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Sample records for asteroid eros gravity

  1. Determination of Eros Physical Parameters for Near Earth Asteroid Rendezvous Orbit Phase Navigation

    Science.gov (United States)

    Miller, J. K.; Antreasian, P. J.; Georgini, J.; Owen, W. M.; Williams, B. G.; Yeomans, D. K.

    1995-01-01

    used in February of 2001. The initial attitude and spin rate of Eros, as well as estimates of reference landmark locations, are obtained from images of the asteroid. These initial estimates are used as a priori values for a more precise refinement of these parameters by the orbit determination software which combines optical measurements with Doppler tracking data to obtain solutions for the required parameters. As the spacecraft is maneuvered; closer to the asteroid, estimates of spacecraft state, asteroid attitude, solar pressure, landmark locations and Eros physical parameters including mass, moments of inertia and gravity harmonics are determined with increasing precision. The determination of the elements of the inertia tensor of the asteroid is critical to spacecraft orbit determination and prediction of the asteroid attitude. The moments of inertia about the principal axes are also of scientific interest since they provide some insight into the internal mass distribution. Determination of the principal axes moments of inertia will depend on observing free precession in the asteroid's attitude dynamics. Gravity harmonics are in themselves of interest to science. When compared with the asteroid shape, some insight may be obtained into Eros' internal structure. The location of the center of mass derived from the first degree harmonic coefficients give a direct indication of overall mass distribution. The second degree harmonic coefficients relate to the radial distribution of mass. Higher degree harmonics may be compared with surface features to gain additional insight into mass distribution. In this paper, estimates of Eros physical parameters obtained from the December 23,1998 flyby will be presented. This new knowledge will be applied to simplification of Eros orbital operations in February of 2001. The resulting revision to the orbit determination strategy will also be discussed.

  2. Capillary Action in a Crack on the Surface of Asteroids with an Application to 433 Eros

    CERN Document Server

    Jiang, Yu

    2016-01-01

    Some asteroids contain water ice, and a space mission landing on an asteroid may take liquid to the surface of the asteroid. Gas pressure is very weak on the surface of asteroids. Here we consider the capillary action in a crack on the surface of irregular asteroids. The crack is modelled as a capillary which has a fixed radius. An asteroid s irregular gravitational potential influences the height of the liquid in the capillary. The height of the liquid in the capillary on the surface of such asteroids is derived from the asteroid s irregular gravitational potential. Capillary mechanisms are expected to produce an inhomogeneaous distribution of emergent liquid on the surface. This result is applied to asteroid 433 Eros, which has an irregular, elongated, and concave shape. Two cases are considered 1) we calculate the height of the liquid in the capillary when the direction of the capillary is perpendicular to the local surface of the asteroid; 2) we calculate the height of the liquid in the capillary when the...

  3. Comprehensive Gravity and Dynamics Model Determination of Binary Asteroid Systems

    Science.gov (United States)

    Fahnestock, Eugene G.

    2009-09-01

    I present the development of additional tools within the framework of JPL's in-house Mirage / Orbit Determination Program (ODP) software to allow the determination of a comprehensive gravity and dynamics model for any binary asteroid system potentially visited by a spacecraft rendezvous mission. This involves a concurrent global solution for the gravity fields of both components, sufficient parametric description of their fully-coupled translational and rotational dynamics, the spacecraft state, and all other relevant force model parameters. This estimation process primarily uses spacecraft radio tracking data (range and Doppler measurements), supplemented by in-situ imaging observations data types. A solution for the gravity field (gravity analysis) and a simultaneous solution for the spacecraft motion and other system properties has been performed before using the ODP for solitary irregular small solar system bodies (e.g. Eros, visited by the NEAR mission), but never for any closely gravitationally bound pair of irregular small solar system bodies. I am expanding NASA's tool set to allow the latter, in preparation for potential future spacecraft rendezvous missions. This is nontrivial, because of the need to incorporate propagation of the binary system's fully-coupled rigid-body dynamical model either along with the spacecraft state within Mirage/ODP or "offline", followed by interpolating an appropriate "binary dynamics ephemeris” representation. Further, this model optionally incorporates formulations for body gravity fields not previously used in this context, and it can be computationally very expensive. However, successfully performing this model determination at a binary asteroid yields valuable science results concerning internal mass distributions and structures of the components and insight into the system's formation and evolution. In this poster I present my current progress in the development of this capability and results for the quality of science

  4. NEAR MSI Images of Asteroid Eros: New Data Products and Analysis

    Science.gov (United States)

    Blewett, David T.; Ernst, Carolyn; Shusterman, Morgan L.; Nguyen, Lillian; Espiritu, Raymond C.; Turner, Russell J.; Barnouin, Olivier S.

    2016-10-01

    The Near-Earth Asteroid Rendezvous (NEAR) spacecraft orbited asteroid Eros for approximately one year in 2000–2001, returning thousands of images obtained with the MultiSpectral Imager (MSI) camera system. R. Gaskell used ~20,000 of these images to construct a high-resolution shape model of Eros that was archived in the NASA Planetary Data System (PDS) in 2008. We have produced backplanes for this set of images, and are in the process of preparing them for delivery to the PDS. The 16 backplanes contain information of interest for each pixel in an image: 1. Image pixel value. 2. x value of point, body centered coords. 3. y value of point. 4. z value of point. 5. Latitude. 6. Longitude. 7. Distance from center of asteroid. 8. Solar incidence angle. 9. Emergence angle. 10. Phase angle. 11. Horizontal pixel scale (km/pixel). 12. Vertical pixel scale. 13. Slope. 14. Elevation. 15. Gravitational acceleration. 16. Gravitational potential. This set of backplanes will be provided to the PDS Small Bodies Node, with PDS-4 labels. The Gaskell shape model, produced with stereophotoclinometry, has more than 3.1 million plates. Hence this model has more than an order of magnitude better spatial resolution compared with the older shape model (200,700 plates). The high-resolution shape model permits substantial improvements in photometric normalization of images to be made, because the incidence, emergence, and phase angles can be determined at smaller scales. We plan to perform new photometric normalization of color image sets in order to search for mineralogical variations at higher resolution than was previously possible. In addition, we will carry out phase-ratio analysis to extract information on surface texture and scattering behavior for features of special interest.

  5. Computing and analysis of gravity field of Eros433 using polyhedron model%多面体模型的Eros433引力场计算与分析

    Institute of Scientific and Technical Information of China (English)

    崔祜涛; 张振江; 余萌

    2012-01-01

    To better understand the properties of gravity field of irregularly shaped asteroid,this paper adopted the Polyhedron modeling method to calculate the gravity filed of asteroid Eros433,and analyzed the distributing properties of this asteroid's gravity field.Firstly this article introduced the concept of Polyhedron model and the method of calculating polyhedron model of asteroid,and then the polyhedron model of asteroid Eros433 was given.After that,Gauss Law and Green's formula are applied to the calculation,and by twice integral transformation the triple integral of gravitational potential function can be transformed into single integral,which can be used in polyhedron model to derive the formulas of gravitational potential function,gravitational acceleration and Laplacian.Finally,the formulas derived were applied to calculate and analyze the distributing properties of gravity field of Eros433,after taking the self-rotation of asteroid into consideration,Pseudo-potential surface and Zero velocity curve are used to analyze the orbital dynamic environment around the asteroid and the position conditions of equilibrium points of asteroid.%为更好的认识不规则小行星引力场的特点,本文采用多面体模型法对Eros433小行星的引力场进行计算,并由此分析了小行星引力场的分布特点.首先介绍了多面体模型的概念和小行星多面体模型的计算方法.然后,应用高斯公式和格林公式,通过两次积分变换将引力势函数的三重积分转化为一重积分,并将其应用到多面体模型中,推导了多面体模型的引力势函数、引力加速度和拉普拉斯算子的计算公式.最后,计算并分析了Eros433小行星引力场的分布特点,应用伪势能曲面和零速度曲线分析了小行星周围的轨道动力学环境和平衡点的位置情况,通过与JPL实验室公布的数据对比表明,本方法最大计算误差为1.52%,具有较高的精度.

  6. The landing of the NEAR-Shoemaker spacecraft on asteroid 433 Eros

    Science.gov (United States)

    Veverka, J.; Farquhar, B.; Robinson, M.; Thomas, P.; Murchie, S.; Harch, A.; Antreasian, P.G.; Chesley, S.R.; Miller, J.K.; Owen, W.M.; Williams, B.G.; Yeomans, D.; Dunham, D.; Heyler, G.; Holdridge, M.; Nelson, R.L.; Whittenburg, K.E.; Ray, J.C.; Carcich, B.; Cheng, A.; Chapman, C.; Bell, J.F.; Bell, M.; Bussey, B.; Clark, B.; Domingue, D.; Gaffey, M.J.; Hawkins, E.; Izenberg, N.; Joseph, J.; Kirk, R.; Lucey, P.; Malin, M.; McFadden, L.; Merline, W.J.; Peterson, C.; Prockter, L.; Warren, J.; Wellnitz, D.

    2001-01-01

    The NEAR-Shoemaker spacecraft was designed to provide a comprehensive characterization of the S-type asteroid 433 Eros (refs 1-3), an irregularly shaped body with approximate dimensions of 34 ?? 13 ?? 13 km. Following the completion of its year-long investigation, the mission was terminated with a controlled descent to its surface, in order to provide extremely high resolution images. Here we report the results of the descent on 12 February 2001, during which 70 images were obtained. The landing area is marked by a paucity of small craters and an abundance of 'ejecta blocks'. The properties and distribution of ejecta blocks are discussed in a companion paper. The last sequence of images reveals a transition from the blocky surface to a smooth area, which we interpret as a 'pond'. Properties of the 'ponds' are discussed in a second companion paper. The closest image, from an altitude of 129 m, shows the interior of a 100-m-diameter crater at 1-cm resolution.

  7. Modeling the seismic response of 2D models of asteroid 433 Eros, based on the spectral-element method.

    Science.gov (United States)

    Blitz, Celine; Komatitsch, Dimitri; Lognonné, Philippe; Martin, Roland; Le Goff, Nicolas

    The understanding of the interior structure of Near Earth Objects (NEOs) is a fundamental issue to determine their evolution and origin, and also, to design possible mitigation techniques (Walker and Huebner, 2004). Indeed, if an oncoming Potentially Hazardous Object (PHO) were to threaten the Earth, numerous methods are suggested to prevent it from colliding our planet. Such mitigation techniques may involve nuclear explosives on or below the object surface, impact by a projectile, or concentration of solar energy using giant mirrors (Holsapple, 2004). The energy needed in such mitigation techniques highly depends on the porosity of the hazardous threatening object (asteroid or comet), as suggested by Holsapple, 2004. Thus, for a given source, the seismic response of a coherent homogeneous asteroid should be very different from the seismic response of a fractured or rubble-pile asteroid. To assess this hypothesis, we performed numerical simulations of wave propagation in different interior models of the Near Earth Asteroid 433 Eros. The simulations of wave propagation required a shape model of asteroid Eros, kindly provided by A. Cheng and O. Barnouin-Jha (personal communication). A cross-section along the longest axis has been chosen to define our 2D geometrical model, and we study two models of the interior: a homogeneous one, and a complex one characterized by fault networks below the main crosscut craters, and covered by a regolith layer of thickness ranging from 50 m to 150 m. To perform the numerical simulations we use the spectral-element method, which solves the variational weak form of the seismic wave equation (Komatitsch and Tromp, 1999) on the meshes of the 2D models of asteroid Eros. The homogeneous model is composed of an elastic material characterized by a pressure wave velocity Vp = 3000 m.s-1 , a shear wave velocity Vs = 1700 m.s-1 and a density of 2700 kg.m-3 . The fractured model possesses the same characteristics except for the presence of

  8. Fourth-order gravity gradient torque of spacecraft orbiting asteroids

    CERN Document Server

    Wang, Yue; Xu, Shijie

    2014-01-01

    The dynamical behavior of spacecraft around asteroids is a key element in design of such missions. An asteroid's irregular shape, non-spherical mass distribution and its rotational sate make the dynamics of spacecraft quite complex. This paper focuses on the gravity gradient torque of spacecraft around non-spherical asteroids. The gravity field of the asteroid is approximated as a 2nd degree and order-gravity field with harmonic coefficients C20 and C22. By introducing the spacecraft's higher-order inertia integrals, a full fourth-order gravity gradient torque model of the spacecraft is established through the gravitational potential derivatives. Our full fourth-order model is more precise than previous fourth-order model due to the consideration of higher-order inertia integrals of the spacecraft. Some interesting conclusions about the gravity gradient torque model are reached. Then a numerical simulation is carried out to verify our model. In the numerical simulation, a special spacecraft consisted of 36 po...

  9. Enhanced Gravity Tractor Derived from the Asteroid Redirect Mission for Deflecting Hypothetical Asteroid 2017 PDC

    Science.gov (United States)

    Mazanek, Daniel D.; Reeves, David M.; Abell, Paul A.; Shen, Haijun; Qu, Min

    2017-01-01

    The Asteroid Redirect Mission (ARM) concept would robotically visit a hazardous-size near-Earth asteroid (NEA) with a rendezvous spacecraft, collect a multi-ton boulder and regolith samples from its surface, demonstrate an innovative planetary defense technique known as the Enhanced Gravity Tractor (EGT), and return the asteroidal material to a stable orbit around the Moon, allowing astronauts to explore the returned material in the mid-2020s. Launch of the robotic vehicle to rendezvous with the ARM reference target, NEA (341843) 2008 EV5, would occur in late 2021 [1,2]. The robotic segment of the ARM concept uses a 40 kW Solar Electric Propulsion (SEP) system with a specific impulse (Isp) of 2600 s, and would provide the first ever demonstration of the EGT technique on a hazardous-size asteroid and validate one method of collecting mass in-situ. The power, propellant, and thrust capability of the ARM robotic spacecraft can be scaled from a 40 kW system to 150 kW and 300 kW, which represent a likely future power level progression. The gravity tractor technique uses the gravitational attraction of a station-keeping spacecraft with the asteroid to provide a velocity change and gradually alter the trajectory of the asteroid. EGT utilizes a spacecraft with a high-efficiency propulsion system, such as Solar Electric Propulsion (SEP), along with mass collected in-situ to augment the mass of the spacecraft, thereby increasing the gravitational force between the objects [3]. As long as the spacecraft has sufficient thrust and propellant capability, the EGT force is only limited by the amount of in-situ mass collected and can be increased several orders of magnitude compared to the traditional gravity tractor technique in which only the spacecraft mass is used to generate the gravitational attraction force. This increase in available force greatly reduces the required deflection time. The collected material can be a single boulder, multiple boulders, regolith, or a

  10. Near Earth Asteroid redirect missions based on gravity assist maneuver

    Science.gov (United States)

    Ledkov, Anton; Shustov, Boris M.; Eismont, Natan; Boyarsky, Michael; Nazirov, Ravil; Fedyaev, Konstantin

    During last years several events attracted world community attention to the hazards of hitting the Earth by sky objects. One of these objects is Apophis asteroid what was expected with nonzero probability to hit the Earth in 2036. Luckily after more precise measurements this event is considered as practically improbable. But the other object has really reached the Earth, entered the atmosphere in the Chelyabinsk area and caused vast damages. After this the hazardous near Earth objects problem received practical confirmation of the necessity to find the methods of its resolution. The methods to prevent collision of the dangerous sky object with the Earth proposed up to now look not practical enough if one mentions such as gravitational tractor or changing the reflectivity of the asteroid surface. Even the method supposing the targeting of the spacecraft to the hazardous object in order to deflect it from initial trajectory by impact does not work because its low mass as compared with the mass of asteroid to be deflected. For example the mass of the Apophis is estimated to be about 40 million tons but the spacecraft which can be launched to intercept the asteroid using contemporary launchers has the mass not more than 5 tons. So the question arises where to find the heavier projectile which is possible to direct to the dangerous object? The answer proposed in our paper is very simple: to search it among small near Earth asteroids. As small ones we suppose those which have the cross section size not more than 12-15 meters and mass not exceeding 1500 -1700 tons. According to contemporary estimates the number of such asteroids is not less than 100000. The other question is how to redirect such asteroid to the dangerous one. In the paper the possibilities are studied to use for that purpose gravity assist maneuvers near Earth. It is shown that even among asteroids included in contemporary catalogue there are the ones which could be directed to the trajectory of the

  11. Mission concepts and operations for asteroid mitigation involving multiple gravity tractors

    Science.gov (United States)

    Foster, Cyrus; Bellerose, Julie; Mauro, David; Jaroux, Belgacem

    2013-09-01

    The gravity tractor concept is a proposed method to deflect an imminent asteroid impact through gravitational tugging over a time scale of years. In this study, we present mission scenarios and operational considerations for asteroid mitigation efforts involving multiple gravity tractors. We quantify the deflection performance improvement provided by a multiple gravity tractor campaign and assess its sensitivity to staggered launches. We next explore several proximity operation strategies to accommodate multiple gravity tractors at a single asteroid including formation-flying and mechanically-docked configurations. Finally, we utilize 99942 Apophis as an illustrative example to assess the performance of a multiple gravity tractor campaign.

  12. Towing Asteroids with Gravity Tractors Enhanced by Tethers and Solar Sails

    Science.gov (United States)

    Shen, Haijun; Roithmayr, Carlos M.

    2015-01-01

    Material collected from an asteroid's surface can be used to increase gravitational attraction between the asteroid and a Gravity Tractor (GT); the spacecraft therefore operates more effectively and is referred to as an Enhanced Gravity Tractor (EGT). The use of tethers and solar sails to further improve effectiveness and simplify operations is investigated. By employing a tether, the asteroidal material can be placed close to the asteroid while the spacecraft is stationed farther away, resulting in a better safety margin and improved thruster efficiency. A solar sail on a spacecraft can naturally provide radial offset and inter-spacecraft separation required for multiple EGTs.

  13. Optimal Flight to Near-Earth Asteroids with Using Electric Propulsion and Gravity Maneuvers

    Science.gov (United States)

    Chernov, A. V.

    Optimal space flight to near-Earth asteroid for deflection asteroids from the Earth and prevention their possible collision is investigated. The deflection is realized by means of impact-kinetic effect of the spacecraft on the asteroid and changing the asteroid orbit. The effectiveness of this method for preventing asteroid-Earth collision is estimated by means of optimal space flights, which are found. The flight of spacecraft (SC) is realized by means of using electric propulsion system. To increase effectiveness the optimal gravity maneuvers of spacecraft near Mars and Venus are using. Criterion of the space flight optimization is maximal deflection of the asteroid from the Earth at the moment of asteroid-Earth nearest approach. For determination of optimal trajectories the maximum Pontrjagin principle is used. It is assumed that the thrust of electric propulsion is unrestricted or corresponding to electric engine SPT-140 with solar battery as energy source. The technique of choice of first approximation for optimal trajectory determination on base of search optimal trajectories in more simple statement is used. The optimal trajectories are determined for wide ranges of the space flight times to near-Earth asteroids with different orbit elements. A comparison with a case of the space flight using a high thrust only or without gravity-assisted maneuvers is carried out.

  14. Impact Craters on Asteroids: Does Gravity or Strength Control Their Size?

    Science.gov (United States)

    Nolan, Michael C.; Asphaug, Erik; Melosh, H. Jay; Greenberg, Richard

    1996-12-01

    The formation of kilometer-size craters on asteroids is qualitatively different from the formation of meter-size (laboratory- and weapons-scale) craters on Earth. A numerical hydrocode model is used to examine the outcomes of various-size cratering impacts into spheres and half-spaces. A shock wave fractures the target in advance of the crater excavation flow; thus, for impactors larger than 100 m, impacting at typical asteroid impact velocities, target tensile strength is irrelevant to the impact outcome. This result holds whether the target is initially intact or a “rubble pile,” even ignoring the effects of gravity. Because of the shock-induced fracture, crater excavation is controlled by gravity at smaller sizes than would otherwise be predicted. Determining the strength-gravity transition by comparing the physical strength of the material to the force of gravity will not work, because strength is eliminated by the shock wave.

  15. Earth resonant gravity assists for asteroid retrieval missions

    OpenAIRE

    Sanchez, J. P.; E. M. Alessi; D. G. Yarnoz; McInnes, C.R.

    2013-01-01

    Asteroids and comets are of strategic importance for science in an effort to uncover the formation, evolution and composition of the Solar System. Near-Earth objects (NEOs) are of particular interest because of their accessibility from Earth, but also because of their speculated wealth of material resources. The possibility of retrieving entire NEOs from accessible heliocentric orbits and moving them into the Earth’s neighbourhood is today a credible possibility considered by NASA, within its...

  16. The gravimeter "B-grave" for the in-situ surface gravity measurements of an asteroid

    Science.gov (United States)

    van Ruymbeke, Michel; karatekin, ozgur; rasson, jean; wielant, françois; dumont, Phillipe; Ritter, Birgit; zhu, Ping

    2016-04-01

    In the context of the preliminary study phase for the CubeSats supporting ESA's Asteroid Impact Mission (AIM) to the Didymos, we investigate a miniaturized gravimeter as part of the geophysical instrument package for the Asteroid Geophysical Explorer (AGEX). AGEX intends to land a CubeSat on the secondary object in the Didymos system, Didymoon in order to characterize the asteroid surface and internal structure A 3D compact gravimeter is developed at the Royal Observatory of Belgium. Its design allows to meter a weak 50 μm/sec² gravity field corresponding to 5 ppm of Earth gravity in a harsh environment. A system with three components mounted in an orthogonal geometry allows obtaining the gravity field in amplitude and in angular position without any requirement of levelling. B-GRAVES will use a in-situ calibration and multi-parameter approach for validation of the measurements. A laboratory simulation is induced with centrifugal forces applied to the pendulum set-up in a vertical position to reject the Earth gravity field. Signal treatment and uncertainties are discussed keeping in mind questions of thermal and vibration influence. The B-GRAVES can serve as a novel and robust instrument for future lander and rover missions .

  17. 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.

  18. 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...

  19. Asteroid mining

    Science.gov (United States)

    Gertsch, Richard E.

    1992-01-01

    The earliest studies of asteroid mining proposed retrieving a main belt asteroid. Because of the very long travel times to the main asteroid belt, attention has shifted to the asteroids whose orbits bring them fairly close to the Earth. In these schemes, the asteroids would be bagged and then processed during the return trip, with the asteroid itself providing the reaction mass to propel the mission homeward. A mission to one of these near-Earth asteroids would be shorter, involve less weight, and require a somewhat lower change in velocity. Since these asteroids apparently contain a wide range of potentially useful materials, our study group considered only them. The topics covered include asteroid materials and properties, asteroid mission selection, manned versus automated missions, mining in zero gravity, and a conceptual mining method.

  20. Studying low-velocity impacts in reduced gravity: an asteroid landing experiment

    Science.gov (United States)

    Murdoch, Naomi; Calandry, Alexis; Sunday, Cecily; Avila Martinez, Iris; Cherrier, Olivier; Cadu, Alexandre; Zenou, Emmanuel; Gourinat, Yves

    2016-10-01

    Several current and future small body missions include lander components e.g., MASCOT and the MINERVA rovers on-board JAXA's Hayabusa-2 mission [1], MASCOT2 and possibly AGEX on board ESA's AIM mission [2,3]. The understanding of surface-lander interactions is important for all such landers as these considerations influence the deployment strategy, the mission design and operations, and even the choice of payload. The dynamics of low-velocity interactions with granular material in reduced gravity are also important for other missions, such as OSIRIS-REx (NASA), that will interact directly with the asteroid's surface in order to retrieve a regolith sample.In our experiment, reduced gravity is simulated by releasing a free-falling projectile into a surface container with a downward acceleration less than that of Earth's gravity. The acceleration of the surface is controlled through the use of an Atwood machine, or a system of pulleys and counterweights. The experiment is built into an existing 5.5 m drop-tower frame and has required the custom design of all components, including the projectiles, surface sample container and release mechanism [4].Previous experiments using similar methods have demonstrated the important role of gravity in the peak accelerations and collision timescales during low velocity granular impacts [5,6]. The design of our experiment accommodates collision velocities and effective accelerations that are lower than in previous experiments (benchmark different numerical simulation approaches. These simulations can then subsequently be used to extrapolate the results to even lower gravity regimes.[1] Tsuda, Y. et al., Acta Astronaut, 2013; [2] Michel, P. et al., Adv Space Res, 2016; [3] Karatekin, O., et al., EGU, 2016; [4] Sunday, C., et al, RSI accepted, 2016; [5] Altshuler, E, arxiv 2013; [6] Goldman, D. I. and Umbanhowar, P., PRE, 2008.

  1. Analysis and Design of Asteroid Retrieval Missions Using Luni-Solar Gravity Assists

    Science.gov (United States)

    Chen, Hongru

    2016-07-01

    This paper will present the utilization of lunar and solar gravity assists for retrieving asteroids into lunar orbits. The Sun-perturbed Moon-to-Moon transfers can change the relative velocity to the Moon (v_∞). This strategy can be utilized to decrease the v_∞ with respect to Moon for libration orbit insertion. It is desirable to find a multiple lunar swingby sequence to reach a sufficiently low v_∞. The paper discusses several types of Moon-to-Moon transfers and establishes a database for all types. The database is used for choosing patchable Moon-to-Moon arcs. The mismatch between two consecutive arcs is made up by impulsive Δv. The optimization routine will be developed to optimize the correction Δv. Computing the required Δv for different insertion conditions (energy and direction) will reveal the relationship between the retrievable mass and retrievable energy of asteroids. The result can also serve as a database in the optimization of the total Δv of the insertion (from heliocentric orbit to Sun-Earth Hill's region) phase and retrieval phase, in the manner of dynamic programming.

  2. The surface roughness of (433) Eros as measured by thermal-infrared beaming

    Science.gov (United States)

    Rozitis, B.

    2017-01-01

    In planetary science, surface roughness is regarded to be a measure of surface irregularity at small spatial scales, and causes the thermal-infrared beaming effect (i.e. re-radiation of absorbed sunlight back towards to the Sun). Typically, surface roughness exhibits a degeneracy with thermal inertia when thermophysical models are fitted to disc-integrated thermal-infrared observations of asteroids because of this effect. In this work, it is demonstrated how surface roughness can be constrained for near-Earth asteroid (433) Eros (i.e. the target of NASA's NEAR Shoemaker mission) when using the Advanced Thermophysical Model with thermal-infrared observations taken during an `almost pole-on' illumination and viewing geometry. It is found that the surface roughness of (433) Eros is characterized by an rms slope of 38 ± 8° at the 0.5-cm spatial scale associated with its thermal-infrared beaming effect. This is slightly greater than the rms slope of 25 ± 5° implied by the NEAR Shoemaker laser ranging results when extrapolated to this spatial scale, and indicates that other surface shaping processes might operate, in addition to collisions and gravity, at spatial scales under one metre in order to make asteroid surfaces rougher. For other high-obliquity asteroids observed during `pole-on' illumination conditions, the thermal-infrared beaming effect allows surface roughness to be constrained when the sub-solar latitude is greater than 60°, and if the asteroids are observed at phase angles of less than 40°. They will likely exhibit near-Earth asteroid thermal model beaming parameters that are lower than expected for a typical asteroid at all phase angles up to 100°.

  3. Nonlinear attitude stability of a spacecraft on a stationary orbit around an asteroid subjected to gravity gradient torque

    CERN Document Server

    Wang, Yue

    2014-01-01

    The classical problem of attitude stability in a central gravity field is generalized to that on a stationary orbit around a uniformly-rotating asteroid. This generalized problem is studied in the framework of geometric mechanics. Based on the natural symplectic structure, the non-canonical Hamiltonian structure of the problem is derived. The Poisson tensor, Casimir functions and equations of motion are obtained in a differential geometric method. The equilibrium of the equations of motion, i.e. the equilibrium attitude of the spacecraft, is determined from a global point of view. Nonlinear stability conditions of the equilibrium attitude are obtained with the energy-Casimir method. The nonlinear attitude stability is then investigated versus three parameters of the asteroid, including the ratio of the mean radius to the stationary orbital radius, the harmonic coefficients C20 and C22. It is found that when the spacecraft is located on the intermediate-moment principal axis of the asteroid, the nonlinear stab...

  4. 基于433 Eros的多面体引力模型精度与运行时间研究%Research on the Accuracy and Operation Time of Polyhedron Gravity Model Base on 433 Eros

    Institute of Scientific and Technical Information of China (English)

    肖尧; 阮晓钢; 魏若岩

    2016-01-01

    This paper adopts the polyhedron gravity modeling methodto calculate the surface gravitational acceleration of 433 Eros using the 3D polyhedron shape models of 433 Eros published by the Planetary Data System(PDS). The accuracy and operation time with different facets of the 3D polyhedron gravity model are also analyzed. The experiments show that the time complexity of polyhedron gravity model isO(n). In the simulation of the guidance, navigation and controlfor landing on 433 Eros, using the shape model with 22 540-facetscan achieve a tradeoff between the computation rate and accuracy.Moreover, since the gravity acceleration can be computed in real-time, it can be used in the hardware-in-the-loop simulation.%基于Planetary Data System(PDS)公布的433 Eros多面体模型,使用多面体模型法计算了433 Eros的表面引力加速度分布情况,并研究了该方法在不同精度的多面体模型下的计算时间和误差。实验结果表明:1)多面体模型法的时间复杂度为O(n);2)在以433 Eros为目标天体的着陆导航与制导控制相关仿真计算中,使用面数为22540的多面体模型进行引力加速度计算,可以同时满足计算速度和精度的要求,并且由于计算速度接近实时,可用于半物理仿真实验中。

  5. Precise and Fast Computation of the Gravitational Field of a General Finite Body and Its Application to the Gravitational Study of Asteroid Eros

    Science.gov (United States)

    Fukushima, Toshio

    2017-10-01

    In order to obtain the gravitational field of a general finite body inside its Brillouin sphere, we developed a new method to compute the field accurately. First, the body is assumed to consist of some layers in a certain spherical polar coordinate system and the volume mass density of each layer is expanded as a Maclaurin series of the radial coordinate. Second, the line integral with respect to the radial coordinate is analytically evaluated in a closed form. Third, the resulting surface integrals are numerically integrated by the split quadrature method using the double exponential rule. Finally, the associated gravitational acceleration vector is obtained by numerically differentiating the numerically integrated potential. Numerical experiments confirmed that the new method is capable of computing the gravitational field independently of the location of the evaluation point, namely whether inside, on the surface of, or outside the body. It can also provide sufficiently precise field values, say of 14–15 digits for the potential and of 9–10 digits for the acceleration. Furthermore, its computational efficiency is better than that of the polyhedron approximation. This is because the computational error of the new method decreases much faster than that of the polyhedron models when the number of required transcendental function calls increases. As an application, we obtained the gravitational field of 433 Eros from its shape model expressed as the 24 × 24 spherical harmonic expansion by assuming homogeneity of the object.

  6. Gravity Defied From Potato Asteroids to Magnetised Neutron Stars1. The Self-Gravitating Objects

    Indian Academy of Sciences (India)

    Sushan Konar

    2017-03-01

    Gravitation, the universal attractive force, acts upon all matter(and radiation) relentlessly. Left to itself, gravity wouldpull everything together, and the Universe would be nothingbut a gigantic black hole. Nature throws almost every bit ofphysics – rotation, magnetic field, heat, quantum effects andso on, at gravity to escape such a fate. In this series of articles,we shall explore systems where the eternal pull of gravity hasbeen held off by one or another such means.

  7. Eros / Aare Ermel

    Index Scriptorium Estoniae

    Ermel, Aare, 1957-2013

    2006-01-01

    Kolmest iseseisvast armastusloost koosnev episoodfilm "Eros" : režissöörid Wong Kar-Wai ("Käsi"), Steven Soderbergh ("Tasakaal" / "Equilibrium"), Michelangelo Antonioni ("Asjade ohtlik käik") : Hongkong - Hiina - USA - Prantsuse - Itaalia 2004

  8. Mission Analysis for Multiple Rendezvous of Near-Earth Asteroids Using Earth Gravity Assist

    Science.gov (United States)

    2010-03-01

    and there are potentially undiscovered thousands. This creates what many call an interstellar “shooting gallery” within which the Earth...continually travels . William Napier, in the article Hazards from Comets and Asteroids (as cited in Bostrom, and, Cirkovic, 2008) writes, “Multiplying the low... travel and the like. Unlike these more mundane risks, however, the impact hazard is unbounded: a big one could end civilization (2008: 234).” The

  9. Formation flying solar-sail gravity tractors in displaced orbit for towing near-Earth asteroids

    Science.gov (United States)

    Gong, Shengping; Li, Junfeng; Baoyin, Hexi

    2009-11-01

    Several methods of asteroid deflection have been proposed in literature and the gravitational tractor is a new method using gravitational coupling for near-Earth object orbit modification. One weak point of gravitational tractor is that the deflection capability is limited by the mass and propellant of the spacecraft. To enhance the deflection capability, formation flying solar sail gravitational tractor is proposed and its deflection capability is compared with that of a single solar sail gravitational tractor. The results show that the orbital deflection can be greatly increased by increasing the number of the sails. The formation flying solar sail gravitational tractor requires several sails to evolve on a small displaced orbit above the asteroid. Therefore, a proper control should be applied to guarantee that the gravitational tractor is stable and free of collisions. Two control strategies are investigated in this paper: a loose formation flying realized by a simple controller with only thrust modulation and a tight formation realized by the sliding-mode controller and equilibrium shaping method. The merits of the loose and tight formations are the simplicity and robustness of their controllers, respectively.

  10. Gravity Defied From Potato Asteroids to Magnetised Neutron Stars 2. The Failed Stars

    Indian Academy of Sciences (India)

    Sushan Konar

    2017-04-01

    Gravitation, the universal attractive force, acts upon all matter(and radiation) relentlessly. Stable extended structurescan exist only when gravity is held off by other forces of nature.This series of articles explores this interplay, looking atobjects that just missed being stars in this particular installment.

  11. I satelliti della missione EROS

    Directory of Open Access Journals (Sweden)

    Stefano De Corso

    2009-03-01

    Full Text Available EROS mission satellitesThe EROS (Earth Remote Observation Satellite constellation is property of ImageSat International N.V. an international company and a commercial provider of high-resolution, satellite earth-imagery collected by its Earth Remote Observation Satellite. EROS A is equipped with a camera whose focal plane of CCD (Charge Coupled Device detectors produces a standard image resolution of 1.9 meters. EROS B slightly larger and similar in appearance to EROS A, the new satellite has superior capabilities, including a larger camera of CCD/ TDI type (Charge Coupled Device/Time Delay Integration, with standard panchromatic resolution of 0.70 m at an altitude of about 500 km, a larger on-board recorder, improved pointing accuracy and a faster data communication link.

  12. EROS resources for the classroom

    Science.gov (United States)

    ,

    2015-01-01

    The U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center has several educational resources that demonstrate how satellite imagery is used to understand our changing world.

  13. 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.

  14. 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.

  15. Professor@s e Eros Teachers and Eros

    Directory of Open Access Journals (Sweden)

    Deborah P. Britzman

    2009-01-01

    Full Text Available Professores/as são testemunhas do fantástico mundo da sexualidade. Esse artigo explora a centralidade de Eros para a educação e estabelece uma relação entre o desejo do/a professor/a e os acontecimentos emocionais da relação própria relação aluno/professor. Eu proponho que o aprendizado deva envolver nosso "eu" erótico, além das nossas fantasias. Mas esta perspectiva requer que professores/as considerem uma psicologia do amor como um caminho principal para a as situações emocionais de Eros. Na sua conclusão este trabalho sugere uma pedagogia que dê as boas vindas tanto à homossexualidade como a heterossexualidade como expressões humanas do amor.Teachers bear witness to the wondrous world of sexuality. This essay explores the centrality of Eros to education and links the teacher's desire to the emotional situation of the student/teacher relationship. I propose that learning involves our erotic selves and our fantasy life. But such a view requires that teachers consider a psychology of love as lending insight into the emotional situation of Eros. The paper concludes by suggesting a pedagogy that welcomes homosexuality and heterosexuality as human expressions of love.

  16. Boundary problem solution of an optimal control transfer between circular orbits for an electric propulsion spacecraft in an irregular gravitational field of an asteroid

    Science.gov (United States)

    Shornikov, Andrey; Starinova, Olga

    2017-01-01

    There is a problem to control spacecraft's motion near objects with irregular gravitational fields as asteroids. In this paper we present a mathematical model of spacecraft motion with an electric propulsion engine in an irregular non-spherical gravitational field of the asteroid Eros 433. We propose to use the model of single gravity points for simulation of the motion of a spacecraft in the irregular gravitational field. The equations of spacecraft motion are corresponding equations of the n-body problem. A boundary task of the control spacecraft's transfer between circular orbits from 200 km to 100 km is considered. Authors propose a combination of the Pontryagin's maximum principle and the Newton's step by step approximation as solutions methods for the boundary problem.

  17. Gravity

    CERN Document Server

    Gamow, George

    2003-01-01

    A distinguished physicist and teacher, George Gamow also possessed a special gift for making the intricacies of science accessible to a wide audience. In Gravity, he takes an enlightening look at three of the towering figures of science who unlocked many of the mysteries behind the laws of physics: Galileo, the first to take a close look at the process of free and restricted fall; Newton, originator of the concept of gravity as a universal force; and Einstein, who proposed that gravity is no more than the curvature of the four-dimensional space-time continuum.Graced with the author's own draw

  18. The global elemental composition of 433 Eros: First results from the NEAR gamma-ray spectrometer orbital dataset

    Science.gov (United States)

    Peplowski, Patrick N.

    2016-12-01

    A primary goal of the Near-Earth Asteroid Rendezvous (NEAR) mission was to compare the elemental composition of the S-type asteroid 433 Eros to the chemical compositions of meteorites, with the specific objective of testing the hypothesis that the S-type asteroids are the source of the ordinary chondrite (OC) meteorites. To that end, NEAR carried an X-ray and Gamma-ray Spectrometer (XGRS) to measure the elemental composition of Eros from orbit. To date, no Eros-originating signal had been reported in GRS orbital measurements, a consequence of NEAR's high orbital altitudes about Eros. A reanalysis of the NEAR GRS orbital dataset, particularly data collected during a series of low-altitude flyovers, has finally revealed the first positively identified gamma-ray signals from Eros. This dataset, which amounts to just 10 h of data collection, was used to produce the first GRS-derived global elemental composition values. Results include the first absolute concentrations of Fe and Th, and the first global K concentration. The data confirm prior conclusions that the elemental composition of Eros' surface is inconsistent with achondritic and volatile-rich carbonaceous chondritic compositions. In contrast, ordinary chondrites, volatile-poor carbonaceous chondrites, and enstatite chondrites have compositions that are consistent with Eros' gamma-ray emissions. When placed in the context of other gamma-ray spectrometer investigations, this analysis indicates that successful gamma-ray spectroscopy investigations require extended periods of time (≥10 days) at orbital altitudes less than or equal to the radius of the target body.

  19. Optimal Trajectory Determination and Mission Design for Asteroid/Deep-Space Exploration via Multibody Gravity Assist Maneuvers

    Directory of Open Access Journals (Sweden)

    Sean Fritz

    2017-01-01

    Full Text Available This paper discusses the creation of a genetic algorithm to locate and optimize interplanetary trajectories using gravity assist maneuvers to improve fuel efficiency of the mission. The algorithm is implemented on two cases: (i a Centaur-class target close to the ecliptic plane and (ii a Centaur-class target with a high inclination to the ecliptic plane. Cases for multiple numbers of flybys (up to three are discussed and compared. It is shown that, for the targets considered here, a single flyby of Jupiter is the most efficient trajectory to either target with the conditions and limitations discussed in this paper. In this paper, we also iterate on possible reasons for certain results seen in the analysis and show how these previously observed behaviors could be present in any trajectory found. The parameters and methods used in the algorithm are explained and justified over multiple real-life interplanetary missions to provide deeper insights into the development choices.

  20. Asteroid Redirect

    OpenAIRE

    De Aquino, Fran

    2017-01-01

    Asteroids are a great threat to mankind. Here we will show that it is possible to redirect them from their trajectories by means of a strong gravitational repulsion, produced by the gravitational interaction between the asteroid and a Gravitational Spacecraft positioned close to the asteroid.

  1. Asteroid Photometry

    CERN Document Server

    Li, Jian-Yang; Buratti, Bonnie J; Takir, Driss; Clark, Beth Ellen

    2015-01-01

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

  2. The manifold spectra and morphologies of EROs

    CERN Document Server

    Cimatti, A; Cassata, P; Pignatelli, E; Fasano, G; Vernet, J; Fomalont, E; Kellermann, K; Zamorani, G; Mignoli, M; Pozzetti, L; Renzini, A; Alighieri, S S; Franceschini, A; Giallongo, E; Fontana, A

    2003-01-01

    Deep VLT optical spectroscopy, HST+ACS (GOODS) imaging and VLA observations are used to unveil the nature of a complete sample of 47 EROs with R-Ks>5 and Ks<20. The spectroscopic redshift completeness is 62%. Morphological classification was derived for each ERO through visual inspection and surface brightness profile fitting. Three main ERO morphological types are found: E/S0 galaxies (30-37%), spiral-like (24-46%) and irregular systems (17-39%). The only ERO detected in the radio is likely to host an obscured AGN. The average radio luminosity of the star-forming EROs undetected in the radio implies star formation rates of the order of 33 Msun yr^-1. The colors, redshifts and masses of the E/S0 galaxy subsample imply a minimum formation redshift z_f \\sim 2. With this z_f there is enough time to have old and massive stellar spheroids already assembled at z \\sim 1. We verify that the R-Ks vs. J-Ks color diagram is efficient in segregating old and dusty-star-forming EROs.

  3. 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.

  4. 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...

  5. Comparing near-surface and bulk densities of asteroids using radar scattering properties

    Science.gov (United States)

    Zambrano Marin, Luisa Fernanda; Nolan, Michael C.; Taylor, Patrick A.; Virkki, Anne

    2016-10-01

    Dual-polarization radar measurements of asteroids provide a joint constraint on the near-surface density and porosity, which can give insights on asteroid composition and evolution. Magri et al. (2001) used (433) Eros radar and spacecraft data as calibration for estimating the near-surface densities and porosities of 45 other radar-detected asteroids (36 main-belt and 9 near-Earth). At that time, only (433) Eros had both radar observations and a measured bulk density. Now that there have been spacecraft observations of several other asteroids and radar measurements of the densities of several binary near-Earth asteroids with various compositions, we can expand the calibration to include those objects. We begin by applying the method of Magri et al. to Ceres, Vesta, Itokawa, 1994 CC, 2001 SN263, 1998 QE2, and 2000 DP107 to explore the differences between the bulk density and the near-surface density measured with radar. We expect significant differences between Ceres and Vesta and the small near-Earth asteroids as the porosities of these objects are expected to be quite different. However, we expect that small binary objects likely have similar internal structures, so that any differences should depend on composition and perhaps surface weathering.Reference: Magri et al., "Radar constraints on asteroid Properties using 433 Eros as ground truth". Meteoritics & Planetary Science 36, 1697-1709, 2001.

  6. Self-organizing control strategy for asteroid intelligent detection swarm based on attraction and repulsion

    Science.gov (United States)

    An, Meiyan; Wang, Zhaokui; Zhang, Yulin

    2017-01-01

    The self-organizing control strategy for asteroid intelligent detection swarm, which is considered as a space application instance of intelligent swarm, is developed. The leader-follower model for the asteroid intelligent detection swarm is established, and the further analysis is conducted for massive asteroid and small asteroid. For a massive asteroid, the leader spacecraft flies under the gravity field of the asteroid. For a small asteroid, the asteroid gravity is negligible, and a trajectory planning method is proposed based on elliptic cavity virtual potential field. The self-organizing control strategy for the follower spacecraft is developed based on a mechanism of velocity planning and velocity tracking. The simulation results show that the self-organizing control strategy is valid for both massive asteroid and small asteroid, and the exploration swarm forms a stable configuration.

  7. 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

  8. Periodic Motion near the Surface of Asteroids

    CERN Document Server

    Jiang, Yu; Li, Hengnian

    2015-01-01

    We are interested in the periodic motion and bifurcations near the surface of an asteroid. The gravity field of an irregular asteroid and the equation of motion of a particle near the surface of an asteroid are studied. The periodic motions around the major body of triple asteroid 216 Kleopatra and the OSIRIS REx mission target asteroid 101955 Bennu are discussed. We find that motion near the surface of an irregular asteroid is quite different from the motion near the surface of a homoplastically spheroidal celestial body. The periodic motions around the asteroid 101955 Bennu and 216 Kleopatra indicate that the geometrical shapes of the orbits are probably very sophisticated. There exist both stable periodic motions and unstable periodic motions near the surface of the same irregular asteroid. This periodic motion which is unstable can be resonant or non resonant. The period doubling bifurcation and pseudo period doubling bifurcation of periodic orbits coexist in the same gravity field of the primary of the t...

  9. Thermo-Reflectance Spectra of Eros: Unambiguous Detection of Olivine

    Science.gov (United States)

    Lucey, P. G.; Hinrichs, J. L.; Urquhart-Kelly, M.; Wellnitz, D.; Bell, J. F., III; Clark, B. E.

    2001-01-01

    Olivine is readily detected on 433 Eros using the new thermo-reflectance spectral technique applied to near-IR spectra obtained at Eros by the NEAR spacecraft. Additional information is contained in the original extended abstract.

  10. Asteroid structure

    Science.gov (United States)

    Asphaug, E.

    2014-07-01

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

  11. The TNG EROs Spectroscopic Identification Survey (TESIS)

    CERN Document Server

    Saracco, P; Ceca, R D; Severgnini, P; Braito, V; Bender, R; Drory, N; Feulner, G; Hopp, U; Mannucci, F; Maraston, C

    2003-01-01

    We are carrying on a near-IR very low resolution spectroscopic follow-up in parallel with XMM-Newton observations of a complete sample of ~30 bright (K'<18.5) Extremely Red Objects (EROs) selected over an area of 360 arcmin^2 of the MUNICS survey. We here present the preliminary results of the spectroscopic and X-ray data analysis.

  12. Socrates, Plato, "Eros" and Liberal Education

    Science.gov (United States)

    McPherran, Mark L.

    2010-01-01

    This paper focuses on the educational method--the "elenchos"--of Plato's Socrates, arguing, against some prominent interpretations, that it is love, both "eros" and "philia", that is the key that links Socrates' philosophy with his education. This analysis, of course, raises some difficult questions regarding the relationship between teacher and…

  13. The Surface Roughness of (433) Eros as Measured by Thermal-Infrared Beaming

    CERN Document Server

    Rozitis, Ben

    2016-01-01

    In planetary science, surface roughness is regarded to be a measure of surface irregularity at small spatial scales, and causes the thermal-infrared beaming effect (i.e. re-radiation of absorbed sunlight back towards to the Sun). Typically, surface roughness exhibits a degeneracy with thermal inertia when thermophysical models are fitted to disc-integrated thermal-infrared observations of asteroids because of this effect. In this work, it is demonstrated how surface roughness can be constrained for near-Earth asteroid (433) Eros (i.e. the target of NASA's NEAR Shoemaker mission) when using the Advanced Thermophysical Model with thermal-infrared observations taken during an "almost pole-on" illumination and viewing geometry. It is found that the surface roughness of (433) Eros is characterised by an RMS slope of 38 $\\pm$ 8{\\deg} at the 0.5-cm spatial scale associated with its thermal-infrared beaming effect. This is slightly greater than the RMS slope of 25 $\\pm$ 5{\\deg} implied by the NEAR Shoemaker laser ran...

  14. 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.

  15. Low Gravity Anchoring System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future sampling missions to the Moon, Mars and Asteroids will likely involve drilling and in-situ analysis from mobile robotic platforms in low gravity. Past...

  16. 从日地系统L2出发借力月球飞越近地小行星%Near-Earth Asteroid Flyby Trajectories from the Sun-Earth L2 via Lunar Gravity Assist

    Institute of Scientific and Technical Information of China (English)

    何胜茂; 彭超; 高扬

    2016-01-01

    There are several flight options for the Chang’E-2 spacecraft after its remaining at the Sun-Earth L2 point, for example, impacting the Moon or recapture into lunar orbit, returning to Earth orbit or atmospheric reentry, heading for halo orbits of the Earth-Moon L1 or L2 or the Sun-Earth L1 point, as well as flying by near-Earth asteroids in interplanetary space (Finally, Chang’E-2 successfully implemented a close flyby of Toutatis, a potentially hazardous near-Earth asteroid, on Dec.13, 2012). The analyses of these flight options require designing preliminary transfer trajectories with total velocity impulses no more than 100 m/s in four-body dynamics, in which the motion of the spacecraft is influenced by the gravities of the Sun, Earth, and Moon. In this study, we shall present low-energy Toutatis flyby trajectories from a Sun-Earth L2 quasi-periodic orbit, specifically, via a single lunar gravity assist that is intentionally utilized for exploring potential benefits, compared with the direct transfer manner that is adopted in the practical mission. Compared with the direct transfer trajectories to the asteroid, lunar gravity assist is demonstrated to be capable of saving propellant for the Toutatis flyby mission, and the equivalent velocity impulses are 58.46 m/s.%对于停留在日地系统L2的“嫦娥2号”探测器,其后续飞行方案有多个选项,例如主动撞月或重返月球轨道、返回地球轨道或再入大气、飞往地月系统L1/L2或日地系统L1、进入深空飞越近地小行星(最终,“嫦娥2号”于2012年12月13日成功地实现了对Toutatis小行星的近距离飞越)。探讨上述的飞行方案需要对飞行轨道进行初步设计,总的速度脉冲限制在100 m/s以内并且需要考虑探测器同时受到太阳、地球、月球的引力作用。本研究设计了探测器从日地系统L2出发借力月球实现Toutatis小行星飞越的飞行方案,与直接飞越方案相比

  17. Asteroid Sufaces/Regoliths Deduced by Remote Sensing

    Science.gov (United States)

    Price, S.

    Resolved imagery on a small number of asteroids provides information about the size, density and surface relief from which inferences may be made regarding their regoliths; Eros Eros is the best studied asteroid in this regard However, remote sensing is necessary to deduce properties for the large majority of objects. These techniques include: spectroscopy and multi-spectral band photometry, which provide clues as to the chemical composition of the surface, infrared (plus visible) radiometry, from which physical bulk and surface properties may be inferred through the derived albedo and thermal inertia, and radar, which permits one to deduce the near surface bulk density. This article reviews what these techniques have revealed about the surface characteristics of asteroids. Asteroids have been classified by the broad emissive properties of the surface as indicated by filter band photometry. Recently, observations from large scale surveys - 2MASS (Denis to a lesser extent) and the Sloan Digital Sky Survey - provided taxonomic classifications for thousands of asteroids. The mineralogy is more secure at higher spectral resolution. Silicates on the surface of asteroids have been inferred from IRAS, ISO and Kuiper Airborne infrared spectra. Infrared radiometry has been used to derive the albedos and diameters of ~2300 asteroids observed by IRAS and MSX. The simplified Standard Thermal Model (STM) works well for main belt asteroids. The model assumes that the asteroid does not rotate and is in instantaneous thermal equilibrium between absorbed sunlight and emitted radiation. Empirical factors for flux enhancement (beaming) and phase function are adopted. There is a dichotomy between large and small asteroids in this database. About 20% of the asteroids with diameters inertia, rotation rate, orientation of the rotation pole, surface roughness and degree of cratering. A complex model is required to account for all the variables. Such a model was developed using full

  18. Small asteroid system evolution

    OpenAIRE

    Jacobson, Seth A.

    2014-01-01

    Observations with radar, photometric and direct imaging techniques have discovered that multiple asteroid systems can be divided clearly into a handful of different morphologies, and recently, the discovery of small unbound asteroid systems called asteroid pairs have revolutionized the study of small asteroid systems. Simultaneously, new theoretical advances have demonstrated that solar radiation dictates the evolution of small asteroids with strong implications for asteroid internal structur...

  19. Small asteroid system evolution

    OpenAIRE

    Jacobson, Seth A.

    2014-01-01

    Observations with radar, photometric and direct imaging techniques have discovered that multiple asteroid systems can be divided clearly into a handful of different morphologies, and recently, the discovery of small unbound asteroid systems called asteroid pairs have revolutionized the study of small asteroid systems. Simultaneously, new theoretical advances have demonstrated that solar radiation dictates the evolution of small asteroids with strong implications for asteroid internal structur...

  20. Multiple-hopping trajectories near a rotating asteroid

    Science.gov (United States)

    Shen, Hong-Xin; Zhang, Tian-Jiao; Li, Zhao; Li, Heng-Nian

    2017-03-01

    We present a study of the transfer orbits connecting landing points of irregular-shaped asteroids. The landing points do not touch the surface of the asteroids and are chosen several meters above the surface. The ant colony optimization technique is used to calculate the multiple-hopping trajectories near an arbitrary irregular asteroid. This new method has three steps which are as follows: (1) the search of the maximal clique of candidate target landing points; (2) leg optimization connecting all landing point pairs; and (3) the hopping sequence optimization. In particular this method is applied to asteroids 433 Eros and 216 Kleopatra. We impose a critical constraint on the target landing points to allow for extensive exploration of the asteroid: the relative distance between all the arrived target positions should be larger than a minimum allowed value. Ant colony optimization is applied to find the set and sequence of targets, and the differential evolution algorithm is used to solve for the hopping orbits. The minimum-velocity increment tours of hopping trajectories connecting all the landing positions are obtained by ant colony optimization. The results from different size asteroids indicate that the cost of the minimum velocity-increment tour depends on the size of the asteroids.

  1. Data Processing for the Near Earth Asteroid Rendezvous (NEAR), X-Ray and Gamma-Ray Spectrometer (XRS) Ground System

    Science.gov (United States)

    McClanahan, Timothy P.; Mikheeva, I.; Trombka, J. I.; Floyd, S. R.; Boynton, W. V.; Bailey, H.; Bhangoo, J.; Starr, R.; Clark, P. E.; Evans, L. G.

    1999-01-01

    An X-ray and Gamma-ray spectrometer (XGRS) is onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433Eros. The Eros asteroid is highly non-spherical in physical shape and the development of data management and analysis methodologies are in several areas a divergence from traditional remotely sensed geographical information systems techniques. Field of view and asteroid surface geometry must be derived virtually and then combined with real measurements of solar, spectral and instrument calibration information to derive meaningful scientific results. Spatial resolution of planned geochemical maps will be improved from the initial conditions of low statistical significance per integration by repeated surface flyovers and regional spectral accumulation. This paper describes the results of a collaborative effort of design and development of the NEAR XGRS instrument ground system undertaken by participants at the Goddard Space Flight Center, University of Arizona, Cornell University, Applied Physics Laboratory, and Max Plank institute.

  2. Data Processing for the Near Earth Asteroid Rendezvous (NEAR), X-ray and Gamma-ray Spectrometer (XGRS) Ground System

    Science.gov (United States)

    McClanahan, Timothy P.; Mikheeva, I.; Trombka, J. I.; Floyd, S. R.; Boynton, W. V.; Bailey, H.; Bhangoo, J.; Starr, R.; Clark, P. E.; Evans, L. G.

    1999-01-01

    An X-ray and Gamma-ray spectrometer (XGRS) is onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433Eros. The Eros asteroid is highly non-spherical in physical shape and the development of data management and analysis methodologies are in several areas a divergence from traditional remotely sensed geographical information systems techniques. Field of view and asteroid surface geometry must be derived virtually and then combined with real measurements of solar, spectral and instrument calibration information to derive meaningful scientific results. Spatial resolution of planned geochemical maps will be improved from the initial conditions of low statistical significance per integration by repeated surface flyovers and regional spectral accumulation. This paper describes the results of a collaborative effort of design and development of the NEAR XGRS instrument ground system undertaken by participants at the Goddard Space Flight Center, University of Arizona, Cornell University, Applied Physics Laboratory, and Max Plank institute.

  3. Resonances and librations of some Apollo and Amor asteroids with the Earth.

    Science.gov (United States)

    Ip, W.-H.; Mehra, R.

    1973-01-01

    The orbital evolution of the Apollo asteroids 1620 Geographos and 1685 Toro and Amor asteroids 433 Eros, 1221 Amor, and 1627 Ivar are investigated by numerical integration. All these asteroids, with the exception of Geographos, exhibit systematic orbital couplings with the Earth during the time interval studied (1600-2350 A.D.). 1685 Toro is captured into libration once with Venus due to the 13.5 resonance, and once with the Earth due to the 8:5 resonance. Both librations are unstable because of the effect of the 13:8 near commensurability of the Venus-Earth system. 433 Eros exhibits no libration pattern; the regular variation of its orbital period is due to the beat-effect of the 4:7 resonance with the Earth.

  4. Search for Asteroid-Asteroid Encounters

    Directory of Open Access Journals (Sweden)

    Luis A. Mammana

    2001-01-01

    Full Text Available Earlier studies about asteroids did not consider mutual interactions since they assume a negligible asteroid mass. In 1966 Hertz took into account for the first time the gravitational effects produced by an asteroid on another for mass determination. This gravitational action becomes relevant for enough effective encounters. The most efficient gravitational interaction is that produced in a large time interval and for small distances. For each particular caseful it is relevant to perform a care analysis in order to determinate the feasibility in the mass determination and improved orbital elements. In the present paper we performed a search of asteroid-asteroid encounters occurred in the twenty century for the first 3000 numbered asteroids . Of all encounters we have selected only those asteroid pairs in which one of the asteroids has a diameter larger than 200 km and the other one (the smaller an observational interval of at least ten years.

  5. The Divine State of Love--Eros

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In contrast with the modem love based on a relationship, eros is even harder to understand. It is a series of mysteries that how eros is started and ended in a process. There are some clues in the classics where love is about nothing but some sentiment, and thus closer to its divine state. There are also modern arguments to compare love's original and modern forms. This essay first argues how eros falls when being involved into scientific research. Then, based on the information from classical literature, it inteprets the activation of eros a divine inspiration. At last, the essay explains how eros cannot be managed by any power after being inspired.%现代社会中的爱情多是由恋爱关系中的职责和权力确定。在希腊神话的黄金年代,当爱情起源于爱神厄洛斯射向情侣的一支箭时,爱情由生到灭的过程便是一个难解的迷。在爱情尚且无关利益权衡年代,一些经典的文学作品在展现更具神性的爱情时,留下了关于爱神厄洛斯的蛛丝马迹。同时,当今的一些文学评论也在对比爱情在古神话和现代社会中不同的变现形态。尽管厄洛斯的爱情在科学分析的力量下难以避免地堕落下神坛,爱情在文学经典中却单纯始于爱神的灵感;然而在爱情被激发后,即便神性的力量也难以操控其之后的发展——因为爱情本身已有了独立的生命。

  6. Asteroid retrieval missions enabled by invariant manifold dynamics

    Science.gov (United States)

    Sánchez, Joan Pau; García Yárnoz, Daniel

    2016-10-01

    Near Earth Asteroids are attractive targets for new space missions; firstly, because of their scientific importance, but also because of their impact threat and prospective resources. The asteroid retrieval mission concept has thus arisen as a synergistic approach to tackle these three facets of interest in one single mission. This paper reviews the methodology used by the authors (2013) in a previous search for objects that could be transported from accessible heliocentric orbits into the Earth's neighbourhood at affordable costs (or Easily Retrievable Objects, a.k.a. EROs). This methodology consisted of a heuristic pruning and an impulsive manoeuvre trajectory optimisation. Low thrust propulsion on the other hand clearly enables the transportation of much larger objects due to its higher specific impulse. Hence, in this paper, low thrust retrieval transfers are sought using impulsive trajectories as first guesses to solve the optimal control problem. GPOPS-II is used to transcribe the continuous-time optimal control problem to a nonlinear programming problem (NLP). The latter is solved by IPOPT, an open source software package for large-scale NLPs. Finally, a natural continuation procedure that increases the asteroid mass allows to find out the largest objects that could be retrieved from a given asteroid orbit. If this retrievable mass is larger than the actual mass of the asteroid, the asteroid retrieval mission for this particular object is said to be feasible. The paper concludes with an updated list of 17 EROs, as of April 2016, with their maximum retrievable masses by means of low thrust propulsion. This ranges from 2000 tons for the easiest object to be retrieved to 300 tons for the least accessible of them.

  7. Asteroid Redirect Mission Proximity Operations for Reference Target Asteroid 2008 EV5

    Science.gov (United States)

    Reeves, David M.; Mazanek, Daniel D.; Cichy, Benjamin D.; Broschart, Steve B.; Deweese, Keith D.

    2016-01-01

    NASA's Asteroid Redirect Mission (ARM) is composed of two segments, the Asteroid Redirect Robotic Mission (ARRM), and the Asteroid Redirect Crewed Mission (ARCM). In March of 2015, NASA selected the Robotic Boulder Capture Option1 as the baseline for the ARRM. This option will capture a multi-ton boulder, (typically 2-4 meters in size) from the surface of a large (greater than approx.100 m diameter) Near-Earth Asteroid (NEA) and return it to cis-lunar space for subsequent human exploration during the ARCM. Further human and robotic missions to the asteroidal material would also be facilitated by its return to cis-lunar space. In addition, prior to departing the asteroid, the Asteroid Redirect Vehicle (ARV) will perform a demonstration of the Enhanced Gravity Tractor (EGT) planetary defense technique2. This paper will discuss the proximity operations which have been broken into three phases: Approach and Characterization, Boulder Capture, and Planetary Defense Demonstration. Each of these phases has been analyzed for the ARRM reference target, 2008 EV5, and a detailed baseline operations concept has been developed.

  8. Asteroid Mining and Prospecting

    OpenAIRE

    Esty, Thomas

    2013-01-01

    There has been a recent increase in interest in the idea of mining asteroids, as seen from the founding of multiple companies who seek to make this science fiction idea science fact. We analyzed a number of prior papers on asteroids to make an estimate as to whether mining asteroids is within the realm of possibility. Existing information on asteroid number, composition, and orbit from past research was synthesized with a new analysis using binomial statistics of the number of probes that wou...

  9. On enigmatic properties of the main belt asteroids

    Science.gov (United States)

    Kochemasov, G.

    Two properties of the main belt asteroids still bother planetologists: why they are mainly of an oblong shape and why the larger bodies rotate faster than the smaller ones. According to the excepted impact theory constantly produced fragments should be rather more or less of equal dimensions. Larger bodies are more difficult to make rotating by hits than the smaller ones. The comparative wave planetology states that "orbits make structures". It means that as all celestial bodies move in non-round keplerian elliptic (and parabolic) orbits with periodically changing accelerations they are subjected to an action of inertia-gravity waves causing body warpings. These warpings in rotating bodies (but all celestial bodies rotate!) acquire stationary character and 4 ortho- and diagonal directions. An interference of these waves produces uprising (+), subsiding (-) and neutral (0) tectonic blocks size of which depends on the warping wavelengths. The fundamental wave 1 long 2πR makes one hemisphere to rise (bulge) and the opposite one to fall (press in) - this two-segment construction is the ubiquitous tectonic dichotomy. The first overtone wave 2 long πR is responsible for tectonic sectoring complicating the dichotomic segments. This already rather complicated structural picture is further complicated by a warping action of individual waves lengths of which are inversely proportional to orbital frequencies : higher frequency - smaller wave and , vice versa, lower frequency - larger waves. These waves produce tectonic granulation, granule size being a half of a wavelength. All terrestrial planets and the belt asteroids according to their orb. fr. are strictly arranged in the following row of granule sizes: Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1. The waves lengths and amplitudes increase with the solar distance, their warping action accordingly increases. If Mercury, Venus and Earth are more or less globular, Mars is already elliptical because

  10. 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...

  11. [Archetypal aspects of aging: from Eros to Thanatos].

    Science.gov (United States)

    Pérez Urdániz, A; Bueno Carrera, G; Santos García, J M; Molina Ramos, R; Rubio Larrosa, V

    1999-01-01

    From a Junguian point of view, the different archetypal roles of the aging process, along the life cycle, are studied: eros, puer, logos, hero, persona, mascara, anima, animus, king, warrior, magician, lover, mother, virgin, afrodite, witch, self, senex, shadow, tanatos.

  12. Hydrokinetic energy resource estimates of River ERO at Lafiagi ...

    African Journals Online (AJOL)

    Hydrokinetic energy resource estimates of River ERO at Lafiagi, Kwara State, North-Central Nigeria. ... Exploiting the kinetic energy of water currents is considered a smart and cost-effective renewable energy solution without ... Article Metrics.

  13. Mitigation of Hazardous Comets and Asteroids

    Science.gov (United States)

    Belton, Michael J. S.; Morgan, Thomas H.; Samarasinha, Nalin H.; Yeomans, Donald K.

    2011-03-01

    Preface; 1. Recent progress in interpreting the nature of the near-Earth object population W. Bottke, A. Morbidelli and R. Jedicke; 2. Earth impactors: orbital characteristics and warning times S. R. Chesley and T. B. Spahr; 3. The role of radar in predicting and preventing asteroid and comet collisions with Earth S. J. Ostro and J. D. Giorgini; 4. Interior structures for asteroids and cometary nuclei E. Asphaug; 5. What we know and don't know about surfaces of potentially hazardous small bodies C. R. Chapman; 6. About deflecting asteroids and comets K. A. Holsapple; 7. Scientific requirements for understanding the near-Earth asteroid population A. W. Harris; 8. Physical properties of comets and asteroids inferred from fireball observations M. D. Martino and A. Cellino; 9. Mitigation technologies and their requirements C. Gritzner and R. Kahle; 10. Peering inside near-Earth objects with radio tomography W. Kofman and A. Safaeinili; 11. Seismological imvestigation of asteroid and comet interiors J. D. Walker and W. F. Huebner; 12. Lander and penetrator science for near-Earth object mitigation studies A. J. Ball, P. Lognonne, K. Seiferlin, M. Patzold and T. Spohn; 13. Optimal interpretation and deflection of Earth-approaching asteroids using low-thrust electric propulsion B. A. Conway; 14. Close proximity operations at small bodies: orbiting, hovering, and hopping D. J. Scheeres; 15. Mission operations in low gravity regolith and dust D. Sears, M. Franzen, S. Moore, S. Nichols, M. Kareev and P. Benoit; 16. Impacts and the public: communicating the nature of the impact hazard D. Morrison, C. R. Chapman, D. Steel and R. P. Binzel; 17. Towards a program to remove the threat of hazardous NEOs M. J. S. Belton.

  14. Microspine Gripping Mechanism for Asteroid Capture

    Science.gov (United States)

    Merriam, Ezekiel G.; Berg, Andrew B.; Willig, Andrew; Parness, Aaron; Frey, Tim; Howell, Larry L.

    2016-01-01

    This paper details the development and early testing of a compliant suspension for a microspine gripper device for asteroid capture or micro-gravity percussive drilling. The microspine gripper architecture is reviewed, and a proposed microspine suspension design is presented and discussed. Prototyping methods are discussed, as well as testing methods and results. A path forward is identified from the results of the testing completed thus far. Key findings include: the microspine concept has been established as a valid architecture and the compliant suspension exhibits the desired stiffness characteristics for good gripping behavior. These developments will aid in developing the capability to grasp irregularly shaped boulders in micro-gravity.

  15. Asteroid exploration and utilization

    Science.gov (United States)

    Radovich, Brian M.; Carlson, Alan E.; Date, Medha D.; Duarte, Manny G.; Erian, Neil F.; Gafka, George K.; Kappler, Peter H.; Patano, Scott J.; Perez, Martin; Ponce, Edgar

    1992-01-01

    The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources possessed by asteroids have enormous potential for aiding and enhancing human space exploration as well as life on Earth. Project STONER (Systematic Transfer of Near Earth Resources) is based on mining an asteroid and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plan for humans to utilize asteroid resources. Project STONER is divided into two parts: asteroid selection and explorer spacecraft design. The spacecraft design team is responsible for the selection and integration of the subsystems: GNC, communications, automation, propulsion, power, structures, thermal systems, scientific instruments, and mechanisms used on the surface to retrieve and store asteroid regolith. The sample return mission scenario consists of eight primary phases that are critical to the mission.

  16. Driving Mechanism of the Brazil Nut Effect in Asteroids

    Science.gov (United States)

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

    2016-10-01

    Asteroids are remnant objects from the early planet formation process. Most asteroids are considered rubble-piles since they are likely conglomerates of smaller objects held together by gravity and possibly cohesion. Due to that particular structure, asteroids may be studied using techniques of granular flow. One particular effect called the Brazil Nut Effect (BNE) has previously been proposed to be relevant to asteroids. This effect entails the size-sorting of particles when shaken, where larger particles migrate against the direction of gravity while the smaller particles migrate towards the direction of gravity. Analysis of data from the Hayabusa mission led to asteroid 25143 Itokawa being considered an example where the BNE has occurred bringing large boulders to its surface. Since spacecraft data are limited due to the cost of space missions, there are two other methods of studying this effect: experiments and computer simulations. Though experiments have been done under terrestrial gravity and in low-gravity conditions on parabolic flights, experimental setups cannot fully model the BNE for three-dimensional, self-gravitating, conglomerate objects such as asteroids. Computer simulations have been done in low-gravity conditions utilizing rectangular and cylindrical box configurations and recently in a spherical configuration of particles. Most works have focused on using one large particle embedded with smaller particles (i.e. the intruder model). This has been due to the simplicity and the lack of detailed knowledge about the interior of asteroids. However, in this work we show that the intruder BNE, though important in a wider granular flow context, is not relevant to asteroids. We have run BNE simulations for one, two, and three intruders in a spherical configuration of particles and we find that unless the intruder starts off near the surface of our simulated aggregates they generally do not rise to the surface. This contrasts with a bimodal population of

  17. Dynamic retention of Ero1alpha and Ero1beta in the endoplasmic reticulum by interactions with PDI and ERp44.

    Science.gov (United States)

    Otsu, Mieko; Bertoli, Gloria; Fagioli, Claudio; Guerini-Rocco, Elena; Nerini-Molteni, Silvia; Ruffato, Elena; Sitia, Roberto

    2006-01-01

    Disulfide bonds are formed in the endoplasmic reticulum (ER) by sequential interchange reactions: Ero1alpha and Ero1beta transfer oxidative equivalents to protein disulfide isomerase (PDI), which in turn oxidizes cargo proteins. Neither Ero1alpha nor Ero1beta contains known ER localization motif(s), raising the question of how they are retained in this organelle. Here the authors show that, unlike endogenous molecules, overexpressed Ero1alpha and Ero1beta are secreted by HeLa transfectants, suggesting saturation of their normal retention mechanism(s). Co-expression of either PDI or ERp44 prevents Ero1 secretion in a KDEL/RDEL dependent way. Covalent interactions between ERp44 and Ero1 are essential for retention. In contrast, a mutant PDI lacking the four cysteines in the two active sites still inhibits secretion, albeit less efficiently. PDI and ERp44 compete for Ero1 binding. PDI also prevents Ero1 aggregation and dimerization, thus chaperoning its own oxidase. This dynamic retention mechanism of Ero1 may be important for fine-tuning the regulation of ER redox homeostasis and quality control.

  18. Eros u Vetranovićevoj Istoriji od Dijane

    Directory of Open Access Journals (Sweden)

    Krešimir Šimić

    2014-03-01

    Full Text Available Eros in Vetranović's Istorija od Dijane After the discovery of the Perast and Milan manuscripts, namely the complete text of Vetranović's Istorija od Dijane, not much has been written about this dramatic work. This paper focuses on a scene near the end of the play which describes Mercury's intervention after Diana frees Cupid. The intervention of the messengers of the Gods invites a procreative interpretation of Eros, which is a certain specificity in relation to other Croatian and, to go even further, other pastorals of the sixteenth century.

  19. Eros as godsdiens (of die religieuse viering van seks

    Directory of Open Access Journals (Sweden)

    Eben Scheffler

    2008-01-01

    Full Text Available Eros as religion (or the religious celebration of sex This article unashamedly argues for the positive value of sexuality and its profound religious dimensions. A stance is taken that goes beyond moralizing and ethicizing. The relationship in the Bible between eros and religion is explored by referring to the sexual image of God in Genesis 1:26-27, the religious dimension of the book of Song of Songs and Jesus’ stance in contrast with that of Paul. Through religion humans’ sexual experience should be enhanced in stead of being suppressed. Society should be sexualized.

  20. 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...

  1. Asteroid Redirect Crewed Mission Nominal Design and Performance

    Science.gov (United States)

    Condon, Gerald; williams, Jacob

    2014-01-01

    Mission (ARCM) nominal design and performance costs associated with an Orion based crewed rendezvous mission to a captured asteroid in an Earth-Moon DRO. The ARM study includes two fundamental mission phases: 1) The Asteroid Redirect Robotic Mission (ARRM) and 2) the ARCM. The ARRM includes a solar electric propulsion based robotic asteroid return vehicle (ARV) sent to rendezvous with a selected near Earth asteroid, capture it, and return it to a DRO in the Earth-Moon vicinity. The DRO is selected over other possible asteroid parking orbits due to its achievability (by both the robotic and crewed vehicles) and by its stability (e.g., no orbit maintenance is required). After the return of the asteroid to the Earth-Moon vicinity, the ARCM is executed and carries a crew of two astronauts to a DRO to rendezvous with the awaiting ARV with the asteroid. The outbound and inbound transfers employ lunar gravity assist (LGA) flybys to reduce the Orion propellant requirement for the overall nominal mission, which provides a nominal mission with some reserve propellant for possible abort situations. The nominal mission described in this report provides a better understanding of the mission considerations as well as the feasibility of such a crewed mission, particularly with regard to spacecraft currently undergoing development, such as the Orion vehicle and the Space Launch System (SLS).

  2. Applied Astronomy: Asteroid Prospecting

    Science.gov (United States)

    Elvis, M.

    2013-09-01

    In the age of asteroid mining the ability to find promising ore-bearing bodies will be valuable. This will give rise to a new discipline- "Applied Astronomy". Just as most geologists work in industry, not in academia, the same will be true of astronomers. Just how rare or common ore-rich asteroids are likely to be, and the skills needed to assay their value, are discussed here, with an emphasis on remote - telescopic - methods. Also considered are the resources needed to conduct extensive surveys of asteroids for prospecting purposes, and the cost and timescale involved. The longer-term need for applied astronomers is also covered.

  3. Near-Sun asteroids

    Science.gov (United States)

    Emel'yanenko, V. V.

    2017-01-01

    As follows from dynamical studies, in the course of evolution, most near-Earth objects reach orbits with small perihelion distances. Changes of the asteroids in the vicinity of the Sun should play a key role in forming the physical properties, size distribution, and dynamical features of the near-Earth objects. Only seven of the discovered asteroids are currently moving along orbits with perihelion distances q orbits farther from the Sun. In this study, we found asteroids that have been recently orbiting with perihelion distances q orbits for hundreds to tens of thousands of years. To carry out astrophysical observations of such objects is a high priority.

  4. Giorgio Perlasca, 'Giusto tra le nazioni' e 'eroe italiano'

    NARCIS (Netherlands)

    Jansen, M.M.

    2008-01-01

    Giorgio Perlasca che, fingendosi console spagnolo, nel 1944 salvò più di cinquemila ebrei ungheresi a Budapest, è stato proclamato “Giusto tra le Nazioni” a Yad Vashem nel 1989, dopo di che è seguito il suo riconoscimento all’estero ed in Italia come “uomo giusto” e come “eroe italiano”. Dopo il

  5. Giorgio Perlasca, 'Giusto tra le nazioni' e 'eroe italiano'

    NARCIS (Netherlands)

    Jansen, M.M.

    2008-01-01

    Giorgio Perlasca che, fingendosi console spagnolo, nel 1944 salvò più di cinquemila ebrei ungheresi a Budapest, è stato proclamato “Giusto tra le Nazioni” a Yad Vashem nel 1989, dopo di che è seguito il suo riconoscimento all’estero ed in Italia come “uomo giusto” e come “eroe italiano”. Dopo il fil

  6. J. M. Coetzee’s Disgrace: Eros, (Disgrace, & the Body

    Directory of Open Access Journals (Sweden)

    Shadi Neimneh

    2013-03-01

    Full Text Available This paper looks at the problematic of the body in Coetzee’s novel Disgrace. It argues that the novel’s protagonist is initially driven by eros, impulsive sexual desires beyond his control. However, Lurie’s conception of the body changes in the course of the novel from one dominated by eros to an ethical one associated with (dishonor and (disgrace. Rather than a self-centered eros, Lurie’s new awareness of the body is one based on our essential embodiment and the humiliations of dying and ageing. This is why his new understanding of the body, which is the result of a change in his personality, makes him care about the body of the other. Lurie spends much time trying to "honor" the bodies of dead dogs or simply spare them from the disgrace of dying. My reading of the novel explores an ethical conception of the body in Coetzee’s novel. Already a contested political site, the body in Coetzee’s novel emerges as an ethically (and psychoanalytically nuanced one.  Keywords: Coetzee; Post-Apartheid/South African Literature; Body; Eros; Ethics; (Disgrace

  7. Space weathering of asteroids

    CERN Document Server

    Shestopalov, D I; Cloutis, E A

    2012-01-01

    Analysis of laboratory experiments simulating space weathering optical effects on atmosphereless planetary bodies reveals that the time needed to alter the spectrum of an ordinary chondrite meteorite to resemble the overall spectral shape and slope of an S-type asteroid is about ~ 0.1 Myr. The time required to reduce the visible albedo of samples to ~ 0.05 is ~ 1 Myr. Since both these timescales are much less than the average collisional lifetime of asteroids larger than several kilometers in size, numerous low-albedo asteroids having reddish spectra with subdued absorption bands should be observed instead of an S-type dominated population. It is not the case because asteroid surfaces cannot be considered as undisturbed, unlike laboratory samples. We have estimated the number of collisions occurring in the time of 105 yr between asteroids and projectiles of various sizes and show that impact-activated motions of regolith particles counteract the progress of optical maturation of asteroid surfaces. Continual r...

  8. Hyperactivity of the Ero1α Oxidase Elicits Endoplasmic Reticulum Stress but No Broad Antioxidant Response

    DEFF Research Database (Denmark)

    Hansen, Henning Gram; Schmidt, Jonas Damgard; Soltoft, Cecilie Lutzen

    2012-01-01

    Oxidizing equivalents for the process of oxidative protein folding in the endoplasmic reticulum (ER) of mammalian cells are mainly provided by the Ero1α oxidase. The molecular mechanisms that regulate Ero1α activity in order to harness its oxidative power are quite well understood. However......, the overall cellular response to oxidative stress generated by Ero1α in the lumen of the mammalian ER is poorly characterized. Here we investigate the effects of overexpressing a hyperactive mutant (C104A/C131A) of Ero1α. We show that Ero1α hyperactivity leads to hyperoxidation of the ER oxidoreductase ERp57...... the cellular glutathione redox buffer, we conclude that the observed effects of Ero1α-C104A/C131A overexpression are likely caused by an oxidative perturbation of the ER glutathione redox buffer. In accordance, we show that Ero1α hyperactivity affects cell viability when cellular glutathione levels...

  9. Target selection and transfer trajectories design for exploring asteroid mission

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Technique of target selection and profiles of transfer trajectory for Chinese asteroid exploring mission are studied systemically.A complete set of approaches to selecting mission targets and designing the transfer trajectory is proposed.First,when selecting a target for mission,some factors regarded as the scientific motivations are discussed.Then,when analyzing the accessibility of targets,instead of the classical strategy,the multiple gravity-assist strategy is provided.The suitable and possible targets,taking into account scientific value and technically feasible,are obtained via selection and estimation.When designing the transfer trajectory for exploring asteroid mission,an approach to selecting gravity-assist celestial body is proposed.Finally,according to the mission constraints,the trajectory profile with 2-years △V-EGA for exploring asteroid is presented.Through analyzing the trajectory profile,unexpected result that the trajectory would pass by two main-belts asteroids is found.So,the original proposal is extended to the multiple flybys mission.It adds the scientific return for asteroid mission.

  10. The Advanced Jovian Asteroid Explorer (AJAX)

    Science.gov (United States)

    Murchie, S. L.; Adams, E. Y.; Mustard, J. F.; Rivkin, A.; Peplowski, P. N.

    2015-12-01

    The Advanced Jovian Asteroid eXplorer (AJAX) is the first mission to characterize the geology, morphology, geophysical properties, and chemistry of a Trojan asteroid. The Decadal Survey outlined a notional New Frontiers class Trojan asteroid rendezvous mission to conduct geological, elemental composition, mineralogical, and geophysical investigations. AJAX, our Discovery mission proposal, addresses the Decadal Survey science goals by using a focused payload and an innovative mission design. By responding to the most important questions about the Trojan asteroids, AJAX advances our understanding of all of the Solar System. Are these objects a remnant population of the local primordial material from which the outer planets and their satellites formed, or did they originate in the Kuiper Belt? Landed measurements of major and minor elements test hypotheses for the Trojan asteroid origin, revealing the outer Solar System dynamical history. How and when were prebiotic materials delivered to the terrestrial planets? AJAX's landed measurements include C and H concentrations, necessary to determine their inventories of volatiles and organic compounds, material delivered to the inner Solar System during the Late Heavy Bombardment. What chemical and geological processes shaped the small bodies that merged to form the planets in our Solar System? AJAX investigates the asteroid internal structure, geology, and regolith by using global high-resolution stereo and multispectral imaging, determining density and estimating interior porosity by measuring gravity, and measuring regolith mechanical properties by landing. AJAX's science phase starts with search for natural satellites and dust lifted by possible cometary activity and shape and pole position determination. AJAX descends to lower altitudes for global mapping, and conducts a low flyover for high-resolution surface characterization and measurement of hydrogen abundance. Finally, it deploys a small landed package, which

  11. The partial fission of fast spinning asteroids

    Science.gov (United States)

    Tardivel, Simon; Sanchez, Paul; Scheeres, Daniel J.

    2016-10-01

    The spin rates of asteroids systematically change over time due the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. Above a certain spin rate that depends on the body's density, regions of an asteroid can enter in tension, with components held to the body by cohesive forces. When the body fails, deformation or fission can occur. Catastrophic fission leading to complete disruption has been directly observed in active asteroid P/2013 R3. Partial fission, the loss of only part of the body, has been proposed as a mechanism for the formation of binaries and is explored here.The equatorial cavities of (341843) 2008 EV5 and of (185851) 2000 DP107 (a binary system) are consistent with a localized partial fission of the body (LPSC 2016 #1036). The examination of the gravity field of these bodies reveals that a mass placed within these cavities could be shed. In this mechanism, the outward pull of inertial forces creates an average stress at the cavity interface of ≈1 Pa for 2008 EV5 and ≈3 Pa for 2000 DP107 at spin periods of ≈3.15 h for the assumed densities of 1.3 g/cm3.This work continues the study of this partial, localized fission. Specifically, it addresses the issue of the low cohesion necessary to the mechanism. These cohesion values are typically lower than global strength values inferred on other asteroids (10 - 200 Pa), meaning that partial fission may occur prior to larger-scale deformations. Yet, several processes can explain the discrepancy, as they can naturally segregate particles by size. For instance, landslides or granular convection (Brazil nut effect) could bring larger boulders to the equator of the body, while finer particles are left at higher latitudes or sink to the center. Conversely, failure of the interior could bring boulders to the surface. The peculiar profile shape of these asteroids, shared by many binaries (e.g. 1999 KW4, 1996 FG3) may also be a clue of this heterogeneity, as this "spin top" shape is obtained in simulations with

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

    Science.gov (United States)

    Frantseva, Kateryna; Mueller, Michael; ten Kate, Inge L.; van der Tak, Floris

    2016-10-01

    Despite intensive search, the presence of organic molecules on Mars could only recently be demonstrated, through Curiosity measurements. On the surface of Mars, organics are highly unstable to photodissociation, but may last longer in the subsurface. It is therefore believed that organics observable today were delivered in geologically recent times; possible parent bodies are certain asteroids, comets, and/orinterplanetary dust particles.We are studying how much organics the known asteroids and comets can deliver to Mars. Comets and certain asteroids (C-class) are known to be organic rich.To this end we perform numerical gravity simulations to study impact rates on Mars within the past few Myr. We use the N-body integrator RMVS/Swifter to propagate the Sun and the eight planets from their current positions. We separately add comets and asteroids to the simulations as massless test particles, based on their current orbital distributions. In our asteroid simulations we differentiate between organic-rich (C-class) asteroids and other taxonomic types, using WISE albedo as a proxy. We expect to present first results at the meeting.

  13. A face pedagógica de Eros The pedagogical face of Eros

    Directory of Open Access Journals (Sweden)

    Marlene de Souza Dozol

    2007-08-01

    Full Text Available O presente trabalho busca descobrir a face pedagógica de Eros. Como ponto de partida, está o fato de a figura do educador/professor ser comumente representado por alguém cuja ocupação não suscita desejos de qualquer espécie. Não raras vezes assistimos a representações literárias e imagens televisivas ou cinematográficas nas quais o professor aparece comicamente como uma caricatura que fala, de modo monótono e sem parar, a alunos cujos rostos oscilam entre o tédio e o escárnio. No entanto, o que é de fato assustador é que, cada vez mais, as imagens que aparecem no discurso das novas gerações, numa tentativa de oposição à caricatura supracitada, associam a figura do professor à de um animador de auditório, performático, divertido, especialista em dinâmicas grupais catárticas, sem conteúdo e igualmente caricatural. Procurando, então, desviar-se de ambas as caricaturas e refletir sobre o gênero específico de libido pedagógica - compreendido como força ou energia espiritual para o progresso moral, intelectual e sensível -, o texto recupera o poder ilustrativo do mito, pensa sobre a força do imaginário na constituição de parâmetros modelares para a Educação e para o exercício da mestria (para isso, propõe notas socráticas, sofísticas e escolásticas com ênfase na linguagem e aponta para a importância dessa discussão diante dos problemas que habitam os espaços educativos contemporâneos.The present work seeks to uncover the pedagogical face of Eros. As a starting point, there is the fact that the figure of the educator/teacher is commonly represented by someone whose occupation does not elicit desires of any kind. It is not unusual to see literary representations and televised or cinema images in which the teacher appears comically as a caricature that talks continuously and monotonically to pupils whose countenances oscillate between boredom and scorn. But what is truly frightening is that, more and

  14. 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

  15. 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...

  16. 2015 Barcelona Asteroid Day

    CERN Document Server

    Gritsevich, Maria; Palme, Herbert

    2017-01-01

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

  17. Probing Galactic structure using micro-lensing with EROS-2

    CERN Document Server

    Ansari, R

    1999-01-01

    EROS has been monitoring few million stars in the Magellanic clouds, as well as toward the Galactic bulge and spiral arms since 1996, to search for microlensing events. In this paper, we present briefly the EROS setup and scientific program and discuss the results obtained from our observations in four directions in the Galactic plane, away from the bulge. Seven light curves, out of 9.1 million stars observed in these directions show luminosity variations interpreted as due to microlensing. The averaged estimated optical depth tau = 0.45 +0.24 -0.11 is compatible with expectations from simple Galactic models. Nonetheless a small excess of short time-scale events may be present in the direction closest to the Galactic center.

  18. 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.

  19. The Active Asteroids

    CERN Document Server

    Jewitt, Dave

    2011-01-01

    Some asteroids eject dust, unexpectedly producing transient, comet-like comae and tails. First ascribed to the sublimation of near-surface water ice, mass losing asteroids (also called "main-belt comets") can in fact be driven by a surprising diversity of mechanisms. In this paper, we consider eleven dynamical asteroids losing mass, in nine of which the ejected material is spatially resolved. We address mechanisms for producing mass loss including rotational instability, impact ejection, electrostatic repulsion, radiation pressure sweeping, dehydration stresses and thermal fracture, in addition to the sublimation of ice. In two objects (133P and 238P) the repetitive nature of the observed activity leaves ice sublimation as the only reasonable explanation while, in a third ((596) Scheila), a recent impact is the cause. Another impact may account for activity in P/2010 A2 but this tiny object can also be explained as having shed mass after reaching rotational instability. Mass loss from (3200) Phaethon is proba...

  20. Manuel's asteroid disruption technique.

    Science.gov (United States)

    John, Manuel; Ipe, Abraham; Jacob, Ivan

    2015-06-01

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

  1. Properties of the moon, Mars, Martian satellites, and near-earth asteroids

    Science.gov (United States)

    Taylor, Jeffrey G.

    1989-01-01

    Environments and surface properties of the moon, Mars, Martian satellites, and near-earth asteroids are discussed. Topics include gravity, atmospheres, surface properties, surface compositions, seismicity, radiation environment, degradation, use of robotics, and environmental impacts. Gravity fields vary from large fractions of the earth's field such as 1/3 on Mars and 1/6 on the moon to smaller fractions of 0.0004 g on an asteroid 1 km in diameter. Spectral data and the analogy with meteor compositions suggest that near-earth asteroids may contain many resources such as water-rich carbonaceous materials and iron-rich metallic bodies. It is concluded that future mining and materials processing operations from extraterrestrial bodies require an investment now in both (1) missions to the moon, Mars, Phobos, Deimos, and near-earth asteroids and (2) earth-based laboratory research in materials and processing.

  2. 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

  3. Asteroid Control and Resource Utilization

    Science.gov (United States)

    Paterson, G.; Radice, G.; Sanchez, J.-P.

    Asteroids are materials rich small solar system bodies which are prime candidates for rendezvous and mining. Up until now much attention has been focused on methods of destroying or deflecting potentially hazardous asteroids from colliding with the Earth. Recently however the concept of asteroid capture has been suggested whereby the asteroid is returned to an orbit close to the Earth before mining can begin. This paper aims to provide a comprehensive introduction to the field for new researchers and to put forward a number of novel strategies for asteroid control.

  4. NASA's Asteroid Redirect Mission (ARM)

    Science.gov (United States)

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

    2017-01-01

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

  5. A novel disulphide switch mechanism in Ero1 balances ER oxidation in human cells

    DEFF Research Database (Denmark)

    Appenzeller-Herzog, Christian; Riemer, Jan; Christensen, Brian

    2008-01-01

    a feedback loop where activation of Ero1 is linked to the availability of its substrate, reduced protein disulphide isomerase (PDI). Overexpression of Ero1 -Cys131Ala or the isoform Ero1 , which does not have an equivalent disulphide switch, leads to augmented ER oxidation. These data reveal a novel...... regulatory feedback system where PDI emerges as a central regulator of ER redox homoeostasis....

  6. 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....

  7. The Asteroid Frontier

    Science.gov (United States)

    Mcfadden, Lucyann A.

    2012-01-01

    There are many ways of studying the Asteroid Frontier as a scientist. In my career, I have used large telescopes atop a 14,000 ft mountain top observatory in Hawaii, used the Hubble Space Telescope in orbit around the Earth, traveled to Antarctica to collect meteorites sitting on the ice waiting for them to be recovered by scientists for scientific investigation, walked the desert with 50 students from University of Khartoum searching for fragments of an asteroid that collided with earth, exploded in the upper atmosphere and rained fragments on the desert floor. Most recently, I have looked at one of the largest Main Belt Asteroids named (4) Vesta through the eyes of a robotic spacecraft named Dawn, exploring the asteroid frontier. I will share my adventures, place the thrill of scientific exploration through NASA's solar system exploration program in context and provide opportunities for students to engage in NASA's exciting missions to expand scientific understanding of Earth and the Universe in which we live

  8. Asteroids, meteorites, and comets

    CERN Document Server

    Elkins-Tanton, Linda T

    2010-01-01

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

  9. Amor: Investigating The Triple Asteroid System 2001 SN263

    Science.gov (United States)

    Jones, T.; Bellerose, Julie; Lee, P.; Prettyman, T.; Lawrence, D.; Smith, P.; Gaffey, M.; Nolan, M.; Goldsten, J.; Thomas, P.; Veverka, J.; Farquhar, R.; Heldmann, J.; Reddy, V.; Williams, B.; Chartres, J.; DeRosee, R.; Dunham, D.

    2010-10-01

    The Amor mission will rendezvous and land at the triple Near-Earth Asteroid system (153591) 2001 SN263 and execute detailed, in-situ science investigations. The spacecraft reaches 2001 SN263 by using a two-year ΔVEGA (ΔV-Earth Gravity Assist) trajectory with a relatively low launch C3 of 33.5 km2/s2. Rendezvous will enable reconnaissance activities including global and regional imaging, shape modeling, system dynamics, and compositional mapping. After landing, Amor will conduct in-situ imaging (panoramic to microscopic scale) and compositional measurements to include elemental abundance. The main objectives are to 1) establish in-situ the long-hypothesized link between C-type asteroids and the primitive carbonaceous chondrite (CC) meteorites, 2) investigate the nature, origin and evolution of C-type asteroids, and 3) investigate the origin and evolution of a multiple asteroid system. The mission also addresses the distribution of volatiles and organic materials, impact hazards, and resources for future exploration. Amor is managed by NASA Ames Research Center in partnership with Orbital Sciences, KinetX, MDA, and Draper with heritage instruments provided by Ball Aerospace, JHU/APL, and Firestar Engineering. The science team brings experience from NEAR, Hayabusa, Deep Impact, Dawn, LCROSS, Kepler, and Mars missions. In this paper, we describe the science, mission design, and main operational challenges of performing in-situ science at this triple asteroid system. Challenges include landing on the asteroid components, thermal environment, short day-night cycles, and the operation of deployed instruments in a low gravity (10^-5 g) environment.

  10. Earth Resources Observation and Science (EROS) Center's Earth as Art Image Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages this collection of Landsat 7 scenes created for aesthetic purposes rather than scientific...

  11. 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.

  12. Visualization of Near-Infrared Spectral Data of Eros Using the Small Body Mapping Tool

    Science.gov (United States)

    Klima, Rachel L.; Ernst, Carolyn

    2016-10-01

    One of the primary drivers for many missions visiting asteroids is to advance our understanding of their composition beyond what can be (and is) already measured by telescopes. Without sample return or lander missions, this task relies primarily on resolved near-infrared spectroscopic measurements. Scientific analysis using spectral data collected by point spectrometers is not as straightforward as for imaging spectrometers, where the local spatial context is immediately available. In the case of Eros and other highly non-spherical bodies, this problem becomes even more severe when trying to locate spectra that cross a mapped feature that bends over an irregularly shaped surface. Thus, it is often the case that outside of the mission teams, few from the community at large delve into these data sets, as they lack the tools necessary to incorporate the spectral information into geological analyses of the asteroids. Ultimately, we seek to make such spectral datasets, which NASA has invested significant amounts of money to obtain, more widely accessible and user-friendly. The Small Bodies Mapping Tool (SBMT) is a Java-based, interactive, three-dimensional visualization tool written and developed at APL to map and analyze features on irregularly shaped solar system bodies. The SBMT can be used to locate and then "drape" spacecraft images, spectra, and laser altimetry around the shape model of such bodies. It provides a means for rapid identification of available data in a region of interest and allows features to be mapped directly onto the shape model. The program allows the free rotation of a shape model (including any overlain data) in all directions, so that the correlation and distribution of mapped features can be easily and globally observed.We will present the results of our work on the NEAR/Near-Infrared Spectrograph (NIS) data, including improvements to the calibration made by using the geometric information provided by the SBMT and improvements to the SMBT

  13. Calculating the Potato Radius of Asteroids using the Height of Mt. Everest

    CERN Document Server

    Caplan, M E

    2015-01-01

    At approximate radii of 200-300 km, asteroids transition from oblong `potato' shapes to spheres. This limit is known as the Potato Radius, and has been proposed as a classification for separating asteroids from dwarf planets. The Potato Radius can be calculated from first principles based on the elastic properties and gravity of the asteroid. Similarly, the tallest mountain that a planet can support is also known to be based on the elastic properties and gravity. In this work, a simple novel method of calculating the Potato Radius is presented using what is known about the maximum height of mountains and Newtonian gravity for a spherical body. This method does not assume any knowledge beyond high school level mechanics, and may be appropriate for students interested in applications of physics to astronomy.

  14. Gravity Before Einstein and Schwinger Before Gravity

    Science.gov (United States)

    Trimble, Virginia L.

    2012-05-01

    Julian Schwinger was a child prodigy, and Albert Einstein distinctly not; Schwinger had something like 73 graduate students, and Einstein very few. But both thought gravity was important. They were not, of course, the first, nor is the disagreement on how one should think about gravity that is being highlighted here the first such dispute. The talk will explore, first, several of the earlier dichotomies: was gravity capable of action at a distance (Newton), or was a transmitting ether required (many others). Did it act on everything or only on solids (an odd idea of the Herschels that fed into their ideas of solar structure and sunspots)? Did gravitational information require time for its transmission? Is the exponent of r precisely 2, or 2 plus a smidgeon (a suggestion by Simon Newcomb among others)? And so forth. Second, I will try to say something about Scwinger's lesser known early work and how it might have prefigured his "source theory," beginning with "On the Interaction of Several Electrons (the unpublished, 1934 "zeroth paper," whose title somewhat reminds one of "On the Dynamics of an Asteroid," through his days at Berkeley with Oppenheimer, Gerjuoy, and others, to his application of ideas from nuclear physics to radar and of radar engineering techniques to problems in nuclear physics. And folks who think good jobs are difficult to come by now might want to contemplate the couple of years Schwinger spent teaching elementary physics at Purdue before moving on to the MIT Rad Lab for war work.

  15. Capture of Asteroids and Transport of Asteroid Materials to Earth

    Science.gov (United States)

    Chiu, Hong-Yee; no Team

    2014-01-01

    Recently there has been much discussion on the capture of asteroids or mining the asteroids. While the technology might be years away, in this paper we will discuss an energy efficient method to transport either a small asteroid or materials gathered from asteroids to the Earth. In particular, I will concentrate on a large and nearby asteroid, 8 Flora in the Flora Family. Generally, asteroids are located between 2 to 3 AU (astronomical unit) from the Earth, and in transporting materials from asteroids to the Earth, an energy equivalent of the gravitational potential energy difference between the Earth and the asteroids to the Sun. This amount of potential energy is a sizable fraction of the orbital kinetic energy of the Earth around the Sun. This amount of energy is considerable. In this paper I propose to use the planet Mars as a medium to remove much of the gravitational energy difference. In the case of the asteroid 8 Flora, it is only necessary to decelerate the asteroid mate- rials by a small decrement, of the order of 3 km/sec. This decrement could even be achieved (pending on the availability of technology) by mechanical devices such as catapults on 8 Flora. It is also proposed to separate a pair of contact asteroid binaries by using impulse propulsion, and to propel one component of the separated asteroids to pass by Mars to be decelerated to reach the Earth orbit and captured by the Earth or the Moon. The plausibility of this ambitious project will be discussed. The author is NASA-GSFC Astrophysicist, Retired.

  16. EURONEAR - Data Mining of Asteroids and Near Earth Asteroids

    OpenAIRE

    Vaduvescu, O.; Curelaru, L.; Birlan, M.; Bocsa, G.; Serbanescu, L.; Tudorica, A.; Berthier, J.

    2009-01-01

    Besides new observations, mining old photographic plates and CCD image archives represents an opportunity to recover and secure newly discovered asteroids, also to improve the orbits of Near Earth Asteroids (NEAs), Potentially Hazardous Asteroids (PHAs) and Virtual Impactors (VIs). These are the main research aims of the EURONEAR network. As stated by the IAU, the vast collection of image archives stored worldwide is still insufficiently explored, and could be mined for known NEAs and other a...

  17. 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

  18. Active Asteroids: Main-Belt Comets and Disrupted Asteroids

    CERN Document Server

    Hsieh, Henry H

    2015-01-01

    The study of active asteroids has attracted a great deal of interest in recent years since the recognition of main-belt comets (which orbit in the main asteroid belt, but exhibit comet-like activity due to the sublimation of volatile ices) as a new class of comets in 2006, and the discovery of the first disrupted asteroids (which, unlike MBCs, exhibit comet-like activity due to a physical disruption such as an impact or rotational destabilization, not sublimation) in 2010. In this paper, I will briefly discuss key areas of interest in the study of active asteroids.

  19. Asteroid family ages

    CERN Document Server

    Spoto, Federica; Knezevic, Zoran

    2015-01-01

    A new family classification, based on a catalog of proper elements with $\\sim 384,000$ numbered asteroids and on new methods is available. For the $45$ dynamical families with $>250$ members identified in this classification, we present an attempt to obtain statistically significant ages: we succeeded in computing ages for $37$ collisional families. We used a rigorous method, including a least squares fit of the two sides of a V-shape plot in the proper semimajor axis, inverse diameter plane to determine the corresponding slopes, an advanced error model for the uncertainties of asteroid diameters, an iterative outlier rejection scheme and quality control. The best available Yarkovsky measurement was used to estimate a calibration of the Yarkovsky effect for each family. The results are presented separately for the families originated in fragmentation or cratering events, for the young, compact families and for the truncated, one-sided families. For all the computed ages the corresponding uncertainties are pro...

  20. Asteroid Impact Monitoring

    Science.gov (United States)

    Milani, A.

    2006-06-01

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

  1. Asteroid impact monitoring

    Directory of Open Access Journals (Sweden)

    Milani A.

    2006-01-01

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

  2. 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.

  3. 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.

  4. The Rafita asteroid family

    Science.gov (United States)

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

    2017-01-01

    The Rafita asteroid family is an S-type group located in the middle main belt, on the right side of the 3J:-1A mean-motion resonance. The proximity of this resonance to the family left side in semi-major axis caused many former family members to be lost. As a consequence, the family shape in the (a, 1/D) domain is quite asymmetrical, with a preponderance of objects on the right side of the distribution. The Rafita family is also characterized by a leptokurtic distribution in inclination, which allows the use of methods of family age estimation recently introduced for other leptokurtic families such as Astrid, Hansa, Gallia, and Barcelona. In this work we propose a new method based on the behavior of an asymmetry coefficient function of the distribution in the (a, 1/D) plane to date incomplete asteroid families such as Rafita. By monitoring the time behavior of this coefficient for asteroids simulating the initial conditions at the time of the family formation, we were able to estimate that the Rafita family should have an age of 490 ± 200 Myr, in good agreement with results from independent methods such as Monte Carlo simulations of Yarkovsky and Yorp dynamical induced evolution and the time behaviour of the kurtosis of the sin (i) distribution. Asteroids from the Rafita family can reach orbits similar to 8% of the currently known near Earth objects. ≃1% of the simulated objects are present in NEO-space during the final 10 Myr of the simulation, and thus would be comparable to objects in the present-day NEO population.

  5. 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.

  6. Modeling of Fragmentation of Asteroids

    Science.gov (United States)

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

    2015-01-01

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

  7. ERO Caught in the Act (Again): Limiting Inclusion to Suit Policy

    Science.gov (United States)

    McMaster, Christopher

    2013-01-01

    In 2010 the Education Review Office (ERO) was tasked with reporting on the progress of New Zealand schools in the inclusion of students with high needs. This paper will explore how ERO limited the concept of inclusion to suit Government policy and limit discussion of inclusion to the parameters set by the resource allocation scheme known as…

  8. Genetic interaction between the ero1-1 and leu2 mutations in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    López-Mirabal, H Reynaldo; Winther, Jakob R; Kielland-Brandt, Morten C

    2007-01-01

    The conditional ero1-1 mutant, deficient in the ER-localized PDI oxidase Ero1p, is blocked in disulfide bond formation under restrictive conditions, such as high temperature, lack of oxygen, or high concentrations of membrane-permeant thiols. Previous studies of the physiological consequences...

  9. 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

  10. Geospatial Visualization of Global Satellite Images with Vis-EROS

    Energy Technology Data Exchange (ETDEWEB)

    Standart, G. D.; Stulken, K. R.; Zhang, Xuesong; Zong, Ziliang

    2011-04-13

    The Earth Resources Observation and Science (EROS) Center of U.S. Geological Survey is currently managing and maintaining the world largest satellite images distribution system, which provides 24/7 free download service for researchers all over the globe in many areas such as Geology, Hydrology, Climate Modeling, and Earth Sciences. A large amount of geospatial data contained in satellite images maintained by EROS is generated every day. However, this data is not well utilized due to the lack of efficient data visualization tools. This software implements a method for visualizing various characteristics of the global satellite image download requests. More specifically, Keyhole Markup Language (KML) files are generated which can be loaded into an earth browser such as Google Earth. Colored rectangles associated with stored satellite scenes are painted onto the earth browser; and the color and opacity of each rectangle is varied as a function of the popularity of the corresponding satellite image. An analysis of the geospatial information obtained relative to specified time constraints provides an ability to relate image download requests to environmental, political, and social events.

  11. CD-ROM technology at the EROS data center

    Science.gov (United States)

    Madigan, Michael E.; Weinheimer, Mary C.

    1993-01-01

    The vast amount of digital spatial data often required by a single user has created a demand for media alternatives to 1/2" magnetic tape. One such medium that has been recently adopted at the U.S. Geological Survey's EROS Data Center is the compact disc (CD). CD's are a versatile, dynamic, and low-cost method for providing a variety of data on a single media device and are compatible with various computer platforms. CD drives are available for personal computers, UNIX workstations, and mainframe systems, either directly connected, or through a network. This medium furnishes a quick method of reproducing and distributing large amounts of data on a single CD. Several data sets are already available on CD's, including collections of historical Landsat multispectral scanner data and biweekly composites of Advanced Very High Resolution Radiometer data for the conterminous United States. The EROS Data Center intends to provide even more data sets on CD's. Plans include specific data sets on a customized disc to fulfill individual requests, and mass production of unique data sets for large-scale distribution. Requests for a single compact disc-read only memory (CD-ROM) containing a large volume of data either for archiving or for one-time distribution can be addressed with a CD-write once (CD-WO) unit. Mass production and large-scale distribution will require CD-ROM replication and mastering.

  12. Numeric Modeling of Granular Asteroid Growth

    Science.gov (United States)

    Beaumont, Benjamin; Lazzati, D.

    2014-01-01

    It is believed that planetesimals and asteroids are created by the constructive collisions of smaller objects, loosely bound under the effect of self-gravity and/or contact forces. However, the internal dynamics of these collisions and whether they trigger growth or fragmentation are poorly understood. Prior research in the topic has established regimes for the results of constructive collisions of particles under contact forces, but neglects gravity, a critical component once particles are no longer touching, and force chains, an uneven distribution of force inherent to granular materials. We run simulations binary collisions of clusters of particles modeled as hard spheres. Our simulations take into account self-gravity, dissipation of energy, friction, and use a potential function for overlapping particles to study force chains. We present here the collision outcome for clusters with variable masses, particle counts, velocities, and impact parameter. We compare our results to other models and simulations, and find that the collisions remain constructive at higher energies than classically predicted.

  13. AIDA: Asteroid Impact & Deflection Assessment

    Science.gov (United States)

    Cheng, A. F.; Galvez, A.; Carnelli, I.; Michel, P.; Rivkin, A.; Reed, C.

    2012-12-01

    To protect the Earth from a hazardous asteroid impact, various mitigation methods have been proposed, including deflection of the asteroid by a spacecraft impact. AIDA, consisting of two mission elements, the Double Asteroid Redirection Test (DART) and the Asteroid Impact Monitoring (AIM) mission, is a demonstration of asteroid deflection. To date, there has been no such demonstration, and there is major uncertainty in the result of a spacecraft impact onto an asteroid, that is, the amount of deflection produced by a given momentum input from the impact. This uncertainty is in part due to unknown physical properties of the asteroid surface, such as porosity and strength, and in part due to poorly understood impact physics such that the momentum carried off by ejecta is highly uncertain. A first mission to demonstrate asteroid deflection would not only be a major step towards gaining the capability to mitigate an asteroid hazard, but in addition it would return unique information on an asteroid's strength, other surface properties, and internal structure. This information return would be highly relevant to future human exploration of asteroids. We report initial results of the AIDA joint mission concept study undertaken by the Johns Hopkins Applied Physics Laboratory and ESA with support from NASA centers including Goddard, Johnson and Jet Propulsion Laboratory. For AIDA, the DART spacecraft impactor study is coordinated with an ESA study of the AIM mission, which would rendezvous with the same asteroid to measure effects of the impact. Unlike the previous Don Quijote mission study performed by ESA in 2005-2007, DART envisions an impactor spacecraft to intercept the secondary member of a binary near-Earth asteroid. DART includes ground-based observations to measure the deflection independently of the rendezvous spacecraft observations from AIM, which also measures deflection and provides detailed characterization of the target asteroid. The joint mission AIDA

  14. Reconstructing the spin distributions of main-belt asteroids

    Science.gov (United States)

    Holsapple, K.

    2014-07-01

    INTRODUCTION: We now have spin data for almost six thousand asteroids, each value being a result of that asteroid's history. Some features of that distribution are now evident. The gravity spin limit at the period of about 2.3 h for asteroids with a diameter greater than a few kilometers is well established (Harris 1996, Pravec and Harris 2000, Holsapple 2001, and others). The strength of smaller asteroids as inferred from the ''fast spinners'' has been presented by Holsapple (2007), Sanchez and Scheeres (2014), and others. Several statistical analyses of the database have been presented (e.g., Pravec and Harris 2002). Here that database is used as a means of investigating the prior history of the asteroid belt. THEORETICAL APPROACHES: A way to understand the data is to attempt to reproduce it using theoretical models and numerical simulations of the physics of the processes that created it. Such studies have evolved since McAdoo and Burns (1973) first suggested collisions as a source of the spins; they include Davis et al. (1979), Dobrovolskis and Burns (1984), Harris (1979), Davis et al. (1989), Farinella et al. (1992), Henych and Pravec (2013), and others. These analyses are based upon averaging the effects of a number of individual impacts into a given target asteroid. I retrace the path and analyses of those authors in this work, but make important modifications and updates. The primary elements introduced in those prior studies include: 1) a population of asteroids in a given space; 2) a distribution of impact velocities and angles; 3) the efficiency of angular-momentum transfer in an impact; 4) the loss or gain of mass and angular inertia; 5) the amount, direction, and speed of the cratering ejecta. The characteristics of the ejecta are especially important: they determine the ''angular-momentum drain'' first identified by Dobrovolskis and Burns (1984). It is caused by the preferential escape of ejecta in the downrange spin direction. Here I revisit, update

  15. EURONEAR - Data Mining of Asteroids and Near Earth Asteroids

    CERN Document Server

    Vaduvescu, O; Birlan, M; Bocsa, G; Serbanescu, L; Tudorica, A; Berthier, J

    2009-01-01

    Besides new observations, mining old photographic plates and CCD image archives represents an opportunity to recover and secure newly discovered asteroids, also to improve the orbits of Near Earth Asteroids (NEAs), Potentially Hazardous Asteroids (PHAs) and Virtual Impactors (VIs). These are the main research aims of the EURONEAR network. As stated by the IAU, the vast collection of image archives stored worldwide is still insufficiently explored, and could be mined for known NEAs and other asteroids appearing occasionally in their fields. This data mining could be eased using a server to search and classify findings based on the asteroid class and the discovery date as "precoveries" or "recoveries". We built PRECOVERY, a public facility which uses the Virtual Observatory SkyBoT webservice of IMCCE to search for all known Solar System objects in a given observation. To datamine an entire archive, PRECOVERY requires the observing log in a standard format and outputs a database listing the sorted encounters of ...

  16. Photometric Study of Selected Asteroids

    Science.gov (United States)

    Shevchenko, Vasilij G.; Velichko, Feodor P.; Checha, Vitaly A.; Krugly, Yurij N.

    2014-07-01

    We performed photometric observations for eleven asteroids. New rotation periods were determined for five asteroids: 2812 Scaltriti (7.596 h), 4716 Urey (6.2 h), 7446 Hadrianus (3.402 h), (26657) 2000 SX293 (2.8 - 3.8 h), and (54063) 2000 GC136 (5.154 h).

  17. Radar Observations of Asteroids

    Science.gov (United States)

    Ostro, S. J.

    2003-05-01

    During the past 25 years, radar investigations have provided otherwise unavailable information about the physical and dynamical properties of more than 200 asteroids. Measurements of the distribution of echo power in time delay and Doppler frequency provide two-dimensional images with spatial resolution as fine as a decameter. Sequences of delay-Doppler images can be used to produce geologically detailed three-dimensional models, to define the rotation state precisely, to constrain the internal density distribution, and to estimate the trajectory of the object's center of mass. Radar wavelengths (4 to 13 cm) and the observer's control of transmitted and received polarizations make the observations sensitive to near-surface bulk density and macroscopic structure. Since delay-Doppler positional measurements are orthogonal to optical angle measurements and typically have much finer fractional precision, they are powerful for refining orbits and prediction ephemerides. Radar astrometry can add decades or centuries to the interval over which an asteroid's close Earth approaches can accurately be predicted and can significantly refine collision probability estimates based on optical astrometry alone. In the highly unlikely case that a small body is on course for an Earth collision in this century, radar reconnaissance would almost immediately distinguish between an impact trajectory and a near miss and would dramatically reduce the difficulty and cost of any effort to prevent the collision. The sizes and rotation periods of radar-detected asteroids span more than four orders of magnitude. These observations have revealed both stony and metallic objects, elongated and nonconvex shapes as well as nearly featureless spheroids, small-scale morphology ranging from smoother than the lunar regolith to rougher than the rockiest terrain on Mars, craters and diverse linear structures, non-principal-axis spin states, contact binaries, and binary systems.

  18. Radar Investigations of Asteroids

    Science.gov (United States)

    Ostro, S.

    2004-05-01

    Radar investigations have provided otherwise unavailable information about the physical and dynamical properties of about 230 asteroids. Measurements of the distribution of echo power in time delay (range) and Doppler frequency (line-of-sight velocity) provide two-dimensional images with spatial resolution as fine as a decameter. Sequences of delay-Doppler images can be used to produce geologically detailed three-dimensional models, to define the rotation state precisely, to constrain the internal density distribution, and to estimate the trajectory of the object's center of mass. Radar wavelengths (4 to 13 cm) and the observer's control of transmitted and received polarizations make the observations sensitive to near-surface bulk density and macroscopic structure. Since delay-Doppler measurements are orthogonal to optical angle measurements and typically have much finer fractional precision, they are powerful for refining orbits and prediction ephemerides. Such astrometric measurements can add decades or centuries to the interval over which an asteroid's close Earth approaches can accurately be predicted and can significantly refine collision probability estimates based on optical astrometry alone. In the highly unlikely case that a small body is on course for an Earth collision in this century, radar reconnaissance would almost immediately distinguish between an impact trajectory and a near miss and would dramatically reduce the difficulty and cost of any effort to prevent the collision. The sizes and rotation periods of radar-detected asteroids span more than four orders of magnitude. The observations have revealed both stony and metallic objects, elongated and nonconvex shapes as well as nearly featureless spheroids, small-scale morphology ranging from smoother than the lunar regolith to rougher than the rockiest terrain on Mars, craters and diverse linear structures, non-principal-axis spin states, contact binaries, and binary systems.

  19. 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.

  20. 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...

  1. MODIS land data at the EROS data center DAAC

    Science.gov (United States)

    Jenkerson, C.B.; Reed, B.C.

    2001-01-01

    The US Geological Survey's (USGS) Earth Resources Observation Systems (EROS) Data Center (EDC) in Sioux Falls, SD, USA, is the primary national archive for land processes data and one of the National Aeronautics and Space Administration's (NASA) Distributed Active Archive Centers (DAAC) for the Earth Observing System (EOS). One of EDC's functions as a DAAC is the archival and distribution of Moderate Resolution Spectroradiometer (MODIS) Land Data collected from the Earth Observing System (EOS) satellite Terra. More than 500,000 publicly available MODIS land data granules totaling 25 Terabytes (Tb) are currently stored in the EDC archive. This collection is managed, archived, and distributed by EOS Data and Information System (EOSDIS) Core System (ECS) at EDC. EDC User Services support the use of MODIS Land data, which include land surface reflectance/albedo, temperature/emissivity, vegetation characteristics, and land cover, by responding to user inquiries, constructing user information sites on the EDC web page, and presenting MODIS materials worldwide.

  2. Sylvia Plath - a woman between Eros and Thanatos

    Directory of Open Access Journals (Sweden)

    Barbara Galle

    2005-12-01

    Full Text Available The opposition between the Hughes family  and the radical feminists led to the emergence of two diametrically opposite Plath  myths: a mentally disturbed, manipulative woman, unstoppably driven towards suicide, or an innocent victim of a treacherous husband? Both sides interpret Plath's life and works in view of her untimely  death, neglecting the underlying life force that pervades her poetry and prose. Relying on the psychoanalytical theory of instincts, the author shows how Eros complements and even makes use of Thanatos on different levels of Plath's writing:  on the level of language asa meaningful structure, on the level of meaning, and in the function of language as therapy. The duality of instics is particulary evident in Sloveirian criticism; where the physicar  and temporal distance from political scandal enabled the development oftwo distinct critical currents: one following Hughes's morbid determinism, the other concentrating on Plath's intelligence and joyful observation of nature.

  3. JOSÉ DONOSO O EL EROS DE LA HOMOFOBIA

    Directory of Open Access Journals (Sweden)

    Miguel Ángel Náter

    2006-04-01

    Full Text Available El artículo destaca la importancia de los "Papeles de Donoso", custodiados en la Universidad de Iwoa, en relación con las ideas de Julio Ortega sobre los mismos, vertidas en el periódico La Tercera de Chile. Además, se realiza una lectura de la homofobia como expresión del eros subrepticio en las novelas El lugar sin límites y El obsceno pájaro de la noche. En contraste con las exposiciones homoeróticas que Ortega señala en los documentos de Donoso, los narradores de las dos novelas más destacadas del escritor chileno expresan un rechazo continuo hacia los personajes marginales, o bien exponen la sodomía como un forma de expresar la inferioridad del subalternoThis article underscores the significance of José Donoso's "Papers", in the custody of Iowa University, in connection whith Julio Ortega's ideas about them, as made known by the newpaper "La Tercera", in Chile. In addition, a reading of homophobia as expression of a surreptitious eros, is made in the novels "El lugar sin límites" and in "El obsceno pájaro de la noche". In contrast to the homoerotic discourse that Ortega detects in Donoso, the narrators in the two best known novels of the Chilean writer express a constant rejection of the marginal characters, or otherwise expose sodomy as a form which expresses the inferiority of the underling

  4. Hyperactivity of the Ero1α Oxidase Elicits Endoplasmic Reticulum Stress but No Broad Antioxidant Response

    Science.gov (United States)

    Hansen, Henning Gram; Schmidt, Jonas Damgård; Søltoft, Cecilie Lützen; Ramming, Thomas; Geertz-Hansen, Henrik Marcus; Christensen, Brian; Sørensen, Esben Skipper; Juncker, Agnieszka Sierakowska; Appenzeller-Herzog, Christian; Ellgaard, Lars

    2012-01-01

    Oxidizing equivalents for the process of oxidative protein folding in the endoplasmic reticulum (ER) of mammalian cells are mainly provided by the Ero1α oxidase. The molecular mechanisms that regulate Ero1α activity in order to harness its oxidative power are quite well understood. However, the overall cellular response to oxidative stress generated by Ero1α in the lumen of the mammalian ER is poorly characterized. Here we investigate the effects of overexpressing a hyperactive mutant (C104A/C131A) of Ero1α. We show that Ero1α hyperactivity leads to hyperoxidation of the ER oxidoreductase ERp57 and induces expression of two established unfolded protein response (UPR) targets, BiP (immunoglobulin-binding protein) and HERP (homocysteine-induced ER protein). These effects could be reverted or aggravated by N-acetylcysteine and buthionine sulfoximine, respectively. Because both agents manipulate the cellular glutathione redox buffer, we conclude that the observed effects of Ero1α-C104A/C131A overexpression are likely caused by an oxidative perturbation of the ER glutathione redox buffer. In accordance, we show that Ero1α hyperactivity affects cell viability when cellular glutathione levels are compromised. Using microarray analysis, we demonstrate that the cell reacts to the oxidative challenge caused by Ero1α hyperactivity by turning on the UPR. Moreover, this analysis allowed the identification of two new targets of the mammalian UPR, CRELD1 and c18orf45. Interestingly, a broad antioxidant response was not induced. Our findings suggest that the hyperoxidation generated by Ero1α-C104A/C131A is addressed in the ER lumen and is unlikely to exert oxidative injury throughout the cell. PMID:23027870

  5. 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.

  6. Asteroids Were Born Big

    CERN Document Server

    Morbidelli, Alessandro; Nesvorny, David; Levison, Harold F

    2009-01-01

    How big were the first planetesimals? We attempt to answer this question by conducting coagulation simulations in which the planetesimals grow by mutual collisions and form larger bodies and planetary embryos. The size frequency distribution (SFD) of the initial planetesimals is considered a free parameter in these simulations, and we search for the one that produces at the end objects with a SFD that is consistent with asteroid belt constraints. We find that, if the initial planetesimals were small (e.g. km-sized), the final SFD fails to fulfill these constraints. In particular, reproducing the bump observed at diameter D~100km in the current SFD of the asteroids requires that the minimal size of the initial planetesimals was also ~100km. This supports the idea that planetesimals formed big, namely that the size of solids in the proto-planetary disk ``jumped'' from sub-meter scale to multi-kilometer scale, without passing through intermediate values. Moreover, we find evidence that the initial planetesimals ...

  7. Itokawa is not Brazil: granular segregation on asteroids

    Science.gov (United States)

    Shinbrot, Troy; Chakraborty, Pinaki; Sabuwala, Tapan

    2015-11-01

    Recent photographs of the asteroid Itokawa have revealed strong separation between regions populated almost entirely by sand and other regions consisting only of larger boulders. This size separation has been attributed to the Brazil Nut Effect (BNE), however we point out here that the BNE depends on conditions such as isotropic gravity, parallel sidewalls and periodic vertical shaking that are wholly absent on asteroids. On the other hand, surface areas of boulders and sand appear to be comparable on Itokawa, and in this situation it follows that the asteroid must have suffered many orders of magnitude more collisions with sand particles than with boulders. We observe that a sand particle will tend to bounce off of a boulder but will sink into a sea of similar sand particles, and so we predict that sand seas must grow on such asteroids. We carry out experiments and simulations to evaluate this and related predictions, and we demonstrate that this new mechanism of segregation based on simple counting of grains can produce the strong separation of sizes reported.

  8. Do Planetary Encounters Reset Surfaces of Near Earth Asteroids?

    CERN Document Server

    Nesvorny, David; Vokrouhlicky, David; Chapman, Clark R; Rafkin, Scot

    2010-01-01

    Processes such as the solar wind sputtering and micrometeorite impacts can modify optical properties of surfaces of airless bodies. This explains why spectra of the main belt asteroids, exposed to these `space weathering' processes over eons, do not match the laboratory spectra of ordinary chondrite (OC) meteorites. In contrast, an important fraction of Near Earth Asteroids (NEAs), defined as Q-types in the asteroid taxonomy, display spectral attributes that are a good match to OCs. Here we study the possibility that the Q-type NEAs underwent recent encounters with the terrestrial planets and that the tidal gravity (or other effects) during these encounters exposed fresh OC material on the surface (thus giving it the Q-type spectral properties). We used numerical integrations to determine the statistics of encounters of NEAs to planets. The results were used to calculate the fraction and orbital distribution of Q-type asteroids expected in the model as a function of the space weathering timescale, t_sw (see m...

  9. Design study for asteroidal exploitation

    Science.gov (United States)

    Adams, Carl; Blissit, Jim; Jarrett, Dave; Sanner, Rob; Yanagawa, Koji

    1985-08-01

    A systematic approach to asteroidal exploitation for the 1990 to 2010 time frame is presented as an initial step toward expanding the use of space beyond the space station by providing a source of lower cost materials. With only a limited amount of information known about the asteroids, reconnaissance and exploration phases to determine the exact locations and compositions of several earth-approaching asteroids are required. Earth-based telescopes are used to locate and study the asteroids, while unmanned probes will return samples of asteroidal material to earth for analysis. After these phases are completed, the retrieval of a 35,000 metric ton piece of the asteroid Anteros is undertaken. A cargo transporter uses magnetoplasmadynamic (MPD) arcjets outbound and a mass-driver using asteroidal material inbound. A crew ship uses ion engines. Low thrust trajectories are used for both spacecraft. A materials processing facility will manufacture propellant pellets and retrieve non-propellant materials for spacecraft use. The cost is 1/10th that to transport the same materials from earth to high earth orbit. The project will cost 25 percent less if done in conjunction with a lunar and Martian base.

  10. Mine Planning for Asteroid Orebodies

    Science.gov (United States)

    Gertsch, L. S.; Gertsch, R. E.

    2000-01-01

    Given that an asteroid (or comet) has been determined to contain sufficient material of value to be potentially economic to exploit, a mining method must be selected and implemented. This paper discusses the engineering necessary to bring a mine online, and the opportunities and challenges inherent in asteroid mineral prospects. The very important step of orebody characterization is discussed elsewhere. The mining methods discussed here are based on enclosing the asteroid within a bag in some fashion, whether completely or partially. In general, asteroid mining methods based on bags will consist of the following steps. Not all will be required in every case, nor necessarily in this particular sequence. Some steps will be performed simultaneously. Their purpose is to extract the valuable material from the body of the asteroid in the most efficient, cost-effective manner possible. In approximate order of initiation, if not of conclusion, the steps are: 1. Tether anchoring to the asteroid. 2. Asteroid motion control. 3. Body/fragment restraint system placement. 4. Operations platform construction. 5. Bag construction. 6. Auxiliary and support equipment placement. 7. Mining operations. 8. Processing operations. 9. Product transport to markets.

  11. 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

  12. Massive Gravity

    National Research Council Canada - National Science Library

    de Rham, Claudia

    2014-01-01

    We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP...

  13. Double Asteroid Redirection Test (DART)

    Science.gov (United States)

    Cheng, A. F.

    2016-12-01

    The Asteroid Impact Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor. AIDA is a joint ESA-NASA cooperative project, consisting of the NASA Double Asteroid Redirection Test (DART) kinetic impactor mission and the ESA Asteroid Impact Mission (AIM) which is the rendezvous spacecraft. The AIDA target is the near-Earth binary asteroid 65803 Didymos. During the Didymos close approach to Earth in October, 2022, the DART spacecraft will impact the Didymos secondary at 6 km/s and deflect its trajectory, changing the orbital period of the binary. This change can be measured by Earth-based optical and radar observations. The primary goals of AIDA are to (1) perform a full-scale demonstration of asteroid deflection by kinetic impact; (2) measure the resulting deflection; and (3) validate and improve models for momentum transfer in high-speed impacts on an asteroid. The combined DART and AIM missions will provide the first measurements of momentum transfer efficiency from a kinetic impact at full scale on an asteroid, where the impact conditions of the projectile are known, and physical properties and internal structures of the target asteroid are also characterized. In addition to a measurable change in the binary orbit period, the DART kinetic impact is predicted to induce forced librations of the Didymos secondary of up to several degrees amplitude. It will furthermore make a crater that will be studied in detail by the AIM spacecraft, and it will release a volume of particulate ejecta that may be directly observable from Earth or even resolvable as a coma or an ejecta tail by ground-based telescopes. Updates will be given on DART status and study results.

  14. Gravity Investigations with the MarcoPolo-R Radio Science Experiment RSE

    Science.gov (United States)

    Andert, T. P.; Pätzold, M.; Bellerose, J.; Barriot, J. P.; Oberst, J.; Hahn, M.; Tellmann, S.; Remus, S.; Förstner, R.; Häusler, B.

    2013-09-01

    The ESA sample return mission MarcoPolo-R is one of the current candidate M3 missions. It will rendezvous with a primitive Near Earth Asteroid (NEA), scientifically characterize it at multiple scales, and return a unique sample to Earth [3] The determination of the global physical properties of the mission target, the Near Earth Asteroid 2008 EV5, is among others one science objective of the MarcoPolo-R mission. In this context one key parameter is the gravity field, especially GM (gravitational constant times the mass) and the low order gravity coefficients C20 and C22 of the asteroid.

  15. Massive gravity

    OpenAIRE

    Claudia de Rham

    2016-01-01

    We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...

  16. Massive Gravity

    OpenAIRE

    de Rham, Claudia

    2014-01-01

    We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...

  17. Massive Gravity

    OpenAIRE

    2014-01-01

    We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware–Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...

  18. Spinfoam Gravity

    Science.gov (United States)

    Bianchi, Eugenio

    The following sections are included: * Introduction * Topological Field Theory and Gravity * Classical Spinfoam Gravity: Degrees of Freedom and Foams * Unitary Representations of the Rotation and the Lorentz Group * Boundary Variables and the Loop Quantum Gravity Hilbert Space * Spinfoam Partition Function and the Vertex Amplitude * Cellular Quantum Geometry: A Single Atom of Space * Cellular Quantum Geometry: Coherent Spin-networks * Vertex-amplitude Asymptotics and Regge Gravity * Reconstructing a Semiclassical Spacetime * Conclusions * References

  19. 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

  20. Evolution History of Asteroid Itokawa Based on Block Distribution Analysis

    Science.gov (United States)

    Mazrouei, Sara; Daly, Michael; Barnouin, Olivier; Ernst, Carolyn

    2013-04-01

    of whether or not Itokawa is a contact binary. References: [1] E. G. Kahn, et al. A tool for the visualization of small body data. In LPSC XLII, 2011. [2] A. Fujiwara, et al. The rubble-pile asteroid Itokawa as observed by Hayabusa. Science, 312(5778):1330-1334, June 2006. [3] A. F. Cheng, et al. Small-scale topography of 433 Eros from laser altimetry and imaging. Icarus, 155(1):51-74, 2002

  1. Earth Resources Observation and Science (EROS) Center's Landsat State Mosaics Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages the this gallery of images of the 50 U.S. states plus Puerto Rico as derived by Landsat data.

  2. Earth Resources Observation and Science (EROS) Center's Earth as Art Image Gallery 2

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages this collection of forty-five new scenes developed for their aesthetic beauty, rather than for...

  3. Earth Resources Observation and Science (EROS) Center's Journey of Lewis and Clark Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages the this gallery of Landsat-derived images of one of the most remarkable and productive scientific...

  4. Disulphide production by Ero1a-PDI relay is rapid and effectively regulated

    DEFF Research Database (Denmark)

    Appenzeller-Herzog, Christian; Riemer, Jan; Zito, Ester

    2010-01-01

    protein disulphide isomerase (PDI) strongly contribute to the rapid recovery kinetics, but experiments in ERO1-deficient cells indicate the existence of parallel pathways for disulphide generation. We find PDI to be the main substrate of Ero1a, and mixed-disulphide complexes of Ero1 primarily form...... with PDI, to a lesser extent with the PDI-family members ERp57 and ERp72, but are not detectable with another homologue TMX3. We also show for the first time that the oxidation level of PDIs and glutathione is precisely regulated. Apparently, this is achieved neither through ER import of thiols nor...... by transport of disulphides to the Golgi apparatus. Instead, our data suggest that a dynamic equilibrium between Ero1- and glutathione disulphide-mediated oxidation of PDIs constitutes an important element of ER redox homeostasis....

  5. Earth Resources Observation and Science (EROS) Center's Earth as Art Image Gallery 3

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages the Earth as Art Three exhibit, which provides fresh and inspiring glimpses of different parts of...

  6. PAO Image Gallery = Public Affairs Photos of EROS Projects: 1972 - 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The EROS Image Gallery collection is composed of a wide variety of images ranging from low altitude aircraft to satellite and NASA imagery; oblique photographs and...

  7. Dynamic regulation of Ero1α and peroxiredoxin 4 localization in the secretory pathway.

    Science.gov (United States)

    Kakihana, Taichi; Araki, Kazutaka; Vavassori, Stefano; Iemura, Shun-ichiro; Cortini, Margherita; Fagioli, Claudio; Natsume, Tohru; Sitia, Roberto; Nagata, Kazuhiro

    2013-10-11

    In the early secretory compartment (ESC), a network of chaperones and enzymes assists oxidative folding of nascent proteins. Ero1 flavoproteins oxidize protein disulfide isomerase (PDI), generating H2O2 as a byproduct. Peroxiredoxin 4 (Prx4) can utilize luminal H2O2 to oxidize PDI, thus favoring oxidative folding while limiting oxidative stress. Interestingly, neither ER oxidase contains known ER retention signal(s), raising the question of how cells prevent their secretion. Here we show that the two proteins share similar intracellular localization mechanisms. Their secretion is prevented by sequential interactions with PDI and ERp44, two resident proteins of the ESC-bearing KDEL-like motifs. PDI binds preferentially Ero1α, whereas ERp44 equally retains Ero1α and Prx4. The different binding properties of Ero1α and Prx4 increase the robustness of ER redox homeostasis.

  8. Dynamic Regulation of Ero1α and Peroxiredoxin 4 Localization in the Secretory Pathway*

    Science.gov (United States)

    Kakihana, Taichi; Araki, Kazutaka; Vavassori, Stefano; Iemura, Shun-ichiro; Cortini, Margherita; Fagioli, Claudio; Natsume, Tohru; Sitia, Roberto; Nagata, Kazuhiro

    2013-01-01

    In the early secretory compartment (ESC), a network of chaperones and enzymes assists oxidative folding of nascent proteins. Ero1 flavoproteins oxidize protein disulfide isomerase (PDI), generating H2O2 as a byproduct. Peroxiredoxin 4 (Prx4) can utilize luminal H2O2 to oxidize PDI, thus favoring oxidative folding while limiting oxidative stress. Interestingly, neither ER oxidase contains known ER retention signal(s), raising the question of how cells prevent their secretion. Here we show that the two proteins share similar intracellular localization mechanisms. Their secretion is prevented by sequential interactions with PDI and ERp44, two resident proteins of the ESC-bearing KDEL-like motifs. PDI binds preferentially Ero1α, whereas ERp44 equally retains Ero1α and Prx4. The different binding properties of Ero1α and Prx4 increase the robustness of ER redox homeostasis. PMID:23979138

  9. Structural Stability of Asteroids

    Science.gov (United States)

    Hirabayashi, Toshi

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

  10. Diseño de una plataforma de computación distribuida cooperativa, utilizando servicios de una red compañero a compañero

    OpenAIRE

    Bordignon, Fernando Raúl Alfredo

    2005-01-01

    El modelo de arquitectura compañero a compañero (P2P), utilizado en la construcción de sistemas distribuidos, ha tomado un auge importante con la expansión de Internet. Los servicios basados en sistemas P2P permiten que computadoras de usuario final se conecten directamente formando comunidades, cuya finalidad es el compartir recursos de distinta índole. En esta tesis se exponen, a modo de contribución original, un prototipo de middleware denominado GnutWare, que brinda soporte de comunicacio...

  11. 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...

  12. 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

  13. 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.

  14. Roles of Shape and Internal Structure in Rotational Disruption of Asteroids

    Science.gov (United States)

    Hirabayashi, Masatoshi; Scheeres, Daniel Jay

    2015-08-01

    An active research area over the last decade has been to explore configuration changes of rubble pile asteroids due to rotationally induced disruption, initially driven by the remarkable fact that there is a spin period threshold of 2 hr for asteroids larger than a few hundred meters in size. Several different disruption modes due to rapid rotation can be identified, as surface shedding, fission and failure of the internal structure. Relevant to these discussions are many observations of asteroid shapes that have revealed a diversity of forms such as oblate spheroids with equatorial ridges, strongly elongated shapes and contact binaries, to say nothing of multi-body systems. With consideration that rotationally induced deformation is one of the primary drivers of asteroid evolution, we have been developing two techniques for investigating the structure of asteroids, while accounting for their internal mechanical properties through plastic theory. The first technique developed is an analytical model based on limit analysis, which provides rigorous bounds on the asteroid mechanical properties for their shapes to remain stable. The second technique applies finite element model analysis that accounts for plastic deformation. Combining these models, we have explored the correlation between unique shape features and failure modes. First, we have been able to show that contact binary asteroids preferentially fail at their narrow necks at a relatively slow spin period, due to stress concentration. Second, applying these techniques to the breakup event of active asteroid P/2013 R3, we have been able to develop explicit constraints on the cohesion within rubble pile asteroids. Third, by probing the effect of inhomogeneous material properties, we have been able to develop conditions for whether an oblate body will fail internally or through surface shedding. These different failure modes can be tested by measuring the density distribution within a rubble pile body through

  15. A mission concept for a Grand Tour of Multiple Asteroid Systems

    Science.gov (United States)

    Marchis, F.; Dankanich, J.; Tricarico, P.; Bellerose, J.

    2009-12-01

    with several multiple asteroid systems located in the main belt. This mission concept uses the NASA's evolutionary Xenon Thruster (NEXT), the second generation of electric propulsion with 3 times more input power than the previous generation (NSTAR) of the Dawn mission. The mission objectives for each rendezvous asteroid are i) the characterization of the surface geology by direct imaging in visible and thermal infrared spectroscopy, ii) the characterization of the shape and gravity coupling visible observations with LIDAR ranging data, iii) the determination of the thermophysical properties of the surface, and iv) the identification of the surface composition by visible and near-infrared spectroscopy. The trajectory, science package and mission operations of the mission will be described. This work is supported by the National Science Foundation 05-608, "Astronomy and Astrophysics Research Grants (AAG)" No AST-0807468

  16. The EPOCH Project: I. Periodic Variable Stars in the EROS-2 LMC Database

    CERN Document Server

    Kim, Dae-Won; Bailer-Jones, Coryn A L; Byun, Yong-Ik; Chang, Seo-Won; Marquette, Jean-Baptiste; Shin, Min-Su

    2014-01-01

    The EPOCH (EROS-2 periodic variable star classification using machine learning) project aims to detect periodic variable stars in the EROS-2 light curve database. In this paper, we present the first result of the classification of periodic variable stars in the EROS-2 LMC database. In order to classify these variables, we first build a training set by compiling known variables in the Large Magellanic Could area from the OGLE and MACHO surveys. We crossmatch these variables with the EROS-2 sources and extract 22 variability features from 28,392 light curves of the corresponding EROS-2 sources. We then use Random Forests to classify the EROS-2 sources in the training set. We design the model to separate not only $\\delta$ Scuti stars, RR Lyraes, Cepheids, eclipsing binaries and long-period variables, the "superclasses", but also their subclasses, such as RRab, RRc, RRd and RRe for RR Lyraes, and similarly for the other variable types. The model trained using only the superclasses shows 99% recall and precision w...

  17. An improved quasar detection method in EROS-2 and MACHO LMC datasets

    CERN Document Server

    Pichara, Karim; Kim, Dae-Won; Marquette, Jean-Baptiste; Tisserand, Patrick; 10.1111/j.1365-2966.2012.22061.x

    2013-01-01

    We present a new classification method for quasar identification in the EROS-2 and MACHO datasets based on a boosted version of Random Forest classifier. We use a set of variability features including parameters of a continuous auto regressive model. We prove that continuous auto regressive parameters are very important discriminators in the classification process. We create two training sets (one for EROS-2 and one for MACHO datasets) using known quasars found in the LMC. Our model's accuracy in both EROS-2 and MACHO training sets is about 90% precision and 86% recall, improving the state of the art models accuracy in quasar detection. We apply the model on the complete, including 28 million objects, EROS-2 and MACHO LMC datasets, finding 1160 and 2551 candidates respectively. To further validate our list of candidates, we crossmatched our list with a previous 663 known strong candidates, getting 74% of matches for MACHO and 40% in EROS-2. The main difference on matching level is because EROS-2 is a slightly...

  18. Solar Radiation and Asteroidal Motion

    CERN Document Server

    Klacka, J

    2000-01-01

    Effects of solar wind and solar electromagnetic radiation on motion of asteroids are discussed. The results complete the statements presented in Vokrouhlick\\'{y} and Milani (2000). As for the effect of electromagnetic radiation, the complete equation of motion is presented to the first order in $v/c$ -- the shape of asteroid (spherical body is explicitly presented) and surface distribution of albedo should be taken into account. Optical quantities must be calculated in proper frame of reference.

  19. Enhanced Gravity Tractor Technique for Planetary Defense

    Science.gov (United States)

    Mazanek, Daniel D.; Reeves, David M.; Hopkins, Joshua B.; Wade, Darren W.; Tantardini, Marco; Shen, Haijun

    2015-01-01

    Given sufficient warning time, Earth-impacting asteroids and comets can be deflected with a variety of different "slow push/pull" techniques. The gravity tractor is one technique that uses the gravitational attraction of a rendezvous spacecraft to the impactor and a low-thrust, high-efficiency propulsion system to provide a gradual velocity change and alter its trajectory. An innovation to this technique, known as the Enhanced Gravity Tractor (EGT), uses mass collected in-situ to augment the mass of the spacecraft, thereby greatly increasing the gravitational force between the objects. The collected material can be a single boulder, multiple boulders, regolith or a combination of different sources. The collected mass would likely range from tens to hundreds of metric tons depending on the size of the impactor and warning time available. Depending on the propulsion system's capability and the mass collected, the EGT approach can reduce the deflection times by a factor of 10 to 50 or more, thus reducing the deflection times of several decades to years or less and overcoming the main criticism of the traditional gravity tractor approach. Additionally, multiple spacecraft can orbit the target in formation to provide the necessary velocity change and further reduce the time needed by the EGT technique to divert hazardous asteroids and comets. The robotic segment of NASA's Asteroid Redirect Mission (ARM) will collect a multi-ton boulder from the surface of a large Near-Earth Asteroid (NEA) and will provide the first ever demonstration of the EGT technique and validate one method of collecting in-situ mass on an asteroid of hazardous size.

  20. Approximate Equilibrium Shapes for Spinning, Gravitating Rubble Asteroids

    Science.gov (United States)

    Burns, Joseph A.; Sharma, I.; Jenkins, J. T.

    2007-10-01

    Approximate Equilibrium Shapes for Spinning, Gravitating Rubble Asteroids Joseph A. Burns, Ishan Sharma and James T. Jenkins Many asteroids are thought to be particle aggregates held together principally by self-gravity. Here we study those equilibrium shapes of spinning asteroids that are permitted for rubble piles. As in the case of spinning fluid masses, not all shapes may be compatible with a granular rheology. We take the asteroid to always be an ellipsoid with an interior modeled as a rigid-plastic, cohesion-less material. Using an approximate volume-averaged procedure, based on the classical method of moments, we investigate the dynamical process by which such objects may achieve equilibrium. First, to instill confidence in our approach, we have collapsed our dynamical approach to its statical limit to re-derive regions in spin-shape parameter space that allow equilibrium solutions to exist. Not surprisingly, our results duplicate static results reported by Holsapple (Icarus 154 [2001], 432; 172 [2004], 272) since the two sets of final equations match, although the formalisms to reach these expressions differ. We note that the approach applied here was obtained independently by I.S. in his Ph.D. dissertation (Cornell University, 2004); it provides a general, though approximate, framework that is amenable to systematic improvements and flexible enough to incorporate the dynamical effects of a changing shape, different rheologies and complex rotational histories. To demonstrate the power of our technique, we investigate the non-equilibrium dynamics of rigid-plastic, spinning, prolate asteroids to watch the simultaneous histories of shape and spin rate for rubble piles. We have succeeded in recovering most results of Richardson et al. (Icarus 173 [2004], 349), who obtained equilibrium shapes by studying numerically the passage into equilibrium of aggregates containing discrete, interacting, frictionless, spherical particles. Our mainly analytical approach aids

  1. Moving an asteroid with electric solar wind sail

    Science.gov (United States)

    Merikallio, S.; Janhunen, P.

    2010-12-01

    The electric solar wind sail (E-Sail) is a new propulsion method for interplanetary travel which was invented in 2006 and is currently under development. The E-Sail uses charged tethers to extract momentum from the solar wind particles to obtain propulsive thrust. According to current estimates, the E-Sail is 2-3 orders of magnitude better than traditional propulsion methods (chemical rockets and ion engines) in terms of produced lifetime-integrated impulse per propulsion system mass. Here we analyze the problem of using the E-Sail for directly deflecting an Earth-threatening asteroid. The problem then culminates into how to attach the E-Sail device to the asteroid. We assess alternative attachment strategies, namely straightforward direct towing with a cable and the gravity tractor method which works for a wider variety of situations. We also consider possible techniques to scale up the E-Sail force beyond the baseline one Newton level to deal with more imminent or larger asteroid or cometary threats. As a baseline case we consider an asteroid of effective diameter of 140 m and mass of 3 million tons, which can be deflected with a baseline 1 N E-Sail within 10 years. With a 5 N E-Sail the deflection could be achieved in 5 years. Once developed, the E-Sail would appear to provide a safe and reasonably low-cost way of deflecting dangerous asteroids and other heavenly bodies in cases where the collision threat becomes known several years in advance.

  2. Overview and Updated Status of the Asteroid Redirect Mission (ARM)

    Science.gov (United States)

    Abell, Paul; Mazanek, Daniel D.; Reeves, David M.; Chodas, Paul; Gates, Michele; Johnson, Lindley N.; Ticker, Ronald

    2016-10-01

    The National Aeronautics and Space Administration (NASA) is developing a mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder and regolith samples from its surface, demonstrate a planetary defense technique known as the enhanced gravity tractor, and return the asteroidal material to 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 and other destinations, as well as provide other broader benefits. 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. Current plans are for the robotic mission to be launched in late 2021 with the crewed mission segment conducted using an Orion capsule via a Space Launch System rocket in 2026. In order to maximize the knowledge return from the mission, NASA is providing accommodations for payloads to be carried on the robotic segment of the mission and also organizing an ARM Investigation Team. The Investigation Team will be comprised of scientists, technologists, and other qualified and interested individuals from US industry, government, academia, and international institutions to help plan the implementation and execution of ARM. The presentation will provide a mission overview and the most recent update concerning the robotic and crewed segments of ARM, including the mission requirements, and potential

  3. An efficient algorithm for global periodic orbits generation near irregular-shaped asteroids

    Science.gov (United States)

    Shang, Haibin; Wu, Xiaoyu; Ren, Yuan; Shan, Jinjun

    2017-07-01

    Periodic orbits (POs) play an important role in understanding dynamical behaviors around natural celestial bodies. In this study, an efficient algorithm was presented to generate the global POs around irregular-shaped uniformly rotating asteroids. The algorithm was performed in three steps, namely global search, local refinement, and model continuation. First, a mascon model with a low number of particles and optimized mass distribution was constructed to remodel the exterior gravitational potential of the asteroid. Using this model, a multi-start differential evolution enhanced with a deflection strategy with strong global exploration and bypassing abilities was adopted. This algorithm can be regarded as a search engine to find multiple globally optimal regions in which potential POs were located. This was followed by applying a differential correction to locally refine global search solutions and generate the accurate POs in the mascon model in which an analytical Jacobian matrix was derived to improve convergence. Finally, the concept of numerical model continuation was introduced and used to convert the POs from the mascon model into a high-fidelity polyhedron model by sequentially correcting the initial states. The efficiency of the proposed algorithm was substantiated by computing the global POs around an elongated shoe-shaped asteroid 433 Eros. Various global POs with different topological structures in the configuration space were successfully located. Specifically, the proposed algorithm was generic and could be conveniently extended to explore periodic motions in other gravitational systems.

  4. Anatomy of an Asteroid Breakup

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

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

  5. La agonía del Eros, Han (2014.

    Directory of Open Access Journals (Sweden)

    Laura Díaz Traversa

    2016-11-01

    Full Text Available Byung-Chul Han, Dr. en Filosofía de origen coreano, realizó sus estudios en Alemania, donde reside actualmente y se desempeña como docente de Filosofía y Estudios Culturales en la Universidad de las Artes de Berlín. Desde el punto de vista teórico-académico se inscribe en el Pensamiento Crítico de la escuela de Frankfurt, siendo alumno privilegiado de Honneth. Es considerado una de las voces filosóficas más prestigiosas de dicho país, y sus obras se caracterizan por ser breves, de fácil lectura, sorprendiendo al público por su fuerza y pertinencia en la actualidad. La agonía del Eros es la tercera obra del autor traducida al castellano y promete seguir el mismo camino que las anteriores, es decir, convertirse en una obra fundamental del Pensamiento Crítico.

  6. Disengagement, Pedagogical Eros and (the undoing of? Dialogic pedagogy

    Directory of Open Access Journals (Sweden)

    James Cresswell

    2016-09-01

    Full Text Available Dialogic pedagogy is an approach to education influenced by Bakhtin, Freire, and others. It is an approach that is critical of conventional education, which tends to be didactic and alienating to students. Student engagement is made central as dialogue takes priority over standardization and core cannons of content. Dialogic pedagogy also emphasizes the importance of communities of learners where teachers are co-learners along with students as all parties work on problems together. I seek to raise challenges to Dialogic Pedagogy and these come from scholars working on the “conduct of everyday life” and from Charles Taylor’s notion of “strong evaluations”. The conduct of everyday life involves a focus on first-person subjectivities with an eye to their constitution in social and power relations. Strong evaluations enhance this discussion by addressing how people can engage in decisions that involve weighing options about the qualitative kind of person one is. I outline how education involves a conduct of everyday life where strong evaluations are promoted. Taking such an approach to education grounds two challenges to dialogic pedagogy. One challenge is that students are reticent to engage in strong evaluations and the modern identity is one disposed to disengagement. The converse challenge is that student engagement entails pedagogical eros, which is easily converted into power and abuse by a pedagogue.

  7. History of greenness mapping at the EROS data center

    Science.gov (United States)

    Van Beek, Carolyn; Vandersnick, Richard

    1993-01-01

    In 1987, the U.S. Geological Survey's EROS Data Center (EDC)installed a system to acquire, process, and distribute advanced very high resolution radiometer (AVHRR) satellite image data collected over North America. Using this system, the EDC began an experimental greenness mapping program as part of the U.S. Agency for the International Development Famine Early Warning System. The program used the greenness information derived from AVHRR data to identify potential outbreaks of locusts and grasshoppers in the Sahelian region of Africa. In 1988, the EDC began greenness mapping projects in Africa and the northern Great Plains of the United States. In 1989, the system was augmented to acquire AVHRR information for the rest of the world. As a result, the greenness mapping program was able to collect data for fire danger assessment, agricultural assessment, and land characterization. Illustrations of each of the mapping projects trace the chronology of the greenness mapping program at the EDC. Displays represent the initial activity in Africa and the transition of the north Great Plains project to the current conterminous U.S. project. The program's expansion to include Alaska, Eurasia, a prototype North America data set, and ultimately, an experimental global land 1-km product is also shown. The poster describes major technical advances in data processing, the development of derivative products, the magnitude of the data volume of each level, and major applications.

  8. A 2 km-size asteroid challenging the rubble-pile spin barrier - a case for cohesion

    CERN Document Server

    Polishook, D; Binzel, R P; Burt, B; DeMeo, F E; Hinkle, M L; Lockhart, M; Mommert, M; Person, M; Thirouin, A; Thomas, C A; Trilling, D; Willman, M; Aharonson, O

    2015-01-01

    The rubble pile spin barrier is an upper limit on the rotation rate of asteroids larger than ~200-300 m. Among thousands of asteroids with diameters larger than ~300 m, only a handful of asteroids are known to rotate faster than 2.0 h, all are in the sub-km range (<=0.6 km). Here we present photometric measurements suggesting that (60716) 2000 GD65, an S-complex, inner-main belt asteroid with a relatively large diameter of 2.3 +0.6-0.7 km, completes one rotation in 1.9529+-0.0002 h. Its unique diameter and rotation period allow us to examine scenarios about asteroid internal structure and evolution: a rubble pile bound only by gravity; a rubble-pile with strong cohesion; a monolithic structure; an asteroid experiencing mass shedding; an asteroid experiencing YORP spin-up/down; and an asteroid with a unique octahedron shape results with a four-peak lightcurve and a 3.9 h period. We find that the most likely scenario includes a lunar-like cohesion that can prevent (60716) 2000 GD65 from disrupting without re...

  9. Refining the asteroid taxonomy by polarimetric observations

    Science.gov (United States)

    Belskaya, I. N.; Fornasier, S.; Tozzi, G. P.; Gil-Hutton, R.; Cellino, A.; Antonyuk, K.; Krugly, Yu. N.; Dovgopol, A. N.; Faggi, S.

    2017-03-01

    We present new results of polarimetric observations of 15 main belt asteroids of different composition. By merging new and published data we determined polarimetric parameters characterizing individual asteroids and mean values of the same parameters characterizing different taxonomic classes. The majority of asteroids show polarimetric phase curves close to the average curve of the corresponding class. We show that using polarimetric data it is possible to refine asteroid taxonomy and derive a polarimetric classification for 283 main belt asteroids. Polarimetric observations of asteroid (21) Lutetia are found to exhibit possible variations of the position angle of the polarization plane over the surface.

  10. 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

  11. GRASPING THE NATURE OF POTENTIALLY HAZARDOUS ASTEROIDS

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-15

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

  12. On Possibility of Direct Asteroid Deflection by Electric Solar Wind Sail

    Science.gov (United States)

    Merikallio, Sini; Janhunen, Pekka

    2010-05-01

    The Electric Solar Wind Sail (E-sail) is a new propulsion method for interplanetary travel which was invented in 2006 and is currently under development. The E-sail uses charged tethers to extract momentum from the solar wind particles to obtain propulsive thrust. According to current estimates, the E-sail is 2-3 orders of magnitude better than traditional propulsion methods (chemical rockets and ion engines) in terms of produced lifetime-integrated impulse per propulsion system mass. Here we analyze the problem of using the E-sail for directly deflecting an Earth-threatening asteroid. The problem then culminates into how to attach the E-sail device to the asteroid. We assess a number of alternative attachment strategies and arrive at a recommendation of using the gravity tractor method because of its workability for a wide variety of asteroid types. We also consider possible techniques to scale up the E-sail force beyond the baseline one Newton level to deal with more imminent or larger asteroid or cometary threats. As a baseline case we consider a 3 million ton asteroid which can be deflected with a baseline 1 N E-sail in 5-10 years. Once developed, the E-sail would appear to provide a safe and reasonably low-cost way of deflecting dangerous asteroids and other heavenly bodies in cases where the collision threat becomes known several years in advance.

  13. Spacecraft Mission Design for the Mitigation of the 2017 PDC Hypothetical Asteroid Threat

    Science.gov (United States)

    Barbee, Brent W.; Sarli, Bruno V.; Lyzhoft, Josh; Chodas, Paul W.; Englander, Jacob A.

    2017-01-01

    This paper presents a detailed mission design analysis results for the 2017 Planetary Defense Conference (PDC) Hypothetical Asteroid Impact Scenario, documented at https:cneos.jpl.nasa.govpdcspdc17. The mission design includes campaigns for both reconnaissance (flyby or rendezvous) of the asteroid (to characterize it and the nature of the threat it poses to Earth) and mitigation of the asteroid, via kinetic impactor deflection, nuclear explosive device (NED) deflection, or NED disruption. Relevant scenario parameters are varied to assess the sensitivity of the design outcome, such as asteroid bulk density, asteroid diameter, momentum enhancement factor, spacecraft launch vehicle, and mitigation system type. Different trajectory types are evaluated in the mission design process from purely ballistic to those involving optimal midcourse maneuvers, planetary gravity assists, and/or low-thrust solar electric propulsion. The trajectory optimization is targeted around peak deflection points that were found through a novel linear numerical technique method. The optimization process includes constrain parameters, such as Earth departure date, launch declination, spacecraft, asteroid relative velocity and solar phase angle, spacecraft dry mass, minimum/maximum spacecraft distances from Sun and Earth, and Earth-spacecraft communications line of sight. Results show that one of the best options for the 2017 PDC deflection is solar electric propelled rendezvous mission with a single spacecraft using NED for the deflection.

  14. Molecular bases of cyclic and specific disulfide interchange between human ERO1alpha protein and protein-disulfide isomerase (PDI).

    Science.gov (United States)

    Masui, Shoji; Vavassori, Stefano; Fagioli, Claudio; Sitia, Roberto; Inaba, Kenji

    2011-05-06

    In the endoplasmic reticulum (ER) of human cells, ERO1α and protein-disulfide isomerase (PDI) constitute one of the major electron flow pathways that catalyze oxidative folding of secretory proteins. Specific and limited PDI oxidation by ERO1α is essential to avoid ER hyperoxidation. To investigate how ERO1α oxidizes PDI selectively among more than 20 ER-resident PDI family member proteins, we performed docking simulations and systematic biochemical analyses. Our findings reveal that a protruding β-hairpin of ERO1α specifically interacts with the hydrophobic pocket present in the redox-inactive PDI b'-domain through the stacks between their aromatic residues, leading to preferred oxidation of the C-terminal PDI a'-domain. ERO1α associated preferentially with reduced PDI, explaining the stepwise disulfide shuttle mechanism, first from ERO1α to PDI and then from oxidized PDI to an unfolded polypeptide bound to its hydrophobic pocket. The interaction of ERO1α with ERp44, another PDI family member protein, was also analyzed. Notably, ERO1α-dependent PDI oxidation was inhibited by a hyperactive ERp44 mutant that lacks the C-terminal tail concealing the substrate-binding hydrophobic regions. The potential ability of ERp44 to inhibit ERO1α activity may suggest its physiological role in ER redox and protein homeostasis.

  15. Molecular Bases of Cyclic and Specific Disulfide Interchange between Human ERO1α Protein and Protein-disulfide Isomerase (PDI)*

    Science.gov (United States)

    Masui, Shoji; Vavassori, Stefano; Fagioli, Claudio; Sitia, Roberto; Inaba, Kenji

    2011-01-01

    In the endoplasmic reticulum (ER) of human cells, ERO1α and protein-disulfide isomerase (PDI) constitute one of the major electron flow pathways that catalyze oxidative folding of secretory proteins. Specific and limited PDI oxidation by ERO1α is essential to avoid ER hyperoxidation. To investigate how ERO1α oxidizes PDI selectively among more than 20 ER-resident PDI family member proteins, we performed docking simulations and systematic biochemical analyses. Our findings reveal that a protruding β-hairpin of ERO1α specifically interacts with the hydrophobic pocket present in the redox-inactive PDI b′-domain through the stacks between their aromatic residues, leading to preferred oxidation of the C-terminal PDI a′-domain. ERO1α associated preferentially with reduced PDI, explaining the stepwise disulfide shuttle mechanism, first from ERO1α to PDI and then from oxidized PDI to an unfolded polypeptide bound to its hydrophobic pocket. The interaction of ERO1α with ERp44, another PDI family member protein, was also analyzed. Notably, ERO1α-dependent PDI oxidation was inhibited by a hyperactive ERp44 mutant that lacks the C-terminal tail concealing the substrate-binding hydrophobic regions. The potential ability of ERp44 to inhibit ERO1α activity may suggest its physiological role in ER redox and protein homeostasis. PMID:21398518

  16. Thermal Emission Spectroscopy (5.2 To 38 Microns) And Analysis Of 10 Near-earth Asteroids

    Science.gov (United States)

    Dave, Riddhi; Emery, J.; Cruikshank, D.; Mueller, M.; Delbo, M.; Trilling, D. E.; Mommert, M.

    2010-10-01

    Near Earth Asteroids (NEAs- 0.983AUSolar System. Information about the albedo and size distribution of the NEAs is an essential prerequisite for exploring their physical nature, thermal properties, mineralogy, taxonomy and for developing reliable NEA population models. In support of the ExploreNEOs campaign of the Warm Spitzer program, we will present initial results from study of a sample of NEAs using the Infrared Spectrograph (IRS) on NASA's Spitzer Space Telescope [Programs 88 and 91- Extinct Comets and Low-Albedo Asteroids]. These data were reduced with Spitzer IRS Custom Extraction (SPICE) a JAVA-based tool built for interactive extraction of Spitzer IRS spectra. The 5.2-38 m thermal emission spectra[R 60-130] have been fitted with models of the thermal continuum employing the Near Earth Asteroid Thermal Model [NEATM](Harris 1998) and a Thermophysical model. Simultaneous measurements of the asteroid flux in the thermal infrared, combined with a thermal model, allow both the diameter and the albedo to be determined. The sample of Asteroids to be a part of this study are 1602 Geographos, 1580 Betulia, 433 Eros, 2212 Hephaistos, 1685 Toro, 1917 Cuyo, 1566 Icarus, 3200 Phaethon, 7092 Cadmus and 1866 Sisyphus. This study will give in-depth understanding of the applicability of the NEATM for NEAs observed at higher phase angles, having larger thermal inertia than main-belt asteroids, and/or displaying varied geometries. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.

  17. Excluding interlopers from asteroid families

    Science.gov (United States)

    Novakovic, B.; Radovic, V.

    2014-07-01

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

  18. Asteroid airburst altitude vs. strength

    Science.gov (United States)

    Robertson, Darrel; Wheeler, Lorien; Mathias, Donovan

    2016-10-01

    Small NEO asteroids (<Ø140m) may not be a threat on a national or global level but can still cause a significant amount of local damage as demonstrated by the Chelyabinsk event where there was over $33 million worth of damage (1 billion roubles) and 1500 were injured, mostly due to broken glass. The ground damage from a small asteroid depends strongly on the altitude at which they "burst" where most of the energy is deposited in the atmosphere. The ability to accurately predict ground damage is useful in determining appropriate evacuation or shelter plans and emergency management.Strong asteroids, such as a monolithic boulder, fail and create peak energy deposition close to the altitude at which ram dynamic pressure exceeds the material cohesive strength. Weaker asteroids, such as a rubble pile, structurally fail at higher altitude, but it requires the increased aerodynamic pressure at lower altitude to disrupt and disperse the rubble. Consequently the resulting airbursts have a peak energy deposition at similar altitudes.In this study hydrocode simulations of the entry and break-up of small asteroids were performed to examine the effect of strength, size, composition, entry angle, and speed on the resulting airburst. This presentation will show movies of the simulations, the results of peak burst height, and the comparison to semi-analytical models.

  19. On Asteroid Engineering

    CERN Document Server

    Lechtenfeld, Olaf

    2015-01-01

    I pose the question of maximal Newtonian surface gravity on a homogeneous body of a given mass and volume but with variable shape. In other words, given an amount of malleable material of uniform density, how should one shape it in order for a microscopic creature on its surface to experience the largest possible weight? After evaluating the weight on an arbitrary cylinder, at the axis and at the equator and comparing it to that on a spherical ball, I solve the variational problem to obtain the shape which optimizes the surface gravity in some location. The boundary curve of the corresponding solid of revolution is given by $\\ (x^2+z^2)^3-(4\\,z)^2=0\\ $ or $\\ r(\\theta)=2\\sqrt{\\cos\\theta}$, and the maximal weight (at $x=z=0$) exceeds that on a solid sphere by a factor of $\\frac35\\root3\\of5$, which is an increment of $2.6\\%$. Finally, the values and the achievable maxima are computed for three other families of shapes.

  20. Closed-loop control for global coverage and equatorial hovering about an asteroid

    Science.gov (United States)

    Guelman, Mauricio M.

    2017-08-01

    The purpose of this work is to develop a simple control law to implement stable orbits about a small rotating celestial body to achieve global coverage as well as fixed-body hovering on the equatorial plane. The celestial body is assumed to be rotating about a principal axis, with constant rotational velocity along the largest moment of inertia. A simple three dimensional closed-loop guidance law function of position and velocity is defined and analyzed, enabling the determination of the guidance constants to assure convergence to any desired circular orbit about the irregular celestial body, controlling independently five orbital parameters: inclination, right ascension of the ascending node, orbital radius, orbital rate and equatorial longitude. Representative numerical results are presented for an Eros type asteroid.

  1. Gravity investigations

    Energy Technology Data Exchange (ETDEWEB)

    Healey, D.L. [Geological Survey, Denver, CO (USA)

    1983-12-31

    A large density contrast exists between the Paleozoic rocks (including the rocks of Climax stock) and less dense, Tertiary volcanic rocks and alluvium. This density contrast ranges widely, and herein for interpretive purposes, is assumed to average 0.85 Mg/m{sup 3} (megagrams per cubic meter). The large density contrast makes the gravity method a useful tool with which to study the interface between these rock types. However, little or no density contrast is discernible between the sedimentary Paleozoic rocks that surround the Climax stock and the intrusive rocks of the stock itself. Therefore the gravity method can not be used to define the configuration of the stock. Gravity highs coincide with outcrops of the dense Paleozoic rocks, and gravity lows overlie less-dense Tertiary volcanic rocks and Quaternary alluvium. The positions of three major faults (Boundary, Yucca, and Butte faults) are defined by steep gravity gradients. West of the Climax stock, the Tippinip fault has juxtaposed Paleozoic rocks of similar density, and consequently, has no expression in the gravity data in that area. The gravity station spacing, across Oak Spring Butte, is not sufficient to adequately define any gravity expression of the Tippinip fault. 18 refs., 5 figs.

  2. The Ero1alpha-PDI redox cycle regulates retro-translocation of cholera toxin.

    Science.gov (United States)

    Moore, Paul; Bernardi, Kaleena M; Tsai, Billy

    2010-04-01

    Cholera toxin (CT) is transported from the plasma membrane of host cells to the endoplasmic reticulum (ER) where the catalytic CTA1 subunit retro-translocates to the cytosol to induce toxicity. Our previous analyses demonstrated that the ER oxidoreductase protein disulfide isomerase (PDI) acts as a redox-dependent chaperone to unfold CTA1, a reaction postulated to initiate toxin retro-translocation. In its reduced state, PDI binds and unfolds CTA1; subsequent oxidation of PDI by Ero1alpha enables toxin release. Whether this in vitro model describes events in cells that control CTA1 retro-translocation is unknown. Here we show that down-regulation of Ero1alpha decreases retro-translocation of CTA1 by increasing reduced PDI and blocking efficient toxin release. Overexpression of Ero1alpha also attenuates CTA1 retro-translocation, an effect due to increased PDI oxidation, which prevents PDI from engaging the toxin effectively. Interestingly, Ero1alpha down-regulation increases interaction between PDI and Derlin-1, an ER membrane protein that is a component of the retro-translocation complex. These findings demonstrate that an appropriate Ero1alpha-PDI ratio is critical for regulating the binding-release cycle of CTA1 by PDI during retro-translocation, and implicate PDI's redox state in targeting it to the retro-translocon.

  3. Disulphide production by Ero1α-PDI relay is rapid and effectively regulated.

    Science.gov (United States)

    Appenzeller-Herzog, Christian; Riemer, Jan; Zito, Ester; Chin, King-Tung; Ron, David; Spiess, Martin; Ellgaard, Lars

    2010-10-06

    The molecular networks that control endoplasmic reticulum (ER) redox conditions in mammalian cells are incompletely understood. Here, we show that after reductive challenge the ER steady-state disulphide content is restored on a time scale of seconds. Both the oxidase Ero1α and the oxidoreductase protein disulphide isomerase (PDI) strongly contribute to the rapid recovery kinetics, but experiments in ERO1-deficient cells indicate the existence of parallel pathways for disulphide generation. We find PDI to be the main substrate of Ero1α, and mixed-disulphide complexes of Ero1 primarily form with PDI, to a lesser extent with the PDI-family members ERp57 and ERp72, but are not detectable with another homologue TMX3. We also show for the first time that the oxidation level of PDIs and glutathione is precisely regulated. Apparently, this is achieved neither through ER import of thiols nor by transport of disulphides to the Golgi apparatus. Instead, our data suggest that a dynamic equilibrium between Ero1- and glutathione disulphide-mediated oxidation of PDIs constitutes an important element of ER redox homeostasis.

  4. Iconografía textil q'ero como texto: leyendo el rombo dualista Hatun Inti

    Directory of Open Access Journals (Sweden)

    1994-01-01

    Full Text Available L'ICONOGRAPHIE TEXTILE Q'ERO VUE EN TANT QUE TEXTE: LECTURE DU LOSANGE DUALISTE HATUN INTI. Les Q'ero, ainsi que les autres natifs du département de Cusco, lisent le motif géométrique dualiste Hatun Inti en l'associant à des conceptions spatiales. Les éléments graphiques qui forment ce losange ont des noms et des significations spécifiques, et créent un véritable lexique graphique. Los Q’ero y otros nativos del departamento del Cusco leen el motivo geométrico dualista Hatun Inti, con referencia a concepciones espaciales. Los elementos gráficos que forman este rombo toman nombres y significados específicos, creando un verdadero léxico gráfico. Q'ERO TEXTILE ICONOGRAPHY PERCEIVED AS TEXT: READING THE HALVED HATUN INTI. The Q’ero and other natives who live in the Department of Cusco read halved diamond motif as it refers to spatial concepts. The graphic elements which form this motif have specific names and meanings, creating a true graphic lexicon.

  5. Benchmarking Asteroid-Deflection Experiment

    Science.gov (United States)

    Remington, Tane; Bruck Syal, Megan; Owen, John Michael; Miller, Paul L.

    2016-10-01

    An asteroid impacting Earth could have devastating consequences. In preparation to deflect or disrupt one before it reaches Earth, it is imperative to have modeling capabilities that adequately simulate the deflection actions. Code validation is key to ensuring full confidence in simulation results used in an asteroid-mitigation plan. We are benchmarking well-known impact experiments using Spheral, an adaptive smoothed-particle hydrodynamics code, to validate our modeling of asteroid deflection. We describe our simulation results, compare them with experimental data, and discuss what we have learned from our work. 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-695540

  6. 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 ...

  7. Nonlocal gravity

    CERN Document Server

    Mashhoon, Bahram

    2017-01-01

    Relativity theory is based on a postulate of locality, which means that the past history of the observer is not directly taken into account. This book argues that the past history should be taken into account. In this way, nonlocality---in the sense of history dependence---is introduced into relativity theory. The deep connection between inertia and gravitation suggests that gravity could be nonlocal, and in nonlocal gravity the fading gravitational memory of past events must then be taken into account. Along this line of thought, a classical nonlocal generalization of Einstein's theory of gravitation has recently been developed. A significant consequence of this theory is that the nonlocal aspect of gravity appears to simulate dark matter. According to nonlocal gravity theory, what astronomers attribute to dark matter should instead be due to the nonlocality of gravitation. Nonlocality dominates on the scale of galaxies and beyond. Memory fades with time; therefore, the nonlocal aspect of gravity becomes wea...

  8. Asteroid Perturbations and Mass Determination for the ASTROD Space Mission

    CERN Document Server

    Tang, C J; Tang, Chien-Jen; Ni, Wei-Tou

    2004-01-01

    Due to the high-precision nature of the ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) mission concept, the asteroid perturbations on the ASTROD spacecraft is crucial. These perturbations need to be modelled and determined together with relativistic effects and other solar-system parameters. In a previous investigation (Su et al., Planetary and Space Science, 47, 339-43[1999]), we used the mass estimation of Ceres, Pallas and Vesta in the literature to calculate their perturbations on the ASTROD spacecraft. Recently, we established an ephemeris framework (CGC 1) including the 3 big asteroids and used this ephemeris framework to simulate the determination of their masses together with other solar-system parameters and relativistic-gravity parameters. In this paper, we extend the CGC 1 to CGC 2 ephemeris framework to include 492 asteroids (with diameter > 65 km) . We then use CGC 2 to simulate the determination of ten parameters -- the masses of Ceres, Pallas and Vesta, the six average d...

  9. 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...

  10. Dynamics of Rotationally Fissioned Asteroids

    Science.gov (United States)

    Jacobson, Seth A.; Scheeres, D. J.

    2010-10-01

    We present a model for near-Earth asteroid (NEA) rotational fission that results in the evolution of all observed types of NEA systems: synchronous binaries, asteroid pairs, doubly synchronous binaries, high-e binaries, ternary systems, and contact binaries. The model consists of "rubble pile” asteroid geophysics, the YORP and binary YORP effects, and mutual gravitational interactions. An NEA can be modeled as a ``rubble pile"--a collection of gravitationally bound boulders with a distribution of size scales and very little tensile strength between them. The YORP effect torques a "rubble pile” asteroid until the asteroid reaches its disruption spin limit, and then two collections of boulders will enter into orbit about each other determined by the largest distance between mass centers. This binary system dynamically evolves under the effects of non-spherical gravitational potentials, solar gravitational perturbations, and mutual body tides. The coupling between the spin states and orbit state chaotically drives the system into the observed asteroid classes with mass ratio, q, distinguishing two evolutionary tracks. High mass ratio systems, q>0.2, evolve tidally into doubly synchronous binaries and then continued to be evolved by BYORP. Low mass ratio systems, qfission, creating a chaotic ternary system. We call this new process secondary fission. The resulting triple system may eject one body or, more often, send one into a slow speed impact with the primary. These processes tend to stabilize the initially chaotic binaries to create synchronous binaries. These results emphasize the importance of the initial component size distribution and configuration within the parent body. This work is supported by NASA's PGG and OPR programs through grants: NNX08AL51G and NNX09AU23G.

  11. Project RAMA: Reconstructing Asteroids Into Mechanical Automata

    Science.gov (United States)

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

    2017-01-01

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

  12. Magnetism of Minor Bodies in the Solar System: From 433 Eros, passing Braille, Steins, and Lutetia towards Churyumov-Gerasimenko and 1999 JU3.

    Science.gov (United States)

    Hercik, David; Auster, Hans-Ulrich; Heinisch, Philip; Richter, Ingo; Glassmeier, Karl-Heinz

    2015-04-01

    Minor bodies in the solar system, such as asteroids and comets, are important sources of information for our knowledge of the solar system formation. Besides other aspects, estimation of a magnetization state of such bodies might prove important in understanding the early aggregation phases of the protoplanetary disk, showing the level of importance of the magnetic forces in the processes involved. Meteorites' magnetization measurements suggest that primitive bodies consist of magnetized material. However, space observations from various flybys give to date diverse results for a global magnetization estimation. The flybys at Braille and Gaspra indicate possible higher magnetization (~ 10-3 Am2/kg), while flybys at Steins and Lutetia show no significant values in the global field change illustrating low global magnetization. Furthermore, the interpretation of remote (during flybys) measurements is very difficult. For correct estimates on the local magnetization one needs (in the best case) multi-point surface measurements. Single point observation has been done by NEAR-Shoemaker on 433 Eros asteroid, revealing no signature in magnetic field that could have origin in asteroid magnetization. Similar results, no magnetization observed, have been provided by evaluation of recent data from ROMAP (Philae lander) and RPC-MAG (Rosetta orbiter) instruments from comet 67P/Churyumov-Gerasimenko. The ROMAP instrument provided measurements from multiple points of the cometary surface as well as data along ballistic path between multiple touchdowns, which support the conclusion of no global magnetization. However, even in case of the in-situ on surface observations the magnetization estimate has a limiting spatial resolution that is dependent on the distance from the surface (~ 50 cm in case of ROMAP). To get information about possible smaller magnetized grains distribution and magnetization strength, the sensor shall be placed as close as possible to the surface. For such

  13. THE FORMS OF EROS IN THE NOVEL “BARBARIUS” BY CONSTANTIN ȚOIU

    Directory of Open Access Journals (Sweden)

    Ionela-Viviana LUCA

    2015-04-01

    Full Text Available After a true initiatory journey, with dramatic sequences when it seemed that he lost his identity, Barbarius manages to return to his own self, the real man who can love and be loved. At the end of the novel, the protagonist achieves that much desired inner balance along with Dr. Zamfirita Micescu. However, we can not speak of eros without taking into account the desire, because the place where desire appears, also appears the needs to satisfy it. The feeling of fullness, inner balance, satisfaction manages to materialize through the harmonious fusion between the two forms of eros, namely sexuality and spiritual love. Therefore, we can state that along with Dr. Micescu, Caesar achieves a high hypostasis of eros. The narrator admirably manages to capture the reader's attention from the first chapter of the novel, which describes a passionate scene, of heartbreaking love that ends in a perverse cruelty and murder.

  14. Flying Through Dust From Asteroids

    Science.gov (United States)

    Kohler, Susanna

    2016-11-01

    How can we tell what an asteroid is made of? Until now, weve relied on remote spectral observations, though NASAs recently launched OSIRIS-REx mission may soon change this by landing on an asteroid and returning with a sample.But what if we could learn more about the asteroids near Earth without needing to land on each one? It turns out that we can by flying through their dust.The aerogel dust collector of the Stardust mission. [NASA/JPL/Caltech]Ejected CluesWhen an airless body is impacted by the meteoroids prevalent throughout our solar system, ejecta from the body are flung into the space around it. In the case of small objects like asteroids, their gravitational pull is so weak that most of the ejected material escapes, forming a surrounding cloud of dust.By flying a spacecraft through this cloud, we could perform chemical analysis of the dust, thereby determining the asteroids composition. We could even capture some of the dust during a flyby (for example, by using an aerogel collector like in the Stardust mission) and bring it back home to analyze.So whats the best place to fly a dust-analyzing or -collecting spacecraft? To answer this, we need to know what the typical distribution of dust is around a near-Earth asteroid (NEA) a problem that scientists Jamey Szalay (Southwest Research Institute) and Mihly Hornyi (University of Colorado Boulder) address in a recent study.The colors show the density distribution for dust grains larger than 0.3 m around a body with a 10-km radius. The distribution is asymmetric, with higher densities on the apex side, shown here in the +y direction. [Szalay Hornyi 2016]Moon as a LaboratoryTo determine typical dust distributions around NEAs, Szalay and Hornyi first look at the distribution of dust around our own Moon, caused by the same barrage of meteorites wed expect to impact NEAs. The Moons dust cloud was measured in situ in 2013 and 2014 by the Lunar Dust Experiment (LDEX) on board the Lunar Atmosphere and Dust Environment

  15. Simulation and Prototype Design of Variable Step Angle Techniques Based Asteroid Deflection for Future Planetary Mission

    Science.gov (United States)

    Sathiyavel, C.

    2016-07-01

    side is apply equal force is like 1000mN], direction of Asteroid in far from the geosynchronous orbit. Suppose, the asteroid is coming of 22.5 angle from asteroid orbit between Mars and Jupiter or other orbit, then rotates the Stepper motor to require angle is 22.5 angle and also changes of ADM Mission at static position through Radar Communication system. The ion propulsion is producing opposite velocity [from simulation results but experimental output result is small because low quality of Components is used in Research Lab] to hit the asteroid surface is like 7km/s ,10km/s ,15km/s,20Km/s due to actual gravity in orbit. If the simulation result changes the deflection of asteroid the actual direction will be 22.5 angle to 30 angle.

  16. EROS Data Center Landsat digital enhancement techniques and imagery availability

    Science.gov (United States)

    Rohde, Wayne G.; Lo, Jinn Kai; Pohl, Russell A.

    1978-01-01

    The US Geological Survey's EROS Data Center (EDC) is experimenting with the production of digitally enhanced Landsat imagery. Advanced digital image processing techniques are used to perform geometric and radiometric corrections and to perform contrast and edge enhancements. The enhanced image product is produced from digitally preprocessed Landsat computer compatible tapes (CCTs) on a laser beam film recording system. Landsat CCT data have several geometric distortions which are corrected when NASA produces the standard film products. When producing film images from CCT's, geometric correction of the data is required. The EDC Digital Image Enhancement System (EDIES) compensates for geometric distortions introduced by Earth's rotation, variable line length, non-uniform mirror scan velocity, and detector misregistration. Radiometric anomalies such as bad data lines and striping are common to many Landsat film products and are also in the CCT data. Bad data lines or line segments with more than 150 contiguous bad pixels are corrected by inserting data from the previous line in place of the bad data. Striping, caused by variations in detector gain and offset, is removed with a destriping algorithm applied after digitally enhancing the data. Image enhancement is performed by applying a linear contrast stretch and an edge enhancement algorithm. The linear contrast enhancement algorithm is designed to expand digitally the full range of useful data recorded on the CCT over the range of 256 digital counts. This minimizes the effect of atmospheric scattering and saturates the relative brightness of highly reflecting features such as clouds or snow. It is the intent that no meaningful terrain data are eliminated by the digital processing. The edge enhancement algorithm is designed to enhance boundaries between terrain features that exhibit subtle differences in brightness values along edges of features. After the digital data have been processed, data for each Landsat band

  17. Spectral Classification of Asteroids by Random Forest

    Science.gov (United States)

    Huang, C.; Ma, Y. H.; Zhao, H. B.; Lu, X. P.

    2016-09-01

    With the increasing asteroid spectral and photometric data, a variety of classification methods for asteroids have been proposed. This paper classifies asteroids based on the observations of Sloan Digital Sky Survey (SDSS) Moving Object Catalogue (MOC) by using the random forest algorithm. With the training data derived from the taxonomies of Tholen, Bus, Lazzaro, DeMeo, and Principal Component Analysis, we classify 48642 asteroids according to g, r, i, and z SDSS magnitudes. In this way, asteroids are divided into 8 spectral classes (C, X, S, B, D, K, L, and V).

  18. 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.

  19. New insights into main belt asteroid collisional lifetimes

    Science.gov (United States)

    Henych, Tomas; Holsapple, Keith

    2016-10-01

    We are developing a new Monte Carlo code to study the collisional and spin evolution of main belt asteroids. A byproduct is information on asteroid lifetimes. We find new interpretations and values of those lifetimes.In the conventional approach, the "collisional lifetime" is measured by the time when an asteroid is struck by an impactor large enough to remove one-half of the target's mass. That event is called a catastrophic disruption (CD). From an assumed population of impactors and Poisson statistics, one can estimate the largest expected impactor to impact in a given time interval to get its expected collisional lifetime. However, our Monte Carlo simulations give lifetimes that are distinctly shorter. That raises questions about the basic definition of catastrophic disruption.During its presence in the main belt, many other asteroids of all sizes continually strike a target asteroid. Before the CD one happens, there are many small impacts, and a few less than but not equal to the CD one. Each impact erodes the target asteroid. Very commonly, it is eroded to a much smaller mass before some CD event. We will present examples.So what shall we define as its collisional lifetime? Should it be the time for which its mass is reduced to one-half of its original mass, irrespective of how that happened, perhaps from many impacts? Or when any single impact reduces its mass to one-half of its original mass? Or when a single impact reduces it to one-half of its current mass?We propose that collisional lifetime is defined as the time at which it reaches 50% of its original mass, from any combination of small and/or large events. We use cratering and ejecta scaling formulas (e.g. Holsapple, 1993, Housen and Holsapple, 2011) to calculate the eroded mass history of the target for a history of impactors and calculate the outcome of any impact using the current size. In the gravity regime, the eroded body is easier to disrupt. We will present our lifetime estimates and those of

  20. Artificial Gravity

    CERN Document Server

    Clément, Gilles

    2007-01-01

    Protecting the health, safety, and performance of exploration-class mission crews against the physiological deconditioning resulting from long-term weightlessness during transit and long-term reduced gravity during surface operations will require effective, multi-system countermeasures. Artificial gravity, which would replace terrestrial gravity with inertial forces generated by rotating the transit vehicle or by short-radius human centrifuge devices within the transit vehicle or surface habitat, has long been considered a potential solution. However, despite its attractiveness as an efficient

  1. The OSIRIS-REx Sample Return Mission from Asteroid Bennu

    Science.gov (United States)

    Lauretta, Dante; Clark, Benton

    2016-07-01

    The primary objective of the Origins, Spectral Interpretation, Resource Identification, and Security‒Regolith Explorer (OSIRIS-REx) mission is to return and analyze a sample of pristine regolith from asteroid 101955 Bennu, a primitive carbonaceous asteroid and also a potentially hazardous near-Earth object. Returned samples are expected to contain primitive ancient Solar System materials formed in planetary, nebular, interstellar, and circumstellar environments. In addition, the OSIRIS-REx mission will obtain valuable information on sample context by imaging the sample site; characterize its global geology; map global chemistry and mineralogy; investigate dynamic history by measuring the Yarkovsky effect; and advance asteroid astronomy by characterizing surface properties for direct comparison with ground-based telescopic observations of the entire asteroid population. Following launch in September 2016, the spacecraft will encounter Bennu in August 2018, then embark on a systematic study of geophysical and morphological characteristics of this ~500-meter-diameter object, including a systematic search for satellites and plumes. For determination of context, composition, and sampleability of various candidate sites, advanced instruments for remote global observations include OVIRS (visible to mid-IR spectrometric mapper), OTES (mid- to far-IR mineral and thermal emission mapper), OLA (mapping laser altimeter), and a suite of scientific cameras (OCAMS) with sub-cm pixel size from low-altitude Reconnaissance passes. A unique sample acquisition mechanism (SAM) capable of collecting up to one liter of regolith under ideal conditions (abundant small particulates tested in ground tests, and also on reduced-gravity airplane flights, to evaluate collection efficiency for various surfaces. Special cleaning techniques and contamination monitoring with in-flight witness plates are employed to assure a pristine sample. In September 2023, the entire TAGSAM end-effector stowed

  2. Simultaneous Mass Determination for Gravitationally Coupled Asteroids

    Science.gov (United States)

    Baer, James; Chesley, Steven R.

    2017-08-01

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

  3. A PDI-catalyzed thiol-disulfide switch regulates the production of hydrogen peroxide by human Ero1.

    Science.gov (United States)

    Ramming, Thomas; Okumura, Masaki; Kanemura, Shingo; Baday, Sefer; Birk, Julia; Moes, Suzette; Spiess, Martin; Jenö, Paul; Bernèche, Simon; Inaba, Kenji; Appenzeller-Herzog, Christian

    2015-06-01

    Oxidative folding in the endoplasmic reticulum (ER) involves ER oxidoreductin 1 (Ero1)-mediated disulfide formation in protein disulfide isomerase (PDI). In this process, Ero1 consumes oxygen (O2) and releases hydrogen peroxide (H2O2), but none of the published Ero1 crystal structures reveal any potential pathway for entry and exit of these reactants. We report that additional mutation of the Cys(208)-Cys(241) disulfide in hyperactive Ero1α (Ero1α-C104A/C131A) potentiates H2O2 production, ER oxidation, and cell toxicity. This disulfide clamps two helices that seal the flavin cofactor where O2 is reduced to H2O2. Through its carboxyterminal active site, PDI unlocks this seal by forming a Cys(208)/Cys(241)-dependent mixed-disulfide complex with Ero1α. The H2O2-detoxifying glutathione peroxidase 8 also binds to the Cys(208)/Cys(241) loop region. Supported by O2 diffusion simulations, these data describe the first enzymatically controlled O2 access into a flavoprotein active site, provide molecular-level understanding of Ero1α regulation and H2O2 production/detoxification, and establish the deleterious consequences of constitutive Ero1 activity.

  4. The TESIS project: Are type 2 QSO hidden in X-ray emitting EROs?

    CERN Document Server

    Severgnini, P; Braito, V; Saracco, P; Longhetti, M; Bender, R; Drory, N; Feulner, G; Hopp, U; Mannucci, F; Maraston, C

    2003-01-01

    Here we present the results obtained from the analysis of 75 ksec of XMM-Newton observations of a sample of EROs selected from one MUNICS field (K'<19.5 mag). We find 6 EROs with a X-ray counterpart down to a 2--10 keV flux limit of ~10^{-15} cgs. For all of them the X-ray--to--optical flux ratios and the 2--10 keV luminosities suggest the presence of AGN. In particular, a complete X-ray spectral analysis shows that high luminosity, obscured AGNs (i.e. QSO2 candidates) are present in 3 of them.

  5. TAWA INTI QOCHA, SIMBOLO DE LA COSMOLOGIA ANDINA: CONCEPCION Q'ERO DEL ESPACIO

    Directory of Open Access Journals (Sweden)

    Gaíl Silverman-Proust

    1988-12-01

    Full Text Available Este artículo trata solamente de la concepción espacial que está registrada en los tejidos Q'ero. Primero estudiaremos la organización socio-política, religiosa, y económica de los Q'ero. Segundo daremos una descripción del motivo Tawa Inti Qocha, enfocando su técnica de tejido, su organización formal en el traje y su distribución temporal-espacial. Por último mostraremos como este diseño significa el espacio social tanto dualista como cuatripartito.

  6. Astronomical Observations of Volatiles on Asteroids

    CERN Document Server

    Rivkin, Andrew S; Emery, Joshua P; Howell, Ellen S; Licandro, Javier; Takir, Driss; Vilas, Faith

    2015-01-01

    We have long known that water and hydroxyl are important components in meteorites and asteroids. However, in the time since the publication of Asteroids III, evolution of astronomical instrumentation, laboratory capabilities, and theoretical models have led to great advances in our understanding of H2O/OH on small bodies, and spacecraft observations of the Moon and Vesta have important implications for our interpretations of the asteroidal population. We begin this chapter with the importance of water/OH in asteroids, after which we will discuss their spectral features throughout the visible and near-infrared. We continue with an overview of the findings in meteorites and asteroids, closing with a discussion of future opportunities, the results from which we can anticipate finding in Asteroids V. Because this topic is of broad importance to asteroids, we also point to relevant in-depth discussions elsewhere in this volume.

  7. Astronomical observations of volatiles on asteroids

    Science.gov (United States)

    Rivkin, Andrew S.; Campins, Humberto; Emery, Joshua P.; Howell, Ellen S.; Licandro, Javier; Takir, Driss; Vilas, Faith; Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    2015-01-01

    We have long known that water and hydroxyl are important components in meteorites and asteroids. However, in the time since the publication of Asteroids III, evolution of astronomical instrumentation, laboratory capabilities, and theoretical models have led to great advances in our understanding of H2O/OH on small bodies, and spacecraft observations of the Moon and Vesta have important implications for our interpretations of the asteroidal population. We begin this chapter with the importance of water/OH in asteroids, after which we will discuss their spectral features throughout the visible and near-infrared. We continue with an overview of the findings in meteorites and asteroids, closing with a discussion of future opportunities, the results from which we can anticipate finding in Asteroids V. Because this topic is of broad importance to asteroids, we also point to relevant in-depth discussions elsewhere in this volume.

  8. Asteroid taxonomic signatures from photometric phase curves

    CERN Document Server

    Oszkiewicz, D A; Wasserman, L H; Muinonen, K; Penttilä, A; Pieniluoma, T; Trilling, D E; Thomas, C A

    2012-01-01

    We explore the correlation between an asteroid's taxonomy and photometric phase curve using the H, G12 photometric phase function, with the shape of the phase function described by the single parameter G12. We explore the usability of G12 in taxonomic classification for individual objects, asteroid families, and dynamical groups. We conclude that the mean values of G12 for the considered taxonomic complexes are statistically different, and also discuss the overall shape of the G12 distribution for each taxonomic complex. Based on the values of G12 for about half a million asteroids, we compute the probabilities of C, S, and X complex membership for each asteroid. For an individual asteroid, these probabilities are rather evenly distributed over all of the complexes, thus preventing meaningful classification. We then present and discuss the G12 distributions for asteroid families, and predict the taxonomic complex preponderance for asteroid families given the distribution of G12 in each family. For certain ast...

  9. The empty primordial asteroid belt.

    Science.gov (United States)

    Raymond, Sean N; Izidoro, Andre

    2017-09-01

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

  10. Applications of granular-dynamics numerical simulations to asteroid surfaces

    Science.gov (United States)

    Richardson, D. C.; Michel, P.; Schwartz, S. R.; Yu, Y.; Ballouz, R.-L.; Matsumura, S.

    2014-07-01

    Spacecraft images and indirect observations including thermal inertia measurements indicate most small bodies have surface regolith. Evidence of granular flow is also apparent in the images. This material motion occurs in very low gravity, therefore in a totally different gravitational environment than on the Earth. Upcoming sample-return missions to small bodies, and possible future manned missions, will involve interaction with the surface regolith, so it is important to develop tools to predict the surface response. We have added new capabilities to the N-body gravity tree code pkdgrav [1,2] that permit the simulation of granular dynamics, including multi-contact physics and friction forces, using the soft-sphere discrete-element method [3]. The numerical approach has been validated through comparison with laboratory experiments (e.g., [3,4]). (1) We carried out impacts into granular materials using different projectile shapes under Earth's gravity [5] and compared the results to laboratory experiments [6] in support of JAXA's Hayabusa 2 asteroid sample-return mission. We tested different projectile shapes and confirmed that the 90-degree cone was the most efficient at excavating mass when impacting 5-mm-diameter glass beads. Results are sensitive to the normal coefficient of restitution and the coefficient of static friction. Preliminary experiments in micro-gravity for similar impact conditions show both the amount of ejected mass and the timescale of the impact process increase, as expected. (2) It has been found (e.g., [7,8]) that ''fresh'' (unreddened) Q-class asteroids have a high probability of recent planetary encounters (˜1 Myr; also see [9]), suggesting that surface refreshening may have occurred due to tidal effects. As an application of the potential effect of tidal interactions, we carried out simulations of Apophis' predicted 2029 encounter with the Earth to see whether regolith motion might occur, using a range of plausible material parameters

  11. Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft.

    Science.gov (United States)

    Nakamura, Eizo; Makishima, Akio; Moriguti, Takuya; Kobayashi, Katsura; Tanaka, Ryoji; Kunihiro, Tak; Tsujimori, Tatsuki; Sakaguchi, Chie; Kitagawa, Hiroshi; Ota, Tsutomu; Yachi, Yusuke; Yada, Toru; Abe, Masanao; Fujimura, Akio; Ueno, Munetaka; Mukai, Toshifumi; Yoshikawa, Makoto; Kawaguchi, Jun'ichiro

    2012-03-13

    Records of micrometeorite collisions at down to submicron scales were discovered on dust grains recovered from near-Earth asteroid 25143 (Itokawa). Because the grains were sampled from very near the surface of the asteroid, by the Hayabusa spacecraft, their surfaces reflect the low-gravity space environment influencing the physical nature of the asteroid exterior. The space environment was examined by description of grain surfaces and asteroidal scenes were reconstructed. Chemical and O isotope compositions of five lithic grains, with diameters near 50 μm, indicate that the uppermost layer of the rubble-pile-textured Itokawa is largely composed of equilibrated LL-ordinary-chondrite-like material with superimposed effects of collisions. The surfaces of the grains are dominated by fractures, and the fracture planes contain not only sub-μm-sized craters but also a large number of sub-μm- to several-μm-sized adhered particles, some of the latter composed of glass. The size distribution and chemical compositions of the adhered particles, together with the occurrences of the sub-μm-sized craters, suggest formation by hypervelocity collisions of micrometeorites at down to nm scales, a process expected in the physically hostile environment at an asteroid's surface. We describe impact-related phenomena, ranging in scale from 10(-9) to 10(4) meters, demonstrating the central role played by impact processes in the long-term evolution of planetary bodies. Impact appears to be an important process shaping the exteriors of not only large planetary bodies, such as the moon, but also low-gravity bodies such as asteroids.

  12. Dawn Vesta Raw Gravity Science V1.0

    Science.gov (United States)

    Buccino, D. R.; Konopliv, A. S.; Park, R. S.; Asmar, S. W.

    2014-10-01

    This data set contains archival raw, partially processed, and ancillary/supporting gravity science data acquired during the Dawn mission while the spacecraft was in orbit around the asteroid Vesta. The radio observations were carried out using the Dawn spacecraft and Earth-based receiving stations of the NASA Deep Space Network (DSN). The data set was designed primarily to support generation of high-resolution gravity field models for Vesta. Of most interest are likely to be the Orbit Data Files in the ODF directory, which provided the raw input to gravity investigations, as well as the ionospheric and tropospheric media calibration files in the ION and TRO directories, respectively.

  13. The Hypothermic Influence on CHOP and Ero1-α in an Endoplasmic Reticulum Stress Model of Cerebral Ischemia

    DEFF Research Database (Denmark)

    Poone, Gagandip K.; Hasseldam, Henrik; Munkholm, Nina

    2015-01-01

    of ischemic stroke, we investigated whether hypothermia regulates the unfolded protein response of CHOP and Endoplas micreticulum oxidoreductin-α (Ero1-α), because Ero1-α is suggested to be a downstream CHOP target. The gene expression of CHOP and Ero1-α was measured using Quantitative-PCR (Q-PCR) in rat...... hippocampi following global cerebral ischemia, and inhypoxic pheochromocytoma cells during normothermic (37 °C) and hypothermic (31 °C)conditions. As a result of ischemia, a significant increase in expression of CHOP andEro1-α was observed after three, six and twelve hours of reperfusion following...... globalischemia. A stable increase in CHOP expression was observed throughout the time course (p Ero1-α expression peaked at three to six hours (p

  14. Gravity brake

    Science.gov (United States)

    Lujan, Richard E.

    2001-01-01

    A mechanical gravity brake that prevents hoisted loads within a shaft from free-falling when a loss of hoisting force occurs. A loss of hoist lifting force may occur in a number of situations, for example if a hoist cable were to break, the brakes were to fail on a winch, or the hoist mechanism itself were to fail. Under normal hoisting conditions, the gravity brake of the invention is subject to an upward lifting force from the hoist and a downward pulling force from a suspended load. If the lifting force should suddenly cease, the loss of differential forces on the gravity brake in free-fall is translated to extend a set of brakes against the walls of the shaft to stop the free fall descent of the gravity brake and attached load.

  15. Gravity waves

    Science.gov (United States)

    Fritts, David

    1987-02-01

    Gravity waves contributed to the establishment of the thermal structure, small scale (80 to 100 km) fluctuations in velocity (50 to 80 m/sec) and density (20 to 30%, 0 to peak). Dominant gravity wave spectrum in the middle atmosphere: x-scale, less than 100 km; z-scale, greater than 10 km; t-scale, less than 2 hr. Theorists are beginning to understand middle atmosphere motions. There are two classes: Planetary waves and equatorial motions, gravity waves and tidal motions. The former give rise to variability at large scales, which may alter apparent mean structure. Effects include density and velocity fluctuations, induced mean motions, and stratospheric warmings which lead to the breakup of the polar vortex and cooling of the mesosphere. On this scale are also equatorial quasi-biennial and semi-annual oscillations. Gravity wave and tidal motions produce large rms fluctuations in density and velocity. The magnitude of the density fluctuations compared to the mean density is of the order of the vertical wavelength, which grows with height. Relative density fluctuations are less than, or of the order of 30% below the mesopause. Such motions may cause significant and variable convection, and wind shear. There is a strong seasonal variation in gravity wave amplitude. Additional observations are needed to address and quantify mean and fluctuation statistics of both density and mean velocity, variability of the mean and fluctuations, and to identify dominant gravity wave scales and sources as well as causes of variability, both temporal and geographic.

  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. Autonomous optimal trajectory design employing convex optimization for powered descent on an asteroid

    Science.gov (United States)

    Pinson, Robin Marie

    Mission proposals that land spacecraft on asteroids are becoming increasingly popular. However, in order to have a successful mission the spacecraft must reliably and softly land at the intended landing site with pinpoint precision. The problem under investigation is how to design a propellant (fuel) optimal powered descent trajectory that can be quickly computed onboard the spacecraft, without interaction from ground control. The goal is to autonomously design the optimal powered descent trajectory onboard the spacecraft immediately prior to the descent burn for use during the burn. Compared to a planetary powered landing problem, the challenges that arise from designing an asteroid powered descent trajectory include complicated nonlinear gravity fields, small rotating bodies, and low thrust vehicles. The nonlinear gravity fields cannot be represented by a constant gravity model nor a Newtonian model. The trajectory design algorithm needs to be robust and efficient to guarantee a designed trajectory and complete the calculations in a reasonable time frame. This research investigates the following questions: Can convex optimization be used to design the minimum propellant powered descent trajectory for a soft landing on an asteroid? Is this method robust and reliable to allow autonomy onboard the spacecraft without interaction from ground control? This research designed a convex optimization based method that rapidly generates the propellant optimal asteroid powered descent trajectory. The solution to the convex optimization problem is the thrust magnitude and direction, which designs and determines the trajectory. The propellant optimal problem was formulated as a second order cone program, a subset of convex optimization, through relaxation techniques by including a slack variable, change of variables, and incorporation of the successive solution method. Convex optimization solvers, especially second order cone programs, are robust, reliable, and are guaranteed

  18. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    Science.gov (United States)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  19. Relative Terrain Imaging Navigation (RETINA) Tool for the Asteroid Redirect Robotic Mission (ARRM)

    Science.gov (United States)

    Wright, Cinnamon A.; Van Eepoel, John; Liounis, Andrew; Shoemaker, Michael; DeWeese, Keith; Getzandanner, Kenneth

    2016-01-01

    As a part of the NASA initiative to collect a boulder off of an asteroid and return it to Lunar orbit, the Satellite Servicing Capabilities Office (SSCO) and NASA GSFC are developing an on-board relative terrain imaging navigation algorithm for the Asteroid Redirect Robotic Mission (ARRM). After performing several flybys and dry runs to verify and refine the shape, spin, and gravity models and obtain centimeter level imagery, the spacecraft will descend to the surface of the asteroid to capture a boulder and return it to Lunar Orbit. The algorithm implements Stereophotoclinometry methods to register landmarks with images taken onboard the spacecraft, and use these measurements to estimate the position and orientation of the spacecraft with respect to the asteroid. This paper will present an overview of the ARRM GN&C system and concept of operations as well as a description of the algorithm and its implementation. These techniques will be demonstrated for the descent to the surface of the proposed asteroid of interest, 2008 EV5, and preliminary results will be shown.

  20. 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.

  1. Asteroid exploration and utilization: The Hawking explorer

    Science.gov (United States)

    Carlson, Alan; Date, Medha; Duarte, Manny; Erian, Neil; Gafka, George; Kappler, Peter; Patano, Scott; Perez, Martin; Ponce, Edgar; Radovich, Brian

    1991-01-01

    The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources which may exist on asteroids could have enormous potential for aiding and enhancing human space exploration as well as life on Earth. With the possibly limitless opportunities that exist, it is clear that asteroids are the next step for human existence in space. This report comprises the efforts of NEW WORLDS, Inc. to develop a comprehensive design for an asteroid exploration/sample return mission. This mission is a precursor to proof-of-concept missions that will investigate the validity of mining and materials processing on an asteroid. Project STONER (Systematic Transfer of Near Earth Resources) is based on two utilization scenarios: (1) moving an asteroid to an advantageous location for use by Earth; and (2) mining an asteroids and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plane for humans to utilize asteroid resources. The report concentrates specifically on the selection of the most promising asteroids for exploration and the development of an exploration scenario. Future utilization as well as subsystem requirements of an asteroid sample return probe are also addressed.

  2. Asteroid Origins Satellite (AOSAT) I: An On-orbit Centrifuge Science Laboratory

    Science.gov (United States)

    Lightholder, Jack; Thoesen, Andrew; Adamson, Eric; Jakubowski, Jeremy; Nallapu, Ravi; Smallwood, Sarah; Raura, Laksh; Klesh, Andrew; Asphaug, Erik; Thangavelautham, Jekan

    2017-04-01

    Exploration of asteroids, comets and small moons (small bodies) can answer fundamental questions relating to the formation of the solar system, the availability of resources, and the nature of impact hazards. Near-earth asteroids and the small moons of Mars are potential targets of human exploration. But as illustrated by recent missions, small body surface exploration remains challenging, expensive, and fraught with risk. Despite their small size, they are among the most extreme planetary environments, with low and irregular gravity, loosely bound regolith, extreme temperature variation, and the presence of electrically charged dust. Here we describe the Asteroid Origins Satellite (AOSAT-I), an on-orbit, 3U CubeSat centrifuge using a sandwich-sized bed of crushed meteorite fragments to replicate asteroid surface conditions. Demonstration of this CubeSat will provide a low-cost pathway to physical asteroid model validation, shed light on the origin and geophysics of asteroids, and constrain the design of future landers, rovers, resource extractors, and human missions. AOSAT-I will conduct scientific experiments within its payload chamber while operating in two distinct modes: (1) as a nonrotating microgravity laboratory to investigate primary accretion, and (2) as a rotating centrifuge producing artificial milligravity to simulate surface conditions on asteroids, comets and small moons. AOSAT-I takes advantage of low-cost, off-the-shelf components, modular design, and the rapid assembly and instrumentation of the CubeSat standard, to answer fundamental questions in planetary science and reduce cost and risk of future exploration.

  3. First microlens mass measurement : Planet photometry of EROS BLG-2000-5

    NARCIS (Netherlands)

    An, JH; Albrow, MD; Beaulieu, JP; Caldwell, JAR; DePoy, DL; Dominik, M; Gaudi, BS; Gould, A; Greenhill, J; Hill, K; Kane, S; Martin, R; Menzies, J; Pogge, RW; Pollard, KR; Sackett, PD; Sahu, KC; Vermaak, P; Watson, R; Williams, A

    2002-01-01

    We analyze PLANET photometric observations of the caustic-crossing binary lens microlensing event, EROS BLG-2000-5, and find that modeling the observed light curve requires incorporation of the microlens parallax and the binary orbital motion. The projected Einstein radius ((r) over tilde (E) = 3.61

  4. EROS differential studies of Cepheids in the Magellanic Clouds : Stellar pulsation, stellar evolution and distance scale

    NARCIS (Netherlands)

    Beaulieu, J. P.; Sasselov, D. D.

    1996-01-01

    Abstract: We present a differential study of 500 Magellanic Cepheids with 3 million measurements obtained as a by-product of the EROS microlensing survey. The data-set is unbiased and provides an excellent basis for a differential analysis between LMC and SMC. We investigate the pulsational properti

  5. Näitus Eros külmade kiviseinte vahel / Marika Vernik

    Index Scriptorium Estoniae

    Vernik, Marika

    2001-01-01

    Tšehhi erootiliste ehete näitusest "Eros" Rakvere muuseumis, lähemalt Blanka Sperkova, Martin Pouzari, Lucie Krejcova, Barbora Kalisova, Jolana Sperkova, Blanka, Ctvrteckova, Jan Haseki, Karol Weisslechneri, Susan Ewingi, Jiri Jahelka ja Michal Novotny töödest

  6. Eros in the first century’s Christian theology. Pseudo-Dionysius the Areopagite

    Directory of Open Access Journals (Sweden)

    Mircea Adrian Marica

    2015-11-01

    Full Text Available For among most contemporaries, the concept of Eros seems to have nothing to do with Christianity. Sifting through the psychoanalysis of sexual fantasy, theologically it says nothing. Our study gives reasons showing that for theologians since the dawn of the Christian era, Eros-love plays a fundamental role.. The connotations of this concept, however, are different from those of today, when its sensory meaning is more restricted to sexuality. Greek theologians of the first centuries after Christ, taught the concept of Plato enshrined as a unifying enthusiasm, the attraction of inferior to superior states, as “hungry and thirsty” for something continuously higher, developing, and enriching the connotation. The work of Dionysius ((Pseudo Areopagite, the Idea of Good, leads us step by step up the ascent of the erotically chaste, and is identified with the One-God, who is the very source of love. Consequently, Eros-love originates from God, Eros- love being not only an ascending but firstly a descending love, which calls for a reciprocal communion.

  7. The Asteroid 1998 QE2

    Science.gov (United States)

    Vodniza, Alberto Q.; Pereira, M. R.; Arecibo Observatory Team; JPL Target Asteroids Team

    2013-10-01

    This big asteroid was at 5.8 millions of kilometers from the Earth on May 31 (2013) and it has a diameter of 2.7 km. The radar images obtained by JPL showed that the period of rotation around its axis is close to five hours. Hills. K (2013) reported that the period is of 5.281 +/- 0.002 hours. On June 4 the team of Goldstone-Arecibo found a period of 4.75 +/- 0.01 hours. We also contributed with the light and phase curves to estimate the period by means of the telescope (with red filter). The radar imagery (JPL and Arecibo) revealed that 1998 QE2 has a moon, and we captured a mutual event (eclipse). From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during several days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS. The pictures of the asteroid were captured with the following equipment: CGE PRO 1400 CELESTRON (f/11 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera. We obtained the light curve of the body. Astrometry was carried out, and we calculated the orbital elements. We obtained the following orbital parameters: eccentricity = 0.5692181, semi-major axis = 2.41104631 A.U, orbital inclination = 12.82771 deg, longitude of the ascending node = 250.16876 deg, argument of perihelion = 345.61328 deg, mean motion = 0.26326658 deg/d, perihelion distance = 1.03863508 A.U, aphelion distance = 3.78345755 A.U. The asteroid has an orbital period of 3.74 years The parameters were calculated based on 191 observations (2013 May: 17-24) with mean residual = 0.162 arcseconds. A video of the asteroid from our Observatory was published on the main page of the “SPACEWEATHER” web: http://www.spaceweather.com/archive.php?view=1&day=21&month=05&year=2013 Note: The autors would like to thank to: Dr. Alessondra Springmann (Arecibo Observatory), Dr. Petr Pravec (Czech Republic), Dr. Lance Benner (JPL), Dr. Carl Hergenrother (Target Asteroids Team), and Dr. Dolores Hill

  8. Attitude Analysis and Robust Adaptive Backstepping Sliding Mode Control of Spacecrafts Orbiting Irregular Asteroids

    Directory of Open Access Journals (Sweden)

    Chunhui Liang

    2014-01-01

    Full Text Available Attitude stability analysis and robust control algorithms for spacecrafts orbiting irregular asteroids are investigated in the presence of model uncertainties and external disturbances. Rigid spacecraft nonlinear attitude models are considered and detailed attitude stability analysis of spacecraft subjected to the gravity gradient torque in an irregular central gravity field is included in retrograde orbits and direct orbits using linearized system model. The robust adaptive backstepping sliding mode control laws are designed to make the attitude of the spacecrafts stabilized and responded accurately to the expectation in the presence of disturbances and parametric uncertainties. Numerical simulations are included to illustrate the spacecraft performance obtained using the proposed control laws.

  9. A captured asteroid : Our David's stone for shielding earth and providing the cheapest extraterrestrial material

    Science.gov (United States)

    Massonnet, Didier; Meyssignac, Benoît

    2006-07-01

    The issue of protecting the Earth against an asteroid impact is very popular and many concepts have been proposed to fulfil this objective. In this paper, we develop the idea of capturing a small size asteroid from an orbit close to Earth's in terms of energy and placing it into a loose Earth-bound orbit in order to use it as a shield by engineering its collision with any incoming, threatening body prior to its impact with the Earth. The operations for turning the captured asteroid into an efficient shield appear to be quicker, easier, cheaper and safer than an mission aimed at landing on an incoming impact-bound asteroid either for altering its trajectory or attempting to destroy it. The aim is an asteroid typically 20 40 m in diameter, too small to cause damage on Earth if an improper management leads to its crash, but big enough to destroy and deviate any incoming body if a collision is engineered with it preferably at more than one million km from Earth. Such a collision could be implemented within a 8 month time frame. Such an asteroid would also be a source of material such as liquid oxygen for exploratory missions. We show that the production of this material is much more efficient from an asteroid's surface than from the Moon's. As the celestial surface most accessible from Earth, a captured asteroid is also easier to engineer. Several thousands of tons of oxygen might become available sitting on the outer rim of Earth's gravity field. We examine the advantages and drawbacks of this concept and we propose a stepped approach for making it a reality within a foreseeable future. Key factors are first the detection of a candidate, whose small size make it difficult to spot, among a population of asteroids easy to reach from the Earth. We have identified such a potential candidate in 2000SG344 and describe the parameters of its capture. The second key point is how to deviate the candidate into an loose Earth bound orbit. Our preferred concept is to deposit a

  10. Understanding EROS2 observations toward the spiral arms within a classical Galactic model framework

    Science.gov (United States)

    Moniez, M.; Sajadian, S.; Karami, M.; Rahvar, S.; Ansari, R.

    2017-08-01

    Aims: EROS (Expérience de Recherche d'Objets Sombres) has searched for microlensing toward four directions in the Galactic plane away from the Galactic center. The interpretation of the catalog optical depth is complicated by the spread of the source distance distribution. We compare the EROS microlensing observations with Galactic models (including the Besançon model), tuned to fit the EROS source catalogs, and take into account all observational data such as the microlensing optical depth, the Einstein crossing durations, and the color and magnitude distributions of the catalogued stars. Methods: We simulated EROS-like source catalogs using the HIgh-Precision PARallax COllecting Satellite (Hipparcos) database, the Galactic mass distribution, and an interstellar extinction table. Taking into account the EROS star detection efficiency, we were able to produce simulated color-magnitude diagrams that fit the observed diagrams. This allows us to estimate average microlensing optical depths and event durations that are directly comparable with the measured values. Results: Both the Besançon model and our Galactic model allow us to fully understand the EROS color-magnitude data. The average optical depths and mean event durations calculated from these models are in reasonable agreement with the observations. Varying the Galactic structure parameters through simulation, we were also able to deduce contraints on the kinematics of the disk, the disk stellar mass function (at a few kpc distance from the Sun), and the maximum contribution of a thick disk of compact objects in the Galactic plane (Mthickcompetitive constraints. Conclusions: Our simulation gives a better understanding of the lens and source spatial distributions in the microlensing events. The goodness of a global fit taking into account all the observables (from the color-magnitude diagrams and microlensing observations) shows the validity of the Galactic models. Our tests with the parameters excursions

  11. Regular Motions of Resonant Asteroids

    Science.gov (United States)

    Ferraz-Mello, S.

    1990-11-01

    RESUMEN. Se revisan resultados analiticos relativos a soluciones regulares del problema asteroidal eliptico promediados en la vecindad de una resonancia con jupiten Mencionamos Ia ley de estructura para libradores de alta excentricidad, la estabilidad de los centros de liberaci6n, las perturbaciones forzadas por la excentricidad de jupiter y las 6rbitas de corotaci6n. ABSTRAC This paper reviews analytical results concerning the regular solutions of the elliptic asteroidal problem averaged in the neighbourhood of a resonance with jupiter. We mention the law of structure for high-eccentricity librators, the stability of the libration centers, the perturbations forced by the eccentricity ofjupiter and the corotation orbits. Key words: ASThROIDS

  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. Colorimetry and magnitudes of asteroids

    Science.gov (United States)

    Bowell, E.; Lumme, K.

    1979-01-01

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

  14. Comets and Asteroids with FIRST

    Science.gov (United States)

    Bockelée-Morvan, D.; Crovisier, J.

    2001-07-01

    The infrared and microwave domains have proved to be privileged tools to study the physical and chemical properties of small bodies of the Solar System. After a review of the recent results obtained on comets and asteroids in these wavelength ranges, we forecast the major outcomes that can be expected from their observations with the Herschel Space Observatory (hereafter referred as to FIRST, the former denomination). This prospect is focussed on: 1) observations of water rotational lines in comets to measure water outgassing and study water excitation in the coma and its kinematics; 2) observations of HDO in comets to constrain solar nebula models and formation scenarii of comets; 3) the study of surface properties of asteroids.

  15. A method to determine asteroid poles

    Science.gov (United States)

    Deangelis, G.

    1993-01-01

    The determination of spin axis and shape is well known to be of fundamental importance for studies about the rotational and physical properties of asteroids. In particular, knowledge that the pole coordinate distribution is random or not could indicate the probable non-Maxwellian distribution of asteroid spin axes, while the distribution in terms of size and shape could place important constraints on the theories about the collisional history of some individual asteroids, of asteroid families, and of the asteroid population as a whole. Many kinds of methods have been developed to determine pole coordinates. An EA method is presented, from which it is possible to obtain the solution with no trial poles, but with a simultaneous least square fit on both the E and A part. Results for rotational and shape parameters were obtained for 18 asteroids: the values of the obtained parameters are generally in close agreement with those of others.

  16. 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...

  17. Eccentricity distribution in the main asteroid belt

    CERN Document Server

    Malhotra, Renu

    2016-01-01

    The observationally complete sample of the main belt asteroids now spans more than two orders of magnitude in size and numbers more than 64,000 (excluding collisional family members). We undertook an analysis of asteroids' eccentricities and their interpretation with simple physical models. We find that Plummer's (1916) conclusion that the asteroids' eccentricities follow a Rayleigh distribution holds for the osculating eccentricities of large asteroids, but the proper eccentricities deviate from a Rayleigh distribution: there is a deficit of eccentricities smaller than $\\sim0.1$ and an excess of larger eccentricities. We further find that the proper eccentricities do not depend significantly on asteroid size but have strong dependence on heliocentric distance: the outer asteroid belt follows a Rayleigh distribution, but the inner belt is strikingly different. Eccentricities in the inner belt can be modeled as a vector sum of a primordial eccentricity vector of random orientation and magnitude drawn from a Ra...

  18. Mining the Apollo and Amor asteroids

    Science.gov (United States)

    Oleary, B.

    1977-01-01

    Earth-approaching asteroids could provide raw materials for space manufacturing. For certain asteroids the total energy per unit mass for the transfer of asteroidal resources to a manufacturing site in high earth orbit is comparable to that for lunar materials. For logistical reasons the cost may be many times less. Optical studies suggest that these asteroids have compositions corresponding to those of carbonaceous and ordinary chondrites, with some containing large quantities of iron and nickel; other are thought to contain carbon, nitrogen, and hydrogen, elements that appear to be lacking on the moon. The prospect that several new candidate asteroids will be discovered over the next few years increases the likelihood that a variety of asteroidal resource materials can be retrieved on low-energy missions.

  19. 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...

  20. $BF$ gravity

    CERN Document Server

    Celada, Mariano; Montesinos, Merced

    2016-01-01

    $BF$ gravity comprises all the formulations of gravity that are based on deformations of $BF$ theory. Such deformations consist of either constraints or potential terms added to the topological $BF$ action that turn some of the gauge degrees of freedom into physical ones, particularly giving rise to general relativity. The $BF$ formulations have provided new and deep insights into many classical and quantum aspects of the gravitational field, setting the foundations for the approach to quantum gravity known as spinfoam models. In this review, we present a self-contained and unified treatment of the $BF$ formulations of $D$-dimensional general relativity and other related models, focusing on the classical aspects of them and including some new results.

  1. Quantum gravity

    CERN Document Server

    Kiefer, Claus

    2012-01-01

    The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book presents a self-contained discussion of the concepts, methods and applications that can be expected in such a theory. The two main approaches to its construction - the direct quantisation of Einstein's general theory of relativity and string theory - are covered. Whereas the first attempts to construct a viable theory for the gravitational field alone, string theory assumes that a quantum theory of gravity will be achieved only through a unification of all the interactions. However, both employ the general method of quantization of constrained systems, which is described together with illustrative examples relevant for quantum gravity. There is a detailed presentation of the main approaches employed in quantum general relativity: path-integral quantization, the background-field method and canonical quantum gravity in the metric, connection and loop formulations. The discussion of stri...

  2. BF gravity

    Science.gov (United States)

    Celada, Mariano; González, Diego; Montesinos, Merced

    2016-11-01

    BF gravity comprises all the formulations of gravity that are based on deformations of BF theory. Such deformations consist of either constraints or potential terms added to the topological BF action that turn some of the gauge degrees of freedom into physical ones, particularly giving rise to general relativity. The BF formulations have provided new and deep insights into many classical and quantum aspects of the gravitational field, setting the foundations for the approach to quantum gravity known as spinfoam models. In this review, we present a self-contained and unified treatment of the BF formulations of D-dimensional general relativity and other related models, focusing on the classical aspects of them and including some new results.

  3. Exospheres from Asteroids to Planets

    Science.gov (United States)

    Killen, Rosemary M.; Burger, Matthew H.; Farrell, William M.; DREAM2

    2016-10-01

    The study of exospheres can help us understand the long-term loss of volatiles from planetary bodies due to interactions of planets, satellites, and small bodies with the interplanetary medium (solar wind, meteors, and dust), solar radiation, internal forces including diffusion and outgassing, and surface effects like sticking and chemistry. Recent evidence for water and OH on the moon has spurred interest in processes involving chemistry and sequestration of volatile species at the poles and in voids. In recent years, NASA has sent spacecraft to asteroids including Vesta and Ceres, and ESA sent Rosetta to the asteroids Lutetia and Steins. OSIRIS-REX will return a sample from a primitive asteroid, Bennu, to Earth. It is possible that a Phobos-Deimos flyby will be a precursor to a manned mission to Mars. Exospheric particles are derived from the surface and to some extent from interplanetary dust and meteoroids. By comparing the exospheric compositions before and after major meteor shower events it may be possible to determine the extent to which the exosphere reflects the surface composition. Observation of an escaping exosphere, termed a corona, is challenging. We therefore have embarked on a parametrical study of exospheres as a function of basic controlling parameters such as the mass of the primary object, mass of the exospheric species, heliocentric distance, rotation rate of the primary, composition of the body (asteroid type or icy body). These parameters will be useful for mission planning as well as quick look data to determine the size and location of bodies likely to retain their exospheres and observability of exospheric species. We will also consider the sizes of small clusters that may be gravitationally bound to small bodies such as Phobos. In addition, it is of interest to be able to determine the extent of contamination of the pristine exosphere due to the spacecraft sent to make measurements, and the effect on the measurements of outgassing in the

  4. Radiation Recoil Effects on the Dynamical Evolution of Asteroids

    Science.gov (United States)

    Cotto-Figueroa, Desiree

    The Yarkovsky effect is a radiation recoil force that results in a semimajor axis drift in the orbit that can cause Main Belt asteroids to be delivered to powerful resonances from which they could be transported to Earth-crossing orbits. This force depends on the spin state of the object, which is modified by the YORP effect, a variation of the Yarkovsky effect that results in a torque that changes the spin rate and the obliquity. Extensive analyses of the basic behavior of the YORP effect have been previously conducted in the context of the classical spin state evolution of rigid bodies (YORP cycle). However, the YORP effect has an extreme sensitivity to the topography of the asteroids and a minor change in the shape of an aggregate asteroid can stochastically change the YORP torques. Here we present the results of the first simulations that self-consistently model the YORP effect on the spin states of dynamically evolving aggregates. For these simulations we have developed several algorithms and combined them with two codes, TACO and pkdgrav. TACO is a thermophysical asteroid code that models the surface of an asteroid using a triangular facet representation and which can compute the YORP torques. The code pkdgrav is a cosmological N-body tree code modified to simulate the dynamical evolution of asteroids represented as aggregates of spheres using gravity and collisions. The continuous changes in the shape of an aggregate result in a different evolution of the YORP torques and therefore aggregates do not evolve through the YORP cycle as a rigid body would. Instead of having a spin evolution ruled by long periods of rotational acceleration and deceleration as predicted by the classical YORP cycle, the YORP effect is self-limiting and stochastic on aggregate asteroids. We provide a statistical description of the spin state evolution which lays out the foundation for new simulations of a coupled Yarkovsky/YORP evolution. Both self-limiting YORP and to a lesser

  5. Recovering and Mining Asteroids with a Gas-Sealed Enclosure

    Science.gov (United States)

    Jenniskens, P.; Damer, B.; Norkus, R.; Pilotz, S.; Grigsby, B.; Adams, C.; Blair, B. R.

    2015-01-01

    The internal structure of weakly consolidated rubble piles and primitive asteroids can be studied closer to home, and such asteroids can be mined, if it is possible to create a gas-sealed enclosure around the asteroid.

  6. Storyboard GALILEO CRUISE SCIENCE OPPORTUNITIES describes asteroid encounters

    Science.gov (United States)

    1989-01-01

    Storyboard with mosaicked image of an asteroid and entitled GALILEO CRUISE SCIENCE OPPORTUNITIES describes asteroid objectives. These objectives include: first asteroid encounter; surface geology, composition size, shape, mass; and relation of primitive bodies to meteorites.

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

    Data.gov (United States)

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

  8. 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.

  9. Asteroid families, dynamics and astrometry

    Science.gov (United States)

    Williams, J. G.; Gibson, J.

    1987-01-01

    The proper elements and family assignments for the 1227 Palomar-Leiden Survey asteroids of high quality were tabulated. In addition to the large table, there are also auxiliary tables of Mars crossers and commensurate objects, histograms of the proper element distributions, and a discussion. Probably the most important part of the discussion describes the Mars crossing boundary, how the closest distances of approach to Mars and Jupiter are calculated, and why the observed population of Mars crossers should bombard that planet episodically rather than uniformly. Analytical work was done to derive velocity distributions of family forming events from proper element distributions subject to assumptions which may be appropriate for cratering events. Software was developed for a microcomputer to permit plotting of the proper elements. Three orthogonal views are generated and stereo pairs can be printed when desired. This program was created for the study of asteroid families. The astrometry task is directed toward measuring and reducing positions on faint comets and the minor planets with less common orbits. The observational material is CCD frames taken with the Palomar 1.5 m telescope. Positions of 10 comets and 16 different asteroids were published on the Minor Planet Circulars.

  10. Near Earth Asteroid (NEA) Scout

    Science.gov (United States)

    Johnson, Les; Castillo-Rogez, Julie; Dervan, Jared; McNutt, Leslie

    2017-01-01

    NASA is developing solar sail propulsion for a near-term Near Earth Asteroid (NEA) reconnaissance mission that will lay the groundwork for the future use of solar sails. The NEA Scout mission will use the sail as primary propulsion allowing it to survey and image one NEA's of interest for future human exploration. NEA Scout will launch on the first mission of the Space Launch System (SLS) in 2018. After its first encounter with the Moon, NEA Scout will enter the sail characterization phase by the 86 square meter sail deployment. A mechanical Active Mass Translation (AMT) system, combined with the remaining ACS propellant, will be used for sail momentum management. The spacecraft will perform a series of lunar flybys to achieve optimum departure trajectory before beginning its two year-long cruise. About one month before the asteroid flyby, NEA Scout will start its approach phase using optical navigation on top of radio tracking. The solar sail will provide NEA Scout continuous low thrust to enable a relatively slow flyby of the target asteroid under lighting conditions favorable to geological imaging. Once complete, NASA will have demonstrated the capability to fly low-cost, high delta V CubeSats to perform interplanetary missions.

  11. FBXO6-Mediated Ubiquitination and Degradation of Ero1L Inhibits Endoplasmic Reticulum Stress-Induced Apoptosis

    Directory of Open Access Journals (Sweden)

    Xi Chen

    2016-11-01

    Full Text Available Background/Aims: FBXO6 is the substrate recognition component of a Skp1-Cullin1-F-box protein (SCF ubiquitin E3 ligase complex, recognizing the chitobiose in unfolded N-glycoprotein to target glycoproteins for polyubiquitination and degradation. Although how FBXO6 recognizes glycoprotein has been fully investigated, the ubiquitination substrates of FBXO6 remain largely unknown. Previously, we have systematically identified the glycoproteins that interact with FBXO6 in an N-glycan dependent manner by LC/MS spectrum and confirmed the interaction between FBXO6 and glycosylated Ero1L, a protein disulfide oxidase in endoplasmic reticulum (ER. Methods: The relationship between endogenous Ero1L and exogenous Flag-FBXO6 were determined by Western blot. In vivo ubiquitination assay was used to detect the direct effect of FBXO6 in the regulation of Ero1L. Both CCK8 and FACS assays were used to determine the apoptosis ratio of cells after treatments. Results: Ero1L is a ubiquitination substrate of FBXO6. FBXO6 mediates the degradation of Ero1L through a ubiquitylation-dependent pathway. Overexpression of FBXO6 increased the polyubiquitination and decreased the stability of Ero1L, whereas inhibition of FBXO6 prolonged the half-life of Ero1L. Functionally, we show that FBXO6 inhibits ER stress-induced apoptosis by modulating the protein level of Ero1L. Conclusion: Collectively, our results demonstrate FBXO6 as a functional E3 ubiquitin ligase for Ero1L that plays a critical role in inhibiting ER stress-induced apoptosis.

  12. U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center-fiscal year 2010 annual report

    Science.gov (United States)

    Nelson, Janice S.

    2011-01-01

    The Earth Resources Observation and Science (EROS) Center is a U.S. Geological Survey (USGS) facility focused on providing science and imagery to better understand our Earth. The work of the Center is shaped by the earth sciences, the missions of our stakeholders, and implemented through strong program and project management, and application of state-of-the-art information technologies. Fundamentally, EROS contributes to the understanding of a changing Earth through 'research to operations' activities that include developing, implementing, and operating remote-sensing-based terrestrial monitoring capabilities needed to address interdisciplinary science and applications objectives at all levels-both nationally and internationally. The Center's programs and projects continually strive to meet, and where possible exceed, the changing needs of the USGS, the Department of the Interior, our Nation, and international constituents. The Center's multidisciplinary staff uses their unique expertise in remote sensing science and technologies to conduct basic and applied research, data acquisition, systems engineering, information access and management, and archive preservation to address the Nation's most critical needs. Of particular note is the role of EROS as the primary provider of Landsat data, the longest comprehensive global land Earth observation record ever collected. This report is intended to provide an overview of the scientific and engineering achievements and illustrate the range and scope of the activities and accomplishments at EROS throughout fiscal year (FY) 2010. Additional information concerning the scientific, engineering, and operational achievements can be obtained from the scientific papers and other documents published by EROS staff or by visiting our web site at http://eros.usgs.gov. We welcome comments and follow-up questions on any aspect of this Annual Report and invite any of our customers or partners to contact us at their convenience. To

  13. Geotechnical Tests on Asteroid Simulant Orgueil

    Science.gov (United States)

    Garcia, Alexander D'marco

    2017-01-01

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

  14. Simulating Gravity

    Science.gov (United States)

    Pipinos, Savas

    2010-01-01

    This article describes one classroom activity in which the author simulates the Newtonian gravity, and employs the Euclidean Geometry with the use of new technologies (NT). The prerequisites for this activity were some knowledge of the formulae for a particle free fall in Physics and most certainly, a good understanding of the notion of similarity…

  15. Simulating Gravity

    Science.gov (United States)

    Pipinos, Savas

    2010-01-01

    This article describes one classroom activity in which the author simulates the Newtonian gravity, and employs the Euclidean Geometry with the use of new technologies (NT). The prerequisites for this activity were some knowledge of the formulae for a particle free fall in Physics and most certainly, a good understanding of the notion of similarity…

  16. Optimal design of near-Earth asteroid sample-return trajectories in the Sun-Earth-Moon system

    Science.gov (United States)

    He, Shengmao; Zhu, Zhengfan; Peng, Chao; Ma, Jian; Zhu, Xiaolong; Gao, Yang

    2016-08-01

    In the 6th edition of the Chinese Space Trajectory Design Competition held in 2014, a near-Earth asteroid sample-return trajectory design problem was released, in which the motion of the spacecraft is modeled in multi-body dynamics, considering the gravitational forces of the Sun, Earth, and Moon. It is proposed that an electric-propulsion spacecraft initially parking in a circular 200-km-altitude low Earth orbit is expected to rendezvous with an asteroid and carry as much sample as possible back to the Earth in a 10-year time frame. The team from the Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences has reported a solution with an asteroid sample mass of 328 tons, which is ranked first in the competition. In this article, we will present our design and optimization methods, primarily including overall analysis, target selection, escape from and capture by the Earth-Moon system, and optimization of impulsive and low-thrust trajectories that are modeled in multi-body dynamics. The orbital resonance concept and lunar gravity assists are considered key techniques employed for trajectory design. The reported solution, preliminarily revealing the feasibility of returning a hundreds-of-tons asteroid or asteroid sample, envisions future space missions relating to near-Earth asteroid exploration.

  17. Optimal design of near-Earth asteroid sample-return trajectories in the Sun-Earth-Moon system

    Institute of Scientific and Technical Information of China (English)

    Shengmao He; Zhengfan Zhu; Chao Peng; Jian Ma; Xiaolong Zhu; Yang Gao

    2016-01-01

    In the 6th edition of the Chinese Space Trajec-tory Design Competition held in 2014, a near-Earth asteroid sample-return trajectory design problem was released, in which the motion of the spacecraft is modeled in multi-body dynamics, considering the gravitational forces of the Sun, Earth, and Moon. It is proposed that an electric-propulsion spacecraft initially parking in a circular 200-km-altitude low Earth orbit is expected to rendezvous with an asteroid and carry as much sample as possible back to the Earth in a 10-year time frame. The team from the Technology and Engi-neering Center for Space Utilization, Chinese Academy of Sciences has reported a solution with an asteroid sample mass of 328 tons, which is ranked first in the competition. In this article, we will present our design and optimization methods, primarily including overall analysis, target selec-tion, escape from and capture by the Earth–Moon system, and optimization of impulsive and low-thrust trajectories that are modeled in multi-body dynamics. The orbital res-onance concept and lunar gravity assists are considered key techniques employed for trajectory design. The reported solution, preliminarily revealing the feasibility of returning a hundreds-of-tons asteroid or asteroid sample, envisions future space missions relating to near-Earth asteroid explo-ration.

  18. Experimental study on impact-induced seismic wave propagating through quartz sand simulating asteroid regolith

    Science.gov (United States)

    Matsue, Kazuma; Arakawa, Masahiko; Yasui, Minami; Matsumoto, Rie; Tsujido, Sayaka; Takano, Shota; Hasegawa, Sunao

    2015-08-01

    Introduction: Recent spacecraft surveys clarified that asteroid surfaces were covered with regolith made of boulders and pebbles such as that found on the asteroid Itokawa. It was also found that surface morphologies of asteroids formed on the regolith layer were modified. For example, the high-resolution images of the asteroid Eros revealed the evidence of the downslope movement of the regolith layer, then it could cause the degradation and the erasure of small impact crater. One possible process to explain these observations is the regolith layer collapse caused by seismic vibration after projectile impacts. The impact-induced seismic wave might be an important physical process affecting the morphology change of regolith layer on asteroid surfaces. Therefore, it is significant for us to know the relationship between the impact energy and the impact-induced seismic wave. So in this study, we carried out impact cratering experiments in order to observe the seismic wave propagating through the target far from the impact crater.Experimental method: Impact cratering experiments were conducted by using a single stage vertical gas gun set at Kobe Univ and a two-stage vertical gas gun set at ISAS. We used quartz sands with the particle diameter of 500μm, and the bulk density of 1.48g/cm3. The projectile was a ball made of polycarbonate with the diameter of 4.75mm and aluminum, titan, zirconia, stainless steel, cupper, tungsten carbide projectile with the diameter of 2mm. These projectiles were launched at the impact velocity from 0.2 to 7km/s. The target was set in a vacuum chamber evacuated below 10 Pa. We measured the seismic wave by using a piezoelectric uniaxial accelerometer.Result: The impact-induced seismic wave was measured to show a large single peak and found to attenuate with the propagation distance. The maximum acceleration of the seismic wave was recognized to have a good relationship with the normalized distance x/R, where x is the propagation distance

  19. Stable Orbits in the Didymos Binary Asteroid System - Useful Platforms for Exploration

    Science.gov (United States)

    Damme, Friedrich; Hussmann, Hauke; Wickhusen, Kai; Enrico, Mai; Oberst, Jürgen

    2016-04-01

    We have analyzed particle motion in binary asteroid systems to search for stable orbits. In particular, we studied the motion of particles near the asteroid 1996 GT (Didymos), proposed as a target for the AIDA mission. The combined gravity fields of the odd-shaped rotating objects moving about each other are complex. In addition, orbiting spacecraft or dust particles are affected by radiation pressure, possibly exceeding the faint gravitational forces. For the numerical integrations, we adopt parameters for size, shape, and rotation from telescopic observations. To simulate the effect of radiation pressure during a spacecraft mission, we apply a spacecraft wing-box shape model. Integrations were carried out beginning in near-circular orbits over 11 days, during which the motion of the particles were examined. Most orbits are unstable with particles escaping quickly or colliding with the asteroid bodies. However, with carefully chosen initial positions, we found stable motion (in the orbiting plane of the secondary) associated with the Lagrangian points (L4 and L5), in addition to horseshoe orbits, where particles move from one of the Lagrangian point to the other. Finally, we examined orbits in 1:2 resonances with the motion of the orbital period of the secondary. Stable conditions depend strongly on season caused by the inclination of the mutual orbit plane with respect to Didymos solar orbit. At larger distance from the asteroid pair, we find the well-known terminator orbits where gravitational attraction is balanced against radiation pressure. Stable orbits and long motion arcs are useful for long tracking runs by radio or Laser instruments and are well-suited for modelling of the ephemerides of the asteroid pair and gravity field mapping. Furthermore, these orbits may be useful as observing posts or as platforms for approach. These orbits may also represent traps for dust particles, an opportunity for dust collection - or possibly a hazard to spacecraft

  20. Eccentricity distribution in the main asteroid belt

    Science.gov (United States)

    Malhotra, Renu; Wang, Xianyu

    2017-03-01

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

  1. Stochastic gravity: beyond semiclassical gravity

    Energy Technology Data Exchange (ETDEWEB)

    Verdaguer, E [Departament de Fisica Fonamental and CER en Astrofisica, Fisica de Particules i Cosmologia, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain)

    2007-05-15

    The back-reaction of a classical gravitational field interacting with quantum matter fields is described by the semiclassical Einstein equation, which has the expectation value of the quantum matter fields stress tensor as a source. The semiclassical theory may be obtained from the quantum field theory of gravity interacting with N matter fields in the large N limit. This theory breaks down when the fields quantum fluctuations are important. Stochastic gravity goes beyond the semiclassical limit and allows for a systematic and self-consistent description of the metric fluctuations induced by these quantum fluctuations. The correlation functions of the metric fluctuations obtained in stochastic gravity reproduce the correlation functions in the quantum theory to leading order in an 1/N expansion. Two main applications of stochastic gravity are discussed. The first, in cosmology, to obtain the spectrum of primordial metric perturbations induced by the inflaton fluctuations, even beyond the linear approximation. The second, in black hole physics, to study the fluctuations of the horizon of an evaporating black hole.

  2. Spitzer Survey of the Karin Cluster Asteroids

    NARCIS (Netherlands)

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

    2007-01-01

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

  3. The Steward Observatory asteroid relational database

    Science.gov (United States)

    Sykes, Mark V.; Alvarezdelcastillo, Elizabeth M.

    1992-01-01

    The Steward Observatory Asteroid Relational Database (SOARD) was created as a flexible tool for undertaking studies of asteroid populations and sub-populations, to probe the biases intrinsic to asteroid databases, to ascertain the completeness of data pertaining to specific problems, to aid in the development of observational programs, and to develop pedagogical materials. To date SOARD has compiled an extensive list of data available on asteroids and made it accessible through a single menu-driven database program. Users may obtain tailored lists of asteroid properties for any subset of asteroids or output files which are suitable for plotting spectral data on individual asteroids. A browse capability allows the user to explore the contents of any data file. SOARD offers, also, an asteroid bibliography containing about 13,000 references. The program has online help as well as user and programmer documentation manuals. SOARD continues to provide data to fulfill requests by members of the astronomical community and will continue to grow as data is added to the database and new features are added to the program.

  4. Spitzer Survey of the Karin Cluster Asteroids

    NARCIS (Netherlands)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

  6. The nature of (25143) Itokawa, a target asteroid of HAYABUSA mission

    Science.gov (United States)

    Abe, M.; Fujiwara, A.

    Near-erath asteroid (25143) Itokawa is a target body of Japanese sample return HAYABUSA mission. HAYABUSA was successfully launched by Japanese M-V-5 rocket on May 19, 2003. This asteroid was discovered on September 26, 1998 by the Lincoln Near-Earth Asteroid Research program as 1998 SF36, and closed approach to the earth in 2001 and 2004. The observing campaign for this asteroid was performed during this period. The kinds of observations were visible to near infrared spectroscopy, visible to thermal infrared colorimetry, light variation, and radar observation. The obtained information about the physical property of this asteroid is taxonomic type, size, shape, pole orientation, rotational period, optical and radar albedo, and so on. We can also estimate bulk mass and density, surface density and porosity, surface temperature and thermal inertia, surface gravity and so on. Here we review the physical property of asteroid Itokawa obtained by ground-based observation and estimate the nature of Itokawa. We also mention how these results feedback to the mission scenario. References: Abe M. et al. (2002) LPS XXXIII, Abstract #1666. Binzel R. P. et al. (2001) MAPS, 36, 1167-1172, Kelly M. S. et al. (2001) MAPS, 36, suppl., A95, Ishiguro M. et al. (2003) PASJ, 55, 691-699. Ostro S. J. et al. (2004) MAPS, 39, in printing, Sekiguchi T. et al. (2003) A&A, 397, 325-328, Ohba Y. et al. (2003) EPS, 55, 341-347, Dermawan B. et al. (2003) A&A, 405, L29-L32, Kaasalainen M. et al. (2003) A&A, 405, L29-L32, Lederer S. M. et al. (2004) LPS XXXV, abstract #2058, Kaasalainen M. et al. (2004) A&A 414, L21-L24, Kawaguchi J. et al. (2003) Acta Astronautica, 52, 117-123..

  7. PARIS to Hektor, A Mission to the Jovian Trojan Asteroids

    Science.gov (United States)

    Gold, R. E.; Ensworth, C. B.; McNutt, R. L.; Ostdiek, P. H.; Prockter, L. M.

    2005-12-01

    PARIS (Planetary Access with Radioisotope Ion-drive System) spacecraft enable a new class of missions to the outer solar system. The high power-to-mass ratio of new radioisotope power systems enables New-Frontiers class missions that carry a significant a science payload to new destinations. The PARIS spacecraft take advantage of the high-efficiency of Stirling radioisotope generators (SRGs) or new thermoelectric converters to provide the power for an electric propulsion system. These low-thrust missions launched to a high C3 are especially effective for exploring objects in shallow gravity wells. The Jovian Trojan asteroids are very primitive bodies located near the Jovian L4 and L5 Lagrange points and are discussed as targets in the Solar System Decadal Survey. There are estimated to be more than 105 Jovian Trojans greater than 1 km in diameter. We consider a PARIS mission that can reach the asteroids in less than 5 years, orbit 624 Hektor, the largest of the Jovian Trojans, and go on to orbit at least one other nearby object. The candidate payload for this mission includes wide-field and narrow-field cameras, a UV-Vis-IR spectrograph, gamma-ray and neutron spectrometers, and plasma and energetic particle spectrometers. About 900 W of power are required. The launch mass would be slightly less than 1000 kg. The generation power sources with a specific power of > 8W/kg.

  8. The Hypothermic Influence on CHOP and Ero1-α in an Endoplasmic Reticulum Stress Model of Cerebral Ischemia

    Directory of Open Access Journals (Sweden)

    Gagandip K. Poone

    2015-05-01

    Full Text Available Hypoxia induced endoplasmic reticulum stress causes accumulation of unfolded proteins in the endoplasmic reticulum and activates the unfolded protein response, resulting in apoptosis through CCAAT-enhancer-binding protein homologous protein (CHOP activation. In an in vitro and in vivo model of ischemic stroke, we investigated whether hypothermia regulates the unfolded protein response of CHOP and Endoplasmic reticulum oxidoreductin-α (Ero1-α, because Ero1-α is suggested to be a downstream CHOP target. The gene expression of CHOP and Ero1-α was measured using Quantitative-PCR (Q-PCR in rat hippocampi following global cerebral ischemia, and in hypoxic pheochromocytoma cells during normothermic (37 °C and hypothermic (31 °C conditions. As a result of ischemia, a significant increase in expression of CHOP and Ero1-α was observed after three, six and twelve hours of reperfusion following global ischemia. A stable increase in CHOP expression was observed throughout the time course (p < 0.01, p < 0.0001, whereas Ero1-α expression peaked at three to six hours (p < 0.0001. Induced hypothermia in hypoxia stressed PC12 cells resulted in a decreased expression of CHOP after three, six and twelve hours (p < 0.0001. On the contrary, the gene expression of Ero1-α increased as a result of hypothermia and peaked at twelve hours (p < 0.0001. Hypothermia attenuated the expression of CHOP, supporting that hypothermia suppress endoplasmic reticulum stress induced apoptosis in stroke. As hypothermia further induced up-regulation of Ero1-α, and since CHOP and Ero1-α showed differential regulation as a consequence of both disease (hypoxia and treatment (hypothermia, we conclude that they are regulated independently.

  9. Eros variable stars A catalog of Cepheids in the Magellanic Clouds

    CERN Document Server

    Afonso, C; Alard, C; Amadon, A; Andersen, J; Ansari, R; Aubourg, E; Bauer, F; Bareyre, P; Beaulieu, J P; Blanc, G; Bouquet, A; Char, S; Charlot, X; Couchot, F; Coutures, C; Derue, F; Ferlet, R; Gaucherel, C; Glicenstein, J F; Goldman, B; Gould, A; Graff, D S; Gros, M H; Haïssinski, J; Hamilton, J C; Hardin, D P; De Kat, J; Kim, A; Lasserre, T; Lesquoy, E; Loup, C; Magneville, C; Mansoux, B; Marquette, J B; Maurice, E; Milshtein, A I; Moniez, M; Palanque-Delabrouille, Nathalie; Perdereau, O; Prévôt, L; Renault, C; Regnault, N; Rich, J; Spiro, Michel; Vidal-Madjar, A; Vigroux, L; Zylberajch, S

    1999-01-01

    We present a catalog containing 290 LMC and 590 SMC Cepheids which have been obtained using the two 4k $\\times$ 8k CCD cameras of the EROS~2 microlensing survey. The Cepheids were selected from 1,134,000 and 504,000 stars in the central regions of the LMC and SMC respectively, that were monitored over 150 nights between October 1996 and February 1997, at a rate of one measurement every night. For each Cepheid the light curves, period, magnitudes in the EROS~2 filter system, Fourier coefficients, J2000 coordinates and cross-identifications with objects referenced in the CDS Simbad database are presented. Finding charts of identified Cepheids in clusters NGC 1943, NGC 1958 and Bruck 56 are presented. The catalogue and the individual light--curves will be electronically available through the CDS (Strasbourg).

  10. Origin of igneous meteorites and differentiated asteroids

    Science.gov (United States)

    Scott, E.; Goldstein, J.; Asphaug, E.; Bottke, W.; Moskovitz, N.; Keil, K.

    2014-07-01

    Introduction: Igneously formed meteorites and asteroids provide major challenges to our understanding of the formation and evolution of the asteroid belt. The numbers and types of differentiated meteorites and non-chondritic asteroids appear to be incompatible with an origin by fragmentation of numerous Vesta-like bodies by hypervelocity impacts in the asteroid belt over 4 Gyr. We lack asteroids and achondrites from the olivine-rich mantles of the parent bodies of the 12 groups of iron meteorites and the ˜70 ungrouped irons, the 2 groups of pallasites and the 4--6 ungrouped pallasites. We lack mantle and core samples from the parent asteroids of the basaltic achondrites that do not come from Vesta, viz., angrites and the ungrouped eucrites like NWA 011 and Ibitira. How could core samples have been extracted from numerous differentiated bodies when Vesta's basaltic crust was preserved? Where is the missing Psyche family of differentiated asteroids including the complementary mantle and crustal asteroids [1]? Why are meteorites derived from far more differentiated parent bodies than chondritic parent bodies even though C and S class chondritic asteroids dominate the asteroid belt? New paradigm. Our studies of meteorites, impact modeling, and dynamical studies suggest a new paradigm in which differentiated asteroids accreted at 1--2 au less than 2 Myr after CAI formation [2]. They were rapidly melted by 26Al and disrupted by hit-and-run impacts [3] while still molten or semi-molten when planetary embryos were accreting. Metallic Fe-Ni bodies derived from core material cooled rapidly with little or no silicate insulation less than 4 Myr after CAI formation [4]. Fragments of differentiated planetesimals were subsequently tossed into the asteroid belt. Meteorite evidence for early disruption of differentiated asteroids. If iron meteorites were samples of Fe-Ni cores of bodies that cooled slowly inside silicate mantles over ˜50--100 Myr, irons from each core would have

  11. 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...

  12. Measurement of Cohesion in Asteroid Regolith Materials

    Science.gov (United States)

    Kleinhenz, Julie; Gaier, James; Waters, Deborah; Harvey, Ralph; Zeszut, Zoe; Carreno, Brandon; Shober, Patrick

    2017-01-01

    There is increasing evidence that a large fraction of asteroids, and even Phobos, have such low densities (asteroids are thought to be made up of unconsolidated smaller particles of varying size referred to as rubble piles. Images of the asteroid Itokawa reinforce this hypothesis. What holds the rubble piles together? Gravitational forces alone are not strong enough to hold together rubble pile asteroids, at least not those that are rapidly spinning Van der Waals forces and or Electrostatic forces must therefore be responsible for holding them together. Previous work suggests that electrostatic forces, which are orders of magnitude stronger are far more likely. Charge build-up is a likely consequence of the interaction of airless bodies with the solar wind plasma, analogous to what has been proposed to occur on the moon. Objective: Experimentally measure cohesive forces relevant to those holding rubble pile asteroids together

  13. Contribuyendo al bienestar emocional de los compañeros: evaluación del Programa Compañeros Ayudantes en un instituto madrileño

    Directory of Open Access Journals (Sweden)

    Cristina del Barrio

    2011-06-01

    Full Text Available Un proyecto internacional desarrollado entre noviembre de 2007 y julio de 2009 se propuso implantar y evaluar un sistema de ayuda entre iguales en un centro de secundaria de Inglaterra, Italia y España, como medio de mejora de la convivencia. Los sistemas de ayuda entre iguales implican típicamente seleccionar a algunos estudiantes y entrenarlos para ayudar a sus compañeros. Mediante un diseño de grupo control con dos grupos, se formó a los ayudantes para poner en marcha un servicio de ayuda entre compañeros en los centros objeto de la intervención. Se presentan los resultados españoles de los cuestionarios de evaluación del programa, en la que participaron 248 estudiantes implicados en el programa y posibles usuarios del mismo, y 35 profesores, implicados y no implicados en el programa. Los resultados señalan que el programa es positivamente evaluado, apoyando su continuación profesores y alumnos, que coinciden en señalar las consecuencias positivas para víctimas y alumnos ayudantes, y en considerarlo un recurso para mejorar la convivencia en el centro.

  14. The geography and human cultural resources working group of the EROS program

    Science.gov (United States)

    Gerlach, A. C.

    1972-01-01

    The functions, activities, and objectives of the Geography and Human-Cultural Resources Working Group of the EROS program are outlined. The Group's primary function is to coordinate remote sensing experiments of physical scientists and the needs of socioeconomic and culturally orientated planners, policy makers, administrators, and other user groups. Other functions of the Group include land use analysis, resource mapping, and development of an operational automatic information system receptive to land use and environmental data.

  15. Passive Nosetip Technology (PANT) Program. Volume XVIII. Nosetip Analyses Using the EROS Computer Code

    Science.gov (United States)

    1975-06-01

    transfer Distribution Comarisons 3-7 3-6 Ran 207 Camphor Shape Change Prediction (Reg - 10 x 101/ft) 3-9 3-7 Run 208 Camphor Shape Change Prediction...environment. The film coefficient approach enables the modeling of heterogeneous reaction and sublimation kinetics, unequal species diffusion coefficients...ilar predictions. As an exercise of the shape change numerical procedures in the EROS com- puter code, two camphor shape change solutions were generated

  16. The geography and human cultural resources working group of the EROS program

    Science.gov (United States)

    Gerlach, A. C.

    1972-01-01

    The functions, activities, and objectives of the Geography and Human-Cultural Resources Working Group of the EROS program are outlined. The Group's primary function is to coordinate remote sensing experiments of physical scientists and the needs of socioeconomic and culturally orientated planners, policy makers, administrators, and other user groups. Other functions of the Group include land use analysis, resource mapping, and development of an operational automatic information system receptive to land use and environmental data.

  17. Crystal structures of human Ero1α reveal the mechanisms of regulated and targeted oxidation of PDI.

    Science.gov (United States)

    Inaba, Kenji; Masui, Shoji; Iida, Hiroka; Vavassori, Stefano; Sitia, Roberto; Suzuki, Mamoru

    2010-10-06

    In the endoplasmic reticulum (ER) of eukaryotic cells, Ero1 flavoenzymes promote oxidative protein folding through protein disulphide isomerase (PDI), generating reactive oxygen species (hydrogen peroxide) as byproducts. Therefore, Ero1 activity must be strictly regulated to avoid futile oxidation cycles in the ER. Although regulatory mechanisms restraining Ero1α activity ensure that not all PDIs are oxidized, its specificity towards PDI could allow other resident oxidoreductases to remain reduced and competent to carry out isomerization and reduction of protein substrates. In this study, crystal structures of human Ero1α were solved in its hyperactive and inactive forms. Our findings reveal that human Ero1α modulates its oxidative activity by properly positioning regulatory cysteines within an intrinsically flexible loop, and by fine-tuning the electron shuttle ability of the loop through disulphide rearrangements. Specific PDI targeting is guaranteed by electrostatic and hydrophobic interactions of Ero1α with the PDI b'-domain through its substrate-binding pocket. These results reveal the molecular basis of the regulation and specificity of protein disulphide formation in human cells.

  18. The Danubian Eros and Thanatos in Mihail Sebastian’s Work

    Directory of Open Access Journals (Sweden)

    Alina Beatrice Chesca

    2013-08-01

    Full Text Available The present paper approaches two psychoanalytical concepts – the EROS and the THANATOS – which are extremely complex and, at the same time, fascinating due to their implications and the way they relate to the biography and work of Mihail Sebastian – the writer from the Danube. Art and biography meet in this danubian writer’s work, who tried to fight against his traumas and to heal himself through writing. The Eros and the Thanatos are omnipresent in the fiction of Sebastian’s obsessions and, when he faced destruction at an objective level, this fight resulted in anxiety and anguish. Along one’s life, there are two types of anxiety: the fear of life and the fear of death. The main theme of Sebastian’s work is that the human universe proves its strength only by suffering and that human beings can reach the ultimate dignity through their ability to endure. However, the instinct of death – the Thanatos – is always connected to the instinct of life – the Eros. We do not intend to reduce the latter one to the idea of love or passion, but we will interpret it in a broader sense – that of life, of creative energy, of light. Sebastian himself said: ”Life starts in darkness. There is a night for every day, there is a shadow for every light”.

  19. Q’eros, peru: the regeneration of cosmological relationships and specific identities through Music

    Directory of Open Access Journals (Sweden)

    Holly Wissler

    2010-12-01

    Full Text Available One of the principal purposes of Q’eros music is to actively regenerate and re-create good relationships with the cosmos and the spirit world they believe in. In this paper, I explore how both the Q’eros’ indigenous songs as well as their newly-adopted music and dance for Peru’s largest pilgrimage, Qoyllurit’i, achieve efficacy of purpose through similar techniques of sound production and aesthetics. Even though the specific musical traits (structure, scale, and instrumentation of both musical styles are significantly different, I address how Q’eros’ musical production of both types share the same focus and serve the same end-goals, whether the ritual is an intimate one within the community or shared with thousands of other people from the greater region. In addition, the performance of both styles of music serve as specific identity markers for the Q’eros depending on their contextual use and the identity desired at the time. In other words, the Q’eros’ musical choices allow them to shift identities between traditional Q’eros in their home community and misti (mestizo in Qoyllurit’i.

  20. Asteroid spin-up fission systems

    Science.gov (United States)

    Pravec, P.

    2014-07-01

    Among asteroids smaller than about 15 km in diameter, there is a population of binary and multiple asteroid systems that show characteristics strongly suggesting their formation by spin-up fission. I will review the current observational data we have on the systems and compare them with predictions from theories of formation of asteroid systems. I will show that the best explanation of their observed properties is provided by the theory of fission of cohesionless (rubble-pile) asteroids spun up to the critical spin frequency by the YORP effect. Observed asteroid systems are of two kinds: bound and unbound. Bound asteroid systems typically consist of a larger primary and one or two smaller satellites. Unbound systems consist of two asteroids orbiting the Sun on highly similar orbits, again with one being typically larger (primary) and the other being smaller (secondary). These two groups are not exclusive; there exist systems with one or two bound and an unbound secondary. Our current sample consists of 133 bound asteroid systems (binaries or triples) with primary sizes between 0.12 and 13 km and of 178 asteroid pairs with similar primary sizes. Bound systems have been observed in heliocentric orbits from near the Earth to the outer main belt, while asteroid pairs are recognizable only in the main belt where their orbits are only slowly dispersed so the pairs can be identified for up to 2 Myr after formation. The leading observational techniques for discovery and characterization of asteroid systems are radar imagery (for near-Earth asteroid systems) and lightcurve photometry (for main-belt ones). The observed characteristics of asteroid systems suggesting their formation by rotational fission of parent rubble-pile asteroids after being spun up by the YORP effect are as follows. The angular momentum content of binary asteroids is close to critical. The orientations of satellite orbits are non-random; the orbital poles concentrate near the obliquities of 0 and 180

  1. Reconstructing HST Images of Asteroids

    Science.gov (United States)

    Storrs, A. D.; Bank, S.; Gerhardt, H.; Makhoul, K.

    2003-12-01

    We present reconstructions of images of 22 large main belt asteroids that were observed by Hubble Space Telescope with the Wide-Field/Planetary cameras. All images were restored with the MISTRAL program (Mugnier, Fusco, and Conan 2003) at enhanced spatial resolution. This is possible thanks to the well-studied and stable point spread function (PSF) on HST. We present some modeling of this process and determine that the Strehl ratio for WF/PC (aberrated) images can be improved to 130 ratio of 80 We will report sizes, shapes, and albedos for these objects, as well as any surface features. Images taken with the WFPC-2 instrument were made in a variety of filters so that it should be possible to investigate changes in mineralogy across the surface of the larger asteroids in a manner similar to that done on 4 Vesta by Binzel et al. (1997). Of particular interest are a possible water of hydration feature on 1 Ceres, and the non-observation of a constriction or gap between the components of 216 Kleopatra. Reduction of this data was aided by grant HST-GO-08583.08A from the Space Telescope Science Institute. References: Mugnier, L.M., T. Fusco, and J.-M. Conan, 2003. JOSA A (submitted) Binzel, R.P., Gaffey, M.J., Thomas, P.C., Zellner, B.H., Storrs, A.D., and Wells, E.N. 1997. Icarus 128 pp. 95-103

  2. 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...

  3. Rotational Study of Ambiguous Taxonomic Classified Asteroids

    Science.gov (United States)

    Linder, Tyler R.; Sanchez, Rick; Wuerker, Wolfgang; Clayson, Timothy; Giles, Tucker

    2017-01-01

    The Sloan Digital Sky Survey (SDSS) moving object catalog (MOC4) provided the largest ever catalog of asteroid spectrophotometry observations. Carvano et al. (2010), while analyzing MOC4, discovered that individual observations of asteroids which were observed multiple times did not classify into the same photometric-based taxonomic class. A small subset of those asteroids were classified as having both the presence and absence of a 1um silicate absorption feature. If these variations are linked to differences in surface mineralogy, the prevailing assumption that an asteroid’s surface composition is predominantly homogenous would need to be reexamined. Furthermore, our understanding of the evolution of the asteroid belt, as well as the linkage between certain asteroids and meteorite types may need to be modified.This research is an investigation to determine the rotational rates of these taxonomically ambiguous asteroids. Initial questions to be answered:Do these asteroids have unique or nonstandard rotational rates?Is there any evidence in their light curve to suggest an abnormality?Observations were taken using PROMPT6 a 0.41-m telescope apart of the SKYNET network at Cerro Tololo Inter-American Observatory (CTIO). Observations were calibrated and analyzed using Canopus software. Initial results will be presented at AAS.

  4. Target Asteroids! Observing Campaigns for April through June 2017

    Science.gov (United States)

    Hergenrother, Carl; Hill, Dolores

    2017-04-01

    Asteroid campaigns to be conducted by the Target Asteroids! program during the April-June 2017 quarter are described. In addition to asteroids on the original Target Asteroids! list of easily accessible spacecraft targets, an effort has been made to identify other asteroids that are 1) brighter and easier to observe for small telescope users and 2) analogous to (101955) Bennu and (162173) Ryugu, targets of the OSIRIS-REx and Hayabusa-2 sample return missions.

  5. Dynamics of rotationally fissioned asteroids: Source of observed small asteroid systems

    CERN Document Server

    Jacobson, Seth A

    2014-01-01

    We present a model of near-Earth asteroid (NEA) rotational fission and ensuing dynamics that describes the creation of synchronous binaries and all other observed NEA systems including: doubly synchronous binaries, high- e binaries, ternary systems, and contact binaries. Our model only presupposes the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, "rubble pile" asteroid geophysics, and gravitational interactions. The YORP effect torques a "rubble pile" asteroid until the asteroid reaches its fission spin limit and the components enter orbit about each other (Scheeres, D.J. [2007]. Icarus 189, 370-385). Non-spherical gravitational potentials couple the spin states to the orbit state and chaotically drive the system towards the observed asteroid classes along two evolutionary tracks primarily distinguished by mass ratio. Related to this is a new binary process termed secondary fission - the secondary asteroid of the binary system is rotationally accelerated via gravitational torques until it fissions, thu...

  6. Difficult cases in photometric studies of asteroids

    Science.gov (United States)

    Marciniak, Anna; Pilcher, Frederick; Oszkiewicz, Dagmara; Bartczak, Przemysław; Santana-Ros, Toni; Kamiński, Krzysztof; Urakawa, Seitaro; Ogłoza, Waldemar; Fauvaud, Stéphane; Kankiewicz, Paweł; Kudak, Viktor; Żejmo, Michał; Nishiyama, Kota; Okumura, Shin-ichiro; Nimura, Tokuhiro; Hirsch, Roman; Konstanciak, Izabella; Tychoniec, Łukasz; Figas, Michał

    2016-06-01

    We present a photometric campaign targeted at asteroids that display both long periods of rotation and small amplitudes of brightness variations. Our aim is to debias available sample of spin and shape modelled asteroids and to correct previous wrong period determinations. Our newest findings are corrected period determinations for asteroids (279) Thule (P=23.896h ± 0.005 h), (673) Edda (P=22.340h ± 0.004 h), and (737) Arequipa (P=7.0259h ± 0.0003 h). Supporting lightcurves are presented in this paper.

  7. Spectroscopy of near-Earth asteroids

    DEFF Research Database (Denmark)

    Michelsen, René; Nathues, Andreas; Lagerkvist, Claes-Ingvar

    2006-01-01

    We present spectra and taxonomic classifications of 12 Near-Earth Asteroids (NEAs) and 2 inner Main Belt asteroids. The observations were carried out with the ESO 3.5 m NTT and the Danish 1.54 m telescope at La Silla, Chile. Eleven of the investigated NEAs belong to the S class while only one C......-type has been identified. Two NEAs were observed at phase angles larger than 60 degrees introducing significant phase reddening. In order to allow for comparisons between spectra of asteroids observed at different phase angles we make attempts to correct for this effect. However, it turned out...

  8. Spectroscopy of near-Earth asteroids

    DEFF Research Database (Denmark)

    Michelsen, René; Nathues, Andreas; Lagerkvist, Claes-Ingvar

    2006-01-01

    We present spectra and taxonomic classifications of 12 Near-Earth Asteroids (NEAs) and 2 inner Main Belt asteroids. The observations were carried out with the ESO 3.5 m NTT and the Danish 1.54 m telescope at La Silla, Chile. Eleven of the investigated NEAs belong to the S class while only one C......-type has been identified. Two NEAs were observed at phase angles larger than 60 degrees introducing significant phase reddening. In order to allow for comparisons between spectra of asteroids observed at different phase angles we make attempts to correct for this effect. However, it turned out...

  9. 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.

  10. Dynamics of rotationally fissioned asteroids: Source of observed small asteroid systems

    Science.gov (United States)

    Jacobson, Seth A.; Scheeres, Daniel J.

    2011-07-01

    We present a model of near-Earth asteroid (NEA) rotational fission and ensuing dynamics that describes the creation of synchronous binaries and all other observed NEA systems including: doubly synchronous binaries, high- e binaries, ternary systems, and contact binaries. Our model only presupposes the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, "rubble pile" asteroid geophysics, and gravitational interactions. The YORP effect torques a "rubble pile" asteroid until the asteroid reaches its fission spin limit and the components enter orbit about each other (Scheeres, D.J. [2007]. Icarus 189, 370-385). Non-spherical gravitational potentials couple the spin states to the orbit state and chaotically drive the system towards the observed asteroid classes along two evolutionary tracks primarily distinguished by mass ratio. Related to this is a new binary process termed secondary fission - the secondary asteroid of the binary system is rotationally accelerated via gravitational torques until it fissions, thus creating a chaotic ternary system. The initially chaotic binary can be stabilized to create a synchronous binary by components of the fissioned secondary asteroid impacting the primary asteroid, solar gravitational perturbations, and mutual body tides. These results emphasize the importance of the initial component size distribution and configuration within the parent asteroid. NEAs may go through multiple binary cycles and many YORP-induced rotational fissions during their approximately 10 Myr lifetime in the inner Solar System. Rotational fission and the ensuing dynamics are responsible for all NEA systems including the most commonly observed synchronous binaries.

  11. ASIME 2016 White Paper: In-Space Utilisation of Asteroids: "Answers to Questions from the Asteroid Miners"

    OpenAIRE

    Graps, Amara L.; Blondel, Philippe; Bonin, Grant; Britt, Daniel; Centuori, Simone; Delbo, Marco; Drube, Line; Duffard, Rene; Elvis, Martin; Faber, Daniel; Frank, Elizabeth; Galache, JL; Green, Simon F.; Grundmann, Jan Thimo; Hsieh, Henry

    2016-01-01

    The aim of the Asteroid Science Intersections with In-Space Mine Engineering (ASIME) 2016 conference on September 21-22, 2016 in Luxembourg City was to provide an environment for the detailed discussion of the specific properties of asteroids, with the engineering needs of space missions that utilize asteroids. The ASIME 2016 Conference produced a layered record of discussions from the asteroid scientists and the asteroid miners to understand each other's key concerns and to address key scien...

  12. Southern Africa Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data base (14,559 records) was received in January 1986. Principal gravity parameters include elevation and observed gravity. The observed gravity values are...

  13. NGS Absolute Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NGS Absolute Gravity data (78 stations) was received in July 1993. Principal gravity parameters include Gravity Value, Uncertainty, and Vertical Gradient. The...

  14. Water in Asteroid 4 Vesta

    Science.gov (United States)

    Taylor, G. J.

    2015-01-01

    Eucrite meteorites come from asteroid 4 Vesta, which was recently studied from orbit by NASA's Dawn mission. Adam Sarafian (Woods Hole Oceanographic Institute) and colleagues at Woods Hole, the University of Bristol, England, and the University of New Mexico measured the hydrogen concentration and deuterium/hydrogen (D/H) ratio in crystals of the mineral apatite (calcium phosphate) in eucrites. They found that the D/H ratio is in the same range as in carbonaceous chondrites, most samples of the Earth's mantle, and in samples of basaltic meteorites from Mars. Combined with measurements of the isotopic compositions of nitrogen and carbon, the data suggest that these volatile elements were added to Earth early in its history, probably during its formation. Other studies conclude that water with D/H like that in carbonaceous chondrites, Earth, Mars, and Vesta were likely inherited from interstellar ice that predates formation of the solar system.

  15. 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.

  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. 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...

  18. 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.

  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. Asteroid models from the Lowell photometric database

    Science.gov (United States)

    Ďurech, J.; Hanuš, J.; Oszkiewicz, D.; Vančo, R.

    2016-03-01

    Context. Information about shapes and spin states of individual asteroids is important for the study of the whole asteroid population. For asteroids from the main belt, most of the shape models available now have been reconstructed from disk-integrated photometry by the lightcurve inversion method. Aims: We want to significantly enlarge the current sample (~350) of available asteroid models. Methods: 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. Results: From the analysis of Lowell photometric data of the first 100 000 numbered asteroids, we derived 328 new models. This almost doubles the number of available models. We tested the reliability of our results by comparing models that were derived from purely Lowell data with those based on dense lightcurves, and we found that the rate of false-positive solutions is very low. We also present updated plots of the distribution of spin obliquities and pole ecliptic longitudes that confirm previous findings about a non-uniform distribution of spin axes. However, the models reconstructed from noisy sparse data are heavily biased towards more elongated bodies with high

  1. An Early Warning System for Asteroid Impact

    Science.gov (United States)

    Tonry, John L.

    2011-01-01

    Earth is bombarded by meteors, occasionally by one large enough to cause a significant explosion and possible loss of life. It is not possible to detect all hazardous asteroids, and the efforts to detect them years before they strike are only advancing slowly. Similarly, ideas for mitigation of the danger from an impact by moving the asteroid are in their infancy. 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. With enough warning, a small asteroid impact should not cause loss of life, and even portable property might be preserved. We describe an early warning system that could provide a week’s notice of most sizeable asteroids or comets on track to hit the Earth. This may be all the mitigation needed or desired for small asteroids, and it can be implemented immediately for relatively low cost. This system, dubbed Asteroid Terrestrial-Impact Last Alert System (ATLAS), comprises two observatories separated by about 100 km that simultaneously scan the visible sky twice a night. Software automatically registers a comparison with the unchanging sky and identifies everything that has moved or changed. Communications between the observatories lock down the orbits of anything approaching the Earth, within one night if its arrival is less than a week. The sensitivity of the system permits detection of 140 m asteroids (100 Mton impact energy) three weeks before impact and 50 m asteroids a week before arrival. An ATLAS alarm, augmented by other observations, should result in a determination of impact location and time that is accurate to a few kilometers and a few seconds. In addition to detecting and warning of approaching asteroids, ATLAS will continuously monitor the changing universe around us: most of the variable stars in our Galaxy, many microlensing events from stellar

  2. U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center-Fiscal Year 2009 Annual Report

    Science.gov (United States)

    Nelson, Janice S.

    2010-01-01

    The Earth Resources Observation and Science (EROS) Center is a U.S. Geological Survey (USGS) facility focused on providing science and imagery to better understand our Earth. As part of the USGS Geography Discipline, EROS contributes to the Land Remote Sensing (LRS) Program, the Geographic Analysis and Monitoring (GAM) Program, and the National Geospatial Program (NGP), as well as our Federal partners and cooperators. The work of the Center is shaped by the Earth sciences, the missions of our stakeholders, and implemented through strong program and project management and application of state-of-the-art information technologies. Fundamentally, EROS contributes to the understanding of a changing Earth through 'research to operations' activities that include developing, implementing, and operating remote sensing based terrestrial monitoring capabilities needed to address interdisciplinary science and applications objectives at all levels-both nationally and internationally. The Center's programs and projects continually strive to meet and/or exceed the changing needs of the USGS, the Department of the Interior, our Nation, and international constituents. The Center's multidisciplinary staff uses their unique expertise in remote sensing science and technologies to conduct basic and applied research, data acquisition, systems engineering, information access and management, and archive preservation to address the Nation's most critical needs. Of particular note is the role of EROS as the primary provider of Landsat data, the longest comprehensive global land Earth observation record ever collected. This report is intended to provide an overview of the scientific and engineering achievements and illustrate the range and scope of the activities and accomplishments at EROS throughout fiscal year (FY) 2009. Additional information concerning the scientific, engineering, and operational achievements can be obtained from the scientific papers and other documents published by

  3. Modelling asteroid brightness variations. I - Numerical methods

    Science.gov (United States)

    Karttunen, H.

    1989-01-01

    A method for generating lightcurves of asteroid models is presented. The effects of the shape of the asteroid and the scattering law of a surface element are distinctly separable, being described by chosen functions that can easily be changed. The shape is specified by means of two functions that yield the length of the radius vector and the normal vector of the surface at a given point. The general shape must be convex, but spherical concavities producing macroscopic shadowing can also be modeled.

  4. Olivine-dominated asteroids: Mineralogy and origin

    OpenAIRE

    Sanchez, Juan A.; Reddy, Vishnu; 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 or...

  5. The K20 survey. I. Disentangling old and dusty star-forming galaxies in the ERO population

    CERN Document Server

    Cimatti, A; Mignoli, M; Pozzetti, L; Renzini, A; Zamorani, G; Broadhurst, T J; Fontana, A; Saracco, P; Poli, F; Cristiani, S; D'Odorico, S; Giallongo, E; Gilmozzi, R; Menci, N

    2002-01-01

    We present the results of VLT optical spectroscopy of a complete sample of 78 EROs with R-Ks\\geq5 over a field of 52 arcmin^2. About 70% of the 45 EROs with Ks\\leq19.2 have been spectroscopically identified with old passively evolving and dusty star-forming galaxies at 0.7ERO average spectrum and for Z=Z_{\\odot} we derive a minimum age of \\sim 3 Gyr, corresponding to a formation redshift of z_f \\gtsima 2.4. PLE models with such formation redshifts well reproduce the density of old EROs (consistent with being passively evolving ellipticals), whereas the predictions of the current hierarchical merging models are lower than the observed densities by large factors (up to an order of magnitude). From the average spectrum of the star-forming EROs we estimate a substantial dust extinction with E(B-V) \\gtsima 0.5. The star formation rates, corrected for the average reddening, sugges...

  6. The K20 survey. II. The Different Spatial Clustering of z~1 Old and Dusty Star-Forming EROs

    CERN Document Server

    Daddi, E; Broadhurst, T J; Renzini, A; Zamorani, G; Mignoli, M; Saracco, P; Fontana, A; Pozzetti, L; Poli, F; Cristiani, S; D'Odorico, S; Giallongo, E; Gilmozzi, R; Menci, N

    2002-01-01

    We compare the 3D clustering of old passively-evolving and dusty star-forming z~1 EROs from the K20 survey. With detailed simulations of clustering, the comoving correlation length of dusty star-forming EROs is constrained to be less than r_0~2.5 Mpc/h. In contrast, the old EROs are much more positively correlated, with 5.5<~r_0/(Mpc/h)<~16, consistent with previous claims for z~1 field early-type galaxies based on analyses of ERO angular clustering. The low level of clustering of dusty star-forming EROs does not support these to be major mergers building up an elliptical galaxy, or typical counterparts of SCUBA sources, but it is instead consistent with the weak clustering of high redshift blue galaxies and of luminous local IRAS galaxies. Current hierarchical merging models can explain the large r_0 for z~1 field early-type galaxies, but fail in matching their high number density and overall old ages.

  7. Second Gravity

    CERN Document Server

    Nash, Patrick Lee

    2010-01-01

    A theory of a new gravitational interaction is described. This theory follows naturally from a new Lagrangian formulation of Maxwell's theory for photons and electrons (and positrons) whose associated Euler Lagrange equations imply the conventional Maxwell equations, but which possesses new \\textbf{\\emph{bosonic}} spinor degrees of freedom that may be associated with a new type of fundamental gravitational interaction. The precise character of this gravitational interaction with a photon vector potential is explicitly defined in terms of a local U(1)-invariant Lagrangian in Eq.[\\ref{Lagrangian3}]. However in Section \\ref{ssec:Simple-Cosmolo-Model}, in order to parallel the well known Friedmann model in cosmology, a phenomenological description of the new gravitational interaction coupled to Newton-Einstein gravity that is sourced by an ideal fluid is discussed. % % To lay the foundation for a description of the new gravitational interaction our new formulation of Maxwell's theory must first be described. It i...

  8. Gravity's Rainbow

    CERN Document Server

    Magueijo, J; Magueijo, Joao; Smolin, Lee

    2004-01-01

    Non-linear special relativity (or doubly special relativity) is a simple framework for encoding properties of flat quantum space-time. In this paper we show how this formalism may be generalized to incorporate curvature (leading to what might be called ``doubly general relativity''). We first propose a dual to non-linear realizations of relativity in momentum space, and show that for such a dual the space-time invariant is an energy-dependent metric. This leads to an energy-dependent connection and curvature, and a simple modification to Einstein's equations. We then examine solutions to these equations. We find the counterpart to the cosmological metric, and show how cosmologies based upon our theory of gravity may solve the ``horizon problem''. We discuss the Schwarzchild solution, examining the conditions for which the horizon is energy dependent. We finally find the weak field limit.

  9. Network Gravity

    CERN Document Server

    Lombard, John

    2016-01-01

    We introduce the construction of a new framework for probing discrete emergent geometry and boundary-boundary observables based on a fundamentally a-dimensional underlying network structure. Using a gravitationally motivated action with Forman weighted combinatorial curvatures and simplicial volumes relying on a decomposition of an abstract simplicial complex into realized embeddings of proper skeletons, we demonstrate properties such as a minimal volume-scale cutoff, the necessity of a positive-definite cosmological constant as a regulator for non-degenerate geometries, and naturally emergent simplicial structures from Metropolis network evolution simulations with no restrictions on attachment rules or regular building blocks. We see emergent properties which echo results from both the spinfoam formalism and causal dynamical triangulations in quantum gravity, and provide analytical and numerical results to support the analogy. We conclude with a summary of open questions and intent for future work in develop...

  10. Newtonian gravity in loop quantum gravity

    OpenAIRE

    Smolin, Lee

    2010-01-01

    We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.

  11. Newtonian gravity in loop quantum gravity

    OpenAIRE

    Smolin, Lee

    2010-01-01

    We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.

  12. An ISU study of asteroid mining

    Science.gov (United States)

    Burke, J. D.

    1991-01-01

    During the 1990 summer session of the International Space University, 59 graduate students from 16 countries carried out a design project on using the resources of near-earth asteroids. The results of the project, whose full report is now available from ISU, are summarized. The student team included people in these fields: architecture, business and management, engineering, life sciences, physical sciences, policy and law, resources and manufacturing, and satellite applications. They designed a project for transporting equipment and personnel to a near-earth asteroid, setting up a mining base there, and hauling products back for use in cislunar space. In addition, they outlined the needed precursor steps, beginning with expansion of present ground-based programs for finding and characterizing near-earth asteroids and continuing with automated flight missions to candidate bodies. (To limit the summer project's scope the actual design of these flight-mission precursors was excluded.) The main conclusions were that asteroid mining may provide an important complement to the future use of lunar resources, with the potential to provide large amounts of water and carbonaceous materials for use off earth. However, the recovery of such materials from presently known asteroids did not show an economic gain under the study assumptions; therefore, asteroid mining cannot yet be considered a prospective business.

  13. Formation of asteroid pairs by rotational fission.

    Science.gov (United States)

    Pravec, P; Vokrouhlický, D; Polishook, D; Scheeres, D J; Harris, A W; Galád, A; Vaduvescu, O; Pozo, F; Barr, A; Longa, P; Vachier, F; Colas, F; Pray, D P; Pollock, J; Reichart, D; Ivarsen, K; Haislip, J; Lacluyze, A; Kusnirák, P; Henych, T; Marchis, F; Macomber, B; Jacobson, S A; Krugly, Yu N; Sergeev, A V; Leroy, A

    2010-08-26

    Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their formation-critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs, revealing that the primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero, requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system, which subsequently disrupts under its own internal system dynamics soon after formation.

  14. Asteroid hyalosis--current state of knowledge.

    Science.gov (United States)

    Jabłońska, Anna; Ciszewska, Joanna; Kęcik, Dariusz

    2014-01-01

    The search query into the Cochrane Library, Medline, Web of Science, Embase, Scopus and ScienceDirect enabled selection of research papers addressing the issue of asteroid hyalosis published in English between 1963 and January 2014. Asteroid hyalosis is a degenerative condition of the vitreous in which small, creamy or white, spherical particles (asteroid bodies) are randomly diffused within the vitreous. They consist mainly of calcium and phosphorus and have a structure of hydroxy lapatite. In 80.2-92.0% of cases the condition affects one eye only and it occurs in 0.36-1.96% of population, mostly in patients over 50 years of age and in males. Hypercholesterolemia and hypertension are systemic risk factors, but asteroid hyalosis is postulated to occur more often in retinitis pigmentosa and Leber amaurosis caused by mutations in lecithin retinol acyltransferase gene. Asteroid hyalosis also causes calcification of some intraocular lenses--mostly silicone ones. Vitreous of patients with asteroid hyalosis shows reduced gel liquefaction and anomalous vitreoretinal adhesion.

  15. 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...

  16. 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...

  17. 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...

  18. Efectos de la hipoxia en montañeros expuestos a altitudes extremas

    Directory of Open Access Journals (Sweden)

    Javier Aceña Medina

    2017-03-01

    Full Text Available La práctica del montañismo goza en la actualidad de una gran popularidad entre nuestros deportistas. Los montañeros que se mueven en grandes altitudes se ven expuestos frecuentemente a climatologías muy adversas y vías de gran dificultad física y técnica, pero posiblemente el enemigo más temible al que se tienen que enfrentar tiene que ver con los indeseables efectos de la hipoxia. La presente investigación se centra en constatar posibles deterioros en las habilidades del pensamiento de un grupo de montañeros expuesto a altitudes extremas (por encima de los 5.500 metros, sin ayuda de oxígeno suplementario. Para ello hemos contado con la participación de montañeros de tres expediciones a los “ochomiles” Manaslu, Makalu y Gasherbrum II a los que se aplicaron pruebas de aptitudes mentales antes, durante y después de cada expedición. La singularidad de nuestro estudio reside en haber incorporado resultados de pruebas realizadas en altitudes extremas, en concreto a 5.800, 6.200 y 6.000 metros respectivamente. Los resultados ponen de manifiesto que de todas las áreas y funciones cognitivas evaluadas, parece ser que las más afectadas por los efectos de la hipoxia han sido las relacionadas con la capacidad de razonamiento abstracto, espacial y verbal. Los deterioros más evidentes se observaron en altitud, persistiendo estos a la semana de regresar. Tras seis meses dichos déficits se recuperaron por completo.

  19. Enfoque Fisioterápico del dolor inguinal del montañero

    OpenAIRE

    Caudevilla Polo, Santos; Rubio Ibarzo, Sara; Lucha López, Orosia; Tricás Moreno, José Miguel; Estébanez De Miguel, Elena; Hidalgo García, César

    2002-01-01

    En este artículo se ha realizado un enfoque fisioterapéutico del dolor inguinal del montañero. El dolor inguinal es un problema frecuente y clínicamente complejo en un gran número de deportes. Existen multitud de causas que pueden generar este dolor, pero en este artículo sólo se muestra lo relacionado con la disfunción de la articulación de la cadera y sus músculos. Los estudios de Kaltenborn-Evjenth, Sohier, Ekman, Butler y Chaitow ofrecen información novedosa para el tratamiento d...

  20. LOS RECUERDOS DEL MALTRATO ENTRE COMPAÑEROS EN LA VIDA ESCOLAR

    OpenAIRE

    María Eugenia Reátiga

    2009-01-01

    En este artículo se muestran los resultados de una investigación descriptiva, que buscaba desde una mirada retrospectiva describir la experiencia que se haya vivido en relación a la situación de intimidación o rechazo por compañeros escolares en 648 estudiantes de primer semestre de estrato socioeconómico medio-alto, de una institución universitaria privada. En general, se halló a través del cuestionario RBQ, que el 41.8% recuerda que fue básicamente observador de esta situación; el 12% recue...

  1. Vicente Leñero y el fracaso de su inspector

    OpenAIRE

    Clemens A. Franken K.

    2010-01-01

    Luego de exponer brevemente la obra literaria del escritor Vicente Leñero y su lugar dentro de literatura mexicana, se analiza, en su novela posmoderna Los albañiles, la conducta de los personajes sospechosos, la figura y el método de investigación del detective y de sus colaboradores que fracasan en su búsqueda de la verdad, la crítica social y cultural de la sociedad mexicana de los años sesenta y aspectos formales como, por ejemplo, el lenguaje, el narrador y la forma de asimilación.After ...

  2. Vicente Leñero y el fracaso de su inspector

    OpenAIRE

    2010-01-01

    Luego de exponer brevemente la obra literaria del escritor Vicente Leñero y su lugar dentro de literatura mexicana, se analiza, en su novela posmoderna Los albañiles, la conducta de los personajes sospechosos, la figura y el método de investigación del detective y de sus colaboradores que fracasan en su búsqueda de la verdad, la crítica social y cultural de la sociedad mexicana de los años sesenta y aspectos formales como, por ejemplo, el lenguaje, el narrador y la forma de asimilación.After ...

  3. Eros thanático en Paradiso de José Lezama Lima

    Directory of Open Access Journals (Sweden)

    Edinson Aladino

    2017-08-01

    Full Text Available Los personajes en la novelística de José Lezama Lima no son simples tipologías que devienen bajo la estructura del lenguaje. Los personajes lezamianos son su circunstancia atravesada por la alineación de un destino noble o aciago. Eugenio Foción encara en Paradiso la circunstancia de un destino aciago, arquetipo fundamental en el decurso de la novela que viene a representar la fijeza del deseo como fragmentación de vida. Querencia de muerte o Eros thanático que rodea al corazón del cuerpo para impeler su pulsión vital.

  4. Las Conferencias del Profesor Baudin en el Instituto Riva-Agüero

    Directory of Open Access Journals (Sweden)

    Xavier Kiefer - Marchand

    1947-12-01

    Full Text Available El notable economista francés Louis Baudin. invitado especialmente porla Pontificia Universidad Católica del Perú. dió, durante el mes de Junio de1947, un ciclo de conferencias en el Instituto Riva-Agüero.Los temas de estas conferencias fueron los siguienres:- El Conflicto Contemporáneo de las Doctrinas Económicas.- La MonEda y su Poder Adquisitivo.- Las Reducciones del Paraguay.- El Ahorro y las Nacionalizaciones.

  5. Observation of Microlensing towards the Galactic Spiral Arms EROS II 3 year survey

    CERN Document Server

    Derue, F; Albert, J N; Andersen, J; Ansari, R; Aubourg, E; Bareyre, P; Bauer2, F; Beaulieu, J P; Blanc, G; Bouquet, A; Char, S; Charlot, X; Couchot, F; Couture, C; Ferlet, R; Glicenstein, J F; Goldman, B; Gould, A; Gros, M; Hassinski, J; Hamilton, J C; Hardin, D; deKat, J; Kim, A; Lassere, T; Lesquoy, E; Loup, C; Magneville, C; Mansoux, B; Marquette, J B; Gra, D; Maurice, E; Milsztajn, A; Moniez, M; Palanque-Delabrouille, Nathalie; Perdereau, O; Prévôt, L; Regnault, N; Rich, J; Spiro, M; Vidal-madjar, A; Vigroux, L; Zylberajch, S

    2000-01-01

    We present an analysis of the light curves of 9.1 million stars observed during three seasons by EROS (Experience de Recherche d'Objets Sombres), in the Galactic plane away from the bulge. Seven stars exhibit luminosity variations compatible with gravitational microlensing effects due to unseen objects. The corresponding optical depth, averaged over four directions, is tau = 0.45 +0.24 -0.11 x 10^-6. While this value is compatible with expectations from simple galactic models under reasonable assumptions on the target distances, we find an excess of events with short timescale towards the direction closest to the Galactic Centre.

  6. The Cognition of Priapo. Caricature procedures in Carlo Emilio Gadda’s Eros e Priapo.

    Directory of Open Access Journals (Sweden)

    Paolo Gervasi

    2017-01-01

    As several neuroscientific researches demonstrated, from a cognitive perspective caricature can be considered as a tool for the comprehension of the world. The human mind selects, shapes and emphasises elements in order to detect patterns in the muddle of perceptions. For the human mind misshaping the world means to uncover its hidden features, which would remain unexpressed if not stressed. Similarly, as demonstrated by Eros e Priapo, caricature is a critical device, isolating and emphasising details to upset schemes, while revealing the psychological deformations produced by historical events.

  7. Lightcurves for Two Near-Earth Asteroids by Asteroids Observers (OBAS) - MPPD: 2016 April-May

    Science.gov (United States)

    Martinez, Vicente Mas; Silva, Gonzalo Fornas; Martinez, Angel Flores; Garceran, Alfonso Carreno; Mansego, Enrique Arce; Rodriguez, Pedro Brines; de Haro, Juan Lozano; Silva, Alvaro Fornas; Chiner, Onofre Rodrigo; Porta, David Herrero

    2016-10-01

    We report on the results of photometric analysis of two near-Earth asteroids (NEA) by Asteroids Observers (OBAS). This work is part of the Minor Planet Photometric Database (MPPD) project initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

  8. Sixteen Asteroids Lightcurves at Asteroids Observers (OBAS) - MPPD: 2016 June-November

    Science.gov (United States)

    Brines, Pedro; Lozano, Juan; Rodrigo, Onofre; Fornas, A.; Herrero, David; Mas, Vicente; Fornas, G.; Carreño, A.; Arce, Enrique

    2017-04-01

    We report on the photometric analysis result of sixteen main-belt asteroids (MBA) done by Asteroids Observers (OBAS). This work is part of the Minor Planet Photometric Database tasks, initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

  9. Eighteen Asteroids Lightcurves at Asteroides Observers (OBAS) - MPPD: 2016 March-May

    Science.gov (United States)

    Mansego, Enrique Arce; Rodriguez, Pedro Brines; de Haro, Juan Lozano; Chiner, Onofre Rodrigo; Silva, Alvaro Fornas; Porta, David Herrero; Martinez, Vicente Mas; Silva, Gonzalo Fornas; Garceran, Alfonso Carreno

    2016-10-01

    We report on the analysis of photometric observations of 18 main-belt asteroids (MBA) done by Asteroides Observers (OBAS). This work is part of the Minor Planet Photometric Database program initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

  10. Twenty-three Asteroids Lightcurves at Observadores de Asteroides (OBAS): 2015 October - December

    Science.gov (United States)

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

    2016-04-01

    We report on the photometric analysis results for 23 main-belt asteroids (MBA) done by Observadores de Asteroides (OBAS). This work is part of the Minor Planet Photometric Database that was initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate, complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

  11. International CJMT-1 Workshop on Asteroidal Science

    Science.gov (United States)

    Ip, Wing-Huen

    2014-03-01

    An international workshop on asteroidal science was held between October 16 and 17, 2012, at the Macau University of Science and Technology gathering together experts on asteroidal study in China, Japan, Macao and Taiwan. For this reason, we have called it CJMT-1 Workshop. Though small in sizes, the asteroids orbiting mainly between the orbit of Mars and of Jupiter have important influence on the evolution of the planetary bodies. Topics ranging from killer asteroids to space resources are frequently mentioned in news reports with prominence similar to the search for water on Mars. This also means that the study of asteroids is very useful in exciting the imagination and interest in science of the general public. Several Asian countries have therefore developed long-term programs integrating ground-based observations and space exploration with Japan being the most advanced and ambitious as demonstrated by the very successful Hayabusa mission to asteroid 25143 Itokawa. In this volume we will find descriptions of the mission planning of Hayabusa II to the C-type near-Earth asteroid, 1999 JU3. Not to be outdone, China's Chang-E 2 spacecraft was re-routed to a flyby encounter with asteroid 4179 Toutatis in December 2012. It is planned that in the next CJMT workshop, we will have the opportunity to learn more about the in-depth data analysis of the Toutatis observations and the progress reports on the Hayabusa II mission which launch date is set to be July 2014. Last but not least, the presentations on the ground-based facilities as described in this volume will pave the way for coordinated observations of asteroidal families and Trojan asteroids - across Asia from Taiwan to Uzbekistan. Such international projects will serve as an important symbol of good will and peaceful cooperation among the key members of this group. Finally, I want to thank the Space Science Institute, Macao University of Science and Technology, for generous support, and its staff members

  12. Lineal gravity from planar gravity

    CERN Document Server

    Achúcarro, A

    1993-01-01

    We show how to obtain the two-dimensional black hole action by dimensional reduction of the three-dimensional Einstein action with a non-zero cosmological constant. Starting from the Chern-Simons formulation of 2+1 gravity, we obtain the 1+1 dimensional gauge formulation given by Verlinde. Remarkably, the proposed reduction shares the relevant features of the formulation of Cangemi and Jackiw, without the need for a central charge in the algebra. We show how the Lagrange multipliersin these formulations appear naturally as the remnants of the three dimensional connection associated to symmetries that have been lostin the dimensional reduction. The proposed dimensional reduction involves a shift in the three dimensional connection whose effect is to make the length of the extra dimension infinite.

  13. Lightcurve Survey of V-type Asteroids in the Inner Asteroid Belt

    CERN Document Server

    Hasegawa, Sunao; Mito, Hiroyuki; Sarugaku, Yuki; Ozawa, Tomohiko; Kuroda, Daisuke; Nishihara, Setsuko; Harada, Akari; Yoshida, Michitoshi; Yanagisawa, Kenshi; Shimizu, Yasuhiro; Nagayama, Shogo; Toda, Hiroyuki; Okita, Kouji; Kawai, Nobuyuki; Mori, Machiko; Sekiguchi, Tomohiko; Ishiguro, Masateru; Abe, Takumi; Abe, Masanao

    2013-01-01

    We have observed the lightcurves of 13 V-type asteroids ((1933) Tinchen, (2011) Veteraniya, (2508) Alupka, (3657) Ermolova, (3900) Knezevic, (4005) Dyagilev, (4383) Suruga, (4434) Nikulin, (4796) Lewis, (6331) 1992 $\\mathrm{FZ_{1}}$, (8645) 1998 TN, (10285) Renemichelsen, and (10320) Reiland). Using these observations we determined the rotational rates of the asteroids, with the exception of Nikulin and Renemichelsen. The distribution of rotational rates of 59 V-type asteroids in the inner main belt, including 29 members of the Vesta family that are regarded as ejecta from the asteroid (4) Vesta, is inconsistent with the best-fit Maxwellian distribution. This inconsistency may be due to the effect of thermal radiation Yarkovsky--O'Keefe--Radzievskii--Paddack (YORP) torques, and implies that the collision event that formed V-type asteroids is sub-billion to several billion years in age.

  14. Using Dust from Asteroids as Regolith Microsamples

    Science.gov (United States)

    Cohen, B. A.; Klima, Rachel; Chabot, N. L.; Rivkin, A. S.

    2015-01-01

    Meteorite science is rich with compositional indicators by which we classify parent bodies, but few sample groups are definitively linked with asteroid spectra. More robust links need to be forged between meteorites and their parent bodies to understand the composition, diversity and distribution. A major link can be sample analysis of the parent body material and comparison with meteorite data. Hayabusa, the first sample return mission of the Japanese Aerospace Exploration Agency (JAXA), was developed to rendezvous with and collect samples from asteroid Itokawa and return them to Earth. Thousands of sub-100 micron particles were recovered, apparently introduced during the spacecraft impact into the surface of the asteroid, linking the asteroid Itokawa to LL chondrites [1]. Upcoming missions Hayabusa 2 and OSIRIS-REx will collect more significant sample masses from asteroids. In all these cases, the samples are or will be a collection of regolith particles. Sample return to earth is not the only method for regolith particle analysis. Dust is present around all airless bodies, generated by micrometeorite impact into their airless surfaces, which in turn lofts regolith particles into a "cloud" around the body. The composition, flux, and size-frequency distribution of dust particles can provide significant insight into the geological evolution of airless bodies [2]. For example, the Cassini Cosmic Dust Analyzer (CDA) detected salts in Enceladus' icy plume material, providing evidence for a subsurface ocean in contact with a silicate seafloor [3]. Similar instruments have flown on the Rosetta, LADEE, and Stardust missions. Such an instrument may be of great use in obtaining the elemental, isotopic and mineralogical composition measurement of dust particles originating from asteroids without returning the samples to terrestrial laboratories. We investigated the ability of a limited sample analysis capability using a dust instrument to forge links between asteroid

  15. Different interaction modes for protein-disulfide isomerase (PDI) as an efficient regulator and a specific substrate of endoplasmic reticulum oxidoreductin-1α (Ero1α).

    Science.gov (United States)

    Zhang, Lihui; Niu, Yingbo; Zhu, Li; Fang, Jingqi; Wang, Xi'e; Wang, Lei; Wang, Chih-chen

    2014-11-07

    Protein-disulfide isomerase (PDI) and sulfhydryl oxidase endoplasmic reticulum oxidoreductin-1α (Ero1α) constitute the pivotal pathway for oxidative protein folding in the mammalian endoplasmic reticulum (ER). Ero1α oxidizes PDI to introduce disulfides into substrates, and PDI can feedback-regulate Ero1α activity. Here, we show the regulatory disulfide of Ero1α responds to the redox fluctuation in ER very sensitively, relying on the availability of redox active PDI. The regulation of Ero1α is rapidly facilitated by either a or a' catalytic domain of PDI, independent of the substrate binding domain. On the other hand, activated Ero1α specifically binds to PDI via hydrophobic interactions and preferentially catalyzes the oxidation of domain a'. This asymmetry ensures PDI to function simultaneously as an oxidoreductase and an isomerase. In addition, several PDI family members are also characterized to be potent regulators of Ero1α. The novel modes for PDI as a competent regulator and a specific substrate of Ero1α govern efficient and faithful oxidative protein folding and maintain the ER redox homeostasis.

  16. Eros and Socrates%Eros与苏格拉底——阅读《会饮》

    Institute of Scientific and Technical Information of China (English)

    郭洪体

    2007-01-01

    是柏拉图最重要的对话之一.对话探讨了什么是爱欲(Eros,eros),爱欲与美的关系,与智慧的关系,以及什么才算得上是一种真正的哲学生活.对话最终得出的结论是:只有像苏格拉底这样的爱智慧者、爱美者才是哲学生活的典范.

  17. Mass of Asteroid (25143) Itokawa Determined by Hayabusa Spacecraft

    Science.gov (United States)

    Yoshikawa, M.; Itokawa Mass Determination Team

    Hayabusa MUSES-C is the asteroid sample return mission of Japan It was launched on May 9 2003 and it arrived at its destination Asteroid 25143 Itokawa on September 12 2005 For about three months Hayabusa made detailed observations of Itokawa and tried to touch down on its surface twice after several rehearsal approaches In this mission period Hayabusa was under the effect of gravity attraction of Itokawa In this paper we report about the mass determination of Itokawa At first Hayabusa stayed around the position of 20 km from Itokawa and then it moved a little closer about 7 km from Itokawa Using the range and Doppler data from Sept 12 to Oct 2 the mass of Itokawa was estimated as 3 51 x 10 10 kg Since the effect of the solar radiation pressure is much larger than that of the gravitational attraction from Itokawa at this time the error of this estimation is about 15 We expected that we could get more precise value of the mass when Hayabusa approached much closer to Itokawa However one of the two reaction wheels had a trouble and after Oct 3 the attitude control was done by the chemical thrusters The chemical thrusters generated small orbital acceleration so it became difficult to carry out the precise mass determination of Itokawa Therefore we intentionally stopped the attitude maneuvers on Oct 21-22 when distance from Itokawa is about 3 km On this pass we tried to determine the mass of Itokawa and we got the value of 3 43 x 10 10 kg with the error of 5 Up to this analysis we assume a point mass model

  18. The impact trajectory of asteroid 2008 TC3

    Science.gov (United States)

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

    2017-09-01

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

  19. MarcoPolo-R: Asteroid Sample Return Mission

    Science.gov (United States)

    Brucato, John Robert

    2012-07-01

    applied to individual components of the complex mixture of materials that forms an asteroid regolith, in orer to determine their precise chemical, mineralogical 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 asteroidal material. In addition to addressing the exciting science goals, the MarcoPolo-R mission also involves technologies for which technical development programmes are well under way. It is the ideal platform to (i) demonstrate innovative capabilities such as: accurate planetary navigation and landing, sample return operational chain; (ii) prepare the next generation of curation facilities for extra-terrestrial sample storage and analysis; (iii) develop high speed re-entry capsule; (iv) pave the way as a pathfinder mission for future sample returns from bodies with high surface gravity.

  20. Erosão esternal por aneurisma da aorta. Qual o melhor acesso?

    Directory of Open Access Journals (Sweden)

    CARVALHO Roberto Gomes de

    2001-01-01

    Full Text Available É descrito o caso de um paciente que apresentava erosão esternal ocasionada por aneurisma da aorta ascendente e hemi-arco aórtico proximal. A via de acesso foi toracotomia bilateral uma vez que a erosão era na parte alta do esterno, empregando-se hipotermia profunda e parada circulatória total. Foi interposto enxerto de pericárdio bovino para correção da aorta ascendente e hemi-arco aórtico proximal e outro enxerto entre o tronco braquicefálico e a parede lateral do enxerto de pericárdio bovino. A artéria descendente anterior foi revascularizada por haver oclusão do óstio da artéria coronária esquerda. Após 3 anos da operação o paciente está assintomático.

  1. Erosão esternal por aneurisma da aorta. Qual o melhor acesso?

    Directory of Open Access Journals (Sweden)

    Roberto Gomes de CARVALHO

    2001-03-01

    Full Text Available É descrito o caso de um paciente que apresentava erosão esternal ocasionada por aneurisma da aorta ascendente e hemi-arco aórtico proximal. A via de acesso foi toracotomia bilateral uma vez que a erosão era na parte alta do esterno, empregando-se hipotermia profunda e parada circulatória total. Foi interposto enxerto de pericárdio bovino para correção da aorta ascendente e hemi-arco aórtico proximal e outro enxerto entre o tronco braquicefálico e a parede lateral do enxerto de pericárdio bovino. A artéria descendente anterior foi revascularizada por haver oclusão do óstio da artéria coronária esquerda. Após 3 anos da operação o paciente está assintomático.

  2. O trabalho de Eros e de Tanatos na regulação social

    Directory of Open Access Journals (Sweden)

    Maria de Lurdes Costa Domingos

    2013-04-01

    Full Text Available Este estudo objetiva discutir o trabalho de Eros e de Tanatos no contexto de regulação social na qual a responsabilidade social organizacional é comumente associada a um sistema de gestão capaz de minimizar os efeitos negativos do capitalismo. O trabalho de campo indicou uma falácia entre o discurso e as práticas da responsabilidade. Utilizaram-se dados qualitativos de três organizações, classificados com base na lógica das representações sociais. Identificou-se a responsabilidade social organizacional a serviço de Eros, enquanto possibilidade para vencer a angústia de morte organizacional. Mas este modelo também é vulnerável ao trabalho de Tanatos. Internamente, junto aos trabalhadores, se a RSO não recebe investimentos para ser uma ferramenta eficaz de oxigenação do sistema organizacional torna-se ela mesma parte de sua necrose. Conclui-se que a percepção do trabalho de morte que se instala na dinâmica institucional pode favorecer seu enfrentamento e criar saídas para a necrose do tecido social do qual as organizações também fazem parte.

  3. La sfida al labirinto sessuale. L’eros nell’opera di Italo Calvino

    Directory of Open Access Journals (Sweden)

    Elio Baldi

    2012-12-01

    Full Text Available The Challenge of the Sexual Labyrinth Sensuality in the Work of Italo CalvinoIn this article, the novels, stories and essays of Italo Calvino are being studied from the perspective of sensuality and Eros. In literary criticism Calvino’s work is rarely being associated with sexuality, even though the subject did fuel the imagination of the writer himself. Calvino recognized the importance of the theme of sexuality in literature as well as the challenge inherent in trying to depict faithfully a similar ineffable subject, that has, moreover, been covered by society under a thick layer of clichés and repetitive language and therefore been emptied of meaning. The importance of a non-banal, renewing sexuality in literature inspired Calvino to experiment in a light, humorous, surprising way with a myriad of forms of literary sensuality. Calvino has searched Eros in space, as the prime mover in evolution, amongst animals and celestial bodies (instead of the usual heavenly bodies, in rituals and objects, in the heads of his characters, but seldom there where the reader would expect it to be. In a mild and often indirect way Calvino integrates his reflections on the subject in his short stories and comments on the role of sexuality in modern society and literature.

  4. Entrevista con José María López Piñero.

    Directory of Open Access Journals (Sweden)

    - Consejo de Redacción

    1996-01-01

    Full Text Available Nacido en 1933, López Piñero estudió medicina en Valencia. Su orientación historiográfica, encaminada por Laín Entralgo, cobra forma a partir de su trabajo con grandes maestros alemanes, como Leibbrand, en Munich, y Steude, en Bonn, aunque recorra también otras ciudades europeas. Leyó su tesis doctoral en 1960 sobre historia de la psiquiatría, Orígenes históricos del concepto de neurosis, dirigida por Laín y elaborada entre Alemania y Valencia. Se publicó en 1963; y luego, fue traducida al inglés, en Cambridge. En esa misma línea, redactará más tarde, con J. M. Morales, Neurosis y psicoterapia. López Piñero fundó el Instituto de Historia de la Medicina de Valencia en 1960, en el seno de la institución Alfons el Magnanim (cuya labor difusora de la cultura valenciana y universal ha brillado hasta la actualidad y es actualmente catedrático de Historia de la Medicina y de la Ciencia de la Universidad de Valencia, así como impulsor del Instituto de Estudios Documentales e Históricos sobre la Ciencia (IEDRC, hoy dirigido por Rafael Peris Bonet.

  5. Eros e paz nas comédias de Aristófanes

    Directory of Open Access Journals (Sweden)

    Ana Maria César Pompeu

    2016-07-01

    Full Text Available Aristophanes links Eros to peace in his comedies. In Acharnians, 425 BC, Dikaeopolis, an Athenian citizen, obtains private truce with the Spartans for himself and his family. He does not share his peace with anyone else, except with a bride, because she is  a woman and not is blamed for the war. It will have part of the fiance in their wedding. In Peace, 421 BC, Trigeu a grape-gatherer solves fly in a scarab beetle, who eats feces, to speak to the gods for peace, and ends up rescuing the Eirene goddess (Peace, contained in a cave by Polemos (War. Peace brings the goddess Opora (Autumnal or Harvest, with whom the protagonist marries, and the goddess Theoria (Feast, which is given to prytanes in the theater itself. In Lysistrata, in 411 BC, the women of Greece under the leadership of the Athenian Lysistrata make a sex strike to force their husbands to end up the war. The Myrrhine character and her husband, Kinesias, demonstrate how is the seduction and the refusal of women compared to men. We propose to link Eros to peace in the three pieces presented and Thesmoforiazusai (Demeterkoreazusai, the same year of Lysistrata and very close to it in some important ways, such as bringing a female choir, performing the separation of couples, making the apology of women and promote peace, because it is a religious festival of fertility, the Thesmophoria, parties in honor of the goddesses Demeter and Kore.

  6. Vicente Leñero y el fracaso de su inspector

    Directory of Open Access Journals (Sweden)

    Clemens A Franken K

    2010-01-01

    Full Text Available Luego de exponer brevemente la obra literaria del escritor Vicente Leñero y su lugar dentro de literatura mexicana, se analiza, en su novela posmoderna Los albañiles, la conducta de los personajes sospechosos, la figura y el método de investigación del detective y de sus colaboradores que fracasan en su búsqueda de la verdad, la crítica social y cultural de la sociedad mexicana de los años sesenta y aspectos formales como, por ejemplo, el lenguaje, el narrador y la forma de asimilación.After presenting the literary work of Vicente Leñero and his place in the mexican literature, this article analyzes, within his postmodern novel Los albañiles, the behavior of the suspicious characters, the figure and the investigation method of the detective and his collaborators who fail to look for the truth, the social and cultural criticism of the mexican society in the seventies, along with formal aspects, namely the language, the narrator and the assimilation method.

  7. Low-cost surveys of the Domus of Stallius Eros in Pompeii

    Science.gov (United States)

    Bosco, A.; Barbarino, M.; Valentini, R.; D'Andrea, A.

    2015-02-01

    In the framework of the Project 3D-ICONS (www.3dicons-project.eu), different large archaeological models were acquired in Pompeii. In particular, the 3D Model of the House of Stallius Eros (Regio I, Insula VI, 13 - 14) was realized. This house conserves a rich vertical stratigraphy covering a large chronological period and offers interesting information about the development of this side of the ancient city. To implement a detailed survey of the house and to reconstruct the original structure of the domus, different types of survey were carried out, in order to provide a complete 3D model of the house. Three data-acquisition methodologies were used and their final results were compared in order to measure their accuracy, efficacy and velocity. At first, the domus was surveyed by an electronical total station, then two different interventions with un-calibrated photogrammetry were planned. The paper presents some preliminary results obtained by the three methodologies and the integration of the three models. The computational environments reproducing the ancient Domus of Stallius Eros allows to propose new archaeological interpretations and hypothesis about the reconstruction of the ancient House.

  8. SOME ASPECTS OF SATELLITE IMAGERY INTEGRATION FROM EROS B AND LANDSAT 8

    Directory of Open Access Journals (Sweden)

    A. Fryskowska

    2016-06-01

    Full Text Available The Landsat 8 satellite which was launched in 2013 is a next generation of the Landsat remote sensing satellites series. It is equipped with two new sensors: the Operational Land Imager (OLI and the Thermal Infrared Sensor (TIRS. What distinguishes this satellite from the previous is four new bands (coastal aerosol, cirrus and two thermal infrared TIRS bands. Similar to its antecedent, Landsat 8 records electromagnetic radiation in a panchromatic band at a range of 0.5‐0.9 μm with a spatial resolution equal to 15 m. In the paper, multispectral imagery integration capabilities of Landsat 8 with data from the new high resolution panchromatic EROS B satellite are analyzed. The range of panchromatic band for EROS B is 0.4‐0.9 μm and spatial resolution is 0.7 m. Research relied on improving the spatial resolution of natural color band combinations (bands: 4,3,2 and of desired false color band composition of Landsat 8 satellite imagery. For this purpose, six algorithms have been tested: Brovey’s, Mulitplicative, PCA, IHS, Ehler's, HPF. On the basis of the visual assessment, it was concluded that the best results of multispectral and panchromatic image integration, regardless land cover, are obtained for the multiplicative method. These conclusions were confirmed by statistical analysis using correlation coefficient, ERGAS and R-RMSE indicators.

  9. Encounter of a different kind: Rosetta observes asteroid at close quarters

    Science.gov (United States)

    2008-09-01

    from the belt they could become a threat to Earth. The better we know them, the better we will be able to mitigate the risks some of them might present in the future." "Rosetta performed very well all along," Southwood continued. " This was a complex manoeuvre to keep such a small target in sight, but the spacecraft came through with flying colours. Now we are even more confident in its capacity to conduct the complex tasks that await it at comet Churyumov-Gerasimenko." Science observations of Steins will continue until 10 September. Since its launch by an Ariane 5 rocket on 2 March 2004, Rosetta has already travelled about 3.7 thousand million kilometres and swung by the Earth twice and Mars once for gravity-assist manoeuvres. On 17 December this year Rosetta will reach the maximum distance from the Sun in its current orbit, and will then head back towards Earth for the next and last gravitational kick from our planet on 13 November 2009. This will give the probe its final push toward its cometary target. On its way, Rosetta is scheduled to conduct another flyby, this time with the much larger (21) Lutetia asteroid, on 10 July 2010. Arrival at 67P/Churyumov-Gerasimenko is due by mid-2014. By that time the probe will have covered a distance of about 6.5 thousand million kilometres.

  10. Aqueous alteration on main-belt asteroids

    Science.gov (United States)

    Fornasier, S.; Lantz, C.; Barucci, M.; Lazzarin, M.

    2014-07-01

    The study of aqueous alteration is particularly important for unraveling the processes occurring during the earliest times in Solar System history, as it can give information both on the thermal processes and on the localization of water sources in the asteroid belt, and for the associated astrobiological implications. The aqueous alteration process produces the low temperature (< 320 K) chemical alteration of materials by liquid water which acts as a solvent and produces materials like phyllosilicates, sulphates, oxides, carbonates, and hydroxides. This means that liquid water was present in the primordial asteroids, produced by the melting of water ice by heating sources, very probably by ^{26}Al decay. Hydrated minerals have been found mainly on Mars surface, on primitive main-belt asteroids (C, G, B, F, and P-type, following the classification scheme by Tholen, 1984) and possibly also on few transneptunian objects. Reflectance spectroscopy of aqueous altered asteroids shows absorption features in the 0.6-0.9 and 2.5-3.5-micron regions, which are diagnostic of, or associated with, hydrated minerals. In this work, we investigate the aqueous alteration process on a large sample of 600 visible spectra of C-complex asteroids available in the literature. We analyzed all these spectra in a similar way to characterize the absorption-band parameters (band center, depth, and width) and spectral slope, and to look for possible correlations between the aqueous alteration process and the asteroids taxonomic classes, orbital elements, heliocentric distances, albedo, and sizes. We find that 4.6 % of P, 7.7 % of F, 9.8 % of B, 50.5 % of C, and 100 % of the G-type asteroids have absorption bands in the visible region due to hydrated silicates. Our analysis shows that the aqueous alteration sequence starts from the P-type objects, practically unaltered, and increases through the P → F → B → C → G asteroids, these last being widely aqueously altered, strengthening thus

  11. E-gravity theory

    OpenAIRE

    Linker, Patrick

    2016-01-01

    A couple of quantum gravity theories were proposed to make theoretical predictions about the behavior of gravity. The most recent approach to quantum gravity, called E-theory, is proposed mathematical, but there is not formulated much about what dynamics of gravity this theory proposes. This research paper treats the main results of the application of E-theory to General relativity involving conservation laws and scattering of particles in presence of gravity. Also the low-energy limit of thi...

  12. A semântica de Eros no tempo patrístico

    Directory of Open Access Journals (Sweden)

    Ulysses Roberto Lio Tropia

    2009-05-01

    Full Text Available O objetivo deste artigo é mostrar a semântica da palavra Eros dentro da tradição cristã. Limita-se a algumas dessas significações. A reflexão mostra a limitação dessa expressão na língua portuguesa. Seu significado é muito mais rico na língua grega. Se a tradição cristã carregou esta palavra de forma negativa, outros Padres leram-na em sintonia com Ágape e com outros significados. A relação mística a interpreta como uma relação “erótica” entre homem e Deus. Esta intimidade procura explicar o aspecto do desejo de Deus e da relação mútua entre aquele que ama e o amado, que tem sua raiz na busca mais íntima da humanidade. Negar por preconceitos palavras carregadas de desejos não divinos e nem dignos da humanidade, como na Antigüidade, é reduzir demais seu campo semântico na história. Esta palavra reflete o amor da alma para com Deus numa perspectiva mística, assume variações significativas, dentre tantas, como o amor de Jesus Cristo, como sinônimas de Ágape, do amor de Deus para com os homens, como amor individual ligado a Deus, o Eros como virtude e como castidade. A compreensão das dimensões do amor se realiza na capacidade de ver que todas elas são positivas e importantes para obtermos o equilíbrio da vida humana, numa harmonia destas dimensões constitutivas e importantes para a vida.Palavras-chave: Eros; Patrística; Amor; Alma; Mística; Virtude; Castidade e Ágape.ABSTRACTThis article aims at demonstrating the semantics of the term Eros in Christian tradition, pointing out the limitations of the term in Portuguese. The scope of its meaning is much wider in Greek. If Christian tradition has charged the word with a negative feature, other priests have read it in tune with Agape and other meanings. The mystical perspective interprets it as an ‘erotic’ relationship between man and God. Such intimacy attempts to explain God’s desire and the mutual relation between the one who loves and the

  13. How well do you know The Earth, Asteroids, Comets?

    Science.gov (United States)

    Alexander, C. J.; Lopez, J.; Barkus, R. C.; Angrum, A.

    2011-12-01

    The U.S. Rosetta Project is the NASA contribution to the International Rosetta Mission, an ESA cornerstone mission. The mission will arrive at its target, comet 67 P/Churyumov-Gerasimenko, in 2014, and escort the comet around the Sun for the ensuing 17 months. Along the way, the mission has encountered two asteroids: 21/Lutetia, and 2867/Steins, and enjoyed gravity assists at Mars and several at the Earth. The challenge for outreach coordinators is to convey the excitement of the mission, the manner in which its experiments gather and interpret data, provide context for those interpretations, all in an engaging fashion, without heavy use of camera images -- the camera not being among the NASA contributed instruments. In other words, because the US Rosetta Project expects to present the data and results from: an ultraviolet spectrometer, a plasma instrument, and a microwave spectrometer, outreach is presented with the special challenges of engaging the public in data which at least visually is less accessible than that of camera images. The project has turned to online games, interactive simulations, animated cartoons, and virtual labs to provide a visually stimulating way to explain: how scientists determine the age of asteroids; the context of a timeline of Earth geologic history with which to understand the relative position of the ages of any given asteroid to some event on Earth; a model of the solar system that goes from our Sun to the next Star to understand the spatial distances covered by comets in their journey around the Sun; and a model of early solar system evolution in which to understand the possible scenarios of solar system evolution that comets can help us sort out. In this paper we will present these simulations, even if some of them remain in the beta-development phase at the time of the meeting itself. Work at the Jet Propulsion Laboratory, California Institute of Technology, was supported by NASA. Rosetta is a joint collaboration between NASA

  14. Ero1-PDI interactions, the response to redox flux and the implications for disulfide bond formation in the mammalian endoplasmic reticulum.

    Science.gov (United States)

    Benham, Adam M; van Lith, Marcel; Sitia, Roberto; Braakman, Ineke

    2013-05-05

    The protein folding machinery of the endoplasmic reticulum (ER) ensures that proteins entering the eukaryotic secretory pathway acquire appropriate post-translational modifications and reach a stably folded state. An important component of this protein folding process is the supply of disulfide bonds. These are introduced into client proteins by ER resident oxidoreductases, including ER oxidoreductin 1 (Ero1). Ero1 is usually considered to function in a linear pathway, by 'donating' a disulfide bond to protein disulfide isomerase (PDI) and receiving electrons that are passed on to the terminal electron acceptor molecular oxygen. PDI engages with a range of clients as the direct catalyst of disulfide bond formation, isomerization or reduction. In this paper, we will consider the interactions of Ero1 with PDI family proteins and chaperones, highlighting the effect that redox flux has on Ero1 partnerships. In addition, we will discuss whether higher order protein complexes play a role in Ero1 function.

  15. 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...

  16. A Search for Asteroids, Moons, and Rings Orbiting White Dwarfs

    CERN Document Server

    Di Stefano, Rosanne; Kawaler, Steven D

    2009-01-01

    Do white dwarfs host asteroid systems? Although several lines of argument suggest that white dwarfs may be orbited by large populations of asteroids, transits would provide the most direct evidence. We demonstrate that the Kepler mission has the capability to detect transits of white dwarfs by asteroids. Because white-dwarf asteroid systems, if they exist, are likely to contain many asteroids orbiting in a spatially extended distribution, discoveries of asteroid transits can be made by monitoring only a small number of white dwarfs, compatible with Kepler's primary mission, which is to monitor stars with potentially habitable planets. Possible future missions that survey ten times as many stars with similar sensitivity and minute-cadence monitoring can establish the characteristics of asteroid systems around white dwarfs, such as the distribution of asteroid sizes and semimajor axes. Transits by planets would be more dramatic, but the probability that they will occur is lower. Ensembles of planetary moons and...

  17. 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...

  18. Rotational properties of Maria asteroid family

    CERN Document Server

    Kim, Myung-Jin; Moon, Hong-Kyu; Byun, Yong-Ik; Brosch, Noah; Kaplan, Murat; Kaynar, Suleyman; Uysal, Omer; Guzel, Eda; Behrend, Raoul; Yoon, Joh-Na; Mottola, Stefano; Hellmich, Stephan; Hinse, Tobias C; Eker, Zeki; Park, Jang-Hyun

    2013-01-01

    Maria family is regarded as an old-type (~3 +/- 1 Gyr) asteroid family which has experienced substantial collisional and dynamical evolution in the Main-belt. It is located nearby the 3:1 Jupter mean motion resonance area that supplies Near-Earth asteroids (NEAs) 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 observed rotation rate distribution. The two-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 lightcurves, 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 lightcurve inversion method (Kaa...

  19. 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...

  20. 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.

  1. Search for a Differentiated Asteroid Family

    Science.gov (United States)

    Thomas, Cristina A.; Lim, Lucy F.; Trilling, David E.; Moskovitz, Nicholas

    2014-08-01

    Dynamical asteroid families resulting from catastrophic disruptions represent the interiors of their former parent bodies. Differentiation of a large initially chondritic parent body is expected to produce an ``onion shell" object with a metal core, a thick olivine-rich mantle, and a thin basaltic crust. However, instead of the mineralogical diversity expected from the disruption of a differentiated parent body, most asteroid families tend to show similar spectra among the members. Moreover, spectra of metal-like materials and olivine-dominated assemblages have not been detected in asteroid families in the Main Belt and the expected mantle material is missing from the meteorite record. The deficit of olivine-rich mantle material in the meteorite record and in asteroid observations is known as the ``Missing Mantle" problem. For years the best explanation for the lack of mantle material has been the ``battered to bits" hypothesis that states that all differentiated parent bodies (aside from Vesta) were disrupted very early in the solar system and the resulting olivine-rich material was collisionally broken down until the object diameters fell below our observational limits. However, in a new, competing, hypothesis, Elkins-Tanton et al. (2013) has suggested that previous work has overestimated the amount of olivine produced by the differentiation of a chondritic parent body. We propose to obtain visible spectra of asteroids within the Massalia, Merxia, and Agnia S-type families to search for compositional variations that are indicators of differentiation and to quantitatively constrain the two competing ``Missing Mantle" hypotheses.

  2. 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...

  3. Thermal Tomography of Asteroid Surface Structure

    Science.gov (United States)

    Harris, Alan W.; Drube, Line

    2016-12-01

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

  4. Space Rocks: A Series of Papers on Meteorites and Asteroids

    OpenAIRE

    Hooper, Nina Louise

    2016-01-01

    The subject of this work is the compositions of asteroids and meteorites. Studies of the composition of small Solar System bodies are fundamental to theories of planet formation. Meteorites, samples available for analysis in the lab, help constrain the timeline and conditions in the early Solar System. Asteroid reflectance spectra help define the links between asteroids and meteorites. Studies of the spectral types and sizes of asteroids test dynamical models. These studie...

  5. Characterization of the near-Earth Asteroid 2002NY40

    OpenAIRE

    Roberts, Jr., Lewis C.; Hall, Doyle T.; 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 spectros...

  6. On the Discovery of the Asteroid 3784 Chopin

    Science.gov (United States)

    Elst, E. W.

    Le 31 octobre 1986 lords d'une campagne de recherche d'asteroides a l'observatoire de Haute Provence, un asteroide de septieme magnitude fut decouvert. A l'occasion de l'opposition consecutive en 1988, l'asteroide fut observe a nouveau a l'observatoire de Haute Provence, ce qui entraina la numerotation definitive. L'asteroide recoit le numero 3874 et le nom du grand compositeur polonais, Chopin.

  7. Asteroid Impact and Deflection Assessment mission: the Double Asteroid Redirection Test (DART)

    Science.gov (United States)

    Cheng, A.; Michel, P.

    2015-10-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor. AIDA is a joint ESA-NASA cooperative project, which includes the ESA Asteroid Impact Mission (AIM) rendezvous spacecraft and the NASA Double Asteroid Redirection Test (DART) mission. The AIDA target is the near-Earth binary asteroid 65803 Didymos, which will make an unusually close approach to Earth in October, 2022. The ~300-kg DART spacecraft is designed to impact the Didymos secondary at 6.5 km/s and demonstrate the ability to modify its trajectory through momentum transfer. The primary goals of AIDA are (i) to investigate the binary near-Earth asteroid (65803) Didymos, (ii) to demonstrate asteroid deflection by kinetic impact and to characterize the deflection. The primary DART objectives are to demonstrate a hypervelocity impact on the Didymos moon and to determine the resulting deflection from ground-based observatories. The DART impact on the Didymos secondary will cause a measurable change in the orbital period of the binary.

  8. Orbital Motion in the Vicinity of the Non-collinear Equilibrium Points of a Contact Binary Asteroid

    Science.gov (United States)

    Feng, Jinglang; Noomen, Ron; Yuan, Jianping

    2015-11-01

    The orbital motion around the non-collinear equilibrium points (EPs) of a contact binary asteroid is investigated in this paper. A contact binary asteroid is an asteroid consisting of two lobes that are in physical contact. Here, it is represented by the combination of an ellipsoid and a sphere. The gravity field of the ellipsoid is approximated by a spherical harmonic expansion with terms C20 ,C22 and C40, and the sphere by a straightforward point mass model. The non-collinear EPs are linearly stable for asteroids with slow rotation rates, and become unstable as the rotation rate goes up. To study the motion around the stable EPs, a third-order analytical solution is constructed, by the Lindstedt-Poincaré (LP) method. A good agreement is found between this analytical solution and numerical integrations for the motion in the vicinity of the stable EPs. Its accuracy decreases when the orbit goes further away from the EPs and the asteroid rotates faster. For the unstable EPs, the motions around them are unstable as well. Therefore, the linear feedback control law based on low thrust is introduced to stabilize the motion and track the reference trajectory. In addition, more control force is required as any of the injection error, the amplitude of the analytical reference orbit or the rotation rate of the asteroid increases. For small orbits around the EPs, the third-order analytical solution can serve as a good reference trajectory. However, for large amplitude orbits, accurate numerical orbits are to be used as reference. This avoids an extra control force to track the less accurate third-order analytical solution.

  9. Determination of pole orientations and shapes of asteroids

    Science.gov (United States)

    Magnusson, Per; Barucci, M. Antonietta; Drummond, Jack D.; Lumme, Kari; Ostro, Steven J.

    1989-01-01

    The principles of asteroid light-curve inversion are discussed together with basic principles involved in approaches for deriving asteroid pole and shape parameters from photometry data. The merits of various pole determination techniques are described and compared. Results obtained so far on the pole orientations and shapes of asteroids are presented.

  10. 78 FR 51750 - NASA Asteroid Initiative Idea Synthesis Workshop

    Science.gov (United States)

    2013-08-21

    ... SPACE ADMINISTRATION NASA Asteroid Initiative Idea Synthesis Workshop AGENCY: National Aeronautics and... for the agency's Asteroid Initiative. SUMMARY: The National Aeronautics and Space Administration announces a public conference to provide a status on the Agency's Asteroid Initiative planning and to enable...

  11. 78 FR 31977 - NASA Asteroid Initiative Call for Ideas

    Science.gov (United States)

    2013-05-28

    ... SPACE ADMINISTRATION NASA Asteroid Initiative Call for Ideas AGENCY: National Aeronautics and Space... announces a public forum to provide a status on the agency's asteroid initiative planning and to encourage...: This meeting will be streamed live online. Viewing options will be posted at www.nasa.gov/asteroid...

  12. 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... to the recent RFI for the agency's Asteroid Initiative. SUMMARY: The National Aeronautics and Space Administration announces that the agency will resume the NASA Asteroid Initiative Idea Synthesis public...

  13. Ivar asteroid rendezvous mission system scenario and trajectory design

    Institute of Scientific and Technical Information of China (English)

    崔平远; 李立涛; 崔祜涛; 栾恩杰; 吴伟仁; 田玉龙

    2003-01-01

    The asteroid exploration opportunities are searched and calculated with launch dates in 2006 to2010, and with asteroid Ivar 1627 as the target, the spacecraft and its subsystems are designed and analyzed,and the transfer trajectory is designed using △VEGA technology for the asteroid rendezvous. The design resultssatisfied the energy requirements for small explorers.

  14. Close Approaches of Potentially Hazardous Asteroids during Two Centuries

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Asteroids are the most important small bodies in the solar system and the near-earth asteroids (NEAs) are of especial concern to the world. The reasonis that they will make close approaches to the earth in the near future. We usea reasonable dynamical model and an efficient computing method to calculate the orbits of over 160 Potentially Hazardous Asteroids (PHAs) for two centuries.

  15. Dormant Comets in the Near-Earth Asteroid Population

    NARCIS (Netherlands)

    Mommert, Michael; Harris, Alan W.; Mueller, Michael; Hora, Joseph L.; Trilling, David E.; Knight, Matthew; Bottke, William F.; Thomas, Cristina; Delbo', Marco; Emery, Josh P.; Fazio, Giovanni; Smith, Howard A.

    2015-01-01

    The population of near-Earth objects comprises active comets and asteroids, covering a wide range of dynamical parameters and physical properties. Dormant (or extinct) comets, masquerading as asteroids, have long been suspected of supplementing the near-Earth asteroid (NEA) population. We present a

  16. 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...

  17. Defining a successful commercial asteroid mining program

    Science.gov (United States)

    Andrews, Dana G.; Bonner, K. D.; Butterworth, A. W.; Calvert, H. R.; Dagang, B. R. H.; Dimond, K. J.; Eckenroth, L. G.; Erickson, J. M.; Gilbertson, B. A.; Gompertz, N. R.; Igbinosun, O. J.; Ip, T. J.; Khan, B. H.; Marquez, S. L.; Neilson, N. M.; Parker, C. O.; Ransom, E. H.; Reeve, B. W.; Robinson, T. L.; Rogers, M.; Schuh, P. M.; Tom, C. J.; Wall, S. E.; Watanabe, N.; Yoo, C. J.

    2015-03-01

    This paper summarizes a commercial Asteroid Mining Architecture synthesized by the Senior Space Design Class at the University of Washington in Winter/Spring Quarters of 2013. The main author was the instructor for that class. These results use design-to-cost development methods and focused infrastructure advancements to identify and characterize a workable space industrialization architecture including space transportation elements, asteroid exploration and mining equipment, and the earth orbit infrastructure needed to make it all work. Cost analysis predicts that for an initial investment in time and money equivalent to that for the US North Slope Oil Field, the yearly world supply of Platinum Group Metals could be increased by 50%, roughly 1500 t of LOX/LH2 propellant/year would be available in LEO, and very low cost solar panels could be assembled at GEO using asteroidal materials. The investment also would have a discounted net present value return on investment of 22% over twenty years.

  18. 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

  19. 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.

  20. Measurement of Cohesion in Asteroid Regolith Materials

    Science.gov (United States)

    Kleinhenz, Julie E.; Gaier, James R.; Waters, Deborah L.; Harvey, Ralph; Zeszut, Zoe; Carreno, Brandon; Shober, Patrick

    2017-01-01

    A study has been initiated to examine cohesive forces in asteroid materials to contribute to a better understanding of low density bodies such as asteroids and Phobos, and assist in exploration missions involving interaction with their surface material. The test specimen used in this study was a lightly weathered CM2 meteorite which is spectroscopically similar to Type C (carbonaceous) asteroids, and thought to have representative surface chemistry. To account for sample heterogeneity, adhesion forces were measured between the CM2 sample and its five primary mineral phase components. These adhesive forces bound the range of cohesive force that can be expected for the bulk material. All materials were characterized using a variety of optical and spectroscopic methods. Adhesive forces on the order of 50 to 400 µN were measured using a torsion balance in an ultrahigh vacuum chamber. The mineral samples exhibited clearly different adhesive strengths in the following hierarchy: Serpentine > Siderite > Bronzite > Olivine ˜ Fe-Ni.

  1. SNC meteorites - Evidence against an asteroidal origin

    Science.gov (United States)

    Ashwal, L. D.; Warner, J. L.; Wood, C. A.

    1982-01-01

    About 1.3 billion years ago, on one or more distant planetary bodies, silicate melts formed and produced cumulate rocks which eventually made their way to earth. Nine of these rocks have been recovered. Three distinct groups are involved, including shergottites, nakhlites, and chassignites (abbreviated as SNC). The young crystallization ages and other chemical features of SNC meteorites have prompted several workers to suggest that the specimens may be samples of igneous rock, ejected from the surface of Mars during an impact event. Others have rejected the Martian origin of SNC meteorites in favor of a more traditional asteroidal parent body. The present investigation shows that the petrologic, geochemical, and isotopic evidence is inconsistent with an asteroidal origin for SNC meteorites. It is found that the characteristics of SNC meteorites argue convincingly against their origin in a planetary object as small as the largest asteroid. That these meteorites may be fragments of the Martian surface still remains the most likely possibility.

  2. The Asteroid Geophysical Explorer (AGEX); A proposal to explore Didymos system using Cubesats

    Science.gov (United States)

    Karatekin, Özgür

    2016-07-01

    We present a novel concept for ESA's CubeSat Opportunity Payload Intersatellite Network Sensors (COPINS) planned to be deployed from the ESA AIM spacecraft at the Didymos binary asteroid system: the Asteroid Geophysical Explorer (AGEX). AGEX includes two 3-U CubeSats with geophysical packages that will land on the surface of the small moon of the Didymos system. These geophysical packages will work in synergy on the secondary's surface to fulfill a rich set of scientific and technological mission goals. This includes the measurement of mass during the ballistic descent and landing, and determination of dynamical state, local gravity, geophysical surface properties and sub-surface structure following the landing. As a secondary objective, the assessment of the DART impact on the asteroid dynamical properties will be performed. AGEX will help AIM to meet its science and technology objectives, and will demonstrate the benefits of the deployment of a network of sensors while simultaneously developing technology of relevance to future ESA missions.

  3. Rotational properties of the Maria asteroid family

    Science.gov (United States)

    Kim, M.; Choi, Y.; Moon, H.; Byun, Y.; Brosch, N.; Kaplan, M.; Kaynar, S.; Uysal, O.; Guzel, E.; Behrend, R.; Yoon, J.; Mottola, S.; Hellmich, S.; Hinse, T.; Eker, Z.; Park, J.

    2014-07-01

    Introduction: The Maria family is regarded as an old-type (˜3 ± 1 Gyr) [1] asteroid family which 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 (NEAs) to the inner Solar System. Observations: We carried out observations of Maria family asteroids in 134 nights from July 2008 to May 2013 using 0.5-m to 2-m class telescopes at seven observatories in the northern hemisphere, and derived synodic rotational periods for 51 objects, including new periods for 34 asteroids [2]. Results: We found that there is a significant excess of fast and slow rotators in the observed rotation-rate distribution. From the correlations among rotational periods, the amplitudes of lightcurves, and the sizes, we conclude that the rotational properties of the Maria family asteroids have been changed considerably by non-gravitational forces such as the YORP effect. Using the lightcurve inversion method [3,4], we successfully determined pole orientations for 13 Maria members, and found an excess of prograde spins over retrograde spins with a ratio (N_p/N_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 to 75 Maria family asteroids larger than 1 km have entered the near-Earth space as per 100 Myr [2].

  4. A Proposed Unified Theory of Hydrated Asteroids

    Science.gov (United States)

    Rivkin, Andrew S.

    2016-10-01

    The last decade has seen tremendous growth in the study of hydrated and hydroxylated minerals (hereafter simply called "hydrated minerals") on asteroids. Several workers have used absorptions in the 3-µm region and a correlated absorption near 0.7 µm to determine not only the presence or absence of these minerals but gain insight into the compositions of asteroid surfaces. Spectra of hundreds of asteroids have been measured and published or presented at meetings, and we are in a position to use these newer datasets to globally assess the patterns and relationships we see, as previously done by Jones et al. (1990) and Takir et al. (2012). There are several points to be addressed by any such assessment. Several different band shapes are seen in the 3-µm region, only one of which is seen in the hydrated meteorites in our collections. However, each of the main 3-µm band shapes is represented among parent bodies of collisional families. There seems to be little correlation in general between asteroid spectral class and 3-µm band shape, save for the Ch meteorites which are overwhelmingly likely to share the same band shape as the CM meteorites. Ceres has an unusual but not unique band shape, which has thus far only been found on the largest asteroids. I will present an outline scenario for the formation and evolution of hydrated asteroids, where aqueous alteration serves to lithify some objects while other objects remain unlithified and still others differentiate and suffer collisional modification. While some details will no doubt be altered to account for better or new information, this scenario is offered as a starting point for discussion.

  5. 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.

  6. The thiol oxidant dipyridyl disulfide can supply the PDI-Ero1p pathway with additional oxidative equivalents

    DEFF Research Database (Denmark)

    López-Mirabal, H Reynaldo; Winther, Jakob R

    2007-01-01

    Membrane-permeant oxidants have become a standard tool for studying eukaryotic organisms because they affect the redox state and the redox regulation of different compartments. The ero1-1 mutant is temperature sensitive (37 degrees C) and cannot grow under anaerobic conditions. Low micromolar con...

  7. The Education of Eros: A History of Education and the Problem of Adolescent Sexuality. Studies in Curriculum Theory Series

    Science.gov (United States)

    Carlson, Dennis L.

    2012-01-01

    "The Education of Eros: is the first and only comprehensive history of sexuality education and the "problem" of adolescent sexuality from the mid-20th century to the beginning of the 21st. It explores how professional health educators, policy makers, and social and religious conservatives differed in their approaches, and battled over what gets…

  8. EROs found behind lensing clusters: II.Empirical properties, classification, and SED modelling based on multi-wavelength observations

    CERN Document Server

    Hempel, A; Egami, E; Pelló, R; Wise, M; Richard, J; Le Borgne, J F; Kneib, J -P

    2007-01-01

    We study the properties and nature of extremely red galaxies (ERO, R-K>5.6) found behind two lensing clusters and compare them with other known galaxy populations. New HST/ACS observations, Spitzer IRAC and MIPS, and Chandra/ACIS observations of the two lensing clusters Abell 1835 and AC114 contemplate our earlier optical and near-IR observations and have been used to study extremely red objects (EROs) in these deep fields. We have found 6 and 9 EROs in Abell 1835 and AC114. Several (7) of these objects are undetected up to the I and/or z band, and are hence ``optical'' drop-out sources. The photometric redshifts of most of our sources (80%) are z~0.7-1.5. According to simple colour-colour diagrams the majority of our objects would be classified as hosting old stellar populations. However, there are clear signs of dusty starbursts for several among them. These objects correspond to the most extreme ones in R-K colour. We estimate a surface density of (0.97+-0.31) arcmin-2 for EROs with (R-K>5.6) at K3) is fou...

  9. 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.

  10. 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

  11. Asteroid families - Physical properties and evolution

    Science.gov (United States)

    Chapman, Clark R.; Paolicchi, Paolo; Zappala, Vincenzo; Binzel, Richard P.; Bell, Jeffrey F.

    1989-01-01

    Asteroid families are considered to be fragments from collisional destruction of precursor bodies. However, results available on the inferred mineralogy, size distributions, and spins of family members do not confirm the expectations of the traditional model. Only a handful of nearly 100 proposed families, most of them populous, have distributions of inferred mineralogies consistent with simple cosmochemical models for parent bodies. It is suggested that most catastrophic collisions may not result in observable families, but rather in a spray of smaller particles, thus accounting for the small number of confirmed and consistent families, despite evidence for extensive collisional evolution of asteroids.

  12. Collisional evolution of the early asteroid belt

    Science.gov (United States)

    Gil-Hutton, Ricardo; Brunini, Adrián

    1999-04-01

    We present numerical results obtained by a simulation of the collisional process between asteroids and scattered comets from the Uranus-Neptune zone. This mechanism allows the use of single exponent incremental size distributions for the initial belt reaching a final distribution that matches the observed population very well. Since the cometary bombardment was extremely efficient removing mass from the primordial asteroid belt in a very short time, we always obtained belts with total masses less than 0.001 M ⊕ after ≈ 2×10 7 yrs. This result allows processes with an important initial mass preserving Vestas basaltic crust.

  13. 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.

  14. Manuel′s asteroid disruption technique

    Directory of Open Access Journals (Sweden)

    Manuel John

    2015-01-01

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

  15. NASA's Asteroid Redirect Mission: Overview and Status

    Science.gov (United States)

    Abell, Paul; Gates, Michele; Johnson, Lindley; Chodas, Paul; Brophy, John; Mazanek, Dan; Muirhead, Brian

    A major element of the National Aeronautics and Space Administration’s (NASA) new Asteroid Initiative is the Asteroid Redirect Mission (ARM). This concept was first proposed in 2011 during a feasibility study at the Keck Institute for Space Studies (KISS)[1] and is under consideration for implementation by NASA. The ARM involves sending a high-efficiency (ISP 3000 s), high-power (40 kW) solar electric propulsion (SEP) robotic vehicle that leverages technology developed by NASA’s Space Technology Mission Directorate (STMD) to rendezvous with a near-Earth asteroid (NEA) and return asteroidal material to a stable lunar distant retrograde orbit (LDRO)[2]. There are two mission concepts currently under study, one that captures an entire 7 - 10 meter mean diameter NEA[3], and another that retrieves a 1 - 10 meter mean diameter boulder from a 100+ meter class NEA[4]. Once the retrieved asteroidal material is placed into the LDRO, a two person crew would launch aboard an Orion capsule to rendezvous and dock with the robotic SEP vehicle. After docking, the crew would conduct two extra-vehicular activities (EVA) to collect asteroid samples and deploy instruments prior to Earth return. The crewed portion of the mission is expected to last approximately 25 days and would represent the first human exploration mission beyond low-Earth orbit (LEO) since the Apollo program. The ARM concept leverages NASA’s activities in Human Exploration, Space Technology, and Planetary Defense to accomplish three primary objectives and several secondary objectives. The primary objective relevant to Human Exploration is to gain operational experience with vehicles, systems, and components that will be utilized for future deep space exploration. In regard to Space Technology, the ARM utilizes advanced SEP technology that has high power and long duration capabilities that enable future missions to deep space destinations, such as the Martian system. With respect to Planetary Defense, the ARM

  16. Un abrazo de amigo y compañero para Alejandro Casona

    Directory of Open Access Journals (Sweden)

    Oswaldo Díaz Díaz

    1965-10-01

    Full Text Available El título de este escrito podría parecer vanidoso y logrero si esas hermosas palabras, "un abrazo de amigo y compañero", no estuvieran de puño y letra de Casona en una tarjeta dirigida a mí desde Buenos Aires, con ocasión de haberle enviado dos de mis comedias para someterlas a su autorizado parecer. Ni esta es la primera vez que escribo a propósito del teatro de Alejandro Casona, pues en 1941, en la revista titulada España que editó fugazmente en Bogotá un grupo entusiasta de españoles exilados de su patria, como lo estuvo mucho tiempo Casona, apareció un artículo mío con análogo título y que hoy me sirve de guia para empezar este recuerdo.

  17. A questão de eros na filosofia do cuidado com o corpo

    Directory of Open Access Journals (Sweden)

    Enéas Rangel Teixeira

    2006-01-01

    Full Text Available En el presente artículo se elabora una reflexión teórica y filosófica, cuyo objetivo principal fue reflexionar sobre el concepto de Eros - el cual envuelve el deseo, el afecto y la estética en las prácticas del cuidado con el cuerpo. Este trabajo constituye una síntesis de algunas reflexiones provenientes de trabajos que incluyen la subjetividad y la estética del cuidado. Fueron realizadas relaciones entre las siguientes categorías: la sensibilidad, la estética, lo relacional y la transdisciplinariedad. Se pudo concluir que el enfoque estético aunado a la ética puede ser transformador, ya que remite a lo sensible y a la subjetividad, creando así rupturas con antiguos modelos desubjetivados del cuidado.

  18. "爱欲"视野中的公民教育%Citizen Education in Eros' Vision

    Institute of Scientific and Technical Information of China (English)

    李长伟

    2009-01-01

    "厄洛斯(eros)"是古典政治哲学和教育哲学的主题与内核.爱欲意味着人对美善本身以及与此内在相关的灵魂不朽的执着追求.不过,人的生命不是神的生命,它是可朽的,人若想实现不朽,就必须通过教育,与他人的灵魂结合在一起.正是出于这种对美善的爱,苏格拉底把教化优秀青年,使其卓越,看作是自己的神圣使命,而他自己也在这样的教化中实现了自己的灵魂不朽.

  19. The TESIS Project: Are Type 2 QSO Hidden in X-Ray Emitting EROs?

    Science.gov (United States)

    Severgnini, P.; Della Ceca, R.; Braito, V.; Saracco, P.; Longhetti, M.; Bender, R.; Drory, N.; Feulner, G.; Hopp, U.; Mannucci, F.; Maraston, C.

    X-ray selected EROs are, on average, the hardest X-ray sources in medium and deep X-ray fields. This coupled with their extremely red colors (R-K > 5) suggest that they represent one of the most promising population where looking for high-luminosity (LX > 1044 erg s-1) and X-ray obscured (NH > 1022 cm-2) type2 AGNs, the so called QSO2 (e.g., [5]; [4]; Mignoli et al. submitted to A&A). These latter are predicted in large density by the synthesis model of the Cosmic X-ray background [9] even if only few observational evidences have been found so far (e.g., [1] and references therein; Caccianiga et al. A&A accepted).

  20. Er-O clustering and its influence on the lattice sites of Er in Si

    CERN Document Server

    Wahl, U; Araújo, J P; Vantomme, A; Langouche, G

    1999-01-01

    We present emission channeling experiments on the lattice location of Er in CZ Si single crystals with a well-defined O concentration of 6.5-6.6 $\\times 10^{17}$ cm$^{-3}$ and 60 keV-implanted Tm+Er doses ranging from 4.3 $\\times 10^{12}$ cm$^{-2}$ to 3.6 $\\times 10^{13}$ cm$^{-2}$. The experimental results are compared to the predictions of a simulator which models the formation of Er$_{n}$O$_{m}$ clusters on the basis of simple diffusion and capture kinetics. We find that our experimental data compare favorably with a scenario where the formation of Er$_{n}$O$_{m}$ defects with one or more O atoms is responsible for removing the Er atoms from their tetrahedral interstitial (T) sites. This suggests that Er does no longer occupy the T site even in simple (ErO) pairs.

  1. El aprendizaje mediado entre compañeros para el manejo de programas computacionales

    Directory of Open Access Journals (Sweden)

    Luis Felipe Gómez López

    2012-01-01

    Full Text Available En este artículo se presentan los resultados de una investigación cualitativa que describe las maneras en que los alumnos de una clase de computación en secundaria median el aprendizaje de sus compañeros -mediación entre pares- para el aprendizaje del manejo de programas computacionales. El interés se centró en la identificación de las formas que adopta la medición; de las modalidades y las condiciones que la posibilitan. También se presentan las implicaciones para los profesores en términos de lo que pueden hacer para permitir o favorecer este tipo de mediación en el aprendizaje.

  2. Monte-Carlo Simulations of Chemical Erosion in TEXTOR-94 with the ERO-TEXTOR Code

    Science.gov (United States)

    Kirschner, A.; Philipps, V.; Pospieszczyk, A.; Wienhold, P.

    This paper presents ERO-TEXTOR simulation calculations of chemical erosion of a carbon limiter exposed to the TEXTOR Scrape-Off-Layer. The spatial distribution of CD-emission near a testlimiter is calculated in dependence on the plasma parameters and on the sticking probability for hydrocarbons hitting the limiter surface. The comparison of D/XB values with experimental data on TEXTOR-94 indicates that eroded hydrocarbons returning to the limiter surface have an extremely low effective sticking. This can be understood in terms of a high re-erosion of the freshly deposited a-C:D layer. The comparison of the radial distribution of the CD- and CII-emission between simulation and experiment shows a good agreement.

  3. Failure mode diagram of rubble pile asteroids: Application to (25143) asteroid Itokawa

    Science.gov (United States)

    Hirabayashi, Masatoshi; Scheeres, Daniel J.

    2016-01-01

    Proposing a diagram which shows the variation in asteroidal failure as a function of a spin period, later called the failure mode diagram, this paper considers the failure modes and conditions of asteroid (25143) Itokawa. This diagram is useful to describe when and where failure occurs in an asteroid. Assuming that Itokawa is homogeneous, we use a plastic finite element code to obtain the diagram for this object. The results show that if the bulk cohesive strength is less than 0.1 Pa, Itokawa experiences compressional failure on the neck surface at the current spin period 12.1 hours. At a spin period shorter than 4.5 hours, tension across the neck causes this asteroid to split into two components. It is also found that if the breakup spin period is longer than 5.2 hours, their motion is bounded. This implies that once Itokawa splits, the components may escape from one another.

  4. Hungaria asteroid region telescopic spectral survey (HARTSS) I: Stony asteroids abundant in the Hungaria background population

    Science.gov (United States)

    Lucas, Michael P.; Emery, Joshua P.; Pinilla-Alonso, Noemi; Lindsay, Sean S.; Lorenzi, Vania

    2017-07-01

    The Hungaria asteroids remain as survivors of late giant planet migration that destabilized a now extinct inner portion of the primordial asteroid belt and left in its wake the current resonance structure of the Main Belt. In this scenario, the Hungaria region represents a ;purgatory; for the closest, preserved samples of the asteroidal material from which the terrestrial planets accreted. Deciphering the surface composition of these unique samples may provide constraints on the nature of the primordial building blocks of the terrestrial planets. We have undertaken an observational campaign entitled the Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) to record near-infrared (NIR) reflectance spectra in order to characterize their taxonomy, surface mineralogy, and potential meteorite analogs. The overall objective of HARTSS is to evaluate the compositional diversity of asteroids located throughout the Hungaria region. This region harbors a collisional family of Xe-type asteroids, which are situated among a background (i.e., non-family) of predominantly S-complex asteroids. In order to assess the compositional diversity of the Hungaria region, we have targeted background objects during Phase I of HARTSS. Collisional family members likely reflect the composition of one original homogeneous parent body, so we have largely avoided them in this phase. We have employed NIR instruments at two ground-based telescope facilities: the NASA Infrared Telescope Facility (IRTF), and the Telescopio Nazionale Galileo (TNG). Our data set includes the NIR spectra of 42 Hungaria asteroids (36 background; 6 family). We find that stony S-complex asteroids dominate the Hungaria background population (29/36 objects; ∼80%). C-complex asteroids are uncommon (2/42; ∼5%) within the Hungaria region. Background S-complex objects exhibit considerable spectral diversity as band parameter measurements of diagnostic absorption features near 1- and 2-μm indicate that several

  5. Sensitivity of the Asteroid Redirect Robotic Mission (ARRM) to Launch Date and Asteroid Stay Time

    Science.gov (United States)

    Mcguire, Melissa L.; Burke, Laura M.; McCarty, Steven L.; Strange, Nathan J.; Qu, Min; Shen, Haijun; Vavrina, Matthew A.

    2017-01-01

    National Aeronautics and Space Administrations (NASAs) proposed Asteroid Redirect Mission (ARM) is being designed to robotically capture and then redirect an asteroidal boulder mass into a stable orbit in the vicinity of the moon, where astronauts would be able to visit and study it. The current reference trajectory for the robotic portion, ARRM, assumes a launch on a Delta IV H in the end of the calendar year 2021, with a return for astronaut operations in cislunar space in 2026. The current baseline design allocates 245 days of stay time at the asteroid for operations and boulder collection. This paper outlines analysis completed by the ARRM mission design team to understand the sensitivity of the reference trajectory to launch date and asteroid stay time.

  6. The dynamical environment of asteroid 21 Lutetia according to different internal models

    Science.gov (United States)

    Aljbaae, S.; Chanut, T. G. G.; Carruba, V.; Souchay, J.; Prado, A. F. B. A.; Amarante, A.

    2017-01-01

    One of the most accurate models currently used to represent the gravity field of irregular bodies is the polyhedral approach. In this model, the mass of the body is assumed to be homogeneous, which may not be true for a real object. The main goal of the this paper is to study the dynamical effects induced by three different internal structures (uniform, three- and four-layered) of asteroid (21) Lutetia, an object that recent results from space probe suggest being at least partially differentiated. The Mascon gravity approach used in the this work consists of dividing each tetrahedron into eight parts to calculate the gravitational field around the asteroid. The zero-velocity curves show that the greatest displacement of the equilibrium points occurs in the position of the E4 point for the four-layered structure and the smallest one occurs in the position of the E3 point for the three-layered structure. Moreover, stability against impact shows that the planar limit gets slightly closer to the body with the four-layered structure. We then investigated the stability of orbital motion in the equatorial plane of (21) Lutetia and propose numerical stability criteria to map the region of stable motions. Layered structures could stabilize orbits that were unstable in the homogeneous model.

  7. Dynamical model of binary asteroid systems through patched three-body problems

    Science.gov (United States)

    Ferrari, Fabio; Lavagna, Michèle; Howell, Kathleen C.

    2016-08-01

    The paper presents a strategy for trajectory design in the proximity of a binary asteroid pair. A novel patched approach has been used to design trajectories in the binary system, which is modeled by means of two different three-body systems. The model introduces some degrees of freedom with respect to a classical two-body approach and it is intended to model to higher accuracy the peculiar dynamical properties of such irregular and low gravity field bodies, while keeping the advantages of having a full analytical formulation and low computational cost required. The neighborhood of the asteroid couple is split into two regions of influence where two different three-body problems describe the dynamics of the spacecraft. These regions have been identified by introducing the concept of surface of equivalence (SOE), a three-dimensional surface that serves as boundary between the regions of influence of each dynamical model. A case of study is presented, in terms of potential scenario that may benefit of such an approach in solving its mission analysis. Cost-effective solutions to land a vehicle on the surface of a low gravity body are selected by generating Poincaré maps on the SOE, seeking intersections between stable and unstable manifolds of the two patched three-body systems.

  8. The dynamical environment of asteroid 21 Lutetia according to different internal models

    CERN Document Server

    Aljbaae, Safwan; Carruba, Valerio; Souchay, Jean; Prado, Antonio F B A; Amarante, André

    2016-01-01

    One of the most accurate models currently used to represent the gravity field of irregular bodies is the polyhedral approach. In this model, the mass of the body is assumed to be homogeneous, which may not be true for a real object. The main goal of the present paper is to study the dynamical effects induced by three different internal structures (uniform, three- and four-layers) of asteroid (21) Lutetia, an object that recent results from space probe suggest being at least partially differentiated. The Mascon gravity approach used in the present work, consists of dividing each tetrahedron into eight parts to calculate the gravitational field around the asteroid. The zero-velocity curves show that the greatest displacement of the equilibrium points occurs in the position of the E4 point for the four-layers structure and the smallest one occurs in the position of the E3 point for the three-layers structure. Moreover, stability against impact shows that the planar limit gets slightly closer to the body with the...

  9. Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA.

    Science.gov (United States)

    Rozitis, Ben; MacLennan, Eric; Emery, Joshua P

    2014-08-14

    Space missions and ground-based observations have shown that some asteroids are loose collections of rubble rather than solid bodies. The physical behaviour of such 'rubble-pile' asteroids has been traditionally 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 piles (ten kilometres across or less), and could potentially explain fast rotation rates in the small-asteroid population. The strongest evidence so far has come from an analysis of the rotational breakup of the main-belt comet P/2013 R3 (ref. 7), although that was indirect and poorly constrained by observations. Here we report that the kilometre-sized asteroid (29075) 1950 DA (ref. 8) is a rubble pile that is rotating faster than is allowed by gravity and friction. We find that cohesive forces are required to prevent surface mass shedding and structural failure, and that the strengths of the forces are comparable to, though somewhat less than, the forces found between the grains of lunar regolith.

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

    Science.gov (United States)

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

    2017-04-01

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

  11. Urine specific gravity test

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003587.htm Urine specific gravity test To use the sharing features on this page, please enable JavaScript. Urine specific gravity is a laboratory test that shows the concentration ...

  12. Idaho State Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (24,284 records) were compiled by the U. S. Geological Survey. This data base was received on February 23, 1993. Principal gravity...

  13. Northern Oklahoma Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (710 records) were compiled by Professor Ahern. This data base was received in June 1992. Principal gravity parameters include latitude,...

  14. Andes 1997 Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Central Andes gravity data (6,151 records) were compiled by Professor Gotze and the MIGRA Group. This data base was received in April, 1997. Principal gravity...

  15. DNAG Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Decade of North American Geology (DNAG) gravity grid values, spaced at 6 km, were used to produce the Gravity Anomaly Map of North America (1987; scale...

  16. Cadiz, California Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (32 records) were gathered by Mr. Seth I. Gutman for AridTech Inc., Denver, Colorado using a Worden Prospector gravity meter. This data base...

  17. Classical Weyl Transverse Gravity

    CERN Document Server

    Oda, Ichiro

    2016-01-01

    We study various classical aspects of the Weyl transverse (WTDiff) gravity in a general space-time dimension. First of all, we clarify a classical equivalence among three kinds of gravitational theories, those are, the conformally-invariant scalar tensor gravity, Einstein's general relativity and the WTDiff gravity via the gauge fixing procedure. Secondly, we show that in the WTDiff gravity the cosmological constant is a mere integration constant as in unimodular gravity, but it does not receive any radiative corrections unlike the unimodular gravity. A key point in this proof is to construct a covariantly conserved energy-momentum tensor, which is achieved on the basis of this equivalence relation. Thirdly, we demonstrate that the Noether current for the Weyl transformation is identically vanishing, thereby implying that the Weyl symmetry existing in both the conformally-invariant scalar tensor gravity and the WTDiff gravity is a "fake" symmetry. We find it possible to extend this proof to all matter fields,...

  18. Seven Near-Earth Asteroids at Asteroids Observers (OBAS) - MPPD: 2016 June-November

    Science.gov (United States)

    Lozano, Juan; Flores, Angel; Mas, Vicente; Fornas, Gonzalo; Rodrigo, Onofre; Brines, Pedro; Forna, Alvaro; Herrero, David; Carreño, Alfonso; Arce, Enrique

    2017-04-01

    We report on the results of photometric analysis on seven near-Earth asteroids (NEA) by Asteroides Observers (OBAS). This work is part of the Minor Planet Photometric Database effort that was initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

  19. Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS): Stony Asteroids Abundant in the Background and Family Populations

    Science.gov (United States)

    Lucas, Michael P.; Emery, Joshua P.; Pinilla-Alonso, Noemi; Lindsay, Sean S.; Lorenzi, Vania

    2016-10-01

    The Hungaria region represents a "purgatory" for the closest, preserved samples of the material from which the terrestrial planets accreted. The Hungaria region harbors a collisional family of Xe-type asteroids, which are situated among a background of predominantly S-complex asteroids. Deciphering their surface composition may provide constraints on the nature of the primordial building blocks of the terrestrial planets. We hypothesize that planetesimals in the inner part of the primordial asteroid belt experienced partial- to full-melting and differentiation, the Hungaria region should retain any petrologically-evolved material that formed there.We have undertaken an observational campaign entitled the Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) to record near-infrared (NIR) spectra to characterize taxonomy, surface mineralogy, and potential meteorite analogs. We used NIR instruments at two ground-based facilities (NASA IRTF; TNG). Our data set includes spectra of 82 Hungaria asteroids (61 background; 21 family), 65 were observed during HARTSS. We compare S-complex background asteroids to calibrations developed via laboratory analyses of ordinary chondrites, and to our analyses (EPMA, XRD, VIS+NIR spectra) of 11 primitive achondrite (acapulcoite-lodranite clan) meteorites.We find that stony S-complex asteroids dominate the Hungaria background population (~80%). Background objects exhibit considerable spectral diversity, when quantified by spectral band parameter measurements, translates to a variety of surface compositions. Two main meteorite groups are represented within the Hungaria background: unmelted, nebular L chondrites (and/or L chondrites), and partially-melted primitive achondrites. H-chondrite mineralogies appear to be absent from the Hungaria background. Xe-type Hungaria family members exhibit spectral homogeneity, consistent with the hypothesis that the family was derived from the disruption of a parent body analogous to an enstatite

  20. 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.

  1. Asteroid mass estimation using Markov-Chain Monte Carlo techniques

    Science.gov (United States)

    Siltala, Lauri; Granvik, Mikael

    2016-10-01

    Estimates for asteroid masses are based on their gravitational perturbations on the orbits of other objects such as Mars, spacecraft, or other asteroids and/or their satellites. In the case of asteroid-asteroid perturbations, this leads to a 13-dimensional inverse problem where the aim is to derive the mass of the perturbing asteroid and six orbital elements for both the perturbing asteroid and the test asteroid using astrometric observations. We have developed and implemented three different mass estimation algorithms utilizing asteroid-asteroid perturbations into the OpenOrb asteroid-orbit-computation software: the very rough 'marching' approximation, in which the asteroid orbits are fixed at a given epoch, reducing the problem to a one-dimensional estimation of the mass, an implementation of the Nelder-Mead simplex method, and most significantly, a Markov-Chain Monte Carlo (MCMC) approach. We will introduce each of these algorithms with particular focus on the MCMC algorithm, and present example results for both synthetic and real data. Our results agree with the published mass estimates, but suggest that the published uncertainties may be misleading as a consequence of using linearized mass-estimation methods. Finally, we discuss remaining challenges with the algorithms as well as future plans, particularly in connection with ESA's Gaia mission.

  2. Physics of Artificial Gravity

    Science.gov (United States)

    Bukley, Angie; Paloski, William; Clement, Gilles

    2006-01-01

    This chapter discusses potential technologies for achieving artificial gravity in a space vehicle. We begin with a series of definitions and a general description of the rotational dynamics behind the forces ultimately exerted on the human body during centrifugation, such as gravity level, gravity gradient, and Coriolis force. Human factors considerations and comfort limits associated with a rotating environment are then discussed. Finally, engineering options for designing space vehicles with artificial gravity are presented.

  3. Terrestrial Gravity Fluctuations

    Science.gov (United States)

    Harms, Jan

    2015-12-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10-23 Hz-1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  4. Terrestrial Gravity Fluctuations.

    Science.gov (United States)

    Harms, Jan

    2015-01-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10(-23) Hz(-1/2) above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  5. Terrestrial Gravity Fluctuations

    Directory of Open Access Journals (Sweden)

    Jan Harms

    2015-12-01

    Full Text Available Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^–23 Hz^–1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our

  6. Terrestrial Gravity Fluctuations

    CERN Document Server

    Harms, Jan

    2015-01-01

    The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.

  7. Asteroid modeling for testing spacecraft approach and landing.

    Science.gov (United States)

    Martin, Iain; Parkes, Steve; Dunstan, Martin; Rowell, Nick

    2014-01-01

    Spacecraft exploration of asteroids presents autonomous-navigation challenges that can be aided by virtual models to test and develop guidance and hazard-avoidance systems. Researchers have extended and applied graphics techniques to create high-resolution asteroid models to simulate cameras and other spacecraft sensors approaching and descending toward asteroids. A scalable model structure with evenly spaced vertices simplifies terrain modeling, avoids distortion at the poles, and enables triangle-strip definition for efficient rendering. To create the base asteroid models, this approach uses two-phase Poisson faulting and Perlin noise. It creates realistic asteroid surfaces by adding both crater models adapted from lunar terrain simulation and multiresolution boulders. The researchers evaluated the virtual asteroids by comparing them with real asteroid images, examining the slope distributions, and applying a surface-relative feature-tracking algorithm to the models.

  8. 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 ...

  9. Spectroscopic Survey of X-type Asteroids

    CERN Document Server

    Fornasier, Sonia; Dotto, Elisabetta

    2011-01-01

    We present reflected light spectral observations from 0.4 to 2.5 micron of 24 asteroids chosen from the population of asteroids initially classified as Tholen X-type objects (Tholen, 1984). The X complex in the Tholen taxonomy comprises the E, M and P classes which have very different inferred mineralogies but which are spectrally similar to each other, with featureless spectra in visible wavelengths. The data were obtained during several observing runs in the 2004-2007 years at the NTT, TNG and IRTF telescopes. We find a large variety of near-infrared spectral behaviors within the X class, and we identify weak absorption bands in spectra of 11 asteroids. Our spectra, together with albedos published by Tedesco et al. (2002), can be used to suggest new Tholen classifications for these objects. In order to constrain the possible composition of these asteroids, we perform a least-squares search through the RELAB spectral database. Many of the best fits are consistent with meteorite analogue materials suggested i...

  10. Comet nucleus and asteroid sample return missions

    Science.gov (United States)

    1992-01-01

    Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.

  11. Rotation Properties of Small Jovian Trojan Asteroids

    Science.gov (United States)

    French, Linda M.; Stephens, Robert D.; James, David; Coley, Daniel R.; Warner, Brian D.; Rohl, Derrick

    2016-10-01

    Jovian Trojan asteroids are of interest both as objects in their own right (we have no spectral analogs among meteorite samples) and as possible relics of Solar System formation. Asteroid lightcurves can give information about processes that have affected a group of asteroids; they can also give information about the density of the objects when enough lightcurves have been collected. We have been carrying out a survey of Trojan lightcurve properties for comparison with small asteroids and with comets. In a recent paper (French et al. 2015) we presented evidence that a significant number of Trojans have rotation periods greater than 24 hours. We will report our latest results and compare them with results of sparsely-sampled lightcurves from the Palomar Transient Factory (Waszczak et al. 2015). LF, RS, and DR were visiting astronomers at Cerro Tololo Interamerican Observatory, operated by AURA under contract with the NSF, and with the SMARTS Consortium at CTIO. This research was sponsored by NSF Planetary Astronomy grant 1212115.ReferencesFrench, L.M. et al. 2015. Icarus 254, pp. 1-17.Waszczak, A. et al. 2015. A.J. 150, Issue 3, I.D. 35.

  12. 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.

  13. 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.

  14. Asteroid-Generated Tsunami and Impact Risk

    Science.gov (United States)

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

    2016-12-01

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

  15. Spectroscopic survey of M--type asteroids

    CERN Document Server

    Fornasier, S; Dotto, E; Migliorini, A; Ockert-Bell, M; Barucci, M A

    2010-01-01

    M-type asteroids, as defined in the Tholen taxonomy (Tholen, 1984), are medium albedo bodies supposed to have a metallic composition and to be the progenitors both of differentiated iron-nickel meteorites and enstatite chondrites. We carried out a spectroscopic survey in the visible and near infrared wavelength range (0.4-2.5 micron) of 30 asteroids chosen from the population of asteroids initially classified as Tholen M -types, aiming to investigate their surface composition. The data were obtained during several observing runs during the years 2004-2007 at the TNG, NTT, and IRTF telescopes. We computed the spectral slopes in several wavelength ranges for each observed asteroid, and we searched for diagnostic spectral features. We confirm a large variety of spectral behaviors for these objects as their spectra are extended into the near-infrared, including the identification of weak absorption bands, mainly of the 0.9 micron band tentatively attributed to orthopyroxene, and of the 0.43 micron band that may b...

  16. Asteroid Risk Assessment: A Probabilistic Approach.

    Science.gov (United States)

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

    2016-02-01

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

  17. Asteroid thermal modeling: recent developments and applications

    NARCIS (Netherlands)

    Harris, A. W.; Mueller, M.

    2006-01-01

    A variety of thermal models are used for the derivation of asteroid physical parameters from thermal-infrared observations Simple models based on spherical geometry are often adequate for obtaining sizes and albedos when very little information about an object is available However sophisticated ther

  18. A note on cement in asteroids

    Science.gov (United States)

    Bilalbegović, G.

    2016-09-01

    Cement mineral tobermorite was formed in hydrothermal experiments on alternation of calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondrite meteorites. Unidentified bands at 14 μm 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 μm.

  19. Asteroid thermal modeling: recent developments and applications

    NARCIS (Netherlands)

    Harris, A. W.; Mueller, M.

    2006-01-01

    A variety of thermal models are used for the derivation of asteroid physical parameters from thermal-infrared observations Simple models based on spherical geometry are often adequate for obtaining sizes and albedos when very little information about an object is available However sophisticated

  20. 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

    2009-01-08

    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.

  1. Asteroids Lightcurves Analysis: 2015 October-December

    Science.gov (United States)

    Carbognani, Albino; Buzzi, Luca

    2016-04-01

    Eight asteroids, main-belt (MBA) and near-Earth (NEA), were observed in 2015 Oct-Dec: 6853 Silvanomassaglia, (112985) 2002 RS28, (155110) 2005 TB, (163899) 2003 SD220, (253106) 2002 UR3, (337866) 2001 WL15, 2015 XC, and 2015 WG9.

  2. Collisional Excavation of Asteroid (596) Scheila

    CERN Document Server

    Bodewits, D; Li, J -Y; Landsman, W B; Besse, S; A'Hearn, M F

    2011-01-01

    We observed asteroid (596) Scheila and its ejecta cloud using the Swift UV-optical telescope. We obtained photometry of the nucleus and the ejecta, and for the first time measured the asteroid's reflection spectrum between 290 - 500 nm. Our measurements indicate significant reddening at UV wavelengths (13% per 1000 {\\AA}) and a possible broad, unidentified absorption feature around 380 nm. Our measurements indicate that the outburst has not permanently increased the asteroid's brightness. We did not detect any of the gases that are typically associated with either hypervolatile activity thought responsible for cometary outbursts (CO+, CO2+), or for any volatiles excavated with the dust (OH, NH, CN, C2, C3). We estimate that 6 x 10^8 kg of dust was released with a high ejection velocity of 57 m/s (assuming 1 {\\mu}m sized particles). While the asteroid is red in color and the ejecta have the same color as the Sun, we suggest that the dust does not contain any ice. Based on our observations, we conclude that (59...

  3. Covariant w∞ gravity

    NARCIS (Netherlands)

    Bergshoeff, E.; Pope, C.N.; Stelle, K.S.

    1990-01-01

    We discuss the notion of higher-spin covariance in w∞ gravity. We show how a recently proposed covariant w∞ gravity action can be obtained from non-chiral w∞ gravity by making field redefinitions that introduce new gauge-field components with corresponding new gauge transformations.

  4. Reducing the Asteroid and Comet Impact Hazard

    Science.gov (United States)

    Crawford, David

    1998-10-01

    Of the 140 impact craters known on the surface of Earth, the most famous was created about 65 million years ago when a 10 km asteroid or comet came down in shallow water near the present day town of Chicxulub, Mexico. With a kinetic energy equivalent to 100 trillion tons of TNT, the impact event lofted enough debris onto globe-straddling trajectories to flash heat much of the surface of the Earth and then darken the skies for several years. Numerous investigations have demonstrated that such an event, which happens, on average, every 100 million years, caused extreme stress on Earth's climate and most likely led to the extinction of many species. Computational simulations demonstrate that more numerous asteroids or comets as small as 1 km in diameter, impacting, on average, every 300,000 years may be globally catastrophic. Indeed, the odds of an individual dying from a relatively frequent 1 km impacting object (about 1 in 10,000) are substantially greater than from the impact of an infrequent dinosaur killer (1 in 1,000,000). What can we do to reduce the hazard from impacting comets and asteroids? First, we should find what's out there with our name on it. Only about 10 percent of the potential Earth-crossing asteroids have been found. Even at the greatly increased detection rate of recent years, it will be several decades before we've found 90 percent of the Earth-crossers. Second, we should learn everything we can about the physical, compositional and mechanical properties of asteroids and comets. A recent computational study demonstrated that weakly bound asteroids (little more than rubble piles) are easier to break than deflect(E. Asphaug, S. J. Ostro, R. S. Hudson, D. J. Scheeres and W. Benz (1998), Nature, Vol. 393, pp. 437-440.). Is this an advantage or disadvantage? Third, we should study potential means of mitigating the hazard by deflecting the object while still in space or evacuating affected regions (such as coastlines) of the Earth. Because the

  5. 3-µm Spectroscopy of Asteroid 16 Psyche

    Science.gov (United States)

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

    2016-10-01

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

  6. Massive identification of asteroids in three-body resonances

    Science.gov (United States)

    Smirnov, Evgeny A.; Shevchenko, Ivan I.

    2013-01-01

    An essential role in the asteroidal dynamics is played by the mean motion resonances. Two-body planet-asteroid resonances are widely known, due to the Kirkwood gaps. Besides, so-called three-body mean motion resonances exist, in which an asteroid and two planets participate. Identification of asteroids in three-body (namely, Jupiter-Saturn-asteroid) resonances was initially accomplished by Nesvorný and Morbidelli (Nesvorný D., Morbidelli, A. [1998]. Astron. J. 116, 3029-3037), who, by means of visual analysis of the time behaviour of resonant arguments, found 255 asteroids to reside in such resonances. We develop specialized algorithms and software for massive automatic identification of asteroids in the three-body, as well as two-body, resonances of arbitrary order, by means of automatic analysis of the time behaviour of resonant arguments. In the computation of orbits, all essential perturbations are taken into account. We integrate the asteroidal orbits on the time interval of 100,000 yr and identify main-belt asteroids in the three-body Jupiter-Saturn-asteroid resonances up to the 6th order inclusive, and in the two-body Jupiter-asteroid resonances up to the 9th order inclusive, in the set of ˜250,000 objects from the "Asteroids - Dynamic Site" (AstDyS) database. The percentages of resonant objects, including extrapolations for higher-order resonances, are determined. In particular, the observed fraction of pure-resonant asteroids (those exhibiting resonant libration on the whole interval of integration) in the three-body resonances up to the 6th order inclusive is ≈0.9% of the whole set; and, using a higher-order extrapolation, the actual total fraction of pure-resonant asteroids in the three-body resonances of all orders is estimated as ≈1.1% of the whole set.

  7. OSIRIS-REx, Returning the Asteroid Sample

    Science.gov (United States)

    Ajluni, Thomas, M.; Everett, David F.; Linn, Timothy; Mink, Ronald; Willcockson, William; Wood, Joshua

    2015-01-01

    This paper addresses the technical aspects of the sample return system for the upcoming Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) asteroid sample return mission. The overall mission design and current implementation are presented as an overview to establish a context for the technical description of the reentry and landing segment of the mission.The prime objective of the OSIRIS-REx mission is to sample a primitive, carbonaceous asteroid and to return that sample to Earth in pristine condition for detailed laboratory analysis. Targeting the near-Earth asteroid Bennu, the mission launches in September 2016 with an Earth reentry date of September 24, 2023.OSIRIS-REx will thoroughly characterize asteroid Bennu providing knowledge of the nature of near-Earth asteroids that is fundamental to understanding planet formation and the origin of life. The return to Earth of pristine samples with known geologic context will enable precise analyses that cannot be duplicated by spacecraft-based instruments, revolutionizing our understanding of the early Solar System. Bennu is both the most accessible carbonaceous asteroid and one of the most potentially Earth-hazardous asteroids known. Study of Bennu addresses multiple NASA objectives to understand the origin of the Solar System and the origin of life and will provide a greater understanding of both the hazards and resources in near-Earth space, serving as a precursor to future human missions to asteroids.This paper focuses on the technical aspects of the Sample Return Capsule (SRC) design and concept of operations, including trajectory design and reentry retrieval. Highlights of the mission are included below.The OSIRIS-REx spacecraft provides the essential functions for an asteroid characterization and sample return mission: attitude control propulsion power thermal control telecommunications command and data handling structural support to ensure successful

  8. PRIMitive Asteroids Spectroscopic Survey - PRIMASS: First Results

    Science.gov (United States)

    de Leon, Julia; Pinilla-Alonso, Noemi; Campins, Humberto; Lorenzi, Vania; Licandro, Javier; Morate, David; Tanga, Paolo; Cellino, Alberto; Delbo, Marco

    2015-11-01

    NASA OSIRIS-REx and JAXA Hayabusa 2 sample-return missions have targeted two near-Earth asteroids: (101955) Bennu and (162173) 1999 JU3, respectively. These are primitive asteroids that are believed to originate in the inner belt, where five distinct sources have been identified: four primitive collisional families (Polana, Erigone, Sulamitis, and Clarissa), and a population of low-albedo and low-inclination background asteroids. Identifying and characterizing the populations from which these two NEAs might originate will enchance the science return of the two missions.With this main objective in mind, we initiated in 2010 a spectroscopic survey in the visible and the near-infrared to characterize the primitive collisional families in the inner belt and the low-albedo background population. This is the PRIMitive Asteroids Spectroscopic Survey - PRIMASS. So far we have obtained more than 200 spectra using telescopes located at different observatories. PRIMASS uses a variety of ground based facilities. Most of the spectra have been obtained using the 10.4m Gran Telescopio Canarias (GTC), and the 3.6m Telescopio Nazionale Galileo (TNG), both located at the El Roque de los Muchachos Observatory (La Palma, Spain), and the 3.0m NASA Infrared Telescope Facility on Mauna Kea (Hawai, USA).We present the first results from our on-going survey (de Leon et al. 2015; Pinilla-Alonso et al. 2015; Morate et al. 2015), focused on the Polana and the Erigone primitive families, with visible and near-infrared spectra of more than 200 objects, most of them with no previous spectroscopic data. Our survey is already the largest database of primitive asteroids spectra, and we keep obtaining data on the Sulamitis and the Clarissa families, as well as on the background low-albedo population.

  9. Near Earth Asteroid Characterization for Threat Assessment

    Science.gov (United States)

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

    2017-01-01

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

  10. 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

  11. An experimental study on low-velocity low-gravity collisions into granular surfaces

    Science.gov (United States)

    Sunday, C.; Murdoch, N.; Mimoun, D.

    2014-07-01

    The Japanese Space Agency (JAXA) is scheduled to launch the asteroid sample-return mission, Hayabusa-2, to target body 1999 JU_3 in December 2014 [1]. The spacecraft will arrive at the C-type near-Earth asteroid in mid-2018 and deploy several science payloads to its surface. Among these payloads is a 10-kg lander, the Mobile Asteroid Surface Scout (MASCOT), provided by the German Space Agency (DLR) with cooperation from the Centre National d'Etudes Spatiales (CNES). MASCOT will reach the asteroid's surface with an anticipated impact speed of 10--20 cm/s. In addition to housing four instruments for in-situ science investigation, MASCOT contains a mobility mechanism that will correct its orientation and enable it to ''hop'' to various measurement sites [2]. Based on thermal infrared observations [3,4,5] and previous space missions [6,7], it is strongly believed that 1999 JU_3 is covered by loose regolith. The asteroid's granular surface, in combination with the low surface gravity, makes it difficult to predict the lander's collision behavior from existing theoretical models. However, to ensure that MASCOT can successfully fulfill its mission, it is vital to understand the rebound dynamics of the lander in the asteroid surface environment. The objective of this work, derived from the needs of current and future asteroid missions, is to present an experiment designed to study low-velocity, low-gravity collisions into granular surfaces. The experiment measures the amount of energy lost during impact via a projectile's coefficient of restitution and also the acceleration profile of the projectile during collision. The key challenge to designing an asteroid collision experiment is finding a way to simulate reduced gravity conditions on the Earth so that the prevailing forces in micro-gravity collisions can be reflected in the experimental results. The proposed way to achieve this goal is to let a free-falling projectile impact a surface with a constant downward

  12. Quantization of Emergent Gravity

    CERN Document Server

    Yang, Hyun Seok

    2013-01-01

    Emergent gravity is based on a novel form of the equivalence principle known as the Darboux theorem or the Moser lemma in symplectic geometry stating that the electromagnetic force can always be eliminated by a local coordinate transformation as far as spacetime admits a symplectic structure, in other words, a microscopic spacetime becomes noncommutative (NC). If gravity emerges from U(1) gauge theory on NC spacetime, this picture of emergent gravity suggests a completely new quantization scheme where quantum gravity is defined by quantizing spacetime itself, leading to a dynamical NC spacetime. Therefore the quantization of emergent gravity is radically different from the conventional approach trying to quantize a phase space of metric fields. This approach for quantum gravity allows a background independent formulation where spacetime as well as matter fields is equally emergent from a universal vacuum of quantum gravity.

  13. Quantization of emergent gravity

    Science.gov (United States)

    Yang, Hyun Seok

    2015-02-01

    Emergent gravity is based on a novel form of the equivalence principle known as the Darboux theorem or the Moser lemma in symplectic geometry stating that the electromagnetic force can always be eliminated by a local coordinate transformation as far as space-time admits a symplectic structure, in other words, a microscopic space-time becomes noncommutative (NC). If gravity emerges from U(1) gauge theory on NC space-time, this picture of emergent gravity suggests a completely new quantization scheme where quantum gravity is defined by quantizing space-time itself, leading to a dynamical NC space-time. Therefore the quantization of emergent gravity is radically different from the conventional approach trying to quantize a phase space of metric fields. This approach for quantum gravity allows a background-independent formulation where space-time and matter fields are equally emergent from a universal vacuum of quantum gravity.

  14. EROS-B高分辨率卫星新闻发布会在京召开%EROS-B High-resolution Satellite Press Conference was Held in Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    EROS-B高分辨率卫星新闻发布会”于2008年6月5日在北京友谊宾馆举行。会议由北京博思科空间信息技术有限公司(www.pcc.cn)主办,日本最大的航测公司PASCO公司、以色列ImageSat International公司共同协办。

  15. Regolith Levitation on Small Fast Rotating Asteroids

    Science.gov (United States)

    Campo Bagatin, Adriano; Moreno, Fernando; Molina, Antonio

    2014-11-01

    A number of NEAs larger than few hundred meters are found with relatively high spin rates (from ~2.2 to less than 4 hr, depending on composition). On those bodies, local acceleration near their equator may be directed outwards, as in the case of the primaries of binary asteroids Didymos and 1996 FG3. They both are potential targets of future space missions. What are the effects of high spin states on regolith material at low asteroidal latitudes?NEAs come from the asteroid belt and are believed to be mostly gravitational aggregates at D > 0.5 - 1 km due to their former collisional evolution history (Campo Bagatin et al, 2001). Once in the inner Solar System, NEAs may undergo spin up evolution through YORP causing their components to disperse, shed mass or fission and eventually form binary, multiple systems or asteroid pairs (Walsh et al, 2008, Jacobson and Scheers, 2010, Pravec et al, 2009 and 2010). The end state of those events is often an object spinning above any Chandrasekhar stability limit, kept together by friction (Holsapple, 2007) and sometimes characterized by an equatorial “bulge”, as shown by radar images (Ostro et al, 2006).The centrifugal force acting on surface particles at equatorial latitudes may overcome the gravitational pull of the asteroid itself, and particles may leave its suface. Centrifugal is an apparent contact force, and as soon as particles lift off they mainly move under the gravitational field of the asteroid and the satellite, they may levitate for some time, land on the surface and repeat this cycle over and over. We are studying the motion of particles in the 1 μm to 10 cm range in the non-inertial reference frame of the rotating primary, accounting for centrifugal and Coriolis apparent forces as well as the gravitational fields of the primary, the secondary, the Sun and the radiation forces by the Sun itself. The main features of this effect are presented in the case of Didymos and 1996 FG3.

  16. Enemigos declarados de nuestro sistema. La acción política contrarrevolucionaria de Diego de Agüero y Miguel Fernández de Agüero [1770-1816

    Directory of Open Access Journals (Sweden)

    Mariano Martín Schlez

    2011-11-01

    Full Text Available This article analizes the counter-revolutionary social force of the late colonial Buenos Aires. It takes as observables two of the principal leaders: the monopolistic spanish merchants Diego de Agüero and Miguel Fernández de Agüero. The Agüero had a definite political strategy: to oppose to the revolutionary process and to defend the colonial order. This program was constructed throughout more than thirty years, in which they pass from a reformist alliance to face politically and militarily against the revolutionaries. In this trajectory, the confrontations about the traffic of leather with foreign nations turn out to be a hinge, defending the legal trade for the route of Cadiz, arguing that it's Monarchy's bastions. The above mentioned program is link with its social reproduction, based on a political privilege granted by the colonial State. It destruction, by the action of the Revolution, will produce it commercial, political and military defeat

  17. The work of John Hughlings Jackson: part I by JM López Piñero. 1973.

    Science.gov (United States)

    López Piñero, J M

    2010-03-01

    After returning to Spain from a research period in London on a Wellcome Trust scholarship, José Maria López Piñero published in 1973 a short book entitled John Hughlings Jackson (1835-1911), Evolucionismo y Neurologia (Madrid, Editorial Moneda). Written from the perspective of the classical German medical historiography that the author had imbibed from Werner Leibbrand and Annemarie Wettley, this work truly added to Jacksonian scholarship. Neither hagiographic nor nitpicking, it offered a sober assessment of the contribution of the great Yorkshireman and it was soon to become a minor classic among connoisseurs. Although important additions to Jacksonian scholarship have appeared since 1973, López Piñero's book has retained its relevance. It will be published in History of Psychiatry in two parts.

  18. 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.

  19. Violencia del compañero íntimo en España

    Directory of Open Access Journals (Sweden)

    Vives C.

    2003-01-01

    Full Text Available Objetivo: Estimar la mortalidad y la incidencia de las denuncias por la violencia del compañero íntimo (VCI por grupos de edad y provincias españolas. Métodos: Estudio epidemiológico, descriptivo, basado en los asesinatos registrados en la base de datos de la Federación de Mujeres Separadas y Divorciadas (1998-2001 y las denuncias por VCI del Ministerio del Interior (1997-2000. Se calculó el porcentaje de incremento producido entre las denuncias y las muertes, el riesgo de una mujer de morir y denunciar por VCI por el método acumulativo simple, las tasas de mortalidad específicas por edad y ajustadas por edad y provincias y las tasas de incidencia bruta por provincias de las denuncias por VCI. También se realizó un análisis de regresión simple para explorar la relación entre mortalidad e incidencia de las denuncias. Resultados: Se observó un incremento del 27% en las denuncias y del 49% en los asesinatos desde el primer año del período al último. Durante el período de estudio una de cada 100.000 mujeres fue asesinada por VCI y u na de cada 200 denunció ser víctima de VCI. Las mujeres de 22-41 años y las de 82-86 presentaron las tasas de mortalidad por VCI más altas. La mortalidad y la incidencia de las denuncias por VCI en las provincias españolas no siguió un patrón geográfico definido. No existe correlación entre la mortalidad y la incidencia de las denuncias por VCI por provincias (r² corregida = -0,016. Conclusiones: La violencia del compañero íntimo es un problema de salud pública creciente en España. Parece existir un patrón bimodal por edad en mortalidad por VCI, pero no un patrón geográfico en mortalidad e incidencia de denuncias, ni tampoco una relación entre las provincias de mayor tasa de incidencia de denuncias y las de mayor tasa de mortalidad.

  20. EROS-B高分辨率卫星新闻发布会在京召开

    Institute of Scientific and Technical Information of China (English)

    陈跃峰

    2008-01-01

    "EROS-B高分辨率卫星新闻发布会"于2008年6月5日在北京友谊宾馆举行。会议由北京博思科空间信息技术有限公司(www.pcc.cn)主办。会上,来自日本PASCO公司卫星事业部世川部长、ImageSat公司

  1. EROS-B高分辨率卫星新闻发布会在京召开

    Institute of Scientific and Technical Information of China (English)

    《国土资源信息化》编辑部

    2008-01-01

    EROS-B高分辨率卫旱新闻发布会”于2008年6月5日在北京友谊宾馆举行。会议由北京博思科空间信息技术有限公司(www.pcc.cn)主办,日本最大的航测公刮PASCO公司、以色列ImageSat International公刮共同协办。

  2. Asteroids - the modern challenge of celestial dynamics

    Science.gov (United States)

    Dikova, Smiliana

    2002-11-01

    Among the most powerful statements in Science are those that mark absolute limits to knowledge. For example, Relativity and Quantum Theory touched the limits of speed and accuracy. Deterministic Chaos - the new scientific paradigma of our days, also falls in this class theories. Chaos means complexity in space and unpredictability in time. It shows the limit of our basic counting system and leads to a limited predictability of the long time dynamical evolution. Perhaps for that reason, in 1986 Sir James Lighthill remarked for all physicists: "We collectively wish to apologize for having misled the general educated public by spreading ideas about the determinism of systems satisfying Newton's laws of motion that, after 1960, were proved incorrect." Our main thesis is that Asteroid Dynamics is the arena where the drama Chaos versus predictability is initiated and developed. The aim of the present research is to show the way in which Deterministic Chaos restricts the long term dynamical predictability of asteroid motions.

  3. Computation of Asteroid Proper Elements: Recent Advances

    Science.gov (United States)

    Knežević, Z.

    2017-06-01

    The recent advances in computation of asteroid proper elements are briefly reviewed. Although not representing real breakthroughs in computation and stability assessment of proper elements, these advances can still be considered as important improvements offering solutions to some practical problems encountered in the past. The problem of getting unrealistic values of perihelion frequency for very low eccentricity orbits is solved by computing frequencies using the frequency-modified Fourier transform. The synthetic resonant proper elements adjusted to a given secular resonance helped to prove the existence of Astraea asteroid family. The preliminary assessment of stability with time of proper elements computed by means of the analytical theory provides a good indication of their poorer performance with respect to their synthetic counterparts, and advocates in favor of ceasing their regular maintenance; the final decision should, however, be taken on the basis of more comprehensive and reliable direct estimate of their individual and sample average deviations from constancy.

  4. 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......The study of asteroids is traditionally performed by means of large Earth based telescopes, by means of which orbital elements and spectral properties are acquired. Space borne research, has so far been limited to a few occasional flybys and a couple of dedicated flights to a single selected target....... Although the telescope based research offers precise orbital information, it is limited to the brighter, larger objects, and taxonomy as well as morphology resolution is limited. Conversely, dedicated missions offer detailed surface mapping in radar, visual, and prompt gamma, but only for a few selected...

  5. Is 1220 Crocus a precessing, binary asteroid?

    Science.gov (United States)

    Binzel, R. P.

    1985-01-01

    Photoelectric data of the asteroid 1220 Crocus over a 13 night period in 1984 revealed the presence of two separate periods. The light curves were indicative of a precessing body, but not one in free precession due to motions induced by a collision. Closer examinations revealed periods of 30.7 and 7.9 hr with amplitudes of 0.87 and 0.15 mag, respectively. An analysis of the source of an external torque which could be causing a forced precession led to the hypothesis that 1220 Crocus has a satellite. Verification of the binary asteroid configuration will depend on more detailed light curves, the possible modulation of the shorter period by the longer, and possible use of the Space Telescope.

  6. Is 1220 Crocus a precessing, binary asteroid?

    Science.gov (United States)

    Binzel, R. P.

    1985-07-01

    Photoelectric data of the asteroid 1220 Crocus over a 13 night period in 1984 revealed the presence of two separate periods. The light curves were indicative of a precessing body, but not one in free precession due to motions induced by a collision. Closer examinations revealed periods of 30.7 and 7.9 hr with amplitudes of 0.87 and 0.15 mag, respectively. An analysis of the source of an external torque which could be causing a forced precession led to the hypothesis that 1220 Crocus has a satellite. Verification of the binary asteroid configuration will depend on more detailed light curves, the possible modulation of the shorter period by the longer, and possible use of the Space Telescope.

  7. Asteroid absolute magnitudes and slope parameters

    Science.gov (United States)

    Tedesco, Edward F.

    1991-01-01

    A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.

  8. New CCD photometry of asteroid (1028) Lydina

    Institute of Scientific and Technical Information of China (English)

    Yi-Bo Wang; Xiao-Bin Wang

    2012-01-01

    New CCD photometric observations for asteroid (1028) Lydina,carried out with the 1-m and 2.4-m telescopes at Yunnan Observatory from 2011 December 19 to 2012 February 3,are presented.Using the new light curves,the rotation period of 11.680±0.001 hours is derived with the Phase Dispersion Minimization (PDM) method.In addition,using the Amplitude-Aspect method,the elementary results of the pole orientation of asteroid (1028) Lydina are obtained:λp= 111°+4°-4°,βp= 31°+4°-5°.Meanwhile,the axial ratios of the tri-axial ellipsoid are estimated:a/b = 1.77+0.10-0.08and b/c = 1.17+0.07-0.09.

  9. Equilibrium figures of inhomogeneous synchronous binary asteroids

    Science.gov (United States)

    Descamps, P.

    2010-06-01

    The present paper deals with the application of the classical theory of equilibrium figures of two rotating liquid masses to the case where bodies exhibit a radially stratified internal density distribution so that they can be considered as inhomogeneous bodies. The derived ellipsoidal shape solutions are applied to five real systems of equal-sized synchronous asteroids. Furthermore, internal inhomogeneity puts strong constraints on the surface grain density. A satisfactory model fit is achieved with internal densities of asteroids steadily increasing outwards. In particular, from such an approach we derived grain densities of the considered systems in agreement with their mineralogical composition inferred from reflectance spectroscopy. According to this new approach, 4492 Debussy, presently of unknown spectral type, is predicted to appear as a C-type object with a grain density on the order of 2 g/cm 3.

  10. Effective stability of the Trojan asteroids

    CERN Document Server

    Skokos, C; Skokos, Ch.

    2001-01-01

    We study the spatial circular restricted problem of three bodies in the light of Nekhoroshev theory of stability over large time intervals. We consider in particular the Sun-Jupiter model and the Trojan asteroids in the neighborhood of the Lagrangian point $L_4$. We find a region of effective stability around the point $L_4$ such that if the initial point of an orbit is inside this region the orbit is confined in a slightly larger neighborhood of the equilibrium (in phase space) for a very long time interval. By combining analytical methods and numerical approximations we are able to prove that stability over the age of the universe is guaranteed on a realistic region, big enough to include one real asteroid. By comparing this result with the one obtained for the planar problem we see that the regions of stability in the two cases are of the same magnitude.

  11. Catalogue of ISO LWS observations of asteroids

    CERN Document Server

    Hormuth, Felix

    2009-01-01

    (Abridged) The Long Wavelength Spectrometer (LWS) onboard the Infrared Space Observatory (ISO) observed the four large main-belt asteroids (1) Ceres, (2) Pallas, (4) Vesta, and (10) Hygiea multiple times. The photometric and spectroscopic data cover the wavelength range between 43 and 197 um, and are a unique dataset for future investigations and detailed characterisations of these bodies. The standard ISO archive products, produced through the last post-mission LWS pipeline, were still affected by instrument artefacts. Our goal was to provide the best possible data products to exploit the full scientific potential of these observations. We performed a refined reduction of all measurements, corrected for various instrumental effects, and re-calibrated the data. We outline the data reduction process and give an overview of the available data and the quality of the observations. We apply a thermophysical model to the flux measurements to derive far-IR based diameter and albedo values of the asteroids. The measu...

  12. 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.

  13. 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.

  14. Radar observations of the asteroid 2011 UW158

    Science.gov (United States)

    Ipatov, A. V.; Bondarenko, Yu. S.; Medvedev, Yu. D.; Mishina, N. A.; Marshalov, D. A.; Benner, L. A.

    2016-12-01

    In July 2015 intercontinental bistatic radar observations of the potentially dangerous asteroid 2011 UW158 during its close approach to the Earth were carried out. The asteroid was illuminated at a frequency of 8.4 GHz with the 70-m DSS-14 antenna of the Goldstone Deep Space Communications Complex, while the signal reflected from the asteroid was received with the 32-m radio telescopes of the Quasar VLBI network at the Zelenchukskaya and Badary Observatories. The spectra of the reflected radio signals were obtained. The sizes and rotation period of the asteroid consistent with photometric observations and the ratio of the powers of the reflected signals with left- and right-hand circular polarizations were determined. The derived values suggest that the asteroid has an inhomogeneous surface and a prolate shape. The observations of the Doppler shift of the reflected signal frequency were obtained, which allowed the orbital parameters of the asteroid to be improved.

  15. 3382 Cassidy: A Short Period Asteroid

    Science.gov (United States)

    Risley, Ethan

    2013-04-01

    The asteroid 3382 Cassidy was observed from the Etscorn Campus Observatory (ECO, 2012) at New Mexico Institute of Mining and Technology in Socorro, NM, on nine nights over a span of 43 days in 2012 September-November. A bimodal synodic period of 4.254 ± 0.002 h and an amplitude of 0.15 ± 0.02 mag were obtained.

  16. Polarimetry of M-type asteroids

    Science.gov (United States)

    Gil-Hutton, R.

    2007-03-01

    Aims:Results of a polarimetric program at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina are presented. The aim of this campaign is to estimate the polarimetric properties of asteroids belonging to the X taxonomic class. In this paper results of the campaign for M-type objects are presented. Methods: The data have been obtained with Casprof and Torino polarimeters at the 2.15 m telescope. The Casprof polarimeter is a two-hole aperture polarimeter with rapid modulation and the Torino polarimeter is an instrument that allows simultaneous measurement of polarization in the U-, B-, V-, R-, and I-bands. Results: The campaign began in 2000, and data on a sample of 26 M-type asteroids were obtained. Most of these objects were polarimetricaly observed for the first time. Combining these data with those available in the literature, an estimate of the polarimetric parameters and albedo for 12 objects is presented. Furthermore, the data show that asteroids 21 Lutetia and 77 Frigga have a large inversion angle and 441 Bathilde a deep polarization minimum, implying a controversial taxonomic classification as M-type for these objects. Also, the polarimetric parameters estimated for the M-type asteroids showing in their spectra the 3 μm band and classified as W-type by Rivkin et al. (1995, Icarus, 117, 90; 2000, ApJ, 145, 351) could be different from those without that feature. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, and the National Universities of La Plata, Córdoba and San Juan.

  17. Consequences of Predicted or Actual Asteroid Impacts

    Science.gov (United States)

    Chapman, C. R.

    2003-12-01

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

  18. Simulations of asteroid impacts on water

    Science.gov (United States)

    Gisler, G. R.; Weaver, R. P.; Gittings, M. L.

    2002-05-01

    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 mantle. In two dimensions, we threw asteroid impactors 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) with diameters of 250m, 500m, and 1000m, chosen to compare with the previous work of Crawford and Mader. We also performed some runs with asteroids composed of iron (7.8 g/cc). Because some of the iron asteroids produced craters that penetrated the basalt crust, we included a layer of mantle material in all simulations. A vertical impact produces a large underwater cavity with nearly vertical walls followed by a collapse starting from the bottom and subsequent vertical jetting. Tsunamis up to a kilometer in initial height were generated and followed out to 100 km from the point of impact. In the three-dimensional run, an impactor of iron was thrown at 20 km/s at an angle of 45 degrees. Differences between this run and the vertical two-dimensional runs will be discussed.

  19. 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.

  20. CCD Photometry of Asteroid (147) Protogeneia

    Institute of Scientific and Technical Information of China (English)

    Xi-Liang Zhang; Xiao-Bin Wang; Li-Yun Zhang

    2006-01-01

    We measured the light-curve of the asteroid (147) Protogeneia in November 2004, with a CCD detector attached to the 1-meter telescope at the Yunnan Observatory, China. The synodic period and maximum amplitude of (147) at this apparition are 7.852 hours and 0.25 mag, respectively. The value of a/b for (147), from a preliminary estimation, is not less than 1.26:1.