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Zhang Y, Michel P, Barnouin OS, Roberts JH, Daly MG, Ballouz RL, Walsh KJ, Richardson DC, Hartzell CM, Lauretta DS. Inferring interiors and structural history of top-shaped asteroids from external properties of asteroid (101955) Bennu. Nat Commun 2022; 13:4589. [PMID: 35933392 PMCID: PMC9357032 DOI: 10.1038/s41467-022-32288-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 07/20/2022] [Indexed: 11/30/2022] Open
Abstract
Asteroid interiors play a key role in our understanding of asteroid formation and evolution. As no direct interior probing has been done yet, characterisation of asteroids’ interiors relies on interpretations of external properties. Here we show, by numerical simulations, that the top-shaped rubble-pile asteroid (101955) Bennu’s geophysical response to spinup is highly sensitive to its material strength. This allows us to infer Bennu’s interior properties and provide general implications for top-shaped rubble piles’ structural evolution. We find that low-cohesion (≲0.78 Pa at surface and ≲1.3 Pa inside) and low-friction (friction angle ≲ 35∘) structures with several high-cohesion internal zones can consistently account for all the known geophysical characteristics of Bennu and explain the absence of moons. Furthermore, we reveal the underlying mechanisms that lead to different failure behaviours and identify the reconfiguration pathways of top-shaped asteroids as functions of their structural properties that either facilitate or prevent the formation of moons. Asteroid interiors are key to understand their formation and evolution. Here, the authors show that numerically simulated low-cohesion and low-friction structures with several high-cohesion internal zones can explain asteroid Bennu’s geophysical characteristics and the absence of the moons.
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Affiliation(s)
- Yun Zhang
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France. .,Department of Aerospace Engineering, University of Maryland, College Park, MD, USA.
| | - Patrick Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - Olivier S Barnouin
- The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD, USA
| | - James H Roberts
- The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD, USA
| | - Michael G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - Ronald-L Ballouz
- The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD, USA.,Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | | | - Christine M Hartzell
- Department of Aerospace Engineering, University of Maryland, College Park, MD, USA
| | - Dante S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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2
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Walsh KJ, Ballouz RL, Jawin ER, Avdellidou C, Barnouin OS, Bennett CA, Bierhaus EB, Bos BJ, Cambioni S, Connolly HC, Delbo M, DellaGiustina DN, DeMartini J, Emery JP, Golish DR, Haas PC, Hergenrother CW, Ma H, Michel P, Nolan MC, Olds R, Rozitis B, Richardson DC, Rizk B, Ryan AJ, Sánchez P, Scheeres DJ, Schwartz SR, Selznick SH, Zhang Y, Lauretta DS. Near-zero cohesion and loose packing of Bennu's near subsurface revealed by spacecraft contact. SCIENCE ADVANCES 2022; 8:eabm6229. [PMID: 35857450 PMCID: PMC9262326 DOI: 10.1126/sciadv.abm6229] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
When the OSIRIS-REx spacecraft pressed its sample collection mechanism into the surface of Bennu, it provided a direct test of the poorly understood near-subsurface physical properties of rubble-pile asteroids, which consist of rock fragments at rest in microgravity. Here, we find that the forces measured by the spacecraft are best modeled as a granular bed with near-zero cohesion that is half as dense as the bulk asteroid. The low gravity of a small rubble-pile asteroid such as Bennu effectively weakens its near subsurface by not compressing the upper layers, thereby minimizing the influence of interparticle cohesion on surface geology. The underdensity and weak near subsurface should be global properties of Bennu and not localized to the contact point.
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Affiliation(s)
- Kevin J. Walsh
- Southwest Research Institute, Boulder, CO, USA
- Corresponding author.
| | - Ronald-Louis Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - Erica R. Jawin
- National Air and Space Museum, Smithsonian Institution, Washington, DC, USA
| | - Chrysa Avdellidou
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France
| | | | - Carina A. Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - Brent J. Bos
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Saverio Cambioni
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Harold C. Connolly
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
- Department of Geology, Rowan University, Glassboro, NJ, USA
| | - Marco Delbo
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France
| | | | - Joseph DeMartini
- Department of Astronomy, University of Maryland, College Park, MD, USA
| | - Joshua P. Emery
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA
| | - Dathon R. Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | | | - Huikang Ma
- Lockheed Martin Space, Littleton, CO, USA
| | - Patrick Michel
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - Michael C. Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - Ryan Olds
- Lockheed Martin Space, Littleton, CO, USA
| | - Benjamin Rozitis
- School of Physical Sciences, The Open University, Milton Keynes, UK
| | | | - Bashar Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - Andrew J. Ryan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - Paul Sánchez
- Colorado Center for Astrodynamics Research, University of Colorado Boulder, Boulder, CO, USA
| | - Daniel J. Scheeres
- Colorado Center for Astrodynamics Research, University of Colorado Boulder, Boulder, CO, USA
- Smead Aerospace Engineering Sciences Department, University of Colorado Boulder, Boulder, CO, USA
| | - Stephen R. Schwartz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
- Planetary Science Institute, Tucson, AZ, USA
| | | | - Yun Zhang
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - Dante S. Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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3
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Lauretta DS, Adam CD, Allen AJ, Ballouz RL, Barnouin OS, Becker KJ, Becker T, Bennett CA, Bierhaus EB, Bos BJ, Burns RD, Campins H, Cho Y, Christensen PR, Church ECA, Clark BE, Connolly HC, Daly MG, DellaGiustina DN, Drouet d’Aubigny CY, Emery JP, Enos HL, Freund Kasper S, Garvin JB, Getzandanner K, Golish DR, Hamilton VE, Hergenrother CW, Kaplan HH, Keller LP, Lessac-Chenen EJ, Liounis AJ, Ma H, McCarthy LK, Miller BD, Moreau MC, Morota T, Nelson DS, Nolau JO, Olds R, Pajola M, Pelgrift JY, Polit AT, Ravine MA, Reuter DC, Rizk B, Rozitis B, Ryan AJ, Sahr EM, Sakatani N, Seabrook JA, Selznick SH, Skeen MA, Simon AA, Sugita S, Walsh KJ, Westermann MM, Wolner CWV, Yumoto K. Spacecraft sample collection and subsurface excavation of asteroid (101955) Bennu. Science 2022; 377:285-291. [DOI: 10.1126/science.abm1018] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging and spectral data collected during and after retrieval of a sample from Bennu’s surface. The sampling event mobilized rocks and dust into a debris plume, excavating a 9-m-long elliptical crater. This exposed material that is darker, spectrally redder, and more abundant in fine particulates than the original surface. The bulk density of the displaced subsurface material was 500–700 kg per cubic meter, about half that of the whole asteroid. Particulates that landed on instrument optics spectrally resemble aqueously altered carbonaceous meteorites. The spacecraft stored 250 ± 101 g of material, which will be delivered to Earth in 2023.
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Affiliation(s)
- D. S. Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - A. J. Allen
- Physics Department, University of Central Florida, Orlando, FL, USA
| | - R.-L. Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - O. S. Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - K. J. Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - T. 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
- Goddard Space Flight Center, Greenbelt, MD, USA
| | - R. D. Burns
- Goddard Space Flight Center, Greenbelt, MD, USA
| | - H. Campins
- Physics Department, University of Central Florida, Orlando, FL, USA
| | - Y. Cho
- Department of Earth and Planetary Environmental Science, University of Tokyo, Tokyo, Japan
| | - P. R. Christensen
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | | | - B. E. Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - H. C. Connolly
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
- Department of Geology, Rowan University, Glassboro, NJ, USA
| | - M. G. Daly
- Department of Earth and Space Science and Engineering, York University, Toronto, ON, Canada
| | | | | | - J. P. Emery
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA
| | - H. L. Enos
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | | | | | - D. R. Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | | | | | | | | | | | - H. Ma
- Lockheed Martin Space, Littleton, CO, USA
| | | | | | | | - T. Morota
- Department of Earth and Planetary Environmental Science, University of Tokyo, Tokyo, Japan
| | | | - J. O. Nolau
- Physics Department, University of Central Florida, Orlando, FL, USA
| | - R. Olds
- Lockheed Martin Space, Littleton, CO, USA
| | - M. Pajola
- INAF (Italian National Institute for Astrophysics) – Astronomical Observatory of Padova, Padova, Italy
| | | | - A. T. Polit
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | | | - B. Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B. Rozitis
- School of Physical Sciences, Open University, Milton Keynes, UK
| | - A. J. Ryan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - N. Sakatani
- Department of Physics, Rikkyo University, Tokyo, Japan
| | - J. A. Seabrook
- Department of Earth and Space Science and Engineering, York University, Toronto, ON, Canada
| | - S. H. Selznick
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - A. A. Simon
- Goddard Space Flight Center, Greenbelt, MD, USA
| | - S. Sugita
- Department of Earth and Planetary Environmental Science, University of Tokyo, Tokyo, Japan
| | - K. J. Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - M. M. Westermann
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C. W. V. Wolner
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K. Yumoto
- Department of Earth and Planetary Environmental Science, University of Tokyo, Tokyo, Japan
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4
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Banik D, Gaurav K, Sharma I. Regolith flow on top-shaped asteroids. Proc Math Phys Eng Sci 2022. [DOI: 10.1098/rspa.2021.0972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We develop a continuum framework of regolith flow on asteroids. We focus on top-shaped asteroids that may be taken as consisting of regolith lying on a solid core. Depth-averaging is employed to model the regolith flow, and effects due to the asteroid’s rotation and its complex gravity field are retained. Angular momentum conservation is invoked to couple regolith flow to the asteroid’s changing shape and spin. This framework is first used to explore the equilibrium of regolith as a function of its friction, and the asteroid’s shape and spin rate. Next, we study regolith flow on top-shaped spinning asteroids and find conditions for the regolith’s shedding or deposition. We also discuss how the regolith’s flow and the asteroid’s spin influence each other. Finally, as an application, we propose and investigate the following evolution history of Bennu: a fast spinning Bennu was slowed down by multiple, impact-induced global landslides to its present spin state. Regolith was shed if the spin was higher than a critical rate. Once the spin rate fell below this critical value, regolith flow from higher latitudes began depositing regolith at its equator, giving Bennu its distinctive shape.
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Affiliation(s)
- Deepayan Banik
- Department of Aerospace Engineering, Indian Institute of Technology, Kanpur, India
- Applied Mechanics Laboratory, Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, India
| | - Kumar Gaurav
- Applied Mechanics Laboratory, Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, India
| | - Ishan Sharma
- Applied Mechanics Laboratory, Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, India
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5
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Golish DR, Simon AA, Reuter DC, Ferrone S, Clark BE, Li JY, DellaGiustina DN, Drouet d’Aubigny C, Rizk B, Lauretta DS. Cross-Instrument Comparison of MapCam and OVIRS on OSIRIS-REx. SPACE SCIENCE REVIEWS 2022; 218:5. [PMID: 35250103 PMCID: PMC8885487 DOI: 10.1007/s11214-022-00873-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Two of the instruments onboard the OSIRIS-REx spacecraft, the MapCam color imager and the OVIRS visible and infrared spectrometer, observed the surface of asteroid (101955) Bennu in partially overlapping wavelengths. Significant scientific advances have been enabled by using data from these two instruments in tandem, but a robust statistical understanding of their relationship is needed for future analyses to cross-compare their data as accurately and sensitively as possible. Here we present a cross-instrument comparison of data acquired by MapCam and OVIRS, including methods and results for all global and site-specific observation campaigns in which both instruments were active. In our analysis, we consider both the absolute radiometric offset and the relative (normalized) variation between the two instruments; we find that both depend strongly on the photometric and instrumental conditions during the observation. The two instruments have a large absolute offset (>15%) due to their independent radiometric calibrations. However, they are very consistent (relative offset as low as 1%) when each instrument's response is normalized at a single wavelength, particularly at low phase angles where shadows on Bennu's rough surface are minimized. We recommend using the global datasets acquired at 12:30 pm local solar time for cross-comparisons; data acquired at higher phase angles have larger uncertainties.
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Affiliation(s)
- D. R. Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - A. A. Simon
- NASA Goddard Space Flight Center, Greenbelt, MD USA
| | - D. C. Reuter
- NASA Goddard Space Flight Center, Greenbelt, MD USA
| | - S. Ferrone
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY USA
| | - B. E. Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY USA
| | - J.-Y. Li
- Planetary Science Institute, Tucson, AZ USA
| | | | | | - B. Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - D. S. Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
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6
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Rozitis B, Ryan AJ, Emery JP, Christensen PR, Hamilton VE, Simon AA, Reuter DC, Al Asad M, Ballouz RL, Bandfield JL, Barnouin OS, Bennett CA, Bernacki M, Burke KN, Cambioni S, Clark BE, Daly MG, Delbo M, DellaGiustina DN, Elder CM, Hanna RD, Haberle CW, Howell ES, Golish DR, Jawin ER, Kaplan HH, Lim LF, Molaro JL, Munoz DP, Nolan MC, Rizk B, Siegler MA, Susorney HCM, Walsh KJ, Lauretta DS. Asteroid (101955) Bennu's weak boulders and thermally anomalous equator. SCIENCE ADVANCES 2020; 6:eabc3699. [PMID: 33033037 PMCID: PMC7544501 DOI: 10.1126/sciadv.abc3699] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/09/2020] [Indexed: 05/18/2023]
Abstract
Thermal inertia and surface roughness are proxies for the physical characteristics of planetary surfaces. Global maps of these two properties distinguish the boulder population on near-Earth asteroid (NEA) (101955) Bennu into two types that differ in strength, and both have lower thermal inertia than expected for boulders and meteorites. Neither has strongly temperature-dependent thermal properties. The weaker boulder type probably would not survive atmospheric entry and thus may not be represented in the meteorite collection. The maps also show a high-thermal inertia band at Bennu's equator, which might be explained by processes such as compaction or strength sorting during mass movement, but these explanations are not wholly consistent with other data. Our findings imply that other C-complex NEAs likely have boulders similar to those on Bennu rather than finer-particulate regoliths. A tentative correlation between albedo and thermal inertia of C-complex NEAs may be due to relative abundances of boulder types.
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Affiliation(s)
- B Rozitis
- School of Physical Sciences, The Open University, Milton Keynes, UK.
| | - A J Ryan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J P Emery
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA
| | - P R Christensen
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | | | - A A Simon
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - D C Reuter
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - M Al Asad
- Department of Earth, Atmospheric, and Ocean Science, University of British Columbia, Vancouver, BC, Canada
| | - R-L Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - O S Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M Bernacki
- Mines ParisTech, PSL Research University, CEMEF-Centre de mise en forme des matériaux, Sophia Antipolis Cedex, France
| | - K N Burke
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - S Cambioni
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B E Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - M G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - M Delbo
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C M Elder
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - R D Hanna
- Jackson School of Geosciences, University of Texas, Austin, TX, USA
| | - C W Haberle
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - E S Howell
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E R Jawin
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - H H Kaplan
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - L F Lim
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - J L Molaro
- Planetary Science Institute, Tucson, AZ, USA
| | - D Pino Munoz
- Mines ParisTech, PSL Research University, CEMEF-Centre de mise en forme des matériaux, Sophia Antipolis Cedex, France
| | - 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
| | - M A Siegler
- Planetary Science Institute, Tucson, AZ, USA
| | - H C M Susorney
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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