance to asteroids

    CERN Document Server

    Perera, Viranga; Asphaug, Erik; Ballouz, Ronald-Louis

    2016-01-01

    Many asteroids are likely rubble-piles that are a collection of smaller objects held together by gravity and possibly cohesion. These asteroids are seismically shaken by impacts, which leads to excitation of their constituent particles. As a result it has been suggested that their surfaces and sub-surface interiors may be governed by a size sorting mechanism known as the Brazil Nut Effect. We study the behavior of a model asteroid that is a spherical, self-gravitating aggregate with a binary size-distribution of particles under the action of applied seismic shaking. We find that above a seismic threshold, larger particles rise to the surface when friction is present, in agreement with previous studies that focussed on cylindrical and rectangular box configurations. Unlike previous works we also find that size sorting takes place even with zero friction, though the presence of friction does aid the sorting process above the seismic threshold. Additionally we find that while strong size sorting can take place n...

  13. Coordinated Time Resolved Spectrophotometry of Asteroid 163249 (2002 GT)

    Science.gov (United States)

    Ryan, Erin L.; Woodward, C.; Gordon, M.; Wagner, M. R.; Chesley, S.; Hicks, M.; Pittichova, J.; Pravec, P.

    2013-10-01

    The near-Earth asteroid 163249 (2002 GT), classified as a potentially hazardous asteroid (PHA), has been identified a potential rendezvous target for the NASA Deep Impact spacecraft on 4 Jan 2020. As part of a coordinated international effort to study this asteroid during its 2013 apparition (J. Pittichová et al. DPS 2013), we obtained simultaneous Sloan r-band photometry at the Steward Observatory Bok 2.3-m telescope (+90Prime) and optical spectroscopic observations covering a wavelength interval from ~5400 to ~8500 Angstrom at the MMT 6.5-m (+RedChannel spectrograph) on 2013 June 16 and 17 UT near close Earth approach (heliocentric distance ~1.07 AU; geocentric distance ~0.13 AU) at 180 sec intervals over the ~3.76 hr rotational period. Our objective was to obtain a temporal sequence of spectra to assess surface mineralogy (seeking to potentially detect the 0.7 micron absorption bands attributed to phylosilicate materials) and to determine whether variations in the spectral slope and/or surface mineralogy are evident as a function of rotational period. Here we present initial analysis of these datasets, describing the light-curve and the reflectance spectra as a function of rotational phase. These datasets will be incorporated into a larger compendium describing the characteristics of asteroid 163249. Acknowledgement: This research supported in part by NASA 12-PAST-12-0010 grant NNX13AJ11G , and an appointment (E.L.R.) to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. P.P. was supported by the Grant Agency of the Czech Republic, Grant P209/12/0229.

  14. The recovery of asteroid 2008 TC[subscript 3

    Energy Technology Data Exchange (ETDEWEB)

    Shaddad, Muawia H.; Jenniskens, Peter; Numan, Diyaa; Kudoda, Ayman M.; Elsir, Saadia; Riyad, Ihab F.; Ali, Awad Elkareem; Alameen, Mohammed; Alameen, Nada M.; Eid, Omer; Osman, Ahmed T.; AbuBaker, Mohamed I.; Yousif, Mohamed; Chesley, Steven R.; Chodas, Paul W.; Albers, Jim; Edwards, Wayne N.; Brown, Peter G.; Kuiper, Jacob; Friedrich, Jon M. (CIT); (Juba); (RNMI-Netherlands); (Khartoum); (UWO); (SETI); (Fordham)

    2011-09-06

    On October 7, 2008, asteroid 2008 TC{sub 3} impacted Earth and fragmented at 37 km altitude above the Nubian Desert in northern Sudan. The area surrounding the asteroid's approach path was searched, resulting in the first recovery of meteorites from an asteroid observed in space. This was also the first recovery of remains from a fragile 'cometary' PE = IIIa/b type fireball. In subsequent searches, over 600 mostly small 0.2-379 g meteorites (named 'Almahata Sitta') with a total mass 10.7 kg were recovered from a 30 x 7 km area. Meteorites fell along the track at 1.3 kg km{sup -1}, nearly independent of mass between 1 and 400 g, with a total fallen mass of 39 {+-} 6 kg. The strewn field was shifted nearly 1.8 km south from the calculated approach path. The influence of winds on the distribution of the meteorites, and on the motion of the dust train, is investigated. The majority of meteorites are ureilites with densities around 2.8 g cm{sup -3}, some of an anomalous (porous, high in carbon) polymict ureilite variety with densities as low as 1.5 g cm{sup -3}. In addition, an estimated 20-30% (in mass) of recovered meteorites were ordinary, enstatite, and carbonaceous chondrites. Their fresh look and matching distribution of fragments in the strewn field imply that they were part of 2008 TC{sub 3}. For that reason, they are all referred to as 'Almahata Sitta.' No ureilite meteorites were found that still held foreign clasts, suggesting that the asteroid's clasts were only loosely bound.

  15. Investigating the surface and subsurface properties of the Didymos binary asteroid with a landed CubeSat

    Science.gov (United States)

    Murdoch, Naomi; Cadu, Alexandre; Mimoun, David; Karatekin, Ozgur; Garcia, Raphael; Carrasco, José; Garcia de Quiros, Javier; Vasseur, Hugues; Ritter, Birgit; Eubanks, Marshall; Radley, Charles; Dehant, Veronique

    2016-04-01

    Despite the successes of recent space missions (e.g., Cheng et al., 1997; Fujiwara et al., 2006), there is still no clear understanding of the asteroid internal structure(s). Depending on their size, evolution and physical properties, many different asteroid internal structure models have been suggested from completely cohesive bodies, through to rubble pile objects. The Asteroid Geophysical Explorer (AGEX), a COPINS payload selected by ESA*, will land geophysical instrument packages on the surface of Didymoon; the secondary object in the (65803) Didymos (1996 GT) binary system (Karatekin et al 2016). The instruments will characterize the asteroid surface mechanical properties and probe, for the first time, the sub-surface structure of an asteroid. AGEX will be deployed from AIM on a ballistic transfer to the asteroid surface, several days before the MASCOT-2 package. We expect that AGEX will bounce multiple times before coming to rest on the surface of the asteroid thus providing a unique opportunity to study the asteroid surface properties, perhaps at several locations, using accelerometers. Once stationary, the seismological surface-monitoring phase, using a three-axis set of geophones, can begin. The high speed DART impact will be a major seismic source on Didymoon. However, the seismic payload may also be able to perform seismological investigations using natural seismic sources such as micrometeoroid impacts (e.g., Garcia et al., 2015), thermal cracks (e.g., Delbo et al., 2014), internal quakes due to tidal forces (e.g., Richardson et al. 1998) and other geophysical processes (see Murdoch et al., 2015). We will present the expected signal characteristics of the landing and also of the natural seismic sources that may occur on Didymoon. An understanding of the amplitude and frequency content of such signals is necessary in order to design the optimal geophysical payload for small body exploration using a CubeSat platform. [1.] Cheng, A. et al., Journal of

  16. Dynamical dispersal of primordial asteroid families

    Science.gov (United States)

    Brasil, P. I. O.; Roig, F.; Nesvorný, D.; Carruba, V.; Aljbaae, S.; Huaman, M. E.

    2016-03-01

    Many asteroid families are identified and well characterized all over the main asteroid belt. Interestingly, however, none of them are older than 4 Gyr. Many mechanisms have been proposed to disperse such old primordial asteroid families that presumably have existed, but only very few have really worked. Here we present a plausible mechanism for dispersing primordial asteroid families that is based on the 5-planet instability model known as jumping Jupiter. Using two different evolutions for the jumping-Jupiter model, we have numerically integrated orbits of eight putative primordial families. Our results show that the most important effect on the asteroid families' eccentricity and inclination dispersal is that of the secular resonances, in some cases associated with the mean motion resonances. As for the semimajor axes spreading we find that the principal effect is that of close encounters with the fifth giant planet whose orbit briefly overlaps with (part of) the main belt. Therefore, the existence of a fifth giant planet with the mass comparable with that of Uranus' or Neptune's could contribute in important ways to dispersal of the primordial asteroid families. To have that effect, the interloper planet should go into and considerably interact with the asteroids during the instability phase.

  17. Olivine-dominated Asteroids: Mineralogy and Origin

    CERN Document Server

    Sanchez, Juan A; Kelley, Michael S; Cloutis, Edward A; Bottke, William F; Nesvorný, David; Lucas, Michael P; Hardersen, Paul S; Gaffey, Michael J; Abell, Paul A; Corre, Lucille Le

    2013-01-01

    Olivine-dominated asteroids are a rare type of objects formed either in nebular processes or through magmatic differentiation. The analysis of meteorite samples suggest that at least 100 parent bodies in the main belt experienced partial or complete melting and differentiation before being disrupted. However, only a few olivine-dominated asteroids, representative of the mantle of disrupted differentiated bodies, are known to exist. Due to the paucity of these objects in the main belt their origin and evolution have been a matter of great debate over the years. In this work we present a detailed mineralogical analysis of twelve olivine-dominated asteroids. Within our sample we distinguish two classes, one that we call pure-olivine asteroids and another referred to as olivine-rich asteroids. For the pure-olivine asteroids the olivine chemistry was found to range from ~ Fo49 to Fo70, consistent with the values measured for brachinites and R chondrites. In the case of the olivine-rich asteroids we determined thei...

  18. Latest Developments in LED Standards

    OpenAIRE

    Yurtseven, M. Berker; Onaygil, Sermin

    2015-01-01

    The LED light sources can be stated as the most promising technology for the last decade from the lighting technology point of view. In order to compare LED chips and LED products from different manufacturers and achieve reproducible results, all of the manufacturers shall measure their LEDs or LED based products using same methodology. In this study, it is aimed to explain measurement and performance standards for LED chips and LED based Solid State Lighting products.

  19. Precise measurement of asteroid sizes and shapes from occultations

    International Nuclear Information System (INIS)

    The observational techniques (including photoelectric observations, television recordings, and visual timings) used to measure asteroid dimensions from occultations of stars by asteroids are discussed together with the methods of analysis appropriate to occultation data. Results are presented on the determinations of asteroid diameter, density, and internal structure measures learned from occultations of 36 asteroids. Prospects for continued effective applications of the occultation technique to asteroid studies are discussed. 80 refs

  20. Physical modeling of triple near-Earth Asteroid (153591) 2001 SN263 from radar and optical light curve observations

    Czech Academy of Sciences Publication Activity Database

    Becker, T.M.; Howell, E. S.; Nolan, M. C.; Magri, C.; Pravec, Petr; Taylor, P.A.; Oey, J.; Higgins, D.; Világi, J.; Kornoš, L.; Galád, A.; Gajdoš, Š.; Gaftonyuk, N. M.; Krugly, Y. N.; Molotov, I.E.; Hicks, M. D.; Carbognani, A.; Warner, B. D.; Vachier, F.; Marchis, F.; Pollock, J.

    2015-01-01

    Roč. 248, March (2015), s. 499-515. ISSN 0019-1035 R&D Projects: GA ČR GAP209/12/0229 Grant ostatní: SAV(SK) Vega1/0670/13 Institutional support: RVO:67985815 Keywords : asteroids * near- Earth objects * satellites of asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.038, year: 2014

  1. Catastrophic disruption in the solar system - Asteroid collisional history, origin of Hirayama families and disruption of small satellites

    Science.gov (United States)

    Davis, D. R.

    1986-01-01

    The process of collisional catastrophic disruption has played a significantly role in structuring the solar system. Diverse populations of bodies such as the asteroid belt, small satellites of Jupiter and Saturn and perhaps even the rings of Saturn have been created or substantially changed by catastrophic distruption. Understanding the outcome of large scale impacts is essential to learning about the early history of the solar system in the asteroid zone and the reason why a planet failed to form there.

  2. The Physical Characterization of the Potentially-Hazardous Asteroid 2004 BL86: A Fragment of a Differentiated Asteroid

    CERN Document Server

    Reddy, Vishnu; Sanchez, Juan A; Takir, Driss; Thomas, Cristina A; Hardersen, Paul S; Ogmen, Yenal; Benni, Paul; Kaye, Thomas G; Gregorio, Joao; Garlitz, Joe; Polishook, David; Corre, Lucille Le; Nathues, Andreas

    2015-01-01

    The physical characterization of potentially hazardous asteroids (PHAs) is important for impact hazard assessment and evaluating mitigation options. Close flybys of PHAs provide an opportunity to study their surface photometric and spectral properties that enable identification of their source regions in the main asteroid belt. We observed PHA (357439) 2004 BL86 during a close flyby of the Earth at a distance of 1.2 million km (0.0080 AU) on January 26, 2015, with an array of ground-based telescopes to constrain its photometric and spectral properties. Lightcurve observations showed that the asteroid was a binary and subsequent radar observations confirmed the binary nature and gave a primary diameter of 300 meters and a secondary diameter of 50-100 meters. Our photometric observations were used to derive the phase curve of 2004 BL86 in the V-band. Two different photometric functions were fitted to this phase curve, the IAU H-G model (Bowell et al. 1989) and the Shevchenko model (Shevchenko 1996). From the fi...

  3. A three-parameter asteroid taxonomy

    Science.gov (United States)

    Tedesco, Edward F.; Williams, James G.; Matson, Dennis L.; Veeder, Glenn J.; Gradie, Jonathan C.

    1989-01-01

    Broadband U, V, and x photometry together with IRAS asteroid albedos have been used to construct an asteroid classification system. The system is based on three parameters (U-V and v-x color indices and visual geometric albedo), and it is able to place 96 percent of the present sample of 357 asteroids into 11 taxonomic classes. It is noted that all but one of these classes are analogous to those previously found using other classification schemes. The algorithm is shown to account for the observational uncertainties in each of the classification parameters.

  4. Compositions of near-Earth asteroids

    Science.gov (United States)

    Lebofsky, L. A.; Nelson, M. L.

    1991-01-01

    The goal is to determine whether any of the near-earth asteroids contain water-bearing phyllosilicate (clay) minerals. If these minerals are present, they would provide a readily available source of water for propellant generation and use in life support systems. Telescopic detection of water on the near-earth asteroids is complicated because thermal emission from the asteroid itself masks the diagnostic absorption features for objects this close to the sun. Sophisticated thermal models are necessary to determine whether the absorption features are present. This year, development of these models was continued and more telescopic data to test the models was obtained.

  5. The Physical, Geological, and Dynamical Nature of Asteroid (101955) Bennu - Target of OSIRIS-REx

    Science.gov (United States)

    Lauretta, Dante

    2014-11-01

    OSIRIS-REx will survey asteroid (101955) Bennu to understand its properties, assess its resource potential, refine the impact hazard, and return a sample to Earth. This mission launches in 2016. Bennu is different from all other near-Earth asteroids previously visited by spacecraft. (433) Eros, target of the NEAR-Shoemaker mission, and (25143) Itokawa, target of Hayabusa, are both high-albedo, S-type asteroids with irregular shapes. In contrast, Bennu has a low albedo, is a B-type asteroid, and has a distinct spheroidal shape. While Eros and Itokawa are similar to ordinary chondrites, Bennu is likely related to carbonaceous chondrites, meteorites that record the history of volatiles and organic compounds in the early Solar System.We performed an extensive campaign to determine the properties of Bennu. This investigation provides information on the orbit, shape, mass, rotation state, radar response, photometric, spectroscopic, thermal, regolith, and environmental properties of Bennu. Combining these data with cosmochemical and dynamical models yields a hypothetical timeline for Bennu’s formation and evolution. Bennu is an ancient object that has witnessed over 4.5 Gyr of Solar System history. Its chemistry and mineralogy were established within the first 10 Myr of the Solar System. It likely originated as a discrete asteroid in the main belt ~0.7 - 2 Gyr ago as a fragment from the catastrophic disruption of a large, carbonaceous asteroid. It was delivered to near-Earth space via a combination of Yarkovsky-induced drift and interaction with giant-planet resonances. During its journey, YORP processes and planetary encounters modified Bennu’s spin state, potentially reshaping and resurfacing the asteroid. Bennu is a Potentially Hazardous Asteroids with an ~1-in-2700 chance of impacting the Earth in the late 22nd century. It will most likely end its dynamical life by falling into the Sun. The highest probability for a planetary impact is with Venus, followed by the

  6. Asteroids@home - A BOINC distributed computing project for asteroid shape reconstruction

    CERN Document Server

    Durech, Josef; Vanco, Radim

    2015-01-01

    We present the project Asteroids@home that uses distributed computing to solve the time-consuming inverse problem of shape reconstruction of asteroids. The project uses the Berkeley Open Infrastructure for Network Computing (BOINC) framework to distribute, collect, and validate small computational units that are solved independently at individual computers of volunteers connected to the project. Shapes, rotational periods, and orientations of the spin axes of asteroids are reconstructed from their disk-integrated photometry by the lightcurve inversion method.

  7. Pharmacist-led implementation of a vancomycin guideline across medical and surgical units: impact on clinical behavior and therapeutic drug monitoring outcomes

    Directory of Open Access Journals (Sweden)

    Phillips CJ

    2015-10-01

    Full Text Available Cameron J Phillips,1–3 David L Gordon3,4 1Division of Pharmacy, SA Pharmacy, Flinders Medical Centre, Bedford Park, 2School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, 3Department of Microbiology and Infectious Diseases, School of Medicine, Flinders University, Adelaide, 4Department of Microbiology and Infectious Diseases, SA Pathology, Flinders Medical Centre, Bedford Park, SA, Australia Background: Vancomycin is the antibiotic of choice for the treatment of serious infections such as methicillin-resistant Staphylococcus aureus (MRSA. Inappropriate prescribing of vancomycin can lead to therapeutic failure, antibiotic resistance, and drug toxicity. Objective: To examine the effectiveness of pharmacist-led implementation of a clinical practice guideline for vancomycin dosing and monitoring in a teaching hospital. Methods: An observational pre–post study design was undertaken to evaluate the implementation of the vancomycin guideline. The implementation strategy principally involved education, clinical vignettes, and provision of pocket guidelines to accompany release of the guideline to the hospital Intranet. The target cohort for clinical behavioral change was junior medical officers, as they perform the majority of prescribing and monitoring of vancomycin in hospitals. Assessment measures were recorded for vancomycin prescribing, therapeutic drug monitoring, and patient outcomes. Results: Ninety-nine patients, 53 pre- and 46 post-implementation, were included in the study. Prescribing of a loading dose increased from 9% to 28% (P=0.02, and guideline adherence to starting maintenance dosing increased from 53% to 63% (P=0.32. Dose adjustment by doctors when blood concentrations were outside target increased from 53% to 71% (P=0.12, and correct timing of initial concentration measurement increased from 43% to 57% (P=0.23. Appropriately timed trough concentrations improved from 73% to 81% (P=0.08. Pre-dose (trough

  8. Randomised controlled trials for evaluating the prescribing impact of information meetings led by pharmacists and of new information formats, in General Practice in Italy

    Directory of Open Access Journals (Sweden)

    Magnano Lucia

    2007-09-01

    to evaluate the organisational feasibility and barriers to the implementation of independent information programs led by NHS pharmacists. The objective to assess a 10 or 15% decreases in the prescription of the targeted drugs is quite ambitious in such 'natural' settings, which will be minimally altered by the interventions themselves; this in spite of the quite large sample sizes used comparing to other studies of these kind. Complex interventions like these are not easy to evaluate, given the many different variables into play. Anyway, the pragmatic nature of the two RCTs appears to be also one of their major strengths, helping to provide a deeper insight on what is possible to achieve – in terms of independent information – in a National Health System, with special reference to Italy. Trial registration ISRCTN05866587 (cluster RCT and ISRCTN28525676 (single GPs RCT

  9. Can Plume-Forming Asteroid Airbursts Generate Meteotsunami in Deep Water?

    Science.gov (United States)

    Boslough, M.

    2015-12-01

    Hydrocode simulations suggest that the 1908 Tunguska explosion was a plume-forming airburst analogous to those caused by Comet Shoemaker-Levy 9 (SL9) collisions with Jupiter in 1994. A noctilucent cloud that appeared over Europe following the Tunguska event is similar to post-impact features on Jupiter, consistent with a collapsed plume containing condensation from the vaporized asteroid. Previous workers treated Tunguska as a point explosion and used seismic records, barograms, and extent of fallen trees to determine explosive yield. Estimates were based on scaling laws derived from nuclear weapons data, neglecting directionality, mass, and momentum of the asteroid. This point-source assumption, with other simplifications, led to a significant overestimate. Tunguska seismic data were consistent with ground motion from a vertical point impulse of 7×1018dyn sec caused by the downward blast wave of a 12.5-megaton nuclear explosion at an altitude of 8.5 km for an effective momentum multiplication factor (β) of ~80. However, simulations of a 3-megaton collisional airburst reveal that the upward-directed momentum contained in a ballistic plume can reach this level within the first minute after the explosion (β≈300). The reaction impulse from such an airburst is therefore similar to a much larger non-plume-forming nuclear explosion. Momentum is coupled through the atmosphere to the surface, generating disproportionately large seismic signatures. This 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 because the characteristic time of the plume is closer to that of a long-period wave in deep water. As the plume accelerates upward, it creates a slowly-rising and sustained overpressure with a ramp wave that propagates outward at the speed of sound, generating a tsunami in deep ocean by the same mechanism that yields slower meteotsunami in shallow

  10. 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...

  11. Promoting student led education

    OpenAIRE

    Kotecha, Meena

    2011-01-01

    This paper will discuss the encouraging outcomes of a small scale study in which students were encouraged to actively contribute to various aspects of their education. It will share an innovative Student Led Education Initiative that emerged by extending the author’s teaching practice. First year undergraduate students were encouraged to actively contribute to various aspects of their education. The rationale behind this was to inspire students to lead the way in their education. ...

  12. Student-led education

    OpenAIRE

    Kotecha, Meena

    2012-01-01

    The author has co-presented this presentation with her students to discuss the findings of her individual initiative in which she has discussed how she encouraged her undergraduates to actively contribute to various aspects of their education. She has shared an innovative Student Led Education Initiative that emerged by extending her teaching practice. The rationale behind this was to inspire students to lead the way in their education. This was the author's response to The Higher Education W...

  13. Asteroid 4 Vesta: Dynamical and collisional evolution during the Late Heavy Bombardment

    Science.gov (United States)

    Pirani, S.; Turrini, D.

    2016-06-01

    Asteroid 4 Vesta is the only currently identified asteroid for which we possess samples in the form of meteorites. These meteorites revealed us that Vesta is a differentiated body and that its differentiation produced a relatively thin basaltic crust that survived intact over its entire collisional history. The survival of the vestan basaltic crust has long been identified as a pivotal constraint in the study of the evolution of the asteroid belt and the Solar System but, while we possess a reasonably good picture of the effects of the last 4 Ga on such a crust, little is known about the effects of earlier events like the Late Heavy Bombardment. In this work we address this gap in our knowledge by simulating the Late Heavy Bombardment on Vesta in the different dynamical scenarios proposed for the migration of the giant planets in the broad framework of the Nice Model. The results of the simulations allowed us to assess the collisional history of the asteroid during the Late Heavy Bombardment in terms of produced crater population, surface saturation, mass loss and mass gain of Vesta and number of energetic or catastrophic impacts. Our results reveal that planet-planet scattering is a dynamically favorable migration mechanism for the survival of Vesta and its crust. The number of impacts of asteroids larger than about 1 km in diameter estimated as due to the LHB is 31 ± 5, i.e. about 5 times larger than the number of impacts that would have occurred in an unperturbed main belt in the same time interval. The contribution of a possible extended belt to the collisional evolution of Vesta during the LHB is quite limited and can be quantified in 2 ± 1 impacts of asteroids with diameter greater than or equal to 1 km. The chance of energetic and catastrophic impacts is less than 10% and is compatible with the absence of giant craters dated back to 4 Ga ago and with the survival of the asteroid during the Late Heavy Bombardment. The mass loss caused by the bombardment

  14. Properties of Near-Sun Asteroids

    CERN Document Server

    Jewitt, David

    2013-01-01

    Asteroids near the Sun can attain equilibrium temperatures sufficient to induce surface modification from thermal fracture, desiccation and decomposition of hydrated silicates. We present optical observations of nine asteroids with perihelia <0.25 AU (sub-solar temperatures greater than/equal to 800 K) taken to search for evidence of thermal modification. We find that the broadband colors of these objects are diverse but statistically indistinguishable from those of planet-crossing asteroids having perihelia near 1 AU. Furthermore, images of these bodies taken away from perihelion show no evidence for on-going mass-loss (model-dependent limits roughly less than/equal to 1 kg /s) that might result from thermal disintegration of the surface. We conclude that, while thermal modification may be an important process in the decay of near-Sun asteroids and in the production of debris, our new data provide no evidence for it.

  15. Asteroid Lightcurves from the Preston Gott Observatory

    Science.gov (United States)

    Clark, Maurice

    2012-04-01

    Results of analysis of CCD photometry observations obtained at the Preston Gott Observatory of asteroids 970 Primula, 3015 Candy, 3751 Kiang, 6746 Zagar, 7750 McEwen, 10046 Creighton, and 19251 Totziens are presented.

  16. 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.

  17. Collisional and Rotational Disruption of Asteroids

    CERN Document Server

    Walsh, Kevin J; Richardson, Derek C

    2009-01-01

    Asteroids are leftover pieces from the era of planet formation that help us understand conditions in the early Solar System. Unlike larger planetary bodies that were subject to global thermal modification during and subsequent to their formation, these small bodies have kept at least some unmodified primordial material from the solar nebula. However, the structural properties of asteroids have been modified considerably since their formation. Thus, we can find among them a great variety of physical configurations and dynamical histories. In fact, with only a few possible exceptions, all asteroids have been modified or completely disrupted many times during the age of the Solar System. This picture is supported by data from space mission encounters with asteroids that show much diversity of shape, bulk density, surface morphology, and other features. Moreover, the gravitational attraction of these bodies is so small that some physical processes occur in a manner far removed from our common experience on Earth....

  18. Chelyabinsk: Portrait of an asteroid airburst

    International Nuclear Information System (INIS)

    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

  19. Origins for the near-earth asteroids

    Science.gov (United States)

    Binzel, Richard P.; Xu, Shui; Bus, Schelte J.; Bowell, Edward

    1992-01-01

    Because of their short dynamical lifetimes, the population of near-earth asteroids (NEAs) must be resupplied. Two sources have been hypothesized: main-belt asteroids and extinct comet nuclei. A new survey of physical properties for less than 5 kilometers diameter main-belt asteroids reveals that their spin rate and shape distributions are similar to those of NEAs, as is fully consistent with a main-belt origin for most NEAs. Physical data on comet nuclei are limited. If the existing sample is representative of the comet population, analysis of the asteroid and comet samples constrains the fraction of comet nuclei to between 0 and 40 percent of the total NEA population.

  20. Dynamics of the outer asteroid belt

    International Nuclear Information System (INIS)

    This paper considers the issue of modeling the dynamics of the outer asteroid belt. The hypotheses and assumptions of an asteroid-belt model are discussed together with their problems, of which gaps at some mean-motion resonances with Jupiter and the depletion of the outer belt are the most outstanding ones. Particular attention is given to the theory of the 2:1 gap, the depletion problem, and the mechanisms of dynamical protection against strong perturbations by Jupiter. It is suggested that the observed asteroids must have gone through a process of natural selection as a result of which all objects in unprotected orbits have been ejected from the system. Spectral observations show a reddening in spectral slope with increasing heliocentric distance; it is proposed that this is an evidence that outer-belt asteroids might be primordial objects. 41 refs

  1. Mineralogy and Surface Composition of Asteroids

    CERN Document Server

    Reddy, Vishnu; Thomas, Cristina A; Moskovitz, Nicholas A; Burbine, Thomas H

    2015-01-01

    Methods to constrain the surface mineralogy of asteroids have seen considerable development during the last decade with advancement in laboratory spectral calibrations and validation of our interpretive methodologies by spacecraft rendezvous missions. This has enabled the accurate identification of several meteorite parent bodies in the main asteroid belt and helped constrain the mineral chemistries and abundances in ordinary chondrites and basaltic achondrites. With better quantification of spectral effects due to temperature, phase angle, and grain size, systematic discrepancies due to non-compositional factors can now be virtually eliminated for mafic silicate-bearing asteroids. Interpretation of spectrally featureless asteroids remains a challenge. This paper presents a review of all mineralogical interpretive tools currently in use and outlines procedures for their application.

  2. Colors of Dynamically Associated Asteroid Pairs

    CERN Document Server

    Moskovitz, Nicholas

    2012-01-01

    Recent dynamical studies have identified pairs of asteroids that reside in nearly identical heliocentric orbits. Possible formation scenarios for these systems include dissociation of binary asteroids, collisional disruption of a single parent body, or spin-up and rotational fission of a rubble-pile. Aside from detailed dynamical analyses and measurement of rotational light curves, little work has been done to investigate the colors or spectra of these unusual objects. A photometric and spectroscopic survey was conducted to determine the reflectance properties of asteroid pairs. New observations were obtained for a total of 34 individual asteroids. Additional photometric measurements were retrieved from the Sloan Digital Sky Survey Moving Object Catalog. Colors or spectra for a total of 42 pair components are presented here. The main findings of this work are: (1) the components in the observed pair systems have the same colors within the uncertainties of this survey, and (2) the color distribution of asteroi...

  3. Assessing the Age of an Asteroid's Surface with Data from the International Rosetta Mission

    Science.gov (United States)

    Lopez, Juan Carlos

    2011-01-01

    Rosetta is an international mission led by the European Space Agency (ESA) with key support and instrumentation from the National Aeronautics and Space Administration (NASA). Rosetta is currently on a ten-year mission to catch comet 67P/Churyumov-Gerasimenko (C-G); throughout its voyage, the spacecraft has performed flybys of two main belt asteroids (MBA): Steins and Lutetia. Data on the physical, chemical, and geological properties of these asteroids are currently being processed and analyzed. Accurate interpretation of such data is fundamental in the success of Rosetta's mission and overall objectives. Post-flyby data analyses strive to correlate the size, shape, volume, and rotational rate of Lutetia, in addition to interpreting its multi-color imagining, albedo, and spectral mapping. Although advancements in science have contributed to the examination of celestial bodies, methods to analyze asteroids remain largely empirical, not semi-empirical, nor ab initio. This study aims to interpret and document the scientific methods currently utilized in the characterization of asteroid (21) Lutetia in order to render these processes and methods accessible to the public. Examples include a standardized technique for assessing the age of an asteroid surface, complete with clickable reference maps, methodology of grouping surface characteristics together, and a standardized power law equation for the age. Other examples include determining the density of an object. Context for what both density and age mean is a bi-product of this study. Results of the study will aid in the development of pedagogical material on asteroids for public use, and in creation of an academic database for selected targets that might be used as a reference.

  4. The impact of using computer decision-support software in primary care nurse-led telephone triage: interactional dilemmas and conversational consequences.

    Science.gov (United States)

    Murdoch, Jamie; Barnes, Rebecca; Pooler, Jillian; Lattimer, Valerie; Fletcher, Emily; Campbell, John L

    2015-02-01

    Telephone triage represents one strategy to manage demand for face-to-face GP appointments in primary care. Although computer decision-support software (CDSS) is increasingly used by nurses to triage patients, little is understood about how interaction is organized in this setting. Specifically any interactional dilemmas this computer-mediated setting invokes; and how these may be consequential for communication with patients. Using conversation analytic methods we undertook a multi-modal analysis of 22 audio-recorded telephone triage nurse-caller interactions from one GP practice in England, including 10 video-recordings of nurses' use of CDSS during triage. We draw on Goffman's theoretical notion of participation frameworks to make sense of these interactions, presenting 'telling cases' of interactional dilemmas nurses faced in meeting patient's needs and accurately documenting the patient's condition within the CDSS. Our findings highlight troubles in the 'interactional workability' of telephone triage exposing difficulties faced in aligning the proximal and wider distal context that structures CDSS-mediated interactions. Patients present with diverse symptoms, understanding of triage consultations, and communication skills which nurses need to negotiate turn-by-turn with CDSS requirements. Nurses therefore need to have sophisticated communication, technological and clinical skills to ensure patients' presenting problems are accurately captured within the CDSS to determine safe triage outcomes. Dilemmas around how nurses manage and record information, and the issues of professional accountability that may ensue, raise questions about the impact of CDSS and its use in supporting nurses to deliver safe and effective patient care. PMID:25514212

  5. Collisional and Rotational Disruption of Asteroids

    OpenAIRE

    Walsh, Kevin J.; Michel, Patrick; Richardson, Derek C.

    2009-01-01

    Asteroids are leftover pieces from the era of planet formation that help us understand conditions in the early Solar System. Unlike larger planetary bodies that were subject to global thermal modification during and subsequent to their formation, these small bodies have kept at least some unmodified primordial material from the solar nebula. However, the structural properties of asteroids have been modified considerably since their formation. Thus, we can find among them a great variety of ph...

  6. ISAM - an Interactive Service for Asteroid Models

    Science.gov (United States)

    Bartczak, P.; Marciniak, A.

    2011-10-01

    We present an interactive web service for past and future physical ephemeris of polyhedral asteroid shape models obtained mainly with the lightcurve inversion method. Our tool allows for plane-of-sky views of the models, that can be then compared with asteroid images obtained using different techniques like occultations, radar or thermal infrared. Additionally, lightcurves, animated views, and stereoscopic images can be generated by the users. The service is available at the address: http://isam.astro.amu.edu.pl

  7. NAPAJALNIK SVETIL LED

    OpenAIRE

    Grešak, Aleksander

    2013-01-01

    Namen Diplomskega dela je bilo izdelati napajalnik svetil LED. Predstavljene so teoretične podlage delovanja napajalnika, njegova izdelava, ter opravljene določene meritve. Napajalnik deluje na principu stikalnega usmernika, ki izmenično napetost pri visoki frekvenci pretvarja v enosmerno. Uporabili smo pretvornik navzdol, ker je želena izhodna napetost nižja od vhodne. Prednosti stikalnega napajalnika so boljši izkoristek vezja, vezje je manjše in posledično tudi lažje.

  8. LED-valaistus kasvihuoneisiin

    OpenAIRE

    Anderson, Janne

    2010-01-01

    Valo on kasvien tärkein energian ja informaation lähde. Kasvihuoneviljelyssä voidaan keinovalaistuksen avulla pidentää kasvukautta sekä tehostaa tuotantoa. Keinovalaistuksen vaatima sähköenergia on merkittävä kuluerä suomalaisessa kasvihuoneviljelyssä. Tässä työssä selvitettiin LED - valaistuksen soveltuvuutta kasvihuoneviljelyyn sekä ledien tuomia etuja nykyisiin järjestelmiin verrattuna. Ledien avulla on mahdollista päästä merkittäviin säästöihin energiankulutuksessa sekä parantaa sado...

  9. Vilkkuva led-uistin

    OpenAIRE

    Korkala, Mika

    2016-01-01

    Opinnäytetyön tarkoituksena oli kehittää oman idean pohjalta vilkkuva led-uistin ja selvittää idean mahdollinen laillisuus ja patentoitavuus. Opinnäytetyöhön tutkittiin kalastusta, siinä käytettäviä apuvälineitä, kalojen värinäköä sekä Suomen kalastuslakia. Opinnäytetyötä varten tutkittiin myös patentointiprosesseja ja patentointiin liittyviä muita asioita, voimassa olevia ja jo vanhentuneita patentteja aiheeseen liittyen. Tutkimusmateriaalina käytettiin saatavissa olevia tutkimuksia,...

  10. Comets, Asteroids and Rubble Piles: not just debris

    Science.gov (United States)

    Harold, J. B.; Dusenbery, P.

    2010-12-01

    The National Center for Interactive Learning at the Space Science Institute (NCIL @ SSI) is developing a variety of asteroids related education activities as part of several E/PO projects, including Finding NEO (funded through NSF and NASA SMD); Great Balls of Fire! (funded through NSF); and a partnership with the WISE (Wide-field Infrared Survey Explorer) mission. These activities range from a web site to traveling exhibits in three different sizes. The Killer Asteroids web site (www.killerasteroids.org) includes background information on comets and asteroids as well as a number of interactive activities and games. These include a game that compares the risk of death from an asteroid impact to other hazards; a game and video vignettes on the role of backyard astronomers in light curve research; a physics-based asteroid deflection game; and a Google Earth -based "drop a rock on your house" activity. In addition, the project is developing a small, portable exhibit suitable for use in libraries or visitors centers. Great Balls of Fire! includes two separate traveling exhibitions: a 3000 square foot exhibition for science centers, and a 500 square foot version for smaller venues. Both will begin national tours in the summer of 2011. The Great Balls of Fire! exhibit program includes a free Education Program for docents and educators, and an Outreach Program to amateur astronomers around the country through the Astronomical Society of the Pacific’s (ASP) Astronomy from the Ground Up program. The project will facilitate partnerships between host venues and local astronomy clubs that can interact with the public using a toolkit of activities developed by ASP. Great Balls of Fire! Represents a collaboration between scientists, educators, exhibit designers, graphic artists, evaluators, education researchers, and three teams of middle school students who acted as advisors. The project’s exhibit design firm is Jeff Kennedy Associates Inc. We will present a summary of the

  11. More than 160 near Earth asteroids observed in the EURONEAR network

    Czech Academy of Sciences Publication Activity Database

    Birlan, M.; Vaduvescu, A.; Tudorica, A.; Sonka, A.; Nedelcu, A.; Galád, Adrián; Colas, F.; Pozo, F.; Barr, A.; Toma, R.; Comsa, I.; Rocher, P.; Lainey, V.; Vidican, D.; Asher, D. J.; Opriseanu, C.; Vancea, C.; Colque, J.P.; Soto, C.P.; Rekola, R.; Unda-Sanzana, E.

    2010-01-01

    Roč. 511, February (2010), A40/1-A40/14. ISSN 0004-6361 R&D Projects: GA ČR GA205/09/1107 Institutional research plan: CEZ:AV0Z10030501 Keywords : astrometry * minor planets * asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.410, year: 2010

  12. Effect of main belt perturbers on asteroid-pair age estimation

    Czech Academy of Sciences Publication Activity Database

    Galád, Adrián

    2012-01-01

    Roč. 548, November (2012), A25/1-A25/7. ISSN 0004-6361 R&D Projects: GA ČR GAP209/12/0229 Institutional support: RVO:67985815 Keywords : minor planets * asteroids * celestial mechanics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.084, year: 2012

  13. Lightcurves and synodic periods for asteroids 1998 ST49, (13154) and (27529)

    Czech Academy of Sciences Publication Activity Database

    Galád, Adrián

    2007-01-01

    Roč. 100, 1-2 (2007), s. 77-82. ISSN 0167-9295 R&D Projects: GA ČR(CZ) GA205/05/0604 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * photometry Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.558, year: 2007

  14. Spin Rate of Asteroid (54509) 2000 PH5 Increasing Due to the YORP Effect

    Czech Academy of Sciences Publication Activity Database

    Taylor, P.A.; Margot, J. L.; Vokrouhlický, D.; Scheeres, D.J.; Pravec, Petr; Lowry, S.C.; Fitzsimmons, A.; Nolan, M. C.; Ostro, S. J.; Benner, L. A. M.; Giorgini, J. D.; Magri, C.

    2007-01-01

    Roč. 316, č. 5822 (2007), s. 274-277. ISSN 0036-8075 Grant ostatní: GA ČR(CZ) GA205/99/0255 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids rotation * near-Earth objects * radar observations Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 26.372, year: 2007

  15. Absolute photometry of small main-belt asteroids in 2007-2009

    Czech Academy of Sciences Publication Activity Database

    Chiorny, V. G.; Galád, Adrián; Pravec, Petr; Kušnirák, Peter; Hornoch, Kamil; Gajdoš, Š.; Kornoš, L.; Világi, J.; Husárik, M.; Kanuchová, Z.; Krišandová, Z.; Higgins, D.; Pray, D. P.; Durkee, R.; Dyvig, R.; Reddy, V.; Oey, J.; Marchis, F.; Stephens, R.

    2011-01-01

    Roč. 59, č. 13 (2011), s. 1482-1489. ISSN 0032-0633 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * photometry * light curve Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.224, year: 2011

  16. On the shapes and spins of “rubble pile” asteroids

    Czech Academy of Sciences Publication Activity Database

    Harris, A. W.; Fahnestock, E.G.; Pravec, Petr

    2009-01-01

    Roč. 199, č. 2 (2009), s. 310-318. ISSN 0019-1035 R&D Projects: GA ČR(CZ) GA205/05/0604 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroids * rotational dynamics * tides of solid body Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.340, year: 2009

  17. Rotational properties of the Maria asteroid family

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M.-J.; Byun, Y.-I. [Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, 120-749 Seoul (Korea, Republic of); Choi, Y.-J.; Moon, H.-K.; Hinse, T. C.; Park, J.-H. [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, 305-348 Daejeon (Korea, Republic of); Brosch, N. [Tel Aviv University, P.O. Box 39040, Tel Aviv 69978 (Israel); Kaplan, M.; Kaynar, S.; Uysal, Ö.; Eker, Z. [Akdeniz Universitesi, Fen Fakultesi, Dumlupinar Bulvari, Kampus, 07058 Antalya (Turkey); Güzel, E. [Department of Astronomy and Space Sciences, University of Ege, Bornova, 35100 Izmir (Turkey); Behrend, R. [Geneva Observatory, Rue de Vermont 37, 1202 Geneva (Switzerland); Yoon, J.-N. [Chungbuk National University Observatory, 802-3 Euntan-ri, Jincheon-gun, Chungcheongbuk-do (Korea, Republic of); Mottola, S.; Hellmich, S., E-mail: skarma@galaxy.yonsei.ac.kr [German Aerospace Center (DLR), Rutherfordstrasse 2, D-12489 Berlin (Germany)

    2014-03-01

    The Maria family is regarded as an old-type (∼3 ± 1 Gyr) asteroid family that has experienced substantial collisional and dynamical evolution in the main belt. It is located near the 3:1 Jupiter mean-motion resonance area that supplies near-Earth asteroids to the inner solar system. We carried out observations of Maria family asteroids during 134 nights from 2008 July to 2013 May and derived synodic rotational periods for 51 objects, including newly obtained periods of 34 asteroids. We found that there is a significant excess of fast and slow rotators in the observed rotation rate distribution. The one-sample Kolmogorov-Smirnov test confirms that the spin rate distribution is not consistent with a Maxwellian at a 92% confidence level. From correlations among rotational periods, amplitudes of light curves, and sizes, we conclude that the rotational properties of Maria family asteroids have been changed considerably by non-gravitational forces such as the YORP effect. Using a light-curve inversion method, we successfully determined the pole orientations for 13 Maria members and found an excess of prograde versus retrograde spins with a ratio (N{sub p} /N{sub r} ) of 3. This implies that the retrograde rotators could have been ejected by the 3:1 resonance into the inner solar system since the formation of the Maria family. We estimate that approximately 37-75 Maria family asteroids larger than 1 km have entered near-Earth space every 100 Myr.

  18. Lightcurves of the Karin family asteroids

    Science.gov (United States)

    Yoshida, Fumi; Ito, Takashi; Dermawan, Budi; Nakamura, Tsuko; Takahashi, Shigeru; Ibrahimov, Mansur A.; Malhotra, Renu; Ip, Wing-Huen; Chen, Wen-Ping; Sawabe, Yu; Haji, Masashige; Saito, Ryoko; Hirai, Masanori

    2016-05-01

    The Karin family is a young asteroid family formed by an asteroid breakup 5.8 Myr ago. Since the members of this family probably have not experienced significant orbital or collisional evolution yet, it is possible that they still preserve properties of the original family-forming event in terms of their spin state. We carried out a series of photometric observations of the Karin family asteroids, and here we report on the analysis of the lightcurves including the rotation period of eleven members. The mean rotation rate of the Karin family members turned out to be much lower than those of near-Earth asteroids or small main belt asteroids (diameter D 130 km). We investigated a correlation between the peak-to-trough variation and the rotation period of the eleven Karin family asteroids, and found a possible trend that elongated members have lower spin rates, and less elongated members have higher spin rates. However, this trend has to be confirmed by another series of future observations.

  19. 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.

  20. Asteroid Models from Multiple Data Sources

    CERN Document Server

    Durech, J; Delbo, M; Kaasalainen, M; Viikinkoski, M

    2015-01-01

    In the past decade, hundreds of asteroid shape models have been derived using the lightcurve inversion method. At the same time, a new framework of 3-D shape modeling based on the combined analysis of widely different data sources such as optical lightcurves, disk-resolved images, stellar occultation timings, mid-infrared thermal radiometry, optical interferometry, and radar delay-Doppler data, has been developed. This multi-data approach allows the determination of most of the physical and surface properties of asteroids in a single, coherent inversion, with spectacular results. We review the main results of asteroid lightcurve inversion and also recent advances in multi-data modeling. We show that models based on remote sensing data were confirmed by spacecraft encounters with asteroids, and we discuss how the multiplication of highly detailed 3-D models will help to refine our general knowledge of the asteroid population. The physical and surface properties of asteroids, i.e., their spin, 3-D shape, densit...

  1. Rotational properties of the Maria asteroid family

    International Nuclear Information System (INIS)

    The Maria family is regarded as an old-type (∼3 ± 1 Gyr) asteroid family that has experienced substantial collisional and dynamical evolution in the main belt. It is located near the 3:1 Jupiter mean-motion resonance area that supplies near-Earth asteroids to the inner solar system. We carried out observations of Maria family asteroids during 134 nights from 2008 July to 2013 May and derived synodic rotational periods for 51 objects, including newly obtained periods of 34 asteroids. We found that there is a significant excess of fast and slow rotators in the observed rotation rate distribution. The one-sample Kolmogorov-Smirnov test confirms that the spin rate distribution is not consistent with a Maxwellian at a 92% confidence level. From correlations among rotational periods, amplitudes of light curves, and sizes, we conclude that the rotational properties of Maria family asteroids have been changed considerably by non-gravitational forces such as the YORP effect. Using a light-curve inversion method, we successfully determined the pole orientations for 13 Maria members and found an excess of prograde versus retrograde spins with a ratio (Np /Nr ) of 3. This implies that the retrograde rotators could have been ejected by the 3:1 resonance into the inner solar system since the formation of the Maria family. We estimate that approximately 37-75 Maria family asteroids larger than 1 km have entered near-Earth space every 100 Myr.

  2. 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

  3. 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.

  4. Dynamical Explanation for the Lack of Binary Asteroids Among the Plutinos

    Science.gov (United States)

    Compère, Audrey; Farrelly, D.; Lemaître, A.; Hestroffer, D.

    2013-05-01

    Abstract (2,250 Maximum Characters): Binary asteroids are really common among the trans-Neptunians. However, they seem to be scarce among the Plutinos, i.e. the part of the Kuiper belt population situated inside the 3:2 mean-motion resonance with Neptune. Our hypothesis is that this phenomenon, unexplained up to now, is due to the impact of the 3:2 resonance on the formation of Kuiper belt binaries. Numerical simulations are done in the context of the 2+2 bodies problem (here, Sun, Neptune and two asteroids). As is known, mean-motion resonances between a planet and an asteroid usually have the effect of increasing the eccentricity of the asteroid. Therefore, we include the increase of the eccentricity of the centre of mass of the binary system due to the resonance in the simulations. Chaos maps (obtained using the MEGNO chaos indicator) and histograms of residence times for tests particles are computed in order to analyse the behavioural differences of potential Kuiper belt binaries inside and outside the resonance. The results suggest the following: the stable zones in the MEGNO maps are mainly disrupted in the resonant eccentric case and the number of binary asteroids created in the resonant eccentric case is significantly lower than in the non-resonant one. This provides a clue to explain the lack of binaries among the Plutinos.

  5. Phase reddening on near-Earth asteroids: Implications for mineralogical analysis, space weathering and taxonomic classification

    CERN Document Server

    Sanchez, Juan A; Nathues, Andreas; Cloutis, Edward A; Mann, Paul; Hiesinger, Harald

    2012-01-01

    Phase reddening is an effect that produces an increase of the spectral slope and variations in the strength of the absorption bands as the phase angle increases. In order to understand its effect on spectroscopic observations of asteroids, we have analyzed the visible and near-infrared spectra (0.45-2.5 \\mu m) of 12 near-Earth asteroids observed at different phase angles. All these asteroids are classified as either S-complex or Q-type asteroids. In addition, we have acquired laboratory spectra of three different types of ordinary chondrites at phase angles ranging from 13\\degree to 120\\degree. We have found that both asteroid and meteorite spectra show an increase in band depths with increasing phase angle. The spectral slope of the ordinary chondrites spectra shows a significant increase with increasing phase angle for g > 30\\degree. Variations in band centers and band area ratio (BAR) values were also found, however they seems to have no significant impact on the mineralogical analysis. Our study showed th...

  6. The unusual asteroid 2201 Oljato: Origins and possible debris trail

    Science.gov (United States)

    Connors, M.; Russell, C. T.; Lai, H. R.

    2016-04-01

    Potentially hazardous asteroid Oljato has a very eccentric low-inclination orbit of semimajor axis a 2.17 au, placing it just outside 4:1 resonance with Jupiter. Its association with magnetic field anomalies known as Interplanetary Field Enhancements (IFEs) in the solar wind led to speculation of a cometary nature and origin. Spectroscopic work showed that it was instead of silicate E-type typical of the inner asteroid belt or Hungarias. We have investigated the region potentially subject to 4:1 resonant effects and find that resonant pumping of eccentricity e takes place due to the outer planets, with moderate increases in inclination i in non-ejected cases. The outer planets do not, however, cause a change sufficient to move Oljato to its present location from the resonance. With inner planet effects included, the increase in e and i is in most cases reduced, however a diffusion increases, so that such a pumping/scattering mechanism can explain the present orbit of Oljato. IFEs may plausibly be related to a debris cascade involving secondary material along Oljato's orbit. We investigate the dynamics of such inferred meteoroids, finding that planetary encounters cause gaps in their distribution along the orbit. The control case of Eros confirms that encounters are needed to cause the gaps, with slow diffusion of secondary material in their absence.

  7. Mineralogical Characterization of Baptistina Asteroid Family: Implications for K/T Impactor Source

    CERN Document Server

    Reddy, Vishnu; Lazzaro, Daniela; Michtchenko, Tatiana A; Gaffey, Michael J; Kelley, Michael S; Diniz, Thais Mothé; Candal, Alvaro Alvarez; Moskovitz, Nicholas A; Cloutis, Edward A; Ryan, Erin L; 10.1016/j.icarus.2011.08.027

    2011-01-01

    Bottke et al. (2007) linked the catastrophic formation of Baptistina Asteroid Family (BAF) to the K/T impact event. This linkage was based on dynamical and compositional evidence, which suggested the impactor had a composition similar to CM2 carbonaceous chondrites. However, our recent study (Reddy et al. 2009) suggests that the composition of (298) Baptistina is similar to LL-type ordinary chondrites rather than CM2 carbonaceous chondrites. This rules out any possibility of it being related to the source of the K/T impactor, if the impactor was of CM-type composition. Mineralogical study of asteroids in the vicinity of BAF has revealed a plethora of compositional types suggesting a complex formation and evolution environment. A detailed compositional analysis of 16 asteroids suggests several distinct surface assemblages including ordinary chondrites (Gaffey SIV subtype), primitive achondrites (Gaffey SIII subtype), basaltic achondrites (Gaffey SVII subtype and V-type), and a carbonaceous chondrite. Based on ...

  8. 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.

  9. Dealing with Uncertainties in Asteroid Deflection Demonstration Missions: NEOTwIST

    CERN Document Server

    Eggl, Siegfried; Cano, Juan L; Avila, Javier Martin; Drube, Line; Harris, Alan W; Falke, Albert; Johann, Ulrich; Engel, Kilian; Schwartz, Stephen R; Michel, Patrick

    2016-01-01

    Deflection missions to near-Earth asteroids will encounter non-negligible uncertainties in the physical and orbital parameters of the target object. In order to reliably assess future impact threat mitigation operations such uncertainties have to be quantified and incorporated into the mission design. The implementation of deflection demonstration missions offers the great opportunity to test our current understanding of deflection relevant uncertainties and their consequences, e.g., regarding kinetic impacts on asteroid surfaces. In this contribution, we discuss the role of uncertainties in the NEOTwIST asteroid deflection demonstration concept, a low-cost kinetic impactor design elaborated in the framework of the NEOShield project. The aim of NEOTwIST is to change the spin state of a known and well characterized near-Earth object, in this case the asteroid (25143) Itokawa. Fast events such as the production of the impact crater and ejecta are studied via cube-sat chasers and a flyby vehicle. Long term chang...

  10. Near-Earth Asteroid Scout

    Science.gov (United States)

    McNutt, Leslie; Johnson, Les; Clardy, Dennon; Castillo-Rogez, Julie; Frick, Andreas; Jones, Laura

    2014-01-01

    Near-Earth Asteroids (NEAs) are an easily accessible object in Earth's vicinity. Detections of NEAs are expected to grow in the near future, offering increasing target opportunities. As NASA continues to refine its plans to possibly explore these small worlds with human explorers, initial reconnaissance with comparatively inexpensive robotic precursors is necessary. Obtaining and analyzing relevant data about these bodies via robotic precursors before committing a crew to visit a NEA will significantly minimize crew and mission risk, as well as maximize exploration return potential. The Marshall Space Flight Center (MSFC) and Jet Propulsion Laboratory (JPL) are jointly examining a mission concept, tentatively called 'NEA Scout,' utilizing a low-cost CubeSats platform in response to the current needs for affordable missions with exploration science value. The NEA Scout mission concept would be a secondary payload on the Space Launch System (SLS) Exploration Mission 1 (EM-1), the first planned flight of the SLS and the second un-crewed test flight of the Orion Multi-Purpose Crew Vehicle (MPCV).

  11. From Asteroids to Space Debris

    Science.gov (United States)

    Benkhaldoun, Zouhair; Moon, Hong-Kyu; Daassou, Ahmed; Jang-Hyun, Park; Lazrek, Mohamed

    2015-08-01

    Since 2011, the Oukaimeden Observatory (OUCA) located on the mountains of the Moroccan High Atlas has become one of the successful contributors in asteroid discovery in the world. The discovery statistics of the MOSS (Morocco Oukaimeden Sky Survey) telescope represents more than 2145 new designations to date for their credits. Its discoveries include three new NEOs and four new comets. The exceptional astro-climatic conditions in terms not only of number of clear nights, but also of atmospheric seeing are partly behind this success. Indeed the average number of observable nights is around 280 nights per year, while the average seeing is about 0.8 to 0.9 arcsec.In the meanwhile, the OUCA achieved construction and installation of a new facility in March 2015. It is a compact, 0.5 m aperture fast optics robotic telescope designed and implemented by the Optical Wide-field Patrol (OWL) team of Korea Astronomy and Space Science Institute (KASI). The primary object of the OWL project is to monitor national space-based assets, howevr either wide-field imaging- or fast data acquisition- capabilities enable to undertake observational program to catalog and follow-up various transient events in the night sky. We will brief future plan for this joint project between the OUCA and KASI.Our presentation aims to share the details of instrumentation implemented and cooperation opportunities it can arouse within the community for the data analysis and interpretation.

  12. SOLID STATE PHYSICS OF IMPACT CRATER FORMATION: FURTHER CONSIDERATIONS

    Directory of Open Access Journals (Sweden)

    V. Celebonovic

    2013-01-01

    Full Text Available Impact craters exist on solid surface planets, their satellites and many asteroids. The aim of this paper is to propose a theoretical expression for the product ρr3 v2 1 , where the three symbols denote the mass density, radius and speed of the impactor. The expression is derived using well known results of solid state physics, and it can be used in estimating parameters of impactors which have led to formation of craters on various solid bodies in the Solar System.

  13. SOFIA observations of dark asteroids: Evidence for hydrated minerals on asteroidal surfaces?

    Science.gov (United States)

    McAdam, Margaret; Sunshine, Jessica M.; Kelley, Michael S. P. T.

    2015-11-01

    We present results from recent SOFIA+FORCAST observations of three primitive asteroids and compare these to archived Spitzer Space Telescope (Spitzer) observations of similar objects. Three asteroids from a total of 12 have been observed with SOFIA+FORCAST in our Cycle-3 campaign. Currently, we have observed asteroids 38 Leda, 194 Prokne with both G111 and G227 grisms and asteroid 266 Aline with G227. Both wavelength regions (G111: 8.5-13.5-μm and G227: 17.6-27.7) have recently been shown to contain spectral features directly related degree of alteration of primitive meteorites, including unaltered CO and CV meteorites (McAdam, et al., 2015a ,b). Spectral features in the 17.6-27.7-μm region can be indicative of olivine (19.5-μm), hydrated minerals (21-μm) and silica glass (22-μm). Spitzer observed eight large, primitive, main-belt asteroids using both low-resolution modes (short-low, SL and long-low, LL) of the Infrared Spectrograph (IRS) covering 8.5-38-μm. Additionally, Spitzer observed 22 dark primitive asteroids in the 8.5-13.5-μm region. Asteroids observed with Spitzer fall into three categories: asteroids with a 12-μm feature of 1-5% depth, interpreted as ~60-70% hydrated minerals (McAdam, et al., 2015a) asteroids with a broader 12-13-μm feature with strengths ranging from 4-6% with potential features between 19-22-μm (where observed) and asteroids with a strong 13-μm feature (5-10%), 15-μm and potentially 19-22-μm features (where observed) interpreted as olivine-rich. However, the uncertain calibration at the edges of the LL spectral orders complicates feature identification. 194 Prokne has a feature ~12-13-μm feature and potentially a broad feature between 20-22-μm. This is consistent with primitive asteroids observed with Spitzer that are interpreted as hydrated mineral-bearing. 38 Leda is largely featureless at the noise limit of the spectrum with a potential feature at 25-μm, unlike asteroids observed by Spitzer. 266 Aline has a weak

  14. 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...

  15. 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).

  16. Chasing the Chelyabinsk asteroid N-body style

    CERN Document Server

    Marcos, C de la Fuente; Aarseth, S J

    2015-01-01

    On 2013 February 15 a small asteroid rammed against the atmosphere above the region of Chelyabinsk in Russia, producing the most powerful superbolide since the Tunguska event in 1908. Lacking proper astrometric observations, the pre-impact orbit of this object has been determined using videos, satellite images, and pure geometry. Unfortunately, more than two years after the event, the published estimates vary so much that there is no clear orbital solution that could be used to investigate the origin of the impactor and the existence of dynamically, or perhaps even genetically, related asteroids. Here, we revisit this topic using a full N-body approach. A robust statistical test is applied to published solutions to discard those unable to produce a virtual impact at the observed time (03:20:20.8 s UTC). The same N-body methodology and the latest ephemerides are used to compute a new orbital solution: a=1.6247 AU, e=0.5318, i=3.9750 degrees, Omega=326.4607 degrees, and omega=109.7012 degrees. This new solution...

  17. CCD-Photometry and Pole Coordinates for Eight Asteroids

    Science.gov (United States)

    Shevchenko, V. G.; Tungalag, N.; Chiorny, V. G.; Gaftonyuk, N. M.; Krugly, Y. N.; Harris, A. W.; Young, J. W.

    2012-05-01

    The long time photometric observations were carried out for eight asteroids: (122) Gerda, (153) Hilda, (190) Ismene, (221) Eos, (411) Xanthe, (679) Pax, (700) Auravictrix, (787) Moskva. For the observed asteroids were determined new pole coordinates.

  18. A Fast Ellipsoid Model for Asteroids Inverted From Lightcurves

    CERN Document Server

    Lu, Xiaoping; You, Zhong

    2012-01-01

    The research about asteroids attracts more and more attention recently, especially focusing on their physical structures, such as the spin axis, the rotation period and the shape. The long distance between Earth observers and asteroids makes it impossible to get the shape and other parameters of asteroids directly with the exception of the NEAs (Near Earth Asteroids) and others passed by some spacecrafts. Generally photometric measurement is still the main way to obtain the research data for asteroids now, i.e. the lightcurves recording the brightness and positions of asteroids. Supposing that the shape of the asteroid is a triaxial ellipsoid with a stable spinning status, a new method is present in this article to reconstruct the shape models of asteroids from the lightcurves, with the other physical parameters together. By applying a special curvature function, the method calculates the brightness integration on a unit sphere and Lebedev Quadrature is employed for the discretization. At last the method sear...

  19. Brazil Nuts on Eros: Size-Sorting of Asteroid Regolith

    Science.gov (United States)

    Asphaug, E.; King, P. J.; Swift, M. R.; Merrifield, M. R.

    2001-01-01

    We consider the hypothesis that frequent cratering produces size- or compositionally-sorted asteroid regolith, affecting the structure, texture, and in extreme cases the shape of asteroids. Additional information is contained in the original extended abstract.

  20. Philosophy and updating of the asteroid photometric catalogue

    Science.gov (United States)

    Magnusson, Per; Barucci, M. Antonietta; Capria, M. T.; Dahlgren, Mats; Fulchignoni, Marcello; Lagerkvist, C. I.

    1992-01-01

    The Asteroid Photometric Catalogue now contains photometric lightcurves for 584 asteroids. We discuss some of the guiding principles behind it. This concerns both observers who offer input to it and users of the product.

  1. 78 FR 64253 - NASA Asteroid Initiative Idea Synthesis Workshop

    Science.gov (United States)

    2013-10-28

    ... SPACE ADMINISTRATION NASA Asteroid Initiative Idea Synthesis Workshop AGENCY: National Aeronautics and... Administration announces that the agency will resume the NASA Asteroid Initiative Idea Synthesis public..., Senior Technical Advisor, NASA Human Exploration and Operations Mission Directorate:...

  2. 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...

  3. 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

  4. The Strength of Rubble Pile Asteroids

    Science.gov (United States)

    Scheeres, D. J.; Sanchez, P.

    2012-12-01

    The rubble pile hypothesis for small asteroids in the Near Earth and Main Belt populations have been driven by several factors, including the observed high porosity of those bodies whose mass have been measured, the evident limitation on spin rate of asteroids larger than ~500 meters, and direct observation of the surface morphology of these bodies. Given these observations, it has been presumed that small asteroids should evolve as if they were cohesionless collections of grains. Detailed geophysical analysis of these bodies by Holsapple (Icarus 2010) show that cohesionless bodies will evolve under the addition of angular momentum by the YORP effect into more distended and, paradoxically, more slowly rotating bodies. Additional analysis in Holsapple (Icarus 2007) has shown that cohesional strength within a rubble pile could strengthen a collection of grains to the point where they could sustain rapid rotation. In our current talk we use the above as a starting point and incorporate new observations of the asteroid morphology driven by recent analysis of asteroid Itokawa by the Hayabusa science team and research on the mechanics of grains in the space environment (Scheeres et al. 2010). Analysis of images of Itokawa determined a measured size distribution of 1/d^3 for larger grains on asteroid Itokawa (Michikami et al., Earth Planets Space, 60, 13-20, 2008). Analysis of the sample shows the presence of micron sized dust on that asteroid's surface (Tsuchiyama et al., Science 333, 1125, 2011). Combining these observations provides a global indication of grain distribution within rubble piles. Even assuming a less steep distribution of 1/d^2 for dust grains smaller than 1 mm in size, the interior of Itokawa should still be dominated by the finest dust grains, with the mean grain size equal to ~ twice the smallest grain in the distribution. One implication of this result is that fines are present on the surface of the rubble pile Itokawa and thus should be distributed

  5. Photometric constraints on binary asteroid dynamics

    Science.gov (United States)

    Scheirich, Peter

    2015-08-01

    To date, about 50 binary NEAs, 20 Mars-crossing and 80 small MB asteroids are known. We observe also a population of about 200 unbound asteroid systems (asteroid pairs). I will review the photometric observational data we have for the best observed cases and compare them with theories of binary and paired asteroids evolution.The observed characteristics of asteroid systems suggest their formation by rotational fission of parent rubble-pile asteroids after being spun up by the YORP effect. The angular momentum content of binary asteroids is close to critical. The orientations of satellite orbits of observed binary systems are non-random; the orbital poles concentrate near the obliquities of 0 and 180 degrees, i.e., near the YORP asymptotic states.Recently, a significant excess of retrograde satellite orbits was detected, which is not yet explained characteristic.An evolution of binary system depend heavily on the BYORP effect. If BYORP is contractive, the primary and secondary could end in a tidal-BYORP equilibrium. Observations of mutual events between binary components in at least four apparitions are needed for BYORP to be revealed by detecting a quadratic drift in mean anomaly of the satellite. I will show the observational evidence of single-synchronous binary asteroid with tidally locked satellite (175706 1996 FG3), i.e, with the quadratic drift equal to zero, and binary asteroid with contracting orbit (88710 2001 SL9), with positive value of the quadratic drift (the solution for the quadratic drift is ambiguous so far, with possible values of 5 and 8 deg/yr2).The spin configuration of the satellite play a crucial role in the evolution of the system under the influence of the BYORP effect. I will show that the rotational lightcurves of the satellites show that most of them have small libration amplitudes (up to 20 deg.), with a few interesting exceptions.Acknowledgements: This work has been supported by the Grant Agency of the Czech Republic, Grant P209

  6. 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.

  7. Flyght Dynamics of Artificial Satellite of the Minor Asteroid

    Science.gov (United States)

    Zakharov, Alexander; Eismont, Natan; Ledkov, Anton; Simonov, Alexander; Pol, Vadim

    During last years the scientific interest to the asteroid is constantly growing. It may be explained by different reasons. One of the most important from them is confirmation of the fact that the asteroids present the real hazard to the Earth. The Chelyabinsk event demonstrates strong in support of this statement. Besides, the asteroids exploration promises to supply new data for understanding of the solar system origin and evolution. And the projects aimed to reach this goal have begun from the NASA NEAR mission to Eros. It was the first one when the spacecraft was landed on the surface of the asteroid. The other successive mission was fulfilled by JAXA with Hayabusa spacecraft which has returned to the Earth soil samples of Itokawa asteroid. In the nearest future the mission to RQ 36 asteroid is planned supposing landing and soil samples return. Unavoidable phase of such missions is the spacecraft flight in vicinity of the target asteroid, for example on the asteroid satellite orbit. It should be mentioned that quite visible number of asteroids has geometric form which is far from being sphere. Accordingly the gravity field of such asteroid cannot be presented as the one close to sphere. The problem is that prior to the mission to the asteroid one cannot receive good enough knowledge of its gravity field and even its gravity field constant. In the paper the flight dynamics problem of spacecraft moving along asteroid satellite orbit is explored. It is supposed that the asteroid is comparatively small with diameter (maximum size) about 300 m, like Apophis asteroid has, or less. To approximate the gravity field of asteroid the last is considered as totality of mass points. We assume such approach as more simple and effective as compared with the commonly accepted use of Legendre polynomial expansion. Different orbits near asteroid are analyzed with the sets of orbital parameters determining the size of orbit, its shape and position with respect to the Sun. The goal

  8. Develop an Architecture to Enable Effective Information Process in Mitigating Asteroid's Threat

    Science.gov (United States)

    Yu, M.; Piccione, M.; Sun, M.; Yang, C. P.; Bambacus, M.; Seery, B.

    2015-12-01

    Research on asteroid impacts on Earth is crucial and challenging nationally and globally. Existing efforts for Near Earth Object (NEO) survey such as Catalina Sky Survey and SAO-minor planets center (MPC) have been established. However, our understanding of asteroids still needs to be advanced through physical characterization, modeling of atmospheric entry/breakup, and risk assessments of impacts (land and water), with emphases on small impactors. To achieve the goal of knowledge advancement, activities such as orbit determination, threat analysis, and impact simulation are fundamental, and all require accurate information and effective processing capability. Here we propose a planetary framework including the workflow, information flow, organization dependencies, and most importantly the cyberinfrastructure configuration required to achieve effective information processing. This framework will serve as a foundation for understanding the NEO hazard and building a long-term capability to counter a potential NEO impact threat.

  9. Detecting Mass Loss in Main Belt Asteroids

    Science.gov (United States)

    Sandberg, Erik; Rajagopal, Jayadev; Ridgway, Susan E.; Kotulla, Ralf C.; Valdes, Francisco; Allen, Lori

    2016-01-01

    Sandberg, E., Rajagopal, J., Ridgway, S.E, Kotulla, R., Valdes, F., Allen, L.The Dark Energy Camera (DECam) on the 4m Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) is being used for a survey of Near Earth Objects (NEOs). Here we attempt to identify mass loss in main belt asteroids (MBAs) from these data. A primary motivation is to understand the role that asteroids may play in supplying dust and gas for debris disks. This work focuses on finding methods to automatically pick out asteroids that have qualities indicating possible mass loss. Two methods were chosen: looking for flux above a certain threshold in the asteroid's radial profile, and comparing its PSF to that of a point source. After sifting through 490 asteroids, several have passed these tests and should be followed up with a more rigorous analysis.Sandberg was supported by the NOAO/KPNO Research Experience for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829)

  10. Thermal Tomography of Asteroid Surface Structure

    CERN Document Server

    Harris, Alan

    2016-01-01

    Knowledge of the surface thermal inertia of an asteroid can provide insight into 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. Eviden...

  11. Tracking a Very Near Earth Asteroid

    Science.gov (United States)

    Bruck, R.; Rashid, S.; Peppard, T.

    2013-09-01

    The potential effects of an asteroid passing within close proximity to the Earth were recently realized. During the February 16, 2013 event, Asteroid 2012 DA14 passed within an estimated 27,700 kilometers of the earth, well within the geosynchronous (GEO) orbital belt. This was the closest known approach of a planetoid of this size, in modern history. The GEO belt is a region that is filled with critical communications satellites which provide relays for essential government, business and private datum. On the day of the event, optical instruments at Detachment 3, 21OG, Maui GEODSS were able to open in marginal atmospheric conditions, locate and collect metric and raw video data on the asteroid as it passed a point of near heliocentric orbital propinquity to the Earth. Prior to the event, the Joint Space Operations Center (JSpOC) used propagated trajectory data from NASA's Near Earth Object Program Office at the Jet Propulsion Laboratory to assess potential collisions with man-made objects in Earth orbit. However, the ability to actively track this asteroid through the populated satellite belt not only allowed surveillance for possible late orbital perturbations of the asteroid, but, afforded the ability to monitor possible strikes on all other orbiting bodies of anthropogenic origin either not in orbital catalogs or not recently updated in those catalogs. Although programmed only for tracking satellites in geocentric orbits, GEODSS was able to compensate and maintain track on DA14, collecting one hundred and fifty four metric observations during the event.

  12. The Dynamical Evolution of the Asteroid Belt

    CERN Document Server

    Morbidelli, Alessandro; O'Brien, David P; Minton, David A; Bottke, William F

    2015-01-01

    The asteroid belt is the leftover of the original planetesimal population in the inner solar system. However, currently the asteroids have orbits with all possible values of eccentricities and inclinations compatible with long-term dynamical stability, whereas the initial planetesimal orbits should have been quasi-circular and almost co-planar. The total mass in the asteroid population is a small fraction of that existing primordially. Also, asteroids with different chemical/mineralogical properties are not ranked in an orderly manner with mean heliocentric distance as one could expect from the existence of a radial gradient of the temperature in the proto-planetary disk, but they are partially mixed. These properties show that the asteroid belt has been severely sculpted by one or a series of processes during its lifetime. This paper reviews the processes that have been proposed so far, discussing the properties that they explain and the problems that they are confronted with. Emphasis is paid to the interpl...

  13. 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.

  14. A Fast Ellipsoid Model for Asteroids Inverted From Lightcurves

    OpenAIRE

    Lu, Xiaoping; Zhao, Haibin; You, Zhong

    2012-01-01

    The research about asteroids attracts more and more attention recently, especially focusing on their physical structures, such as the spin axis, the rotation period and the shape. The long distance between Earth observers and asteroids makes it impossible to get the shape and other parameters of asteroids directly with the exception of the NEAs (Near Earth Asteroids) and others passed by some spacecrafts. Generally photometric measurement is still the main way to obtain the research data for ...

  15. Detection of cohesive forces in the rubble-pile asteroid (29075) 1950 DA

    Science.gov (United States)

    Rozitis, Benjamin; MacLennan, Eric; Emery, Joshua P.

    2014-11-01

    The physical behavior of rubble-pile asteroids has traditionally been described using only gravitational and frictional forces within a granular material. Cohesive forces in the form of small van der Waals forces between constituent grains have recently been predicted to be important for small rubble-pile asteroids (less than 10 kilometers in size), and could potentially explain how small fast spinning asteroids remain intact. It is possible to infer the existence of cohesive forces within a rubble-pile asteroid by determining if it has insufficient self-gravity, dictated by its bulk density, to prevent rotational breakup by centrifugal forces. The kilometer-sized and potentially-hazardous asteroid (29075) 1950 DA is one of the largest known candidates for being held together by cohesive forces, as it has a rotation period of 2.1216 h that is just beyond the critical spin limit of 2.2 h estimated for a cohesionless asteroid. Using the Advanced Thermophysical Model (or ATPM), in combination with the radar shape model, WISE thermal-infrared data, and Yarkovsky orbital drift measurement, we determined the thermal inertia, bulk density, and cohesive strength of (29075) 1950 DA (Rozitis et al., 2014, Nature, 512, 174-176). The thermal inertia value is remarkably low at 24 +20/-14 SI units, which gives a corresponding bulk density of 1.7 ± 0.7 g/cm^3 in the Yarkovsky orbital drift analysis. This bulk density is typical of a rubble-pile asteroid, and a minimum cohesive strength of 64 +12/-20 Pa is therefore required to prevent surface mass shedding and structural failure by centrifugal forces. This strength is comparable to, though somewhat less than, the cohesive forces found between the grains of lunar regolith. Finally, as (29075) 1950 DA has a 1 in 19,800 chance of impacting the Earth in 2880, and has the potential to disrupt like main-belt comet P/2013 R3, it raises new implications for impact mitigation against fast spinning rubble-pile asteroids.

  16. 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

  17. Threat from Rubble-Pile Asteroids

    Science.gov (United States)

    Schultz, P. H.

    2015-12-01

    While chondrites are the most common meteoroids to enter our atmosphere, they represent a small fraction of recovered falls. Most stony meteorites disrupt during entry, consumed by ablation or lost by weathering; in contrast, small iron meteorites (entry at altitude; (c) no accessory meteorite falls; (d) "explosion" (not low-speed compression) crater; (e) infrasound/seismic data indicating a high-speed entry/collision; and (f) petrologic evidence for shock deformation/melting in breccias indicative of speeds >4 km/s. Although a monolithic chondrite (~ 10 m across) might allow surviving entry, most objects of this size contain multiple flaws, ensuring atmospheric disruption. Hence, an alternative "needle model" was proposed wherein a small rubble-pile object gradually re-shaped itself during entry [Schultz, 2008], a process that minimizes drag, thermal signatures of entry, and catastrophic disruption. First proposed to account for smaller than expected craters on Venus [Schultz, 1992], such a process resembles subsequent Shoemaker-Levy entry models [Boslough and Crawford, 1997] that predicted much deeper entry than standard models. Laboratory experiments at the NASA Ames Vertical Gun Range simulated this process by breaking-up hypervelocity projectiles into a cloud of debris and tracking its path at near-full atmospheric pressure. The resulting cloud of fragments exhibited less deceleration than a solid sphere at the same speed. Moreover, shadowgraphs revealed constituent fragments "surfing" the pressure jump within the mach cone/column. Previous models proposed that crater-forming impacts must be >50-100 m in diameter in order to survive entry [Bland and Artemieva, 2004]. The "needle model" for the Carancas meteorite entry, however, raises questions about this lower limit for threats by rubble-pile asteroids, e.g., Itokawa. Consequently, we modeled the fate of a rubble-pile entering earth's atmosphere using GEODYN, an Eulerian code with adaptive mesh refinement

  18. Brecciated Chely Abinsk Near-Earth Asteroid and its Catastrophic Air Burst

    Science.gov (United States)

    Kring, D. A.; Swindle, T. D.; Zolensky, M. E.

    2013-01-01

    Determining the hazards of near-Earth asteroid (NEA) impacts has been vexed by a paucity of precise data. Existing estimates of blast damage (e.g., [1]), for example, rely on uncertain impact energies for events like Sikhote-Alin, Tunguska, and Barringer Meteorite Crater. The Chelyabinsk air burst event of 15 February 2013, involving an LL-type NEA, provides an excellent calibration point for enhancing those assessments.

  19. 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.

  20. Megaregolith insulation and the duration of cooling to isotopic closure within differentiated asteroids and the moon

    International Nuclear Information System (INIS)

    Ages determined for extraterrestrial samples by the Sm-Nd and Rb-Sr techniques are commonly assumed to record igneous crystallization events, because in solid silicates, Nd and Sr diffuse at exceedingly slow rates. However, the authors find that for course-grained igneous cumulate rocks from the Moon or from a large, thoroughly brecciated asteroid, this assumption may not be reliable. The Moon and at least one asteroid (the parent body of the eucrite, diogenite, and howardite meteorites) appear to have been largely molten at or about the time they formed. They have modeled global cooling of the Moon and large (R= 40-250 km) asteroids, starting at or near the solidus. A crucial factor in determining the prevailing interval (Ic) of cooling between igenous crystallization and isotopic closure, for any given depth in the crust, is the extent to which the body is insulated by a regolith/megaregolith layer of porous, fragmental impact debris. Given plausible assumptions regarding the thicknesses of such layers on the Moon and the eucrite parent asteroid (and regarding the radius of the eucrite asteroid), results indicate that deep-crustal regions tend to remain above the Nd and Sr isotopic closure temperature for intervals that are long in comparison to the precision of modern Nd- and Sr-based age measurements, and in comparison to suggested chronologic scenarios of global differentiation. Ic intervals of as long as 100 m.y. may be common among available samples of primordial, deep-crustal cumulates from both bodies. Chronologies for the gross solidification of the Moon and the eucrite asteroid should allow for the possibility that any single age for a course-grained plutonic or cumulate-textured rock might be many tens of millions of years younger than the igneous crystallization age

  1. Dynamical Evolution of the Hungaria Asteroids

    Science.gov (United States)

    Cuk, Matija; McEachern, F. M.; Stewart, S. T.

    2009-05-01

    Hungarias are a stable asteroid group of minor planets orbiting between Mars and the main asteroid belt, with high inclinations (16-30 deg), low eccentricities (eland on one of the Martian resonances. The majority of Hungarias should have crossed a Martian resonance in the past, requiring a much larger primordial population to sustain the losses. We propose an alternative scenario of continuous replenishment. We find that certain Mars-crossers can be trapped in Martian resonances for tens of millions of years, making it possible for the Yarkovsky effect to migrate them out of the resonance lock. If this exit happens while the asteroid's eccentricity (which is constantly evolving due to the resonance) is sufficiently low, a stable Hungaria is created. We speculate that S-types are more likely to have been "adopted" into the Hungaria group this way, while at least some of the E-types are likely to be primordial.

  2. 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...

  3. Orbital Mechanics near a Rotating Asteroid

    Indian Academy of Sciences (India)

    Yu Jiang; Hexi Baoyin

    2014-03-01

    This study investigates the different novel forms of the dynamical equations of a particle orbiting a rotating asteroid and the effective potential, the Jacobi integral, etc. on different manifolds. Nine new forms of the dynamical equations of a particle orbiting a rotating asteroid are presented, and the classical form of the dynamical equations has also been found. The dynamical equations with the potential and the effective potential in scalar form in the arbitrary body-fixed frame and the special body-fixed frame are presented and discussed. Moreover, the simplified forms of the effective potential and the Jacobi integral have been derived. The dynamical equation in coefficient-matrix form has been derived. Other forms of the dynamical equations near the asteroid are presented and discussed, including the Lagrange form, the Hamilton form, the symplectic form, the Poisson form, the Poisson-bracket form, the cohomology form, and the dynamical equations on Kähler manifold and another complex manifold. Novel forms of the effective potential and the Jacobi integral are also presented. The dynamical equations in scalar form and coefficient-matrix form can aid in the study of the dynamical system, the bifurcation, and the chaotic motion of the orbital dynamics of a particle near a rotating asteroid. The dynamical equations of a particle near a rotating asteroid are presented on several manifolds, including the symplectic manifold, the Poisson manifold, and complex manifolds, which may lead to novel methods of studying the motion of a particle in the potential field of a rotating asteroid.

  4. The geologic mapping of asteroid Vesta

    Science.gov (United States)

    Williams, D.; Yingst, A.; Garry, B.

    2014-07-01

    As part of NASA's Dawn mission [1,2] we conducted a geologic mapping campaign to provide a systematic, cartography-based initial characterization of the global and regional geology of asteroid Vesta. The goal of geological maps is to place observations of surface features into their stratigraphic context to develop a geologic history of the evolution of planetary surfaces. Geologic mapping reduces the complexity of heterogeneous planetary surfaces into comprehensible portions, defining and characterizing discrete material units based upon physical attributes related to the geologic processes that produced them, and enabling identification of the relative roles of various processes (impact cratering, tectonism, volcanism, erosion and deposition) in shaping planetary surfaces [3,4]. The Dawn Science Team produced cartographic products of Vesta from the Framing Camera images, including global mosaics as well as 15 regional quadrangles [5], which served as bases for the mapping. We oversaw the geologic mapping campaign during the Nominal Mission, including production of a global geologic map at scale 1:500,000 using images from the High Altitude Mapping Orbit [6] and 15 quadrangle geologic maps at scale 1:250,000 using images from the Low Altitude Mapping Orbit [7]. The goal was to support the Dawn Team by providing geologic and stratigraphic context of surface features and supporting the analysis of data from the Visible and Infrared Spectrometer (VIR) and the Gamma Ray and Neutron Detector (GRaND). Mapping was done using ArcGIS™ software, in which quadrangle mapping built on interpretations derived from the global geologic map but were updated and modified to take advantage of the highest spatial resolution data. Despite challenges (e.g., Vesta's highly sloped surface [8] deforms impact craters and produces mass movements that buries contacts), we were successfully able to map the whole surface of Vesta and identify a geologic history as represented in our maps and

  5. Capturing near-Earth asteroids around Earth

    Science.gov (United States)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  6. 6384 Kervin: A Possible Hungaria Binary Asteroid

    Science.gov (United States)

    Warner, Brian D.; Aznar Macia, Amadeo

    2016-04-01

    Analysis of CCD photometric observations in late 2015 of the Hungaria asteroid 6384 Kervin indicates that it may be a binary asteroid with a primary lightcurve of P1 = 3.6194 ± 0.0001 h, A1 = 0.06 ± 0.01 mag. The secondary lightcurve parameters are P2 = 15.94 ± 0.01 h, A2 = 0.03 ± 0.01 mag. No mutual events (occultations or eclipses) were observed. However, other indicators give an estimated diameter ratio on the order of Ds/Dp ~ 0.3, possibly greater.

  7. 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.

  8. 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.

  9. 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.

  10. Characterization of the near-Earth Asteroid 2002NY40

    CERN Document Server

    Roberts, Lewis C; Lambert, John V; Africano, John L; Knox, Keith T; Barros, Jacob K; Hamada, Kris M; Liang, Dennis; Sydney, Paul F; Kervin, Paul

    2007-01-01

    In August 2002, the near-Earth asteroid 2002 NY40, made its closest approach to the Earth. This provided an opportunity to study a near-Earth asteroid with a variety of instruments. Several of the telescopes at the Maui Space Surveillance System were trained at the asteroid and collected adaptive optics images, photometry and spectroscopy. Analysis of the imagery reveals the asteroid is triangular shaped with significant self-shadowing. The photometry reveals a 20-hour period and the spectroscopy shows that the asteroid is a Q-type.

  11. Asteroid Shape and Spin Axis Modeling Via Light Curve Inversion

    Science.gov (United States)

    Friz, Paul; Gokhale, V.

    2013-01-01

    We present light curves and shape and spin axis models for the five asteroids: 291 Alice, 281 Lucretia, 321 Florentina, 714 Ulula, and 3169 Ostro. These models were obtained using data taken from the Truman Observatory, the Asteroid Photometric Catalogue, and the Minor Planet Center. Knowledge of individual asteroids shapes and spin axes is vital to understanding the solar system. However, currently only 213 out of the 500,000 asteroids with known orbits have been modeled. By taking many light curves of asteroids over several apparitions it is possible to determine their shapes and spin axes by a process known as light curve inversion.

  12. 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

  13. Modelling the brightness increase signature due to asteroid collisions

    CERN Document Server

    McLoughlin, Ev; McLoughlin, Alan

    2015-01-01

    We have developed a model to predict the post-collision brightness increase of sub-catastrophic collisions between asteroids and to evaluate the likelihood of a survey detecting these events. It is based on the cratering scaling laws of Holsapple and Housen (2007) and models the ejecta expansion following an impact as occurring in discrete shells each with their own velocity. We estimate the magnitude change between a series of target/impactor pairs, assuming it is given by the increase in reflecting surface area within a photometric aperture due to the resulting ejecta. As expected the photometric signal increases with impactor size, but we find also that the photometric signature decreases rapidly as the target asteroid diameter increases, due to gravitational fallback. We have used the model results to make an estimate of the impactor diameter for the (596) Scheila collision of D=49-65m depending on the impactor taxonomy, which is broadly consistent with previous estimates. We varied both the strength regi...

  14. Core Formation and Evolution of Asteroid 4 Vesta

    Science.gov (United States)

    Kiefer, Walter S.; Mittlefehldt, David W.

    2014-01-01

    The howardites, eucrites, and diogenites (HEDs) are a suite of related meteorite types that formed by igneous and impact processes on the same parent body. Multiple lines of evidence, including infrared spectroscopy of the asteroid belt and the petrology and geochemistry of the HEDs, suggest that the asteroid 4 Vesta is the parent body for the HEDs. Observations by NASA's Dawn spacecraft mission strongly support the conclusion that the HEDs are from Vesta. The abundances of the moderately siderophile elements Ni, Co, Mo, W, and P in eucrites require that most or all of the metallic phase in Vesta segregated to form a core prior to eucrite solidification. These observations place important constraints on the mode and timescale of core formation on Vesta. Possible core formation mechanisms include porous flow, which potentially could occur prior to initiation of silicate melting, and metallic rain in a largely molten silicate magma ocean. Once the core forms, convection within the core could possible sustain a magnetic dynamo for a period of time. We consider each process in turn.

  15. Dust loss from activated asteroid P/2015 X6

    CERN Document Server

    Moreno, F; Cabrera-Lavers, A; Pozuelos, F J

    2016-01-01

    We present observations and dust tail models of activated asteroid P/2015 X6 from deep imaging data acquired at the 10.4m Gran Telescopio Canarias (GTC) from mid-December 2015 to late January 2016. The results of the modeling indicate that the asteroid has undergone a sustained dust loss over a two-month or longer period. The dust parameters, derived from multidimensional fits of the available images, are compatible with either ice sublimation or rotational instability processes. An impulsive event, as it could be associated to an impact with another body, is less likely. A power-law distribution of particles, with minimum and maximum radius of 1 $\\mu$m and 1 cm, and power index of --3.3 is found to be consistent with the observations. Depending on the ejection velocity model adopted, the particle velocities are found in the 0.3 to 10 m s$^{-1}$ range. The activation time was between 18-26 days before discovery. The total ejected mass from that time to the most recent observation is in the range 5-9$\\times$10...

  16. Dust Loss from Activated Asteroid P/2015 X6

    Science.gov (United States)

    Moreno, F.; Licandro, J.; Cabrera-Lavers, A.; Pozuelos, F. J.

    2016-08-01

    We present observations and dust tail models of activated asteroid P/2015 X6 from deep imaging data acquired at the 10.4 m Gran Telescopio Canarias (GTC) from 2015 mid-December to 2016 late January. The results of the modeling indicate that the asteroid has undergone sustained dust loss over a period of two months or longer. The dust parameters, derived from multidimensional fits of the available images, are compatible with either ice sublimation or rotational instability processes. An impulsive event, as might be associated with an impact with another body, is less likely. A power-law distribution of particles, with minimum and maximum radii of 1 μm and 1 cm and a power index of ‑3.3, is found to be consistent with the observations. Depending on the model of ejection velocity adopted, the particle velocities are found to be in the range of 0.3–10 m s‑1. The activation time was between 18 and 26 days before discovery. The total mass ejected from that time to the most recent observation is in the range 5–9 × 106 kg. No dust features giving indication of past activity earlier than the activation time have been observed.

  17. Near-Earth asteroids orbit propagation with Gaia observations

    CERN Document Server

    Bancelin, D; Thuillot, W

    2016-01-01

    Gaia is an astrometric mission that will be launched in 2013 and set on L2 point of Lagrange. It will observe a large number of Solar System Objets (SSO) down to magnitude 20. The Solar System Science goal is to map thousand of Main Belt asteroids (MBAs), Near Earth Objects (NEOs) (including comets) and also planetary satellites with the principal purpuse of orbital determination (better than 5 mas astrometric precision), determination of asteroid mass, spin properties and taxonomy. Besides, Gaia will be able to discover a few objects, in particular NEOs in the region down to the solar elongation 45{\\deg} which are harder to detect with current ground-based surveys. But Gaia is not a follow-up mission and newly discovered objects can be lost if no ground-based recovery is processed. The purpose of this study is to quantify the impact of Gaia data for the known NEAs population and to show how to handle the problem of these discoveries when faint number of observations and thus very short arc is provided.

  18. The Chelyabinsk superbolide: a fragment of asteroid 2011 EO40?

    CERN Document Server

    Marcos, C de la Fuente

    2013-01-01

    Bright fireballs or bolides are caused by meteoroids entering the Earth's atmosphere at high speed. On 2013 February 15, a superbolide was observed in the skies near Chelyabinsk, Russia. Such a meteor could be the result of the decay of an asteroid and here we explore this possibility applying a multistep approach. First, we use available data and Monte Carlo optimization (validated using 2008 TC3 as template) to obtain a robust solution for the pre-impact orbit of the Chelyabinsk impactor (semimajor axis = 1.62 au, eccentricity = 0.53, inclination = 3.82 deg, longitude of the ascending node = 326.41 deg and argument of perihelion = 109.44 deg). Then, we use this most probable orbit and numerical analysis to single out candidates for membership in, what we call, the Chelyabinsk asteroid family. Finally, we perform N-body simulations to either confirm or reject any dynamical connection between candidates and impactor. We find reliable statistical evidence on the existence of the Chelyabinsk cluster. It appears...

  19. Twenty-one Asteroid Lightcurves at Group Observadores de Asteroides (OBAS): Late 2015 to Early 2016

    Science.gov (United States)

    Aznar Macias, Amadeo; Carreno Garcerain, Alfonso; Arce Masego, Enrique; Brines Rodriguez, Pedro; Lozano de Haro, Juan; Fornas Silva, Alvaro; Fornas Silva, Gonzalo; Mas Martinez, Vicente; Rodrigo Chiner, Onofre; Herrero Porta, David

    2016-07-01

    We report on the photometric analysis result of 21 mainbelt asteroids (MBA) done by Observadores de Asteroides (OBAS). This work is part of the Minor Planet Photometric Database task initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as additional incomplete lightcurves to help analysis at future oppositions. This is a compilation of lightcurves obtained during last quarter of 2015 and first quarter of 2016.

  20. Mobile Asteroid Surface Scout (MASCOT) - Design, Development and Delivery of a Small Asteroid Lander Aboard Hayabusa2

    OpenAIRE

    Grundmann, Jan Thimo; Auster, U.; Baturkin, Volodymyr; Bellion, Anthony; Bibring, Jean-Pierre; Biele, Jens; Boden, Ralf; Bompis, Olivier; Borgs, Belinda; Bousquet, Pierre; Canalias, Elisabet; Celotti, Luca; Cenac-Morthe, Céline; Cordero, Federico; Deleuze, Muriel

    2015-01-01

    MASCOT is a small asteroid lander launched on December 3rd, 2014, aboard the Japanese HAYABUSA2 asteroid sample-return mission towards the 980 m diameter C-type near-Earth asteroid (162173) 1999 JU3. MASCOT carries four full-scale asteroid science instruments and an uprighting and relocation device within a shoebox-sized 10 kg spacecraft; a complete lander comparable in mass and volume to a medium-sized science instrument on interplanetary missions. Asteroid surface science will be ob...

  1. The infrared spectrum of asteroid 433 Eros

    Science.gov (United States)

    Larson, H. P.; Fink, U.; Treffers, R. R.; Gautier, T. N., III

    1976-01-01

    The mineralogical composition of asteroid Eros has been determined from its infrared spectrum (0.9-2.7 micrometers; 28/cm resolution). Major minerals include metallic Ni-Fe and pyroxene; no spectroscopic evidence for olivine or plagioclase feldspar was found. The IR spectrum of Eros is most consistent with a stony-iron composition.

  2. NASA hits back in asteroid spat

    Science.gov (United States)

    Cartlidge, Edwin

    2016-07-01

    Nathan Myhrvold, chief executive of the company Intellectual Ventures and a former chief technology officer of Microsoft, is at loggerheads with a group of NASA astrophysicists over the latter's ability to accurately measure the properties of tens of thousands of asteroids in the solar system.

  3. Asteroid models from the Lowell Photometric Database

    CERN Document Server

    Durech, J; Oszkiewicz, D; Vanco, R

    2016-01-01

    We use the lightcurve inversion method to derive new shape models and spin states of asteroids from the sparse-in-time photometry compiled in the Lowell Photometric Database. To speed up the time-consuming process of scanning the period parameter space through the use of convex shape models, we use the distributed computing project Asteroids@home, running on the Berkeley Open Infrastructure for Network Computing (BOINC) platform. This way, the period-search interval is divided into hundreds of smaller intervals. These intervals are scanned separately by different volunteers and then joined together. We also use an alternative, faster, approach when searching the best-fit period by using a model of triaxial ellipsoid. By this, we can independently confirm periods found with convex models and also find rotation periods for some of those asteroids for which the convex-model approach gives too many solutions. From the analysis of Lowell photometric data of the first 100,000 numbered asteroids, we derived 328 new ...

  4. Lightcurves of the Karin family asteroids

    CERN Document Server

    Yoshida, Fumi; Dermawan, Budi; Nakamura, Tsuko; Takahashi, Shigeru; Ibrahimov, Mansur A; Malhotra, Renu; Ip, Wing Huen; Chen, Wen Ping; Sawabe, Yu; Haji, Masashige; Saito, Ryoko; Hirai, Masanori; Miyasaka, Seidai; Fukushima, Hideo; Sato, Hideo; Sato, Yusuke

    2012-01-01

    The Karin family is the first recognized very young asteroid family that was created by an asteroid breakup only 5.8 Myr ago. As the members of this family probably have not experienced significant orbital or collisional evolution yet, it is possible that they still preserve properties of the original collisional event in terms of their rotational status and surface color. We have been carrying out a series of photometric observations of the Karin family asteroids, and here we report the analysis result of lightcurves including the rotation period of eleven members as well as those of an interloper asteroid: (832) Karin, (4507) 1990 FV (an interloper), (7719) 1997 GT36, (10783) 1999 RB9, (11728) Einer, (13765) Nansmith, (16706) Svojsik, (28271) 1999 CK16, (40917) 1999 TR171, (43032) 1999 VR26, (69880) 1998 SQ81, and (71031) 1999 XE68. As for four of them we estimated their absolute magnitudes H_R and the slope parameter G_R of the solar phase curves: (832) Karin, (4507) 1990 FV, (13765) Nansmith, and (69880) ...

  5. The Bering small vehicle asteroid mission concept

    DEFF Research Database (Denmark)

    Michelsen, Rene; Andersen, Anja; Haack, Henning;

    2004-01-01

    targets. The dilemma obviously being the resolution versus distance and the statistics versus DeltaV requirements. Using advanced instrumentation and onboard autonomy, we have developed a space mission concept whose goal is to map the flux, size, and taxonomy distributions of asteroids. The main focus is...

  6. A note on cement in asteroids

    CERN Document Server

    Bilalbegovic, G

    2016-01-01

    Cement mineral tobermorite was formed in hydrothermal experiments on alternation of calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondrite meteorites. Unidentified bands at 14 microns were measured for CAIs and the matrix of the Allende meteorite sample, as well as for Hektor and Agamemnon asteroids. The presence of cement nanoparticles may explain the feature at 14 microns.

  7. Early formation of evolved asteroidal crust.

    Science.gov (United States)

    Day, James M D; Ash, Richard D; Liu, Yang; Bellucci, Jeremy J; Rumble, Douglas; McDonough, William F; Walker, Richard J; Taylor, Lawrence A

    2009-01-01

    Mechanisms for the formation of crust on planetary bodies remain poorly understood. It is generally accepted that Earth's andesitic continental crust is the product of plate tectonics, whereas the Moon acquired its feldspar-rich crust by way of plagioclase flotation in a magma ocean. Basaltic meteorites provide evidence that, like the terrestrial planets, some asteroids generated crust and underwent large-scale differentiation processes. Until now, however, no evolved felsic asteroidal crust has been sampled or observed. Here we report age and compositional data for the newly discovered, paired and differentiated meteorites Graves Nunatak (GRA) 06128 and GRA 06129. These meteorites are feldspar-rich, with andesite bulk compositions. Their age of 4.52 +/- 0.06 Gyr demonstrates formation early in Solar System history. The isotopic and elemental compositions, degree of metamorphic re-equilibration and sulphide-rich nature of the meteorites are most consistent with an origin as partial melts from a volatile-rich, oxidized asteroid. GRA 06128 and 06129 are the result of a newly recognized style of evolved crust formation, bearing witness to incomplete differentiation of their parent asteroid and to previously unrecognized diversity of early-formed materials in the Solar System. PMID:19129845

  8. Small asteroids - rubble piles or boulders?

    Science.gov (United States)

    Harris, Alan W.

    2013-10-01

    The asteroid rotation spin barrier at ~2.2 h period among asteroids 10 km > D > 200 m doesn’t prove all such asteroids are rubble piles, and the faster rotations among smaller asteroids doesn’t require monolithic strength, either. Only a very modest strength, perhaps no more than van der Waals force, might suffice to hold regolith together on a small super-fast rotator (Sanchez & Scheeres, 2013, arXif:1306.1622v1). The problem is that for a constant or only slowly varying strength with respect to diameter, the spin barrier becomes proportional to 1/D below the size where material strength is dominant, or perhaps a bit steeper if strength increases with decreasing D. What we observe in the distribution of asteroid spins versus diameter is that below D ~ 200 m, the spin barrier goes up at least ~D-3.5, if not abruptly. Models with constant or slowly varying strength fail to fit this observation, and the abrupt transition cannot be an observational selection effect: the void in the phase space of rotations would be among the easiest rotations to observe, e.g. the one conspicuous exception, 2001 OE84 (D ~ 0.7 km, P = 0.5 h) was easily and unambiguously measured (Pravec, et al. 2002, Proc. ACM 2002, ESA SP-500, 743-745). This abrupt transition is most easily explained as a real transition in material properties of asteroids in the size range ~200 m diameter, from “rubble pile” to “boulder”, although neither term may be fully descriptive of the actual structure. Two other lines of evidence suggest that this transition in properties is real: the dip in the size-frequency distribution of NEAs is maximum at ~150 m, suggesting that a transition to stronger material structure occurs about there, and we observe, e.g., Tunguska and the recent Chelyabinsk bolide, that bodies in the tens of meters size range entering the atmosphere behave more like solid rocks than rock piles (Boslough & Crawford 2008, Int. J. Imp. Eng. 35, 1441-1448). I encourage those doing computer

  9. Asteroid 4 Vesta: A Fully Differentiated Dwarf Planet

    Science.gov (United States)

    Mittlefehldt, David

    2014-01-01

    One conclusion derived from the study of meteorites is that some of them - most irons, stony irons, some achondrites - hail from asteroids that were heated to the point where metallic cores and basaltic crusts were formed. Telescopic observations show that there remains only one large asteroid with a basaltic crust, 4 Vesta; present day mean radius 263 km. 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 cumulate gabbros, diabases and basalts from the upper crust. Howardites are impact-engendered breccias of diogenites and eucrites. A strong case can be made that HEDs are derived from Vesta. The NASA Dawn spacecraft orbited Vesta for 14 months returning data allowing geological, mineralogical, compositional and geophysical interpretations of Vesta's surface and structure. Combined with geochemical and petrological observations of HED meteorites, differentiation models for Vesta can be developed. Proto-Vesta probably consisted of primitive chondritic materials. Compositional evidence, primarily from basaltic eucrites, indicates that Vesta was melted to high degree (>=50%) which facilitated homogenization of the silicate phase and separation of immiscible Fe,Ni metal plus Fe sulphide into a core. Geophysical models based on Dawn data support a core of 110 km radius. The silicate melt vigorously convected and initially followed a path of equilibrium crystallization forming a harzburgitic mantle, possibly overlying a dunitic restite. Once the fraction of crystals was sufficient to cause convective lockup, the remaining melt collected between the mantle and the cool thermal boundary layer. This melt undergoes fractional crystallization to form a dominantly orthopyroxenite (diogenite) lower crust. The initial thermal boundary layer of primitive chondritic material is gradually replaced by a

  10. On the origin of the Almahata-Sitta meteorite and 2008TC3 asteroid

    CERN Document Server

    Gayon-Markt, Julie; Morbidelli, Alessandro; Marchi, Simone

    2012-01-01

    Asteroid 2008TC3 was a Near Earth Asteroid that impacted the Earth on 2008 October 7. Meteorites were produced by the break-up of 2008TC3 in the high atmosphere and at present, about 600 meteorites - called Almahata Sitta - coming from 2008TC3 have been recovered. A mineralogical study of Almahata Sitta fragments shows that the asteroid 2008TC3 was made of meteorites of different types (ureilites, H, L, and E chondrites). Understanding the origin of this body and how it was put together remain a challenge. Here we perform a detailed spectroscopical and dynamical investigation to show that the most likely source region of 2008TC3 is in the inner Main Belt at low inclination (i<8 degrees). We show that asteroids with spectroscopic classes that can be associated with the different meteorite types of Almahata Sitta are present in the region of the Main Belt that includes the Nysa-Polana family and objects of the Background at low inclination. Searching for a possible scenario of formation for 2008TC3, we show ...

  11. Electric Solar Wind Sail Kinetic Energy Impactor for Asteroid Deflection Missions

    Science.gov (United States)

    Yamaguchi, Kouhei; Yamakawa, Hiroshi

    2016-03-01

    An electric solar wind sail uses the natural solar wind stream to produce low but continuous thrust by interacting with a number of long thin charged tethers. It allows a spacecraft to generate a thrust without consuming any reaction mass. The aim of this paper is to investigate the use of a spacecraft with such a propulsion system to deflect an asteroid with a high relative velocity away from an Earth collision trajectory. To this end, we formulate a simulation model for the electric solar wind sail. By summing thrust vectors exerted on each tether, a dynamic model which gives the relation between the thrust and sail attitude is proposed. Orbital maneuvering by fixing the sail's attitude and changing tether voltage is considered. A detailed study of the deflection of fictional asteroids, which are assumed to be identified 15 years before Earth impact, is also presented. Assuming a spacecraft characteristic acceleration of 0.5 mm/s 2, and a projectile mass of 1,000 kg, we show that the trajectory of asteroids with one million tons can be changed enough to avoid a collision with the Earth. Finally, the effectiveness of using this method of propulsion in an asteroid deflection mission is evaluated in comparison with using flat photonic solar sails.

  12. 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...

  13. To LED or not to LED up a store

    OpenAIRE

    Quartier, Katelijn

    2013-01-01

    This presentation offers a wide talk about LED's and retail lighting. Questions like 'what might be its benefits regarding store experience', 'how do consumers experience LED-lit stores', 'is the use of coloured lighting in stores just a hype or is it a new condition' will be answered. Good and bad examples are used to illustrate the answers.

  14. Nobel Prize for blue LEDs

    Science.gov (United States)

    Kraftmakher, Yaakov

    2015-05-01

    A brief review of lighting technologies is presented. Unavoidable restrictions for incandescent light bulbs caused by the Planck distribution and properties of the human eye are illustrated. The efficiency and luminous efficacy of thermal radiation are calculated for various temperatures; the results clearly show the limitations for thermal radiators. The only way to overcome these limitations is using non-thermal radiators, such as fluorescent lamps and light-emitting diodes (LEDs). Unique advantages of LEDs undoubtedly made a revolution in this field. A crucial element of this progress is the blue LEDs (Nobel Prize 2014). Some experiments with a blue and a green LED are described: (i) the luminescence triggered in a green-yellow phosphor inside a white LED by the blue LED; (ii) radiant spectra and ‘efficiency droop’ in the LEDs; (iii) modulation of the blue LED up to 4 MHz; and (iv) the h/e ratio from the turn-on voltage of the green LED. The experiments are suitable for undergraduate laboratories and usable as classroom demonstrations.

  15. Comparison of different LED Packages

    Science.gov (United States)

    Dieker, Henning; Miesner, Christian; Püttjer, Dirk; Bachl, Bernhard

    2007-09-01

    In this paper different technologies for LED packaging are compared, focusing on Chip on Board (COB) and SMD technology. The package technology which is used depends on the LED application. A critical fact in LED technology is the thermal management, especially for high brightness LED applications because the thermal management is important for reliability, lifetime and electrooptical performance of the LED module. To design certain and long life LED applications knowledge of the heat flow from LEDs to the complete application is required. High sophisticated FEM simulations are indispensable for modern development of high power LED applications. We compare simulations of various substrate materials and packaging technologies simulated using FLOTHERM software. Thereby different substrates such as standard FR4, ceramic and metal core printed circuit boards are considered. For the verification of the simulated results and the testing of manufactured modules, advanced measurement tools are required. We show different ways to experimentally characterize the thermal behavior of LED modules. The thermal path is determined by the transient thermal analysis using the MicReD T3Ster analyzer. Afterwards it will be compared to the conventional method using thermocouples. The heat distribution over the module is investigated by an IR-Camera. We demonstrate and compare simulation and measurement results of Chip-on-Board (COB) and Sub-Mounted Devices (SMD) technology. The results reveal that for different applications certain packages are ideal.

  16. Asteroid occultations today and tomorrow: toward the GAIA era

    Science.gov (United States)

    Tanga, P.; Delbo, M.

    2007-11-01

    Context: Observation of star occultations is a powerful tool to determine shapes and sizes of asteroids. This is key information necessary for studying the evolution of the asteroid belt and to calibrate indirect methods of size determination, such as the models used to analyze thermal infrared observations. Up to now, the observation of asteroid occultations is an activity essentially secured by amateur astronomers equipped with small, portable equipments. However, the accuracy of the available ephemeris prevents accurate predictions of the occultation events for objects smaller than ~100 km. Aims: We investigate current limits in predictability and observability of asteroid occultations, and we study their possible evolution in the future, when high accuracy asteroid orbits and star positions (such as those expected from the mission Gaia of the European Space Agency) will be available. Methods: We use a simple model for asteroid ephemeris uncertainties and numerical algorithms for estimating the limits imposed by the instruments, assuming realistic CCD performances and asteroid size distribution, to estimate the expected occultation rate under different conditions. Results: We show that high accuracy ephemerides which will be available in the future will extend toward much smaller asteroids the possibility of observing asteroid occultations, greatly increasing the number of events and objects involved. A complete set of size measurements down to ~10 km main belt asteroids could be obtained in a few years, provided that a small network of ground-based 1m telescopes are devoted to occultation studies.

  17. 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.

  18. Photometry and models of selected main belt asteroids. IX. Introducing interactive service for asteroid models (ISAM)

    Science.gov (United States)

    Marciniak, A.; Bartczak, P.; Santana-Ros, T.; Michałowski, T.; Antonini, P.; Behrend, R.; Bembrick, C.; Bernasconi, L.; Borczyk, W.; Colas, F.; Coloma, J.; Crippa, R.; Esseiva, N.; Fagas, M.; Fauvaud, M.; Fauvaud, S.; Ferreira, D. D. M.; Hein Bertelsen, R. P.; Higgins, D.; Hirsch, R.; Kajava, J. J. E.; Kamiński, K.; Kryszczyńska, A.; Kwiatkowski, T.; Manzini, F.; Michałowski, J.; Michałowski, M. J.; Paschke, A.; Polińska, M.; Poncy, R.; Roy, R.; Santacana, G.; Sobkowiak, K.; Stasik, M.; Starczewski, S.; Velichko, F.; Wucher, H.; Zafar, T.

    2012-09-01

    Context. The shapes and spin states of asteroids observed with photometric techniques can be reconstructed using the lightcurve inversion method. The resultant models can then be confirmed or exploited further by other techniques, such as adaptive optics, radar, thermal infrared, stellar occultations, or space probe imaging. Aims: During our ongoing work to increase the set of asteroids with known spin and shape parameters, there appeared a need for displaying the model plane-of-sky orientations for specific epochs to compare models from different techniques. It would also be instructive to be able to track how the complex lightcurves are produced by various asteroid shapes. Methods: Basing our analysis on an extensive photometric observational dataset, we obtained eight asteroid models with the convex lightcurve inversion method. To enable comparison of the photometric models with those from other observing/modelling techniques, we created an on-line service where we allow the inversion models to be orientated interactively. Results: Our sample of objects is quite representative, containing both relatively fast and slow rotators with highly and lowly inclined spin axes. With this work, we increase the sample of asteroid spin and shape models based on disk-integrated photometry to over 200. Three of the shape models obtained here are confirmed by the stellar occultation data; this also allowed independent determinations of their sizes to be made. Conclusions: The ISAM service can be widely exploited for past and future asteroid observations with various, complementary techniques and for asteroid dimension determination. http://isam.astro.amu.edu.pl Photometric data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/545/A131

  19. Investigation of the interior of primordial asteroids and the origin of the Earth's water: The INSIDER space mission

    Science.gov (United States)

    Vernazza, P.; Lamy, P.

    2014-07-01

    Today's asteroid belt may not only be populated by objects that formed in situ, typically between 2.2 and 3.3 au, but also by bodies that formed over a very large range of heliocentric distances. It is currently proposed that both the early (700 Myrs after Solar System formation) dynamical evolution of the Solar System was governed by giant planet migrations that led to the insertion of inner (1--3 au) as well as outer (4--13 au) small bodies in the asteroid belt. Taken altogether, the current dynamical models are able to explain many striking features of the asteroid belt including i) its incredible compositional diversity deduced mainly from spectroscopic observations and meteorites measurements, and ii) the evidence of radial mixing experienced by the various asteroid classes (e.g., S-, C-types) after their formation. In a broad stroke, the idea that the asteroid belt is a condensed version of the primordial Solar System is progressively emerging. The asteroid belt therefore presents the double advantage of being easily accessible and of offering crucial tests for the formation models of the Solar System by exploring the building blocks predicted by models of i) the telluric planets, ii) the giant planet cores, iii) the giant planets' satellites, and iv) outer small bodies such TNOs and comets. It also appears as an ideal place to search for the origin of Earth's water. Up to now, only a few asteroid classes (e.g., several S-types) have been visited by spacecraft and the focus of these in situ measurements has been mainly to give a geological context to ground based observations as well as strengthen/validate their interpretation. Most of the tantalizing discoveries of asteroid missions have been realized via images of the objects surfaces. Time has come for asteroid space science to reach a new milestone by extending the reconnaissance of the Belt's diversity and addressing new science questions. The scientific objectives of the INSIDER mission, to be proposed

  20. New Phosphors for White LEDs

    Institute of Scientific and Technical Information of China (English)

    LIU Ru-Shi

    2004-01-01

    White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or UV LEDs) and photoluminescence phosphors. GaN-based highly efficient blue InGaN LEDs combined with phosphors can produce white light. These solid-state LED lamps have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability, and long operating lifetime (about 100,000 hours). For the purpose of development of high energy-efficient white light sources, we need to produce highly efficient new phosphors, which can absorb excitation energy from blue or UV LEDs and generate emissions.In this paper, we investigate the development of blue or UV LEDs by the appropriate combination of new phosphors which can lead us to obtain high brightness white light. The criteria of choosing the best phosphors, for blue (380-450 nm) and UV (360-400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance light between the light emission from blue LEDs and the yellow YAG:Ce,Gd phosphor is important to obtain white light with high color temperature. The phosphors with high efficiency which can be excited by UV LEDs are important to obtain the white light with high color rendering index.

  1. Drift in LED based Photometer

    DEFF Research Database (Denmark)

    Paasch, Kasper

    1999-01-01

    During the development of a low cost industrial optical sensor an unexpected drift phenomenon has shown to be critical to performance. The sensor is based on LED's as light sources and the main source of error could be tracked to the instability of the spatial radiation pattern of the LED's. This...

  2. Advanced poly-LED displays

    Science.gov (United States)

    Childs, Mark; Nisato, Giovanni; Fish, D.; Giraldo, Andrea; Jenkins, A. J.; Johnson, Mark T.

    2003-05-01

    Philips have been actively developing polymer OLED (poly-LED) displays as a future display technology. Their emissive nature leads to a very attractive visual appearance, with wide viewing angle, high brightness and fast response speed. Whilst the first generation of poly-LED displays are likely to be passive-matrix driven, power reduction and resolution increase will lead to the use of active-matrix poly-LED displays. Philips Research have designed, fabricated and characterized five different designs of active-matrix polymer-LED display. Each of the five displays makes use of a distinct pixel programming- or pixel drive-technique, including current programming, threshold voltage measurement and photodiode feedback. It will be shown that hte simplest voltage-programmed current-source pixel suffers from potentially unacceptable brightness non-uniformity, and that advanced pixel circuits can provide a solution to this. Optical-feedback pixel circuits will be discussed, showing that they can be used to improve uniformity and compensate for image burn-in due to polymer-LED material degradation, improving display lifetime. Philips research has also been active in developing technologies required to implement poly-LED displays on flexible substrates, including materials, processing and testing methods. The fabrication of flexible passive-matrix poly-LED displays will be presented, as well as the ongoing work to assess the suitability of processing flexible next-generation poly-LED displays.

  3. An asteroidal origin for water in the Moon

    Science.gov (United States)

    Barnes, Jessica J.; Kring, David A.; Tartèse, Romain; Franchi, Ian A.; Anand, Mahesh; Russell, Sara S.

    2016-01-01

    The Apollo-derived tenet of an anhydrous Moon has been contested following measurement of water in several lunar samples that require water to be present in the lunar interior. However, significant uncertainties exist regarding the flux, sources and timing of water delivery to the Moon. Here we address those fundamental issues by constraining the mass of water accreted to the Moon and modelling the relative proportions of asteroidal and cometary sources for water that are consistent with measured isotopic compositions of lunar samples. We determine that a combination of carbonaceous chondrite-type materials were responsible for the majority of water (and nitrogen) delivered to the Earth–Moon system. Crucially, we conclude that comets containing water enriched in deuterium contributed significantly Moon. Therefore, our work places important constraints on the types of objects impacting the Moon ∼4.5–4.3 billion years ago and on the origin of water in the inner Solar System. PMID:27244672

  4. An asteroidal origin for water in the Moon

    Science.gov (United States)

    Barnes, Jessica J.; Kring, David A.; Tartèse, Romain; Franchi, Ian A.; Anand, Mahesh; Russell, Sara S.

    2016-05-01

    The Apollo-derived tenet of an anhydrous Moon has been contested following measurement of water in several lunar samples that require water to be present in the lunar interior. However, significant uncertainties exist regarding the flux, sources and timing of water delivery to the Moon. Here we address those fundamental issues by constraining the mass of water accreted to the Moon and modelling the relative proportions of asteroidal and cometary sources for water that are consistent with measured isotopic compositions of lunar samples. We determine that a combination of carbonaceous chondrite-type materials were responsible for the majority of water (and nitrogen) delivered to the Earth-Moon system. Crucially, we conclude that comets containing water enriched in deuterium contributed significantly Moon. Therefore, our work places important constraints on the types of objects impacting the Moon ~4.5-4.3 billion years ago and on the origin of water in the inner Solar System.

  5. Near Earth asteroid search and follow-up beyond 22nd magnitude. A pilot program with ESO telescopes

    Czech Academy of Sciences Publication Activity Database

    Boattini, A.; Abramo, G. D.; Scholl, H.; Hainaut, O. R.; Boehnhardt, H.; West, R.; Carpino, M.; Hahn, G.; Michelsen, R.; Forti, G.; Pravec, Petr; Valsecchi, G. B.; Asher, D. J.

    2004-01-01

    Roč. 418, č. 2 (2004), s. 743-750. ISSN 0004-6361 Institutional research plan: CEZ:AV0Z1003909 Keywords : solar system * minor planets * asteroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.694, year: 2004

  6. Internal structure and physical properties of the Asteroid 2008 TC(3) inferred from a study of the Almahata Sitta meteorites

    Czech Academy of Sciences Publication Activity Database

    Kohout, Tomáš; Kiuru, R.; Montonen, M.; Scheirich, Peter; Britt, D.; Macke, R.; Consolmagno, G.

    2011-01-01

    Roč. 212, č. 2 (2011), s. 697-700. ISSN 0019-1035 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10030501 Keywords : asteroid * 2008TC3 * meteorite * Near-Earth objects Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.385, year: 2011

  7. Tracing meteorite source regions through asteroid spectroscopy

    Science.gov (United States)

    Thomas, Cristina Ana

    By virtue of their landing on Earth, meteorites reside in near-Earth object (NEO) orbits prior to their arrival. Thus the population of observable NEOs, in principle, gives the best representation of meteorite source bodies. By linking meteorites to NEOs, and linking NEOs to their most likely main-belt source locations, we seek to gain insight into the original solar system formation locations for different meteorite classes. To forge the first link between meteorites and NEOs, we have developed a three dimensional method for quantitative comparisons between laboratory measurements of meteorites and telescopic measurements of near-Earth objects. We utilize meteorite spectra from the Reflectance Experiment Laboratory (RELAB) database and NEO data from the SpeX instrument on the NASA Infrared Telescope Facility (IRTF). Using the Modified Gaussian Model (MGM) as a mathematical tool, we treat asteroid and meteorite spectra identically in the calculation of 1-micron and 2-micron geometric band centers and their band area ratios (BARs). Using these identical numerical parameters we quantitatively compare the spectral properties of S-, Sq-, Q- and V-type NEOs with the spectral properties of the meteorites in the H, L, LL and HED meteorite classes. For each NEO spectrum, we assign a set of probabilities for it being related to each of these meteorite classes. Our NEO- meteorite correlation probabilities are then convolved with NEO-source region probabilities to yield a final set of meteorite-source region correlations. An apparent (significant at the 2.1-sigma level) source region signature is found for the H chondrites to be preferentially delivered to the inner solar system through the 3:1 mean motion resonance. A 3:1 resonance H chondrite source region is consistent with the short cosmic ray exposure ages known for H chondrites. The spectroscopy of asteroids is subject to several sources of inherent error. The source region model used a variety of S-type spectra without

  8. Reverse Asteroids: Searching for an Effective Tool to Combat Asteroid Belt Misconceptions

    Science.gov (United States)

    Summers, F.; Eisenhamer, B.

    2014-12-01

    The public 'knows' that asteroid belts are densely packed and dangerous for spaceships to cross. Visuals from "Star Wars" to, unfortunately, the recent "Cosmos" TV series have firmly established this astronomical misconception. However, even scientifically correct graphics, such as the Minor Planet Center's plot of the inner solar system, reinforces that view. Each pixel in the image is more than a million kilometers in width, making an accurate representation of the object density impossible.To address this widespread misconception, we are investigating an educational exercise built around a computer interactive that we call "Reverse Asteroids". In the arcade classic video game, the asteroids came to the player's spaceship. For our reverse implementation, we consider an inquiry-based activity in which the spaceship must go hunting for the asteroids, using a database of real objects in our solar system. Both 3D data visualization and basic statistical analysis play crucial roles in bringing out the true space density within the asteroid belt, and perhaps a reconciliation between imagination and reality. We also emphasize that a partnership of scientists and educators is fundamental to the success of such projects.

  9. Investigation of Shapes and Spins of Reaccumulated Remnants from Asteroid Disruption Simulations

    Science.gov (United States)

    Michel, Patrick; Ballouz, R.; Richardson, D. C.; Schwartz, S. R.

    2012-10-01

    Evidence that asteroids larger than a few hundred meters diameter can be gravitational aggregates of smaller, cohesive pieces comes, for instance, from images returned by the Hayabusa spacecraft of asteroid 25143 Itokawa (Fujiwara et al., 2006, Science 312, 1330). These images show an irregular 500-meter-long body with a boulder-strewn surface, as might be expected from reaccumulation following catastrophic disruption of a larger parent asteroid (Michel et al., 2001, Science 294, 1696). However, numerical simulations of this process to date essentially focus on the size/mass and velocity distributions of reaccumulated fragments, matching asteroid families. Reaccumulation was simplified by merging the objects into growing spheres. However, understanding shapes, spins and surface properties of gravitational aggregates formed by reaccumulation is required to interpret information from ground-based observations and space missions. E.g., do boulders on Itokawa originate from reaccumulation of material ejected from a catastrophic impact or from other processes (such as the Brazil-nut effect)? How does reaccumulation affect the observed shapes? A model was developed (Richardson et al., 2009, Planet. Space Sci. 57, 183) to preserve shape and spin information of reaccumulated bodies in simulations of asteroid disruption, by allowing fragments to stick on contact (and optionally bounce or fragment further, depending on user-selectable parameters). Such treatments are computationally expensive, and we could only recently start to explore the parameter space. Preliminary results will be presented, showing that some observed surface and shape features may be explained by how fragments produced by a disruption reaccumulate. Simulations of rubble pile collisions without particle cohesion, and an investigation of the influence of initial target rotation on the outcome will also be shown. We acknowledge the National Science Foundation (AST1009579) and NASA (NNX08AM39G).

  10. Sustainable LED Fluorescent Light Replacement Technology

    Energy Technology Data Exchange (ETDEWEB)

    None

    2011-06-30

    Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: • Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life. • Environmental Impact Review – Designs are

  11. Asteroid occultations today and tomorrow: toward the GAIA era

    CERN Document Server

    Tanga, P

    2008-01-01

    Context: Observation of star occultations is a powerful tool to determine shapes and sizes of asteroids. This is key information necessary for studying the evolution of the asteroid belt and to calibrate indirect methods of size determination, such as the models used to analyze thermal infrared observations. Up to now, the observation of asteroid occultations is an activity essentially secured by amateur astronomers equipped with small, portable equipments. However, the accuracy of the available ephemeris prevents accurate predictions of the occultation events for objects smaller than ~100 km. Aims: We investigate current limits in predictability and observability of asteroid occultations, and we study their possible evolution in the future, when high accuracy asteroid orbits and star positions (such as those expected from the mission Gaia of the European Space Agency) will be available. Methods: We use a simple model for asteroid ephemeris uncertainties and numerical algorithms for estimating the limits impo...

  12. MICROLENS SURVEYS ARE A POWERFUL PROBE OF ASTEROIDS

    International Nuclear Information System (INIS)

    While of order of a million asteroids have been discovered, the number in rigorously controlled samples that have precise orbits and rotation periods, as well as well-measured colors, is relatively small. In particular, less than a dozen main-belt asteroids with estimated diameters D < 3 km have excellent rotation periods. We show how existing and soon-to-be-acquired microlensing data can yield a large asteroid sample with precise orbits and rotation periods, which will include roughly 6% of all asteroids with maximum brightness I < 18.1 and lying within 10° of the ecliptic. This sample will be dominated by small and very small asteroids, down to D ∼ 1 km. We also show how asteroid astrometry could turn current narrow-angle OGLE proper motions of bulge stars into wide-angle proper motions. This would enable one to measure the proper-motion gradient across the Galactic bar.

  13. Asteroid Deflection Using a Spacecraft in Restricted Keplerian Motion

    CERN Document Server

    Ketema, Yohannes

    2016-01-01

    A method for asteroid deflection that makes use of a spacecraft moving back and forth on a segment of an appropriate Keplerian orbit about the asteroid is described and evaluated. It is shown that, on average, the spacecraft describing such a trajectory can exert a significantly larger force on the asteroid than e.g. a stationary gravity tractor, thereby reducing the time needed to effect a desired velocity change for the asteroid. Furthermore, the current method does not require canted thrusters on the spacecraft (unlike a stationary gravity tractor), markedly reducing the amount of fuel needed to create a given change in the asteroid velocity. In addition, the method allows for the simultaneous use of several spacecraft, further strengthening the overall tugging effect on the asteroid, and distributing the thrust requirement among the spacecraft.

  14. Chang'e-2 spacecraft observations of asteroid 4179 Toutatis

    CERN Document Server

    Ji, Jianghui; Zhao, Yuhui; Wang, Su; Yu, Liangliang

    2015-01-01

    On 13 December 2012, Chang'e-2 completed a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 meters from the asteroid's surface. The observations show that Toutatis has an irregular surface and its shape resembles a ginger-root of a smaller lobe (head) and a larger lobe (body). Such bilobate shape is indicative of a contact binary origin for Toutatis. In addition, the high-resolution images better than 3 meters provide a number of new discoveries about this asteroid, such as an 800-meter depression at the end of the large lobe, a sharply perpendicular silhouette near the neck region, boulders, indicating that Toutatis is probably a rubble-pile asteroid. Chang'e-2 observations have significantly revealed new insights into the geological features and the formation and evolution of this asteroid. In final, we brief the future Chinese asteroid mission concept.

  15. Chang'e-2 spacecraft observations of asteroid 4179 Toutatis

    Science.gov (United States)

    Ji, Jianghui; Jiang, Yun; Zhao, Yuhui; Wang, Su; Yu, Liangliang

    2016-01-01

    On 13 December 2012, Chang'e-2 completed a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 meters from the asteroid's surface. The observations show that Toutatis has an irregular surface and its shape resembles a ginger-root of a smaller lobe (head) and a larger lobe (body). Such bilobate shape is indicative of a contact binary origin for Toutatis. In addition, the high-resolution images better than 3 meters provide a number of new discoveries about this asteroid, such as an 800-meter depression at the end of the large lobe, a sharply perpendicular silhouette near the neck region, boulders, indicating that Toutatis is probably a rubble-pile asteroid. Chang'e-2 observations have significantly revealed new insights into the geological features and the formation and evolution of this asteroid. In final, we brief the future Chinese asteroid mission concept.

  16. Asteroid 4 Vesta: dynamical and collisional evolution during the Late Heavy Bombardment

    CERN Document Server

    Pirani, S

    2016-01-01

    Vesta is the only currently identified asteroid for which we possess samples, which revealed us that the asteroid is differentiated and possesses a relatively thin basaltic crust that survived to the evolution of the asteroid belt and the Solar System. However, little is know about the effects of past events like the Late Heavy Bombardment on this crust. We address this gap in our knowledge by simulating the LHB in the different dynamical scenarios proposed for the migration of the giant planets in the broad framework of the Nice Model. The results of simulations generate information about produced crater population, surface saturation, mass loss and mass gain of Vesta and number of energetic or catastrophic impacts during LHB. Our results reveal that planet-planet scattering is a dynamically favourable migration mechanism for the survival of Vesta and its crust. The number of impacts on Vesta estimated as due to the LHB is $31\\pm5$, i.e. about 5 times larger than the number of impacts that would have occurre...

  17. Ancient asteroids enriched in refractory inclusions.

    Science.gov (United States)

    Sunshine, J M; Connolly, H C; McCoy, T J; Bus, S J; La Croix, L M

    2008-04-25

    Calcium- and aluminum-rich inclusions (CAIs) occur in all classes of chondritic meteorites and contain refractory minerals predicted to be the first condensates from the solar nebula. Near-infrared spectra of CAIs have strong 2-micrometer absorptions, attributed to iron oxide-bearing aluminous spinel. Similar absorptions are present in the telescopic spectra of several asteroids; modeling indicates that these contain approximately 30 +/- 10% CAIs (two to three times that of any meteorite). Survival of these undifferentiated, large (50- to 100-kilometer diameter) CAI-rich bodies suggests that they may have formed before the injection of radiogenic 26Al into the solar system. They have also experienced only modest post-accretionary alteration. Thus, these asteroids have higher concentrations of CAI material, appear less altered, and are more ancient than any known sample in our meteorite collection, making them prime candidates for sample return. PMID:18356491

  18. Speckle interferometry of asteroids. I - 433 Eros

    Science.gov (United States)

    Drummond, J. D.; Cocke, W. J.; Hege, E. K.; Strittmatter, P. A.; Lambert, J. V.

    1985-01-01

    Analytical expressions are derived for the semimajor and semiminor axes and orientation angle of the ellipse projected by a triaxial asteroid, and the results are applied speckle-interferometry observations of the 433 Eros asteroid. The expressions were calculated as functions of the dimensions and pole of the body and of the asterocentric position of the earth and the sun. On the basis of the analytical expressions, the dimensions of 433 Eros are obtained. The light curve from December 18, 1981 is compared to the dimensions to obtain a geometric albedo of 0.156 (+ or - 0.010). A series of two-dimensional power spectra and autocorrelation functions for 433 Eros show that it is spinning in space.

  19. EVIDENCE OF AN ASTEROID ENCOUNTERING A PULSAR

    Energy Technology Data Exchange (ETDEWEB)

    Brook, P. R.; Karastergiou, A. [Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Buchner, S. [Hartebeesthoek Radio Astronomy Observatory, P.O. Box 443, Krugersdorp 1740 (South Africa); Roberts, S. J. [Information Engineering, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom); Keith, M. J.; Johnston, S.; Shannon, R. M., E-mail: paul.brook@astro.ox.ac.uk [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia)

    2014-01-10

    Debris disks and asteroid belts are expected to form around young pulsars due to fallback material from their original supernova explosions. Disk material may migrate inward and interact with a pulsar's magnetosphere, causing changes in torque and emission. Long-term monitoring of PSR J0738–4042 reveals both effects. The pulse shape changes multiple times between 1988 and 2012. The torque, inferred via the derivative of the rotational period, changes abruptly from 2005 September. This change is accompanied by an emergent radio component that drifts with respect to the rest of the pulse. No known intrinsic pulsar processes can explain these timing and radio emission signatures. The data lead us to postulate that we are witnessing an encounter with an asteroid or in-falling debris from a disk.

  20. The Physical Characterization of the Potentially Hazardous Asteroid 2004 BL86: A Fragment of a Differentiated Asteroid

    Science.gov (United States)

    Reddy, Vishnu; Gary, Bruce L.; Sanchez, Juan A.; Takir, Driss; Thomas, Cristina A.; Hardersen, Paul S.; Ogmen, Yenal; Benni, Paul; Kaye, Thomas G.; Gregorio, Joao; Garlitz, Joe; Polishook, David; Le Corre, Lucille; Nathues, Andreas

    2015-09-01

    The physical characterization of potentially hazardous asteroids (PHAs) is important for impact hazard assessment and evaluating mitigation options. Close flybys of PHAs provide an opportunity to study their surface photometric and spectral properties that enable the identification of their source regions in the main asteroid belt. We observed PHA (357439) 2004 BL86 during a close flyby of the Earth at a distance of 1.2 million km (0.0080 AU) on 2015 January 26, with an array of ground-based telescopes to constrain its photometric and spectral properties. Lightcurve observations showed that the asteroid was a binary and subsequent radar observations confirmed the binary nature and gave a primary diameter of 300 m and a secondary diameter of 50-100 m. Our photometric observations were used to derive the phase curve of 2004 BL86 in the V-band. Two different photometric functions were fitted to this phase curve, the IAU H-G model and the Shevchenko model. From the fit of the H-G function we obtained an absolute magnitude of H = 19.51 ± 0.02 and a slope parameter of G = 0.34 ± 0.02. The Shevchenko function yielded an absolute magnitude of H = 19.03 ± 0.07 and a phase coefficient b = 0.0225 ± 0.0006. The phase coefficient was used to calculate the geometric albedo (Ag) using the relationship found by Belskaya & Schevchenko, obtaining a value of Ag = 40% ± 8% in the V-band. With the geometric albedo and the absolute magnitudes derived from the H-G and the Shevchenko functions we calculated the diameter (D) of 2004 BL86, obtaining D = 263 ± 26 and D = 328 ± 35 m, respectively. 2004 BL86 spectral band parameters and pyroxene chemistry are consistent with non-cumulate eucrite meteorites. A majority of these meteorites are derived from Vesta and are analogous with surface lava flows on a differentiated parent body. A non-diagnostic spectral curve match using the Modeling for Asteroids tool yielded a best-match with non-cumulate eucrite Bereba. Three other near

  1. Lichtauskopplung aus LEDs mittels Metallnanoteilchen

    OpenAIRE

    Göhler, Tino

    2011-01-01

    Der externe Wirkungsquerschnitt von auf AlGaAs/InGaAlP basierenden Leuchtdioden (LEDs) ist auf Grund von Totalreflexion infolge des hohen Brechungsindex des Halbleitermaterials (n=3...4) beschränkt. Auf die Oberfläche der LED aufgebrachte metallische Nanoteilchen (MNT) können jedoch als Dipolstreuer genutzt werden, um so die Emission der LED zu vergrößern. In dieser Arbeit wurden zunächst einzelne Goldnanoteilchen verschiedener Größe auf einer solchen Leuchtdiode in zwei verschiedenen Der ext...

  2. Phosphors and PDP, LED Technology

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Phosphors for PDP has good prospect for the largepotential of PDP industry. LED technology brings new marketto be developed. Developing phosphors for white LED withhigh efficiency and low light attenuation is an urgent work todo. Application of phosphors in color LED is in initial stage.1. Good Prospect of Phosphors for PDPColor PDP is widely used today. Three-prime-colorphosphor excited by VUV is the key material for color PDP.This makes research on three-prime-color phosphor for colorPDP important. Follow...

  3. Pientalojen energiatehokas led-valaistus

    OpenAIRE

    Viertokangas, Jarmo

    2016-01-01

    Tässä insinöörityössä on tehty tutkimus siitä, miten perinteisen valaistuksen muuttaminen led-valaistukseksi vaikuttaa pientaloenergian kulutukseen. Lisäksi on esimerkkikohteen valaistus- ja sähkösuunnitelma, jossa valaistus on toteutettu energiatehokkaalla led-valaistuksella. Tämä työ on tehty Veikkolan Sähköpalvelu Ky:lle selvitykseksi ja oppaaksi energiatehokkaasta valaistuksesta. Työssä käydään läpi yleisesti erilaisia led-valaistuksen eri vaihtoehtoja pientaloihin sekä mitä mahdollis...

  4. Yleisvalaistuksen muutos LED-valaistukseen

    OpenAIRE

    Heikkinen, Harri

    2015-01-01

    Päättötyön tavoite oli vertailla Mikalo Oy.n asuntokohteiden yleisvalaistuksen nykytilaa mahdolliseen LED-valaistuksella toteutettuun tilaan. Mikalo Oy.n 120.n kohteen yleisvalaistus on merkittävä sähkön kuluttaja, joten selvitys nykyisten valonlähteiden, kuten elohopealamppujen, vaihto voi säästää pitkäai-kaiskäytössä. Uusilla LED-valonlähteillä kulutus saadaan pienennettyä merkittävästi, mutta uusien, tehokkaiden LED-valaisimen hinnat ovat vielä suhteellisen korkealla, ja tämä oli huomi...

  5. Pole orientation, sidereal period, and sense of rotation of asteroids

    Science.gov (United States)

    Taylor, R. C.; Gehrels, T.

    1986-01-01

    Pole orientations of asteroids were determined. The method, called photometric astrometry, takes precise epochs of lightcurves into account. Pole determination research on asteroids 532 Herculina, 45 Eugenia, and 3 Juno continues. Discrepancies between various pole determination techniques presently being used are analyzed. The study of asteroid shapes and creating a generalized master pole determination technique also continues which will incorporate the best features of several current methods.

  6. NEA 2015 VY105: A New Tumbling Asteroid

    Science.gov (United States)

    Carbognani, Albino; Buzzi, Luca

    2016-04-01

    We present the results of photometric observations on near-Earth asteroid (NEA) 2015 VY105. Lightcurve analysis shows that it is a tumbling asteroid with synodic rotation periods P1 = 0.0386 ± 0.0001 h with amplitude A1 = 0.96 mag and P2 = 0.061 ± 0.001 h with amplitude A2 = 0.57 mag. After 2008 TC3, this NEA is the fastest and smallest tumbling asteroid.

  7. Orbital perturbation analysis of earth-crossing asteroids

    OpenAIRE

    Knudson, Wade E.

    1995-01-01

    Earth Crossing Asteroids (ECAs) are those asteroids whose orbit cross section can intersect the capture cross section of the Earth as a result of secular gravitational perturbations. This thesis provides a framework for understanding the origin, nature, and types of ECAs. The change in velocity requirements to achieve a two Earth radii deflection for long and short term warning scenarios are developed. Next, a method of developing hypothetical Earth colliding asteroid orbits is presented. The...

  8. International collaboration leads to new Aten asteroid discovery, 1984 QA

    Science.gov (United States)

    Helin, E. F.; Dunbar, R. S.; Barucci, M. A.

    1986-01-01

    A new earth-crossing asteroid of the Aten type (orbit smaller than earth's) was discovered on August 30, 1984 at Palomar. The asteroid, designated 1984 QA, is the fourth known member of the Aten type and the first discovered since 1978. The discovery of this object was the highlight of a collaboration between the JPL Asteroid Search Team and an ESA scientist, and demonstrates one aspect of an ongoing joint search effort with other Schmidt observers.

  9. Example Solar Electric Propulsion System asteroid tours using variational calculus

    Science.gov (United States)

    Burrows, R. R.

    1985-01-01

    Exploration of the asteroid belt with a vehicle utilizing a Solar Electric Propulsion System has been proposed in past studies. Some of those studies illustrated multiple asteroid rendezvous with trajectories obtained using approximate methods. Most of the inadequacies of those approximations are overcome in this paper, which uses the calculus of variations to calculate the trajectories and associated payloads of four asteroid tours. The modeling, equations, and solution techniques are discussed, followed by a presentation of the results.

  10. NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos

    CERN Document Server

    Nugent, C R; Masiero, J; Bauer, J; Cutri, R M; Grav, T; Kramer, E; Sonnett, S; Stevenson, R; Wright, E L

    2015-01-01

    We present preliminary diameters and albedos for 7,959 asteroids detected in the first year of the NEOWISE Reactivation mission. 201 are near-Earth asteroids (NEAs). 7,758 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using WISE or NEOWISE thermal measurements. Diameters are determined to an accuracy of ~20% or better. If good-quality H magnitudes are available, albedos can be determined to within ~40% or better.

  11. Design of MGA trajectories for main belt asteroid

    Institute of Scientific and Technical Information of China (English)

    崔祜涛; 乔栋; 崔平远; 栾恩杰

    2003-01-01

    Asteroid exploration is one of the most sophisticated missions currently being investigated. Gravityassist trajectories have proven valuable in interplanetary missions such as the Pioneer, Voyager and Galileo. In this paper, we design interplanetary trajectory for main belt asteroid exploration mission with the Mars gravityassist (MGA) using "pork chop" plots and patched-conic theory and give some initial valuable trajectory parameters on main belt asteroid exploration mission with MGA.

  12. Alien Asteroid Belt Compared to our Own

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Figure 1: Band of Light Comparison This artist's concept illustrates what the night sky might look like from a hypothetical alien planet in a star system with an asteroid belt 25 times as massive as the one in our own solar system (alien system above, ours below; see Figure 1). NASA's Spitzer Space Telescope found evidence for such a belt around the nearby star called HD 69830, when its infrared eyes spotted dust, presumably from asteroids banging together. The telescope did not find any evidence for a planet in the system, but astronomers speculate one or more may be present. The movie begins at dusk on the imaginary world, when HD 69830, like our Sun, has begun to set over the horizon. Time is sped up to show the onset of night and the appearance of a brilliant band of light. This light comes from dust in a massive asteroid belt, which scatters sunlight. In our solar system, anybody observing the skies on a moonless night far from city lights can see the sunlight that is scattered by dust in our asteroid belt. Called zodiacal light and sometimes the 'false dawn,' this light appears as a dim band stretching up from the horizon when the Sun is about to rise or set. The light is faint enough that the disk of our Milky Way galaxy remains the most prominent feature in the sky. (The Milky Way disk is shown perpendicular to the zodiacal light in both pictures.) In contrast, the zodiacal light in the HD 69830 system would be 1,000 times brighter than our own, outshining even the Milky Way.

  13. The Cratering History of Asteroid (2867) Steins

    CERN Document Server

    Marchi, S; Kueppers, M; Marzari, F; Davidsson, B; Keller, H U; Besse, S; Lamy, P; Mottola, S; Massironi, M; Cremonese, G

    2010-01-01

    The cratering history of main belt asteroid (2867) Steins has been investigated using OSIRIS imagery acquired during the Rosetta flyby that took place on the 5th of September 2008. For this purpose, we applied current models describing the formation and evolution of main belt asteroids, that provide the rate and velocity distributions of impactors. These models coupled with appropriate crater scaling laws, allow the cratering history to be estimated. Hence, we derive Steins' cratering retention age, namely the time lapsed since its formation or global surface reset. We also investigate the influence of various factors -like bulk structure and crater erasing- on the estimated age, which spans from a few hundred Myrs to more than 1Gyr, depending on the adopted scaling law and asteroid physical parameters. Moreover, a marked lack of craters smaller than about 0.6km has been found and interpreted as a result of a peculiar evolution of Steins cratering record, possibly related either to the formation of the 2.1km ...

  14. Near Earth Asteroids with measurable Yarkovsky effect

    CERN Document Server

    Farnocchia, D; Vokrouhlicky, D; Milani, A; Spoto, F

    2012-01-01

    We seek evidence of the Yarkovsky effect among Near Earth Asteroids (NEAs) by measuring the Yarkovsky-related orbital drift from the orbital fit. To prevent the occurrence of unreliable detections we employ 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 find 21 NEAs whose orbital fits show a measurable orbital drift with a signal to noise ratio (SNR) greater than 3. The best determination is for asteroid (101955) 1999 RQ36, resulting in the recovery of one radar apparition and an orbit improvement by two orders of magnitude. In addition, we find 16 cases with a lower SNR that, despite being less reliable, are good candidates for becoming stronger detections in the future. In some cases it is possible to constrain physical quantities otherwise unknown by means of the detected orbital drift. Furthermore, the distribution of the detected orbital drifts shows an excess of retrograde ro...

  15. UBV photometry of asteroid 433 Eros

    Science.gov (United States)

    Millis, R. L.; Bowell, E.; Thompson, D. T.

    1976-01-01

    UBV observations of asteroid 433 Eros were conducted on 17 nights during the winter of 1974/75. The peak-to-peak amplitude of the lightcurve varied from about 0.3 mag to nearly 1.4 mag. The absolute V mag at maximum light, extrapolated to zero phase, is 10.85. Phase coefficients of 0.0233 mag/degree, 0.0009 mag/degree, and 0.0004 mag/degree were derived for V, B-V and U-B, respectively. The zero-phase color of Eros (B-V = 0.88, U-B = 0.50) is representative of an S (silicaceous) compositional type asteroid. The color does not vary with rotation. The photometric behavior of Eros can be modeled by a cylinder with rounded ends having an axial ratio of about 2.3:1. The asteroid is rotating about a short axis with the north pole at 15 deg ecliptic longitude and 9 deg ecliptic latitude.

  16. DISINTEGRATING ASTEROID P/2013 R3

    Energy Technology Data Exchange (ETDEWEB)

    Jewitt, David; 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); Weaver, Harold [The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, 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 Boulevard, Tucson, AZ 85721-0092 (United States)

    2014-03-20

    Splitting of the nuclei of comets into multiple components has been frequently observed but, to date, no main-belt asteroid has been observed to break up. Using the Hubble Space Telescope, we find that main-belt asteroid P/2013 R3 consists of 10 or more distinct components, the largest up to 200 m in radius (assumed geometric albedo of 0.05) each of which produces a coma and comet-like dust tail. A diffuse debris cloud with total mass ∼2 × 10{sup 8} kg further envelopes the entire system. The velocity dispersion among the components, ΔV ∼ 0.2-0.5 m s{sup –1}, is comparable to the gravitational escape speeds of the largest members, while their extrapolated plane-of-sky motions suggest a break up between 2013 February and September. The broadband optical colors are those of a C-type asteroid. We find no spectral evidence for gaseous emission, placing model-dependent upper limits to the water production rate ≤1 kg s{sup –1}. Breakup may be due to a rotationally induced structural failure of the precursor body.

  17. How Many Ore-Bearing Asteroids?

    CERN Document Server

    Elvis, Martin

    2013-01-01

    A simple formalism is presented to assess how many asteroids contain ore, i.e. commercially profitable material, and not merely a high concentration of a resource. I apply this formalism to two resource cases: platinum group metals (PGMs) and water. Assuming for now that only Ni-Fe asteroids are of interest for PGMs, then 1% of NEOs are rich in PGMs. The dearth of ultra-low delta-v (= US$1 B and the population of near-Earth objects (NEOs) larger than 100 m diameter is ~20,000 (Mainzer et al. 2011) the total population of PGM ore-bearing NEOs is roughly 10. I stress that this is a conservative and highly uncertain value. For example, an order of magnitude increase in PGM ore-bearing NEOs occurs if delta-v can as large as 5.7 km s-1. Water ore for utilization in space is likely to be found in ~1/1100 NEOs. NEOs as small as 18 m diameter can be water-ore-bodies because of the high richness of water (~20%) expected in ~25% of carbonaceous asteroids, bringing the number of water-ore-bearing NEOs to ~9000 out of th...

  18. Formation and Evolution of Binary Asteroids

    CERN Document Server

    Walsh, Kevin J

    2015-01-01

    Satellites of asteroids have been discovered in nearly every known small body population, and a remarkable aspect of the known satellites is the diversity of their properties. They tell a story of vast differences in formation and evolution mechanisms that act as a function of size, distance from the Sun, and the properties of their nebular environment at the beginning of Solar System history and their dynamical environment over the next 4.5 Gyr. The mere existence of these systems provides a laboratory to study numerous types of physical processes acting on asteroids and their dynamics provide a valuable probe of their physical properties otherwise possible only with spacecraft. Advances in understanding the formation and evolution of binary systems have been assisted by: 1) the growing catalog of known systems, increasing from 33 to nearly 250 between the Merline et al. (2002) Asteroids III chapter and now, 2) the detailed study and long-term monitoring of individual systems such as 1999 KW4 and 1996 FG3, 3...

  19. Polarization of asteroid (387) Aquitania: the newest member of a class of large inversion angle asteroids

    CERN Document Server

    Masiero, Joseph

    2008-01-01

    We present new imaging polarimetric observations of two Main Belt asteroids, (234) Barbara and (387) Aquitania, taken in the first half of 2008 using the Dual-Beam Imaging Polarimeter on the University of Hawaii 2.2 meter telescope, located on Mauna Kea, Hawaii. Barbara had been previously shown to exhibit a very unusual polarization-phase curve by Cellino, et al. (2006). Our observations confirm this result and add Aquitania to the growing class of large inversion angle objects. Interestingly, these asteroids show spinel features in their IR spectra suggesting a mineralogical origin to the phase angle-dependent polarimetric features. As spinel is associated with calcium-aluminum-rich inclusions and carbonaceous chondrites, these large inversion angle asteroids may represent some of the oldest surfaces in the solar system. Circular as well as linear polarization measurements were obtained but circular polarization was not detected.

  20. The Nature of C Asteroid Regolith from Meteorite Observations

    Science.gov (United States)

    Zolensky, M.; Mikouchi, T.; Hagiya, K.; Ohsumi, K.; Komatsu, M.; Jenniskens, P.; Le, L.; Yin, Q.-Z; Kebukawa, Y.; Fries, M.

    2013-01-01

    Regolith from C (and related) asteroid bodies are a focus of the current missions Dawn at Ceres, Hayabusa 2 and OSIRIS REx. An asteroid as large as Ceres is expected to be covered by a mature regolith, and as Hayabusa demonstrated, flat and therefore engineeringly-safe ponded deposits will probably be the sampling sites for both Hayabusa 2 and OSIRIS REx. Here we examine what we have learned about the mineralogy of fine-grained asteroid regolith from recent meteorite studies and the examination of the samples harvested from asteroid Itokawa by Hayabusa.

  1. A fast ellipsoid model for asteroids inverted from lightcurves

    Institute of Scientific and Technical Information of China (English)

    Xiao-Ping Lu; Hai-Bin Zhao; Zhong You

    2013-01-01

    Research about asteroids has recently attracted more and more attention,especially focusing on their physical structures,such as their spin axis,rotation period and shape.The long distance between observers on Earth and asteroids makes it impossible to directly calculate the shape and other parameters of asteroids,with the exception of Near Earth Asteroids and others that have passed by some spacecrafts.Photometric measurements are still generally the main way to obtain research data on asteroids,i.e.the lightcurves recording the brightness and positions of asteroids.Supposing that the shape of the asteroid is a triaxial ellipsoid with a stable spin,a new method is presented in this article to reconstruct the shape models of asteroids from the lightcurves,together with other physical parameters.By applying a special curvature function,the method calculates the brightness integration on a unit sphere and Lebedev quadrature is employed for the discretization.Finally,the method searches for the optimal solution by the Levenberg-Marquardt algorithm to minimize the residual of the brightness.By adopting this method,not only can related physical parameters of asteroids be obtained at a reasonable accuracy,but also a simple shape model of an ellipsoid can be generated for reconstructing a more sophisticated shape model.

  2. A fast ellipsoid model for asteroids inverted from lightcurves

    International Nuclear Information System (INIS)

    Research about asteroids has recently attracted more and more attention, especially focusing on their physical structures, such as their spin axis, rotation period and shape. The long distance between observers on Earth and asteroids makes it impossible to directly calculate the shape and other parameters of asteroids, with the exception of Near Earth Asteroids and others that have passed by some spacecrafts. Photometric measurements are still generally the main way to obtain research data on asteroids, i.e. the lightcurves recording the brightness and positions of asteroids. Supposing that the shape of the asteroid is a triaxial ellipsoid with a stable spin, a new method is presented in this article to reconstruct the shape models of asteroids from the lightcurves, together with other physical parameters. By applying a special curvature function, the method calculates the brightness integration on a unit sphere and Lebedev quadrature is employed for the discretization. Finally, the method searches for the optimal solution by the Levenberg-Marquardt algorithm to minimize the residual of the brightness. By adopting this method, not only can related physical parameters of asteroids be obtained at a reasonable accuracy, but also a simple shape model of an ellipsoid can be generated for reconstructing a more sophisticated shape model.

  3. Detecting Extrasolar Asteroid Belts Through Their Microlensing Signatures

    CERN Document Server

    Lake, Ethan; Dong, Subo

    2016-01-01

    We propose that extrasolar asteroid belts can be detected through their gravitational microlensing signatures. Asteroid belt + star lens systems create so-called "pseudo-caustics", regions in the source plane where the magnification exhibits a finite but discontinuous jump. These features allow such systems to generate distinctive microlensing light curves across a wide region of belt parameter space and possess remarkably large lensing cross-sections. Sample light curves for a range of asteroid belt parameters are presented. In the near future, space-based microlensing surveys (e.g., WFIRST) may be able to discover extrasolar asteroid belts with masses of the order of $0.1 M_{\\oplus}$.

  4. Capturing asteroids into bound orbits around the earth: Massive early return on an asteroid terminal defense system

    International Nuclear Information System (INIS)

    Nuclear explosives may be used to capture small asteroids (e.g., 20--50 meters in diameter) into bound orbits around the earth. The captured objects could be used for construction material for manned and unmanned activity in Earth orbit. Asteroids with small approach velocities, which are the ones most likely to have close approaches to the Earth, require the least energy for capture. They are particularly easy to capture if they pass within one Earth radius of the surface of the Earth. They could be intercepted with intercontinental missiles if the latter were retrofit with a more flexible guiding and homing capability. This asteroid capture-defense system could be implemented in a few years at low cost by using decommissioned ICMs. The economic value of even one captured asteroid is many times the initial investment. The asteroid capture system would be an essential part of the learning curve for dealing with larger asteroids that can hit the earth

  5. The OSIRIS-REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations

    Science.gov (United States)

    Lauretta, D. S.; Bartels, A. E.; Barucci, M. A.; Bierhaus, E. B.; Binzel, R. P.; Bottke, W. F.; Campins, H.; Chesley, S. R.; Clark, B. C.; Clark, B. E.; Cloutis, E. A.; Connolly, H. C.; Crombie, M. K.; Delbó, M.; Dworkin, J. P.; Emery, J. P.; Glavin, D. P.; Hamilton, V. E.; Hergenrother, C. W.; Johnson, C. L.; Keller, L. P.; Michel, P.; Nolan, M. C.; Sandford, S. A.; Scheeres, D. J.; Simon, A. A.; Sutter, B. M.; Vokrouhlický, D.; Walsh, K. J.

    2015-04-01

    We review the results of an extensive campaign to determine the physical, geological, and dynamical properties of asteroid (101955) Bennu. This investigation provides information on the orbit, shape, mass, rotation state, radar response, photometric, spectroscopic, thermal, regolith, and environmental properties of Bennu. We combine these data with cosmochemical and dynamical models to develop a hypothetical timeline for Bennu's formation and evolution. We infer that Bennu is an ancient object that has witnessed over 4.5 Gyr of solar system history. Its chemistry and mineralogy were established within the first 10 Myr of the solar system. It likely originated as a discrete asteroid in the inner Main Belt approximately 0.7-2 Gyr ago as a fragment from the catastrophic disruption of a large (approximately 100-km), carbonaceous asteroid. It was delivered to near-Earth space via a combination of Yarkovsky-induced drift and interaction with giant-planet resonances. During its journey, YORP processes and planetary close encounters modified Bennu's spin state, potentially reshaping and resurfacing the asteroid. We also review work on Bennu's future dynamical evolution and constrain its ultimate fate. It is one of the most Potentially Hazardous Asteroids with an approximately 1-in-2700 chance of impacting the Earth in the late 22nd century. It will most likely end its dynamical life by falling into the Sun. The highest probability for a planetary impact is with Venus, followed by the Earth. There is a chance that Bennu will be ejected from the inner solar system after a close encounter with Jupiter. OSIRIS-REx will return samples from the surface of this intriguing asteroid in September 2023.

  6. Light pipes for LED measurements

    Science.gov (United States)

    Floyd, S. R.; Thomas, E. F., Jr.

    1976-01-01

    Light pipe directly couples LED optical output to single detector. Small area detector measures total optical output of diode. Technique eliminates thermal measurement problems and channels optical output to remote detector.

  7. Research on LED Fishing Light

    OpenAIRE

    Li Tian Hua; Jing Xing

    2013-01-01

    In this study , the semiconductor lighting technology with advantages of energy saving, environmental protection and high rapid response speed is regarded as the fishing light source, which can achieve targets of energy conservation, emission reduction, environmental protection, scientific fishing, etc. Then, the characteristics of LED are described to conduct a comparative analysis with the metal halide light source which has been commonly used in fishing light. The results show that LED is ...

  8. Farbmessung an LED-Systemen

    OpenAIRE

    Herrmann, Franziska

    2013-01-01

    Die Information über die farbliche Abstrahlcharakteristik von LED-Systemen wird immer wichtiger. Durch die zu Glühlampen und Leuchtstofflampen unterschiedliche Erzeugung von weißem Licht kann es bei LED-Systemen zu sichtbaren Farbunterschieden in der Abstrahlcharakteristik kommen. Im Rahmen dieser Arbeit wurde eine Methode zur Darstellung und Beschreibung dieser Farbunterschiede entwickelt, basierend auf gängigen Farbmessmethoden.

  9. Valuing Community-Led Design

    OpenAIRE

    Alexiou, Katerina; Zamenopoulos, Theodore; Alevizou, Giota

    2013-01-01

    The ideas and practice of community-led design, participatory design or co-design have a long-standing tradition, especially in the context of urban design, planning and architecture. Community-led design goes beyond the one-dimensional process of consultation, helping involve people in decision-making throughout the design process, from visioning to implementation. There are many benefits from this approach, from improving civic participation and ensuring more democratic outcomes, to creatin...

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

    Science.gov (United States)

    Vellekoop, Johan; Sluijs, Appy; Smit, Jan; Schouten, Stefan; Weijers, Johan W. H.; Sinninghe Damsté, Jaap S.; Brinkhuis, Henk

    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 Chicxulub, present-day Mexico. Although the precise mechanisms that led to this mass extinction remain enigmatic, most postulated scenarios involve a short-lived global cooling, a so-called “impact winter” phase. Here we document a major decline in sea surface temperature during the first months to decades following the impact event, using TEX86 paleothermometry of sediments from the Brazos River section, Texas. We interpret this cold spell to reflect, to our knowledge, the first direct evidence for the effects of the formation of dust and aerosols by the impact and their injection in the stratosphere, blocking incoming solar radiation. This impact winter was likely a major driver of mass extinction because of the resulting global decimation of marine and continental photosynthesis. PMID:24821785

  11. Photometry of asteroids: Lightcurves of 24 asteroids obtained in 1993 2005

    Science.gov (United States)

    Chiorny, V. G.; Shevchenko, V. G.; Krugly, Yu. N.; Velichko, F. P.; Gaftonyuk, N. M.

    2007-05-01

    The results of 1993-2005 photometric observations for 24 main-belt asteroids: 24 Themis, 51 Nemausa, 89 Julia, 205 Martha, 225 Henrietta, 387 Aquitania, 423 Diotima, 505 Cava, 522 Helga, 543 Charlotte, 663 Gerlinde, 670 Ottegebe, 693 Zerbinetta, 694 Ekard, 713 Luscinia, 800 Kressmania, 1251 Hedera, 1369 Ostanina, 1427 Ruvuma, 1796 Riga, 2771 Polzunov, 4908 Ward, 6587 Brassens and 16541 1991 PW18 are presented. The rotation periods of nine of these asteroids have been determined for the first time and others have been improved.

  12. Formation of the "ponds" on asteroid (433) Eros by fluidization

    Science.gov (United States)

    Sears, D. W. G.; Tornabene, L. L.; Osinski, G. R.; Hughes, S. S.; Heldmann, J. L.

    2015-11-01

    The "ponds" on asteroid (433) Eros are fine-grained deposits approximating flat (quasi-equipotential) surfaces with respect to local topographic depressions (e.g., craters) in spacecraft images. These ponds are discussed in the context of laboratory simulation experiments, crater-related ponded and pitted deposits observed on Mars and Vesta, terrestrial phreatic craters, and degassing features associated with eroded impact craters on Earth. While the details of formation of these features on Mars, Vesta and the Earth are thought to be different, they all include mechanisms that require the interactions between surface materials and volatiles (e.g., water vapor). Indeed, analogous features similar to the Eros ponds can be reproduced in the laboratory by the release of vapor (ice sublimation, water evaporation, or N2) through an unconsolidated regolith (independent of regolith composition). Eros is widely thought to be dry, but the discovery of exogenic water on Vesta, and recent arguments that subsurface water might be present in the inner asteroid belt suggest that endogenic water might also be present and serve as a source of the gases produced in the ponds. The amount of water required is comparable to the amount of water observed in little-metamorphosed ordinary chondrites (a few wt%). The primary morphologic characteristics of the Eros ponds can be explained in this model. The heat source for degassing could have been solar heating following transfer from a main belt orbit to a near Earth orbit. Although other hypotheses (e.g., electrostatic levitation, seismic shaking, and comminution of boulders) can account for most of the features of the ponds, recent observations regarding the role of volatiles on planetary surfaces, our laboratory experiments, and fluidization deposits on active comets suggests that degassing is a reasonable hypothesis to be considered and further tested for explaining the Eros ponds, and similar features on other bodies.

  13. A new terminal guidance sensor system for asteroid intercept or rendezvous missions

    Science.gov (United States)

    Lyzhoft, Joshua; Basart, John; Wie, Bong

    2016-02-01

    This paper presents the initial conceptual study results of a new terminal guidance sensor system for asteroid intercept or rendezvous missions, which explores the use of visual, infrared, and radar devices. As was demonstrated by NASA's Deep Impact mission, visual cameras can be effectively utilized for hypervelocity intercept terminal guidance for a 5 kilometer target. Other systems such as Raytheon's EKV (Exoatmospheric Kill Vehicle) employ a different scheme that utilizes infrared target information to intercept ballistic missiles. Another example that uses infrared information is the NEOWISE telescope, which is used for asteroid detection and tracking. This paper describes the signal-to-noise ratio estimation problem for infrared sensors, minimum and maximum range of detection, and computational validation using GPU accelerated simulations. Small targets (50-100 m in diameter) are considered, and scaled polyhedron models of known objects, such as the Rosetta mission's Comet 67P/Churyumov-Gerasimenko, 101,955 Bennu, target of the OSIRIS-REx mission, and asteroid 433 Eros, are utilized. A parallelized ray tracing algorithm to simulate realistic surface-to-surface shadowing of a given celestial body is developed. By using the simulated models and parameters given from the formulation of the different sensors, impact mission scenarios are used to verify the feasibility for intercepting a small target.

  14. Hazards due to Meteor and Asteroids and Infux of Cosmic Matter on the Earth

    Science.gov (United States)

    Kruchynenko, V. G.; Voloshchuk, Yu. I.; Kashcheev, B. L.; Kazantsev, A. M.; Lupishko, D. F.; Yatskiv, Ya. S.

    The problem of meteor and asteroid hazards is considered on the basis of modern studies of small bodies in the solar system. Using one of the largest meteor data banks and the results of calculations of asteroid orbits, new approaches to the search for space bodies which may be dangerous to our planet are formulated. The problem of destruction of meteoroids of various masses in the atmosphere and on the surface of the Earth is considered, and a criterion for distinguishing between impact and explosion meteorites is presented. Analysis of the data on influx of cosmic bodies on the Earth in a wide range of masses is made. The probability of collision of space vehicles with meteoroid particles is given.

  15. VLT/SPHERE- and ALMA-based shape reconstruction of asteroid (3) Juno

    Science.gov (United States)

    Viikinkoski, M.; Kaasalainen, M.; Ďurech, J.; Carry, B.; Marsset, M.; Fusco, T.; Dumas, C.; Merline, W. J.; Yang, B.; Berthier, J.; Kervella, P.; Vernazza, P.

    2015-09-01

    We use the recently released Atacama Large Millimeter Array (ALMA) and VLT/SPHERE science verification data, together with earlier adaptive-optics images, stellar occultation, and lightcurve data to model the 3D shape and spin of the large asteroid (3) Juno with the all-data asteroid modelling (ADAM) procedure. These data set limits on the plausible range of shape models, yielding reconstructions suggesting that, despite its large size, Juno has sizable unrounded features moulded by non-gravitational processes such as impacts. Based on observations collected at the European Southern Observatory, Paranal, Chile (prog. ID: 60.A-9379, 086.C-0785), and at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  16. SEM and TEM Observation of the Surfaces of the Fine-Grained Particles Retrieved from the Muses-C Regio on the Asteroid 25413 Itokawa

    Science.gov (United States)

    Noguchi, T.; Nakamura, T.; Zolensky, Michael E.; Tanaka, M.; Hashimoto, T.; Konno, M.; Nakato, A.; Ogami, T.; Fujimura, A.; Abe, M.; Yada, T.; Mukai, T.; Ueno, M.; Okada, T.; Shirai, K.; Ishibashi, Y.; Okazaki, R.

    2011-01-01

    Surface materials on airless solar system bodies exposed to interplanetary space are gradually changed their visible to near-infrared reflectance spectra by the process called "space weathering", which makes the spectra darker and redder. Hapke et al. proposed a model of space weathering: vapor deposition of nanophase reduced iron (npFe(sup 0)) on the surfaces of the grains within the very surface of lunar regolith. This model has been proved by detailed observation of the surfaces of the lunar soil grains by transmission electron microscope (TEM). They demonstrated that npFe(sup 0) was formed by a combination of vapor deposition and irradiation effects. In other words, both micrometeorite impacts and irradiation by solar wind and galactic cosmic ray play roles on the space weathering on the Moon. Because there is a continuum of reflectance spectra from those of Q-type asteroids (almost the same as those of ordinary chondrites) to those of S-type asteroids, it is strongly suggested that reflectance spectra of asteroids composed of ordinary chondrite-like materials were modified over time to those of S-type asteroids due to space weathering. It is predicted that a small amount of npFe(sup 0) on the surface of grains in the asteroidal regolith composed of ordinary chondrite-like materials is the main agent of asteroidal space weathering.

  17. Impurity Influence on Nitride LEDs

    Directory of Open Access Journals (Sweden)

    O.I. Rabinovich

    2014-07-01

    Full Text Available Light emitting diodes (LEDs are widely used nowadays. They are used in major parts of our life. But it is still necessary to improve their characteristics. In this paper the impurity and Indium atoms influence on the LEDs characteristics is investigated by computer simulation. Simulation was carried out in Sim Windows. The program was improved for this purpose by creating new files for AlGaInN heterostructure and devices including more than 25 basic parameters. It was found that characteristics depend on impurity and indium atoms changes a lot. The optimum impurity concentration for doping barriers between quantum wells was achieved. By varying impurity and Indium concentration the distribution in AlGaInN heterostructure LEDs characteristics could be improved.

  18. LED-valaisimen markkinoille saattaminen

    OpenAIRE

    Ahola, Sami

    2015-01-01

    LED-valaisimien käyttö on yleistynyt sisä- ja ulkotilojen valaistuksessa ja niiden käyttö lisääntyy tulevien vuosien aikana nopeasti. LED-tekniikkaa hyödyntäviä valaisimia ja lamppuja on jo tällä hetkellä markkinoilla suuria määriä. Tämän opinnäytetyön tavoite oli laatia yhteenveto sähkölaitteen markkinoille saattamisesta huomioiden LED-valaisimien erityispiirteet. Työssä perehdyttiin sähkölaitteen markkinoille saattamisen prosessiin direktiivien, lainsäädännön ja standardien pohjalta. Ty...

  19. Electromagnetic spacecraft used for magnetic navigation within asteroid belt, mining concepts and asteroid magnetic classification

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther; Adachi, T.; Mikula, V.

    League City: Lunar and Planetary Institute, 2007 - (Mackwell, S.). Art. 1093-Art. 1093 [Lunar and Planetary Science /38./. 12.03.2007-16.03.2007, League City] Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic navigation * mining concepts * asteroid classification Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  20. Photometry and models of selected main belt asteroids: IX. Introducing interactive service for asteroid models (ISAM)

    DEFF Research Database (Denmark)

    Marciniak, A.; Bartczak, P.; Santana-Ros, T.; Michałowski, T.; Borczyk, W.; Fagas, M.; Hirsch, R.; Kamiński, K.; Kryszczyńska, A.; Kwiatkowski, T.; Polińska, M.; Sobkowiak, K.; Stasik, M.; Antonini, P.; Behrend, R.; Bembrick, C.; Bernasconi, L.; Colas, F.; Coloma, J.; Crippa, R.; Manzini, F.; Esseiva, N.; Santacana, G.; Wucher, H.; Fauvaud, M.; Fauvaud, S.; Ferreira, Desiree Della Monica; Hein Bertelsen, R.P.; Higgins, D.; Kajava, J.J.E.; Michałowski, J.; Michałowski, M.J.; Paschke, A.; Poncy, R.; Roy, R.; Starczewski, S.; Velichko, F.; Zafar, T.

    2012-01-01

    Context. The shapes and spin states of asteroids observed with photometric techniques can be reconstructed using the lightcurve inversion method. The resultant models can then be confirmed or exploited further by other techniques, such as adaptive optics, radar, thermal infrared, stellar occultat...

  1. Physical properties of asteroids in comet-like orbits in infrared asteroid survey catalogs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoonyoung; Ishiguro, Masateru [Department of Physics and Astronomy, Seoul National University, Gwanak, Seoul 151-742 (Korea, Republic of); Usui, Fumihiko [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2014-07-10

    We investigated the population of asteroids in comet-like orbits using available asteroid size and albedo catalogs of data taken with the Infrared Astronomical Satellite, AKARI, and the Wide-field Infrared Survey Explorer on the basis of their orbital properties (i.e., the Tisserand parameter with respect to Jupiter, T{sub J}, and the aphelion distance, Q). We found that (1) there are 123 asteroids in comet-like orbits by our criteria (i.e., Q > 4.5 AU and T{sub J} < 3), (2) 80% of them have low albedo, p{sub v} < 0.1, consistent with comet nuclei, (3) the low-albedo objects among them have a size distribution shallower than that of active comet nuclei, that is, the power index of the cumulative size distribution is around 1.1, and (4) unexpectedly, a considerable number (i.e., 25 by our criteria) of asteroids in comet-like orbits have high albedo, p{sub v} > 0.1. We noticed that such high-albedo objects mostly consist of small (D < 3 km) bodies distributed in near-Earth space (with perihelion distance of q < 1.3 AU). We suggest that such high-albedo, small objects were susceptible to the Yarkovsky effect and drifted into comet-like orbits via chaotic resonances with planets.

  2. Asteroid collisional evolution - Evidence for a much larger early population

    Science.gov (United States)

    Chapman, C. R.; Davis, D. R.

    1975-01-01

    The present population of asteroids is a remnant of a vastly larger one that contained perhaps a planetary mass, dominantly distributed in planetesimals approximately 500 kilometers or less in diameter. It constituted a large reservoir of objects that plausibly were responsible for cratering the moon, Mars, and Mercury. Much asteroidal dust may have accumulated on Mars and other planets.

  3. Investigating the Phyllosilicate Mineralogy of Low Albedo Asteroids

    Science.gov (United States)

    Donovan, C.; Gaffey, M. J.; Henderson, G.; Bergeron, M. A.

    2002-01-01

    Methodology and calibrations are being developed to identify specific clay mineral species in the CCD spectra of dark asteroids. This will constrain the geologic processes within their parent bodies and the production or alteration of organic molecules within such asteroids. Additional information is contained in the original extended abstract.

  4. Earth-approaching asteroids: Populations, origin, and compositional types

    Science.gov (United States)

    Shoemaker, E. M.; Helin, E. F.

    1978-01-01

    Origin, physical properties, and discovery history of smaller asteroids are reviewed. They appear to link the main belt objects, namely the comets and meteorites. Physical observations suggest that a wide variety of compositional types are represented among the near-earth asteroids; the apparent rarity of carbonaceous objects is stated.

  5. Linkages between NAMA - LEDS - MRV

    DEFF Research Database (Denmark)

    Agyemang-Bonsu, William; Benioff, Ron; Cox, Sadie;

    Low Emission Development Strategies (LEDS), Nationally Appropriate Mitigation Actions (NAMAs) and Monitoring, Reporting and Verification (MRV) are three of the key conceptual components emerging as part of the global architecture for a new climate agreement by 2015. The three components are...... how the three components are conceptually interlinked. Identifying the linkages can inform the work on each component and strengthen coordination of work in the context of the three big partnerships; the International Partnership on Mitigation and MRV, the LEDS Global Partnership and the NAMA...

  6. LED-belysning och brukaren

    OpenAIRE

    Adanko, Carina; Küller, Marianne

    2014-01-01

    Ljusforskning är om något diversifierad och omfattar teorier och metoder från skilda discipliner som teknik, medicin och samhällsvetenskap. Det finns också en förväntan att erhållna forskningsresultat skall kunna appliceras direkt i verkliga miljöer. I och med introduktionen av LED har många tidigare studier som behandlat glödlampor, lysrör och andra ljuskällor inaktualiserats. Ny kunskap - och ny forskning - krävs. En inventering av aktuell humanrelaterad LED-forskning genomfördes under 2013...

  7. Implications of NEAR results for asteroid structure

    Science.gov (United States)

    Cheng, A.

    The NEAR Shoemaker spacecraft orbited the near-Earth asteroid 433 Eros from February, 2000 to February, 2001, finally landing on the asteroid and returning additional data from the surface. The NEAR Multispectral Imager, Laser Rangefinder, and Radio Science investigations obtained extensive observations pertinent to structure and morphology. These investigations revealed Eros to be a deeply fractured but largely intact body. The NEAR Infrared Spectrometer, X-ray Spectrometer and Gamma Ray Spectrometer also mapped surface compositions and did not find any evidence of compositional heterogeneity. Evidence from NEAR pertaining to the structure of Eros includes the following, reported by the NEAR team. Eros's average density of 2.67 gm/cc is less than the average bulk density of ordinary chondrites, indicating that bulk Eros is significantly porous and/or fractured. The interior of Eros is nearly uniform in density, as inferred from its gravity field, which is similar to that which would be expected from a uniform density object of the same shape. There is a small center of mass offset from the center of figure which may be consistent with an underdense regolith layer of up to 100 m depth. Surface morphology indicates a regolith up to tens of meters thick in places, inferred from the dearth of small craters (blocks and boulders in varying states of burial, and evidence for burial of small craters and for mass wasting. Craters on Eros are typically shallower than craters of the same diameter on the Moon. Tectonic features are found on Eros, as are structurally controlled craters. Aligned linear structures are common, and some of these are coherent on global scales. These results are compared to those reported by the NEAR team from asteroid 253 Mathilde. In both asteroids, giant craters are found in close proximity to one another. MathildeSs porosity is greater than that of Eros; MathildeSs average density is 1.3 gm/cc. This low density suggests a rubble pile structure

  8. Why we need asteroid sample return mission?

    Science.gov (United States)

    Barucci, Maria Antonietta

    2016-07-01

    Small bodies retain evidence of the primordial solar nebula and the earliest solar system processes that shaped their evolution. They may also contain pre-solar material as well as complex organic molecules, which could have a major role to the development of life on Earth. For these reasons, asteroids and comets have been targets of interest for missions for over three decades. However, our knowledge of these bodies is still very limited, and each asteroid or comet visited by space mission has revealed unexpected scientific results, e.g. the structure and nature of comet 67P/Churyumov-Gerasimenko (67P/C-G) visited by the Rosetta mission. Only in the laboratory can instruments with the necessary precision and sensitivity be applied to individual components of the complex mixture of materials that forms a small body regolith, to determine their precise chemical and isotopic composition. Such measurements are vital for revealing the evidence of stellar, interstellar medium, pre-solar nebula and parent body processes that are retained in primitive material, unaltered by atmospheric entry or terrestrial contamination. For those reasons, sample return missions are considered a high priority by a number of the leading space agencies. Abundant within the inner Solar System and the main impactors on terrestrial planets, small bodies may have been the principal contributors of the water and organic material essential to create life on Earth. Small bodies can therefore be considered to be equivalent to DNA for unravelling our solar system's history, offering us a unique window to investigate both the formation of planets and the origin of life. A sample return mission to a primitive Near-Earth Asteroid (NEA) has been study at ESA from 2008 in the framework of ESA's Cosmic Vision (CV) programme, with the objective to answer to the fundamental CV questions "How does the Solar System work?" and "What are the conditions for life and planetary formations?". The returned material

  9. Space weathering of asteroids: Lessons from Itokawa for future observations

    Science.gov (United States)

    Sasaki, Sho; HIroi, Takahiro

    2016-07-01

    Introduction Space weathering of surface silicate minerals is the main process that should control the change of brightness and color of airless silicate bodies such and the Moon, Mercury and asteroids. Spectra of S-type asteroids exhibit more overall depletion and reddening, and more weakening of absorption bands than spectra of ordinary chondrites. These spectral mismatches are explained by the space weathering, where the primary proven mechanism of such spectral change is production of nanophase metallic iron particles (npFe0) 1), which were confirmed in the amorphous rim of lunar soil grains 2,3). Vapor-deposition through at high-velocity dust particle impacts as well as implantation of intensive solar wind ions would be responsible for producing the space weathering rims bearing nano-iron particles (npFe0). Simulation experiments using nanosecond pulse laser successfully produced vapor-deposition type npFe0 to change optical properties 4,5,6). Laser experiments showed that pyroxene would be weathered less than olivine, for pyroxene, pulse laser irradiation produced melt (amorphous) droplets containing npFe0, rather than vapour deposited rim that should provide stronger optical effect trough multiple scattering of incidental light. Itokawa Observed by Remote Sensing In November 2005, Japanese Asteroid Sample Return Mission HAYABUSA spacecraft rendezvoused S-type asteroid (25143) Itokawa. Optically, the surface of Itokawa is divided into brighter (and bluer) areas and darker (and redder) areas 7,8). In rough zones, dark boulder-rich surfaces usually superpose on bright materials. The near-infrared spectrometer (NIRS) confirmed previous disk-integrated results that suggested Itokawa's spectrum closely matched a weakly weathered LL5/6 chondrite 9). Although the surface is covered with rocks and is apparently lack of fine regolith, Itokawa's surface show darkening and reddening by space weathering. Experimental results suggest rocky meteorite fragments can be

  10. Landslides and Mass Shedding on Spinning Spheroidal Asteroids

    CERN Document Server

    Scheeres, D J

    2014-01-01

    Conditions for regolith landslides to occur on spinning, gravitating spheroidal asteroids and their aftermath are studied. These conditions are developed by application of classical granular mechanics stability analysis to the asteroid environment. As part of our study we determine how slopes evolve across the surface of these bodies as a function of spin rate, the dynamical fate of material that exceeds the angle of repose, and an analysis of how the shape of the body may be modified based on these results. We find specific characteristics for body surfaces and shapes when spun near the surface disruption limit and develop what their observable implications are. The small, oblate and rapidly spinning asteroids such as 1999 KW4 Alpha and 2008 EV5 exhibit some of these observable traits. The detailed mechanisms outlined here can also provide insight and constraints on the recently observed active asteroids such as P/2013 P5, and the creation of asteroidal meteor streams.

  11. The Strength of Regolith and Rubble Pile Asteroids

    CERN Document Server

    Sánchez, Paul

    2013-01-01

    We explore the hypothesis that, due to small van der Waals forces between regolith grains, the strength of small rubble pile asteroids is constant. This creates a scale dependence, with relative strength increasing as size decreases. This counters classical theory that rubble pile asteroids should behave as scale-independent cohesionless collections of rocks. We explore a simple model for asteroid strength that is based on these weak forces, validate it through granular mechanics simulations and comparisons with properties of lunar regolith, and then show its implications and ability to explain and predict observed properties of small asteroids in the NEA and Main Belt populations. A conclusion is that the population of rapidly rotating asteroids consists of both distributions of smaller grains (i.e., rubble piles) and of monolithic boulders whose surfaces may still retain a size distribution of finer grains, potentially of size up to centimeters.

  12. Super-Comet or Big Asteroid Belt?

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Figure 1: Spectrograph of HD 69830 This graph of data from NASA's Spitzer Space Telescope demonstrates that the dust around a nearby star called HD 69830 (upper line) has a very similar composition to that of Comet Hale-Bopp. Spitzer spotted large amounts of this dust in the inner portion of the HD 69830 system. The bumps and dips seen in these data, or spectra, represent the 'fingerprints' of various minerals. Spectra are created when an instrument called a spectrograph spreads light out into its basic parts, like a prism turning sunlight into a rainbow. These particular spectra reveal the presence of the silicate mineral called olivine, and more specifically, a type of olivine called forsterite, which is pictured in the inset box. Forsterite is a bright-green gem found on Earth, on the 'Green Sand Beach' of Hawaii among other places; and in space, in comets and asteroids. Because the dust around HD 69830 has a very similar make-up to that of Comet Hale-Bopp, astronomers speculate that it might be coming from a giant comet nearly the size of Pluto. Such a comet may have been knocked into the inner solar system of HD 69830, where it is now leaving in its wake a trail of evaporated dust. Nonetheless, astronomers say the odds that Spitzer has caught a 'super-comet' spiraling in toward its star - an unusual and relatively short-lived event - are slim. Instead, they favor the theory that the observed dust is actually the result of asteroids banging together in a massive asteroid belt. The data of HD 69830's dust were taken by Spitzer's infrared spectrograph. The data of Comet Hale-Bopp were taken by the European Space Agency's Infrared Observatory Satellite. The picture of forsterite comes courtesy of Dr. George Rossman, California Institute of Technology, Pasadena.

  13. Impulsive orbit control for spacecraft around asteroid

    Institute of Scientific and Technical Information of China (English)

    崔祜涛; 崔平远; 栾恩杰

    2003-01-01

    An impulse feedback control law to change the mean orbit elements of spacecraft around asteroid is presented. First, the mean orbit elements are transferred to the osculating orbit elements at the burning time.Then, the feedback control law based on Gauss' s perturbation equations of motion is given. And the impulse control for targeting from the higher circulation orbit to the specified periapsis is developed. Finally, the numerical simulation is performed and the simulation results show that the presented impulse control law is effective.

  14. Space Weathering Trends Among Carbonaceous Asteroids

    CERN Document Server

    Kaluna, Heather M; Meech, Karen J

    2015-01-01

    We present visible spectroscopic and albedo data of the 2.3 Gyr old Themis family and the 15 km) and small (< 15 km) Themis members suggest these phyllosilicate feature and albedo trends result from regolith variations as a function of diameter. Observations of the Beagle asteroids show a small, but notable fraction of members with phyllosilicate features. The presence of phyllosilicates and the dynamical association of the main-belt comet 133P/Elst-Pizarro with the Beagle family imply the Beagle parent body was a heterogenous mixture of ice and aqueously altered minerals.

  15. An optimal Mars Trojan asteroid search strategy

    OpenAIRE

    Todd, M; Tanga, P.; Coward, D. M.; Zadnik, M. G.

    2012-01-01

    Trojan asteroids are minor planets that share the orbit of a planet about the Sun and librate around the L4 or L5 Lagrangian points of stability. Although only three Mars Trojans have been discovered, models suggest that at least ten times this number should exist with diameters >= 1 km. We derive a model that constrains optimal sky search areas and present a strategy for the most efficient use of telescope survey time that maximizes the probability of detecting Mars Trojans. We show that the...

  16. Multicolor, High Efficiency, Nanotextured LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Jung Han; Arto Nurmikko

    2011-09-30

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and green for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) heteroepitaxy of nitrogen-polar LEDs on sapphire, (ii) heteroepitaxy of semipolar (11{bar 2}2) green LEDs on sapphire, (iii) synthesis of quantum-dot loaded nanoporous GaN that emits white light without phosphor conversion, (iv) demonstration of the highest quality semipolar (11{bar 2}2) GaN on sapphire using orientation-controlled epitaxy, (v) synthesis of nanoscale GaN and InGaN medium, and (vi) development of a novel liftoff process for manufacturing GaN thin-film vertical LEDs. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  17. White LED motorcycle headlamp design

    Science.gov (United States)

    Sun, Wen-Shing

    2015-09-01

    The motorcycle headlamp is composed of a white LED module, an elliptical reflector, a parabolic reflector and a toric lens. We use non-sequential ray to improve the optical efficiency of the compound reflectors. Using the toric lens can meet ECE_113 regulation and obtain a good uniformity.

  18. Super-catastrophic disruption of asteroids at small perihelion distances

    Science.gov (United States)

    Granvik, Mikael; Morbidelli, Alessandro; Jedicke, Robert; Bolin, Bryce; Bottke, William F.; Beshore, Edward; Vokrouhlický, David; Delbò, Marco; Michel, Patrick

    2016-02-01

    Most near-Earth objects came from the asteroid belt and drifted via non-gravitational thermal forces into resonant escape routes that, in turn, pushed them onto planet-crossing orbits. Models predict that numerous asteroids should be found on orbits that closely approach the Sun, but few have been seen. In addition, even though the near-Earth-object population in general is an even mix of low-albedo (less than ten per cent of incident radiation is reflected) and high-albedo (more than ten per cent of incident radiation is reflected) asteroids, the characterized asteroids near the Sun typically have high albedos. Here we report a quantitative comparison of actual asteroid detections and a near-Earth-object model (which accounts for observational selection effects). We conclude that the deficit of low-albedo objects near the Sun arises from the super-catastrophic breakup (that is, almost complete disintegration) of a substantial fraction of asteroids when they achieve perihelion distances of a few tens of solar radii. The distance at which destruction occurs is greater for smaller asteroids, and their temperatures during perihelion passages are too low for evaporation to explain their disappearance. Although both bright and dark (high- and low-albedo) asteroids eventually break up, we find that low-albedo asteroids are more likely to be destroyed farther from the Sun, which explains the apparent excess of high-albedo near-Earth objects and suggests that low-albedo asteroids break up more easily as a result of thermal effects.

  19. LED lighting. Special issue; Led-verlichting. Themanummer

    Energy Technology Data Exchange (ETDEWEB)

    Adams, T. [Spectrum Advies en Design, Putten (Netherlands); Derksen, A. [Isso, Rotterdam (Netherlands); Van Mil, R.; Van Lieshout, M.; Vollebregt, R.

    2010-10-15

    In four articles in this issue the focus on illuminance by LEDs: interview with the director of Velux Netherlands, expert in skylights and daylight solutions; the influence of lighting on the cognitive performance of students; the use of energy efficient, dynamic lighting; the Isso publication (number 90) 'Energy-efficient lighting and around buildings'; and the promise of the OLED flat skylight. [Dutch] In vier artikelen wordt in deze aflevering aandacht besteed aan verlichting d.m.v. LEDs: (interview met de directeur van Velux Nederland, specialist in dakramen en daglichtoplossingen; de invloed van verlichting op leerprestaties van scholieren; het gebruik van energie efficiente, dynamisch verlichtingssystemen; de Isso-publicatie (nummer 90) 'Energie-efficiente verlichting in en rondom gebouwen; en de belofte van de platvallichtbron Oled.

  20. LED lamp power management system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A. M.

    2013-03-19

    An LED lamp power management system and method including an LED lamp having an LED controller 58; a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 reduces power loss in one of the channel switch 62 and the shunt switch 68 when LED lamp electronics power loss (P.sub.loss) exceeds an LED lamp electronics power loss limit (P.sub.lim); and each of the channel switches 62 receives a channel switch control signal 63 from the LED controller 58 and each of the shunt switches 68 receives a shunt switch control signal 69 from the LED controller 58.