Orbit and bulk density of the OSIRIS-REx target Asteroid (101955) Bennu
TL;DR: The OSIRIS-REx asteroid sample return mission target, (101955) Bennu (formerly 1999 RQ 36), is a half-kilometer near-Earth asteroid with an extraordinarily well constrained orbit as mentioned in this paper.
About: This article is published in Icarus.The article was published on 2014-06-01 and is currently open access. It has received 238 citations till now. The article focuses on the topics: Yarkovsky effect & Asteroid.
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University of Arizona1, Goddard Space Flight Center2, Lockheed Martin Corporation3, University of Maryland, College Park4, Johns Hopkins University Applied Physics Laboratory5, Massachusetts Institute of Technology6, Southwest Research Institute7, California Institute of Technology8, Arizona State University9, Ithaca College10, Rowan University11, York University12, University of Tennessee13, Smithsonian Institution14, University of Colorado Boulder15, Ames Research Center16
TL;DR: The OSIRIS-REx spacecraft departed for near-Earth asteroid (101955) Bennu via an United Launch Alliance Atlas V 411 evolved expendable launch vehicle at 7:05 p.m. EDT on September 8, 2016, on a seven-year journey to return samples from Bennu as discussed by the authors.
Abstract: In May of 2011, NASA selected the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) asteroid sample return mission as the third mission in the New Frontiers program. The other two New Frontiers missions are New Horizons, which explored Pluto during a flyby in July 2015 and is on its way for a flyby of Kuiper Belt object 2014 MU69 on January 1, 2019, and Juno, an orbiting mission that is studying the origin, evolution, and internal structure of Jupiter. The spacecraft departed for near-Earth asteroid (101955) Bennu aboard an United Launch Alliance Atlas V 411 evolved expendable launch vehicle at 7:05 p.m. EDT on September 8, 2016, on a seven-year journey to return samples from Bennu. The spacecraft is on an outbound-cruise trajectory that will result in a rendezvous with Bennu in November 2018. The science instruments on the spacecraft will survey Bennu to measure its physical, geological, and chemical properties, and the team will use these data to select a site on the surface to collect at least 60 g of asteroid regolith. The team will also analyze the remote-sensing data to perform a detailed study of the sample site for context, assess Bennu’s resource potential, refine estimates of its impact probability with Earth, and provide ground-truth data for the extensive astronomical data set collected on this asteroid. The spacecraft will leave Bennu in 2021 and return the sample to the Utah Test and Training Range (UTTR) on September 24, 2023.
440 citations
Cites background or methods from "Orbit and bulk density of the OSIRI..."
...Bennu is also one of the most potentially hazardous of all the currently known NEAs, based on its size and calculable nonzero probability of future impacts with Earth (Chesley et al. 2014)....
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...Bennu’s orbit is slightly inclined to the ecliptic plane by 6 degrees, and its orbit semimajor axis is 1.13 AU, yielding an orbit period of 1.20 years and a synodic period with respect to Earth of 6 years....
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...The prime objective of the OSIRIS-REx mission is to return pristine carbonaceous regolith from Bennu to understand both the role that primitive asteroids may have played in the origin of life on Earth and how they served as one of the fundamental “building blocks” of planet formation....
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...The fragment that became Bennu was eventually delivered to near-Earth space via a combination of Yarkovsky-induced drift and interaction with giant-planet gravitational resonances (Campins et al. 2010; Bottke et al. 2015)....
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...[Insert Figure 5 here] Asteroid (101955) Bennu was discovered on September 11, 1999 (Williams 1999) by the Lincoln Near-Earth Asteroid Research (LINEAR) survey using a 1.0-m telescope located in Socorro, New Mexico (Stokes et al. 2000)....
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TL;DR: In this paper, the shape of the near-Earth Asteroid (101955) Bennu was determined based on radar images and optical lightcurve data, along with an initial determination of the rotation period derived from them, simplified and improved the shape modeling.
231 citations
TL;DR: A new approach to the asteroid family classification by combining the Hierarchical Clustering Method (HCM) with a method to add new members to existing families, which allows to solve some difficult cases of families overlapping in the proper elements space but generated by different collisional events.
191 citations
TL;DR: It is reported that the kilometre-sized asteroid (29075) 1950 DA is a rubble pile that is rotating faster than is allowed by gravity and friction and that the strengths of the forces are comparable to, though somewhat less than, the forces found between the grains of lunar regolith.
Abstract: Modelling and observations of the kilometre-sized asteroid (29075) 1950 DA reveal it to be a ‘rubble pile’ that is rotating faster than is allowed by gravity and friction; cohesive forces such as those in lunar regolith are required to prevent it breaking up. Some asteroids are solid bodies but others, known as 'rubble-pile' asteroids, are loose aggregates of sand- to boulder-sized components. The conventional view, that rubble piles are held together by gravitational and frictional forces alone, has recently been questioned. It has been suggested that small van der Waals forces between constituent grains may be an important factor. Here, Ben Rozitis et al. report that the kilometre-sized rubble-pile asteroid (29075) 1950 DA is rotating faster than the breakup limit for its density calculated assuming the action of gravity and friction alone. They conclude that inter-particle cohesive forces must be holding the asteroid together and that the forces are comparable to, though somewhat less than, those found between the grains of lunar regolith. Space missions1 and ground-based observations2 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 material3. 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 population4,5,6. 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.
186 citations
University of Arizona1, Goddard Space Flight Center2, Lockheed Martin Space Systems3, Massachusetts Institute of Technology4, Southwest Research Institute5, University of Central Florida6, Jet Propulsion Laboratory7, Space Science Institute8, Ithaca College9, University of Winnipeg10, The Graduate Center, CUNY11, Kingsborough Community College12, American Museum of Natural History13, University of Nice Sophia Antipolis14, University of Tennessee15, Planetary Science Institute16, University of British Columbia17, Arecibo Observatory18, Ames Research Center19, University of Colorado Boulder20, Charles University in Prague21
TL;DR: In this article, the results of an extensive campaign to determine the physical, geological, and dynamical properties of asteroid (101955) Bennu were presented, and the results were used to develop a hypothetical timeline for Bennu's formation and evolution.
Abstract: We review the results of an extensive campaign to determine the physical, geological, and dynamical properties of asteroid (101955) Bennu. This investigation provides information on the orbit, shape, mass, rotation state, radar response, photometric, spectroscopic, thermal, regolith, and environmental properties of Bennu. We combine these data with cosmochemical and dynamical models to develop a hypothetical timeline for Bennu's formation and evolution. We infer that Bennu is an ancient object that has witnessed over 4.5 Gyr of solar system history. Its chemistry and mineralogy were established within the first 10 Myr of the solar system. It likely originated as a discrete asteroid in the inner Main Belt approximately 0.7–2 Gyr ago as a fragment from the catastrophic disruption of a large (approximately 100-km), carbonaceous asteroid. It was delivered to near-Earth space via a combination of Yarkovsky-induced drift and interaction with giant-planet resonances. During its journey, YORP processes and planetary close encounters modified Bennu's spin state, potentially reshaping and resurfacing the asteroid. We also review work on Bennu's future dynamical evolution and constrain its ultimate fate. It is one of the most Potentially Hazardous Asteroids with an approximately 1-in-2700 chance of impacting the Earth in the late 22nd century. It will most likely end its dynamical life by falling into the Sun. The highest probability for a planetary impact is with Venus, followed by the Earth. There is a chance that Bennu will be ejected from the inner solar system after a close encounter with Jupiter. OSIRIS-REx will return samples from the surface of this intriguing asteroid in September 2023.
179 citations
Cites background or methods from "Orbit and bulk density of the OSIRI..."
...Chesley et al. (2014) determined Bennu’s orbit to unprecedented precision using a high-fidelity force model to compute the asteroid’s trajectory....
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...The Yarkovsky effect was found to be the most significant nongravitational acceleration acting to alter the asteroid’s orbit (Chesley et al. 2014)....
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...Chesley et al. (2014) included the four largest asteroids ([1] Ceres, which is officially a dwarf planet, [2] Pallas, [4] Vesta, and [10] Hygeia) plus the next 12 largest Main Belt asteroids....
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...Thus, the tabulation of potential Earth impacts results in a cumulative impact probability of approximately 1 in 2700 sometime in the 2175–2196 time frame (Chesley et al. 2014)....
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...We have a very precise ephemeris for Bennu between 1654 and 2135 (Chesley et al. 2014)....
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References
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01 Jan 1981TL;DR: In this paper, the authors provide a complete treatment of techniques for analyzing gravitation theory and experience, taking into account the Dicke framework, basic criteria for the viability of a gravitation theories, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973).
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"Orbit and bulk density of the OSIRI..." refers methods in this paper
...e.] 3.3. Relativity We used a full relativistic force model including the contribution of the Sun, the planets, and the Moon. More specically, we used the Einstein-Infeld-Homan (EIH) approximation (Will 1993; Moyer 2003; Soel et al. 2003). Table 5 shows the variations in da=dtand 2135 associated with dierent relativistic models. We found a 1.6% dierence in da=dtwith respect to the basic Sunonly Schw...
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TL;DR: The Yarkovsky and YORP effects are thermal radiation forces and torques that cause small objects to undergo semimajor axis drift and spin vector modifications, respectively, as a function of their spin, orbit, and material properties as discussed by the authors.
Abstract: The Yarkovsky and YORP (Yarkovsky-O’Keefe-Radzievskii-Paddack) effects are thermal radiation forces and torques that cause small objects to undergo semimajor axis drift and spin vector modifications, respectively, as a function of their spin, orbit, and material properties. These mechanisms help to (a) deliver asteroids (and meteoroids) with diameter D < 40 km from their source locations in the main belt to chaotic resonance zones capable of transporting this material to Earth-crossing orbits; (b) disperse asteroid families, with drifting bodies jumping or becoming trapped in mean-motion and secular resonances within the main belt; (c) modify the rotation rates and obliquities of D < 40 km asteroids; and (d ) allow asteroids to enter into spin-orbit resonances, which affect the evolution of their spin vectors and feedback into the Yarkovsky-driven semimajor axis evolution. Accordingly, we suggest that nongravitational forces should now be considered as important as collisions and gravitational perturbations to our overall understanding of asteroid evolution.
661 citations
"Orbit and bulk density of the OSIRI..." refers background in this paper
...The Yarkovsky effect is a subtle nongravitational perturbation that primarily acts as a secular variation in semimajor axis and thus causes a runoff in orbital anomaly that accumulates quadratically with time (Bottke et al. 2006)....
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...This slight nongravitational acceleration arises from the anisotropic re-emission at thermal wavelengths of absorbed solar radiation (Bottke et al. 2006)....
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TL;DR: DeMeo et al. as mentioned in this paper presented a review of the current knowledge of the density of small bodies and compared with meteorite density, allowing to estimate the macroporosity (i.e., amount of voids) within these bodies.
522 citations
TL;DR: Dawn's results confirm predictions that Vesta differentiated and support its identification as the parent body of the HEDs, and present the mineralogical characterization of Vesta, revealing that this asteroid underwent a complex magmatic evolution that led to a differentiated crust and mantle.
Abstract: The Dawn spacecraft targeted 4 Vesta, believed to be a remnant intact protoplanet from the earliest epoch of solar system formation, based on analyses of howardite-eucrite-diogenite (HED) meteorites that indicate a differentiated parent body. Dawn observations reveal a giant basin at Vesta's south pole, whose excavation was sufficient to produce Vesta-family asteroids (Vestoids) and HED meteorites. The spatially resolved mineralogy of the surface reflects the composition of the HED meteorites, confirming the formation of Vesta's crust by melting of a chondritic parent body. Vesta's mass, volume, and gravitational field are consistent with a core having an average radius of 107 to 113 kilometers, indicating sufficient internal melting to segregate iron. Dawn's results confirm predictions that Vesta differentiated and support its identification as the parent body of the HEDs.
470 citations
Book•
31 Jan 2003
TL;DR: In this paper, the authors present algorithms for computing ET-TAI, including the calculation of precision light times and quasar delays, as well as partial derivatives of light times.
Abstract: Foreword. Preface. Acknowledgments. Introduction. Time Scales and Time Differences. Planetary Ephemeris, Small-Body Ephemeris, and Satellite Ephemerides. Spacecraft Ephemeris and Partials File. Geocentric Space-Fixed Position, Velocity, and Acceleration Vectors of Tracking Station. Space-Fixed Position, Velocity, and Acceleration Vectors of a Landed Spacecraft Relative to Center of Mass of Planet, Planetary System, or the Moon. Algorithms for Computing ET-TAI. Light-Time Solution. Angles. Media and Antenna Corrections. Calculation of Precision Light Times and Quasar Delays. Partial Derivatives of Precision Light Times and Quasar Delays. Observables. References. Acronyms. Index.
364 citations