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Lauretta DS, Hergenrother CW, Chesley SR, Leonard JM, Pelgrift JY, Adam CD, Al Asad M, Antreasian PG, Ballouz RL, Becker KJ, Bennett CA, Bos BJ, Bottke WF, Brozović M, Campins H, Connolly HC, Daly MG, Davis AB, de León J, DellaGiustina DN, Drouet d'Aubigny CY, Dworkin JP, Emery JP, Farnocchia D, Glavin DP, Golish DR, Hartzell CM, Jacobson RA, Jawin ER, Jenniskens P, Kidd JN, Lessac-Chenen EJ, Li JY, Libourel G, Licandro J, Liounis AJ, Maleszewski CK, Manzoni C, May B, McCarthy LK, McMahon JW, Michel P, Molaro JL, Moreau MC, Nelson DS, Owen WM, Rizk B, Roper HL, Rozitis B, Sahr EM, Scheeres DJ, Seabrook JA, Selznick SH, Takahashi Y, Thuillet F, Tricarico P, Vokrouhlický D, Wolner CWV. Episodes of particle ejection from the surface of the active asteroid (101955) Bennu. Science 2020; 366:366/6470/eaay3544. [PMID: 31806784 DOI: 10.1126/science.aay3544] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 10/22/2019] [Indexed: 11/02/2022]
Abstract
Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.
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Affiliation(s)
- D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - C W Hergenrother
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - S R Chesley
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | - C D Adam
- KinetX Aerospace, Simi Valley, CA, USA
| | - M Al Asad
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
| | | | - R-L Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B J Bos
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - M Brozović
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - H Campins
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - H C Connolly
- Department of Geology, Rowan University, Glassboro, NJ, USA.,Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - A B Davis
- Smead Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - J de León
- Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.,Department of Geosciences, University of Arizona, Tucson, AZ, USA
| | | | - J P Dworkin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J P Emery
- Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, USA.,Department of Astronomy and Planetary Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - D Farnocchia
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - D P Glavin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C M Hartzell
- Department of Aerospace Engineering, University of Maryland, College Park, MD, USA
| | - R A Jacobson
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - E R Jawin
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - P Jenniskens
- SETI (Search for Extraterrestrial Intelligence) Institute, Mountain View, CA, USA
| | - J N Kidd
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - J-Y Li
- Planetary Science Institute, Tucson, AZ, USA
| | - G Libourel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS (Centre national de la recherche scientifique), Laboratoire Lagrange, Nice, France
| | - J Licandro
- Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | - A J Liounis
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - C K Maleszewski
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C Manzoni
- London Stereoscopic Company, London, UK
| | - B May
- London Stereoscopic Company, London, UK
| | | | - J W McMahon
- Smead Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS (Centre national de la recherche scientifique), Laboratoire Lagrange, Nice, France
| | - J L Molaro
- Planetary Science Institute, Tucson, AZ, USA
| | - M C Moreau
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | | | - W M Owen
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - B Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H L Roper
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rozitis
- School of Physical Sciences, Open University, Milton Keynes, UK
| | - E M Sahr
- KinetX Aerospace, Simi Valley, CA, USA
| | - D J Scheeres
- Smead Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - J A Seabrook
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - S H Selznick
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - Y Takahashi
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - F Thuillet
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS (Centre national de la recherche scientifique), Laboratoire Lagrange, Nice, France
| | - P Tricarico
- Planetary Science Institute, Tucson, AZ, USA
| | - D Vokrouhlický
- Institute of Astronomy, Charles University, Prague, Czech Republic
| | - C W V Wolner
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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Lauretta DS, DellaGiustina DN, Bennett CA, Golish DR, Becker KJ, Balram-Knutson SS, Barnouin OS, Becker TL, Bottke WF, Boynton WV, Campins H, Clark BE, Connolly HC, Drouet d'Aubigny CY, Dworkin JP, Emery JP, Enos HL, Hamilton VE, Hergenrother CW, Howell ES, Izawa MRM, Kaplan HH, Nolan MC, Rizk B, Roper HL, Scheeres DJ, Smith PH, Walsh KJ, Wolner CWV. The unexpected surface of asteroid (101955) Bennu. Nature 2019; 568:55-60. [PMID: 30890786 PMCID: PMC6557581 DOI: 10.1038/s41586-019-1033-6] [Citation(s) in RCA: 268] [Impact Index Per Article: 53.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 02/15/2019] [Indexed: 11/09/2022]
Abstract
NASA'S Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer (OSIRIS-REx) spacecraft recently arrived at the near-Earth asteroid (101955) Bennu, a primitive body that represents the objects that may have brought prebiotic molecules and volatiles such as water to Earth1. Bennu is a low-albedo B-type asteroid2 that has been linked to organic-rich hydrated carbonaceous chondrites3. Such meteorites are altered by ejection from their parent body and contaminated by atmospheric entry and terrestrial microbes. Therefore, the primary mission objective is to return a sample of Bennu to Earth that is pristine-that is, not affected by these processes4. The OSIRIS-REx spacecraft carries a sophisticated suite of instruments to characterize Bennu's global properties, support the selection of a sampling site and document that site at a sub-centimetre scale5-11. Here we consider early OSIRIS-REx observations of Bennu to understand how the asteroid's properties compare to pre-encounter expectations and to assess the prospects for sample return. The bulk composition of Bennu appears to be hydrated and volatile-rich, as expected. However, in contrast to pre-encounter modelling of Bennu's thermal inertia12 and radar polarization ratios13-which indicated a generally smooth surface covered by centimetre-scale particles-resolved imaging reveals an unexpected surficial diversity. The albedo, texture, particle size and roughness are beyond the spacecraft design specifications. On the basis of our pre-encounter knowledge, we developed a sampling strategy to target 50-metre-diameter patches of loose regolith with grain sizes smaller than two centimetres4. We observe only a small number of apparently hazard-free regions, of the order of 5 to 20 metres in extent, the sampling of which poses a substantial challenge to mission success.
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Affiliation(s)
- D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - O S Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - T L Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - W V Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H Campins
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - B E Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - H C Connolly
- Department of Geology, Rowan University, Glassboro, NJ, USA
| | | | - J P Dworkin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J P Emery
- Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, USA
| | - H L Enos
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - C W Hergenrother
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E S Howell
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M R M Izawa
- Institute for Planetary Materials, Okayama University-Misasa, Misasa, Japan
| | - H H Kaplan
- Southwest Research Institute, Boulder, CO, USA
| | - M C Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H L Roper
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D J Scheeres
- Smead Department of Aerospace Engineering, University of Colorado, Boulder, CO, USA
| | - P H Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - C W V Wolner
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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