1
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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2
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DellaGiustina DN, Burke KN, Walsh KJ, Smith PH, Golish DR, Bierhaus EB, Ballouz RL, Becker TL, Campins H, Tatsumi E, Yumoto K, Sugita S, Deshapriya JDP, Cloutis EA, Clark BE, Hendrix AR, Sen A, Al Asad MM, Daly MG, Applin DM, Avdellidou C, Barucci MA, Becker KJ, Bennett CA, Bottke WF, Brodbeck JI, Connolly HC, Delbo M, de Leon J, Drouet d'Aubigny CY, Edmundson KL, Fornasier S, Hamilton VE, Hasselmann PH, Hergenrother CW, Howell ES, Jawin ER, Kaplan HH, Le Corre L, Lim LF, Li JY, Michel P, Molaro JL, Nolan MC, Nolau J, Pajola M, Parkinson A, Popescu M, Porter NA, Rizk B, Rizos JL, Ryan AJ, Rozitis B, Shultz NK, Simon AA, Trang D, Van Auken RB, Wolner CWV, Lauretta DS. Variations in color and reflectance on the surface of asteroid (101955) Bennu. Science 2020; 370:science.abc3660. [PMID: 33033157 DOI: 10.1126/science.abc3660] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/24/2020] [Indexed: 11/02/2022]
Abstract
Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. Here we present multispectral images (0.44 to 0.89 micrometers) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet region (i.e., become bluer at shorter wavelengths), then brighten in the visible to near-infrared region, leading to Bennu's moderately blue average color. Craters indicate that the time scale of these color changes is ~105 years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages.
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Affiliation(s)
- D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA. .,Department of Geosciences, University of Arizona, Tucson, AZ, USA
| | - K N Burke
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - P H Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - R-L Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - T L Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H Campins
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - E Tatsumi
- Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain.,Department of Earth and Planetary Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - K Yumoto
- Department of Earth and Planetary Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - S Sugita
- Department of Earth and Planetary Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - J D Prasanna Deshapriya
- LESIA (Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique), Observatoire de Paris, Université PSL (Paris Sciences & Lettres), CNRS (Centre National de la Recherche Scientifique), Université de Paris, Sorbonne Université, 92195 Meudon, France
| | - E A Cloutis
- Department of Geography, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - B E Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - A R Hendrix
- Planetary Science Institute, Tucson, AZ, USA
| | - A Sen
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - M M Al Asad
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
| | - M G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - D M Applin
- Department of Geography, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - C Avdellidou
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - M A Barucci
- LESIA (Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique), Observatoire de Paris, Université PSL (Paris Sciences & Lettres), CNRS (Centre National de la Recherche Scientifique), Université de Paris, Sorbonne Université, 92195 Meudon, France
| | - 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
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - J I Brodbeck
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H C Connolly
- Department of Geology, Rowan University, Glassboro, NJ, USA
| | - M Delbo
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - J de Leon
- Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | | | - K L Edmundson
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - S Fornasier
- LESIA (Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique), Observatoire de Paris, Université PSL (Paris Sciences & Lettres), CNRS (Centre National de la Recherche Scientifique), Université de Paris, Sorbonne Université, 92195 Meudon, France.,Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris CEDEX 05, France
| | | | - P H Hasselmann
- LESIA (Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique), Observatoire de Paris, Université PSL (Paris Sciences & Lettres), CNRS (Centre National de la Recherche Scientifique), Université de Paris, Sorbonne Université, 92195 Meudon, France
| | - 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
| | - E R Jawin
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - H H Kaplan
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - L Le Corre
- Planetary Science Institute, Tucson, AZ, USA
| | - L F Lim
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - J Y Li
- Planetary Science Institute, Tucson, AZ, USA
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - J L Molaro
- Planetary Science Institute, Tucson, AZ, USA
| | - M C Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J Nolau
- Lockheed Martin Space, Littleton, CO, USA
| | - M Pajola
- Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Padova, Padua, Italy
| | - A Parkinson
- Department of Geography, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - M Popescu
- Astronomical Institute of the Romanian Academy, Bucharest, Romania.,Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | - N A Porter
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J L Rizos
- Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | - A J Ryan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rozitis
- The School of Physical Sciences, The Open University, Milton Keynes, UK
| | - N K Shultz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - A A Simon
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - D Trang
- University of Hawai'i at Mānoa, Hawai'i Institute of Geophysics and Planetology, Honolulu, HI, USA
| | - R B Van Auken
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C W V Wolner
- 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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3
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Hergenrother CW, Adam CD, Chesley SR, Lauretta DS. Introduction to the Special Issue: Exploration of the Activity of Asteroid (101955) Bennu. J Geophys Res Planets 2020; 125:e2020JE006549. [PMID: 33042723 PMCID: PMC7540007 DOI: 10.1029/2020je006549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/02/2020] [Accepted: 07/12/2020] [Indexed: 06/11/2023]
Abstract
Near-Earth asteroid (101955) Bennu is an active asteroid experiencing mass loss. The activity manifests itself in the form of ejection events emitting up to hundreds of millimeter- to centimeter-scale particles. The Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer spacecraft monitored particle activity for a 10-month period that included Bennu's perihelion and aphelion. Novel and classical methods were utilized to detect the particles and characterize their orbital and physical properties. Roughly 30% of the observed particle mass escaped to heliocentric orbit. A majority of particles fell back onto the surface of Bennu after ejection, with the longest-lived particle surviving for 6 days on a temporary orbit. Particle ejection events appear to preferentially take place in the afternoon and evening and from low latitudes, although they can occur at any time or latitude. The reaccumulation of material is biased toward low latitudes resulting in the possible in-fill of craters and growth of Bennu's equatorial bulge. Of the potential mechanisms behind this activity that were investigated in focused studies, meteoroid impacts, thermal fracturing, and ricochet-but not water ice sublimation-were found to be consistent with observations. While phyllosilicate dehydration was not investigated with a focused study, it remains a possible mechanism. These mechanisms are not unique to Bennu, suggesting that many near-Earth asteroids may exhibit activity that has gone undetected thus far. Spacecraft missions with wide-field imagers are encouraged to further characterize this phenomenon.
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Affiliation(s)
| | | | - S. R. Chesley
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - D. S. Lauretta
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
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4
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Leonard JM, Adam CD, Pelgrift JY, Lessac‐Chenen EJ, Nelson DS, Antreasian PG, Liounis AJ, Moreau MC, Hergenrother CW, Chesley SR, Nolan MC, Lauretta DS. Initial Orbit Determination and Event Reconstruction From Estimation of Particle Trajectories About (101955) Bennu. Earth Space Sci 2020; 7:e2019EA000937. [PMID: 33043099 PMCID: PMC7540059 DOI: 10.1029/2019ea000937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 02/10/2020] [Accepted: 02/25/2020] [Indexed: 06/11/2023]
Abstract
The OSIRIS-REx mission has observed multiple instances of particles being ejected from the surface of near-Earth asteroid (101955) Bennu. The ability to quickly identify the particle trajectories and origins is necessary following a particle ejection event. Using proven initial orbit determination techniques, we can rapidly estimate particle trajectories and ejection locations. We present current results pertaining to the identification of particle tracks, an evaluation of the estimated orbits and the excess velocity necessary to induce the particle ejection from the surface, and the uncertainty quantification of the ejection location. We estimate energies per particle ranging from 0.03 to 11.03 mJ for the largest analyzed events and velocities ranging from 5 to 90 cm/s, though we exclude the highest-velocity particles in this technique. We estimate ejection times for eight events and constrain six of the analyzed ejection events to have occurred between about 16:30 and 19:00 local solar time, with the largest events occurring between 16:30 and 18:05.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - S. R. Chesley
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - M. C. Nolan
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - D. S. Lauretta
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
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5
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Bottke WF, Moorhead AV, Connolly HC, Hergenrother CW, Molaro JL, Michel P, Nolan MC, Schwartz SR, Vokrouhlický D, Walsh KJ, Lauretta DS. Meteoroid Impacts as a Source of Bennu's Particle Ejection Events. J Geophys Res Planets 2020; 125:e2019JE006282. [PMID: 32999798 PMCID: PMC7507787 DOI: 10.1029/2019je006282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/07/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
Asteroid (101955) Bennu, a near-Earth object with a primitive carbonaceous chondrite-like composition, was observed by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft to undergo multiple particle ejection events near perihelion between December 2018 and February 2019. The three largest events observed during this period, which all occurred 3.5 to 6 hr after local noon, placed numerous particles <10 cm on temporary orbits around Bennu. Here we examine whether these events could have been produced by sporadic meteoroid impacts using the National Aeronautics and Space Administration's (NASA) Meteoroid Engineering Model 3.0. Most projectiles that impact Bennu come from nearly isotropic or Jupiter-family comets and have evolved toward the Sun by Poynting-Robertson drag. We find that 7,000-J impacts on Bennu occur with a biweekly cadence near perihelion, with a preference to strike in the late afternoon (~6 pm local time). This timing matches observations. Crater scaling laws also indicate that these impact energies can reproduce the sizes and masses of the largest observed particles, provided the surface has the cohesive properties of weak, porous materials. Bennu's ejection events could be caused by the same kinds of meteoroid impacts that created the Moon's asymmetric debris cloud observed by the Lunar Atmosphere and Dust Environment Explorer (LADEE). Our findings also suggest that fewer ejection events should take place as Bennu moves further away from the Sun, a result that can be tested with future observations.
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Affiliation(s)
| | - A. V. Moorhead
- NASA Meteoroid Environment Office, Marshall Space Flight Center EV44HuntsvilleALUSA
| | - H. C. Connolly
- Department of GeologyRowan UniversityGlassboroNJUSA
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | | | | | - P. Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire LagrangeNiceFrance
| | - M. C. Nolan
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - S. R. Schwartz
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - D. Vokrouhlický
- Institute of AstronomyCharles UniversityPragueCzech Republic
| | | | - D. S. Lauretta
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
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6
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Molaro JL, Hergenrother CW, Chesley SR, Walsh KJ, Hanna RD, Haberle CW, Schwartz SR, Ballouz R, Bottke WF, Campins HJ, Lauretta DS. Thermal Fatigue as a Driving Mechanism for Activity on Asteroid Bennu. J Geophys Res Planets 2020; 125:e2019JE006325. [PMID: 32999800 PMCID: PMC7507781 DOI: 10.1029/2019je006325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 07/15/2020] [Accepted: 07/18/2020] [Indexed: 06/11/2023]
Abstract
Many boulders on (101955) Bennu, a near-Earth rubble pile asteroid, show signs of in situ disaggregation and exfoliation, indicating that thermal fatigue plays an important role in its landscape evolution. Observations of particle ejections from its surface also show it to be an active asteroid, though the driving mechanism of these events is yet to be determined. Exfoliation has been shown to mobilize disaggregated particles in terrestrial environments, suggesting that it may be capable of ejecting material from Bennu's surface. We investigate the nature of thermal fatigue on the asteroid, and the efficacy of fatigue-driven exfoliation as a mechanism for generating asteroid activity, by performing finite element modeling of stress fields induced in boulders from diurnal cycling. We develop a model to predict the spacing of exfoliation fractures and the number and speed of particles that may be ejected during exfoliation events. We find that crack spacing ranges from ~1 mm to 10 cm and disaggregated particles have ejection speeds up to ~2 m/s. Exfoliation events are most likely to occur in the late afternoon. These predictions are consistent with observed ejection events at Bennu and indicate that thermal fatigue is a viable mechanism for driving asteroid activity. Crack propagation rates and ejection speeds are greatest at perihelion when the diurnal temperature variation is largest, suggesting that events should be more energetic and more frequent when closer to the Sun. Annual thermal stresses that arise in large boulders may influence the spacing of exfoliation cracks or frequency of ejection events.
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Affiliation(s)
| | | | - S. R. Chesley
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | | | - R. D. Hanna
- Jackson School of GeosciencesUniversity of Texas at AustinAustinTXUSA
| | - C. W. Haberle
- School of Earth and Space ExplorationArizona State UniversityTempeAZUSA
| | - S. R. Schwartz
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - R.‐L. Ballouz
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | | | - H. J. Campins
- Department of PhysicsUniversity of Central FloridaOrlandoFLUSA
| | - D. S. Lauretta
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
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7
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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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8
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Scheeres DJ, McMahon JW, Brack DN, French AS, Chesley SR, Farnocchia D, Vokrouhlický D, Ballouz R, Emery JP, Rozitis B, Nolan MC, Hergenrother CW, Lauretta DS. Particle Ejection Contributions to the Rotational Acceleration and Orbit Evolution of Asteroid (101955) Bennu. J Geophys Res Planets 2020; 125:e2019JE006284. [PMID: 32714726 PMCID: PMC7375169 DOI: 10.1029/2019je006284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 02/07/2020] [Accepted: 02/11/2020] [Indexed: 05/29/2023]
Abstract
This paper explores the implications of the observed Bennu particle ejection events for that asteroid's spin rate and orbit evolution, which could complicate interpretation of the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) and Yarkovsky effects on this body's spin rate and orbital evolution. Based on current estimates of particle ejection rates, we find that the overall contribution to Bennu's spin and orbital drift is small or negligible as compared to the Yarkovsky and YORP effects. However, if there is a large unseen component of smaller mass ejections or a strong directionality in the ejection events, it could constitute a significant contribution that could mask the overall YORP effect. This means that the YORP effect may be stronger than currently assumed. The analysis is generalized so that the particle ejection effect can be assessed for other bodies that may be subject to similar mass loss events. Further, our model can be modified to address different potential mechanisms of particle ejection, which are a topic of ongoing study.
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Affiliation(s)
- D. J. Scheeres
- Smead Department of Aerospace Engineering SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - J. W. McMahon
- Smead Department of Aerospace Engineering SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - D. N. Brack
- Smead Department of Aerospace Engineering SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - A. S. French
- Smead Department of Aerospace Engineering SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - S. R. Chesley
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - D. Farnocchia
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - D. Vokrouhlický
- Institute of AstronomyCharles UniversityPragueCzech Republic
| | - R.‐L. Ballouz
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - J. P. Emery
- Department of Earth and Planetary SciencesUniversity of TennesseeKnoxvilleTNUSA
| | - B. Rozitis
- Planetary and Space Sciences, School of Physical SciencesThe Open UniversityMilton KeynesUK
| | - M. C. Nolan
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | | | - D. S. Lauretta
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
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9
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Golish DR, Drouet d'Aubigny C, Rizk B, DellaGiustina DN, Smith PH, Becker K, Shultz N, Stone T, Barker MK, Mazarico E, Tatsumi E, Gaskell RW, Harrison L, Merrill C, Fellows C, Williams B, O'Dougherty S, Whiteley M, Hancock J, Clark BE, Hergenrother CW, Lauretta DS. Ground and In-Flight Calibration of the OSIRIS-REx Camera Suite. Space Sci Rev 2020; 216:12. [PMID: 32025061 DOI: 10.1007/s11214-017-0460-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 11/27/2019] [Indexed: 05/29/2023]
Abstract
The OSIRIS-REx Camera Suite (OCAMS) onboard the OSIRIS-REx spacecraft is used to study the shape and surface of the mission's target, asteroid (101955) Bennu, in support of the selection of a sampling site. We present calibration methods and results for the three OCAMS cameras-MapCam, PolyCam, and SamCam-using data from pre-flight and in-flight calibration campaigns. Pre-flight calibrations established a baseline for a variety of camera properties, including bias and dark behavior, flat fields, stray light, and radiometric calibration. In-flight activities updated these calibrations where possible, allowing us to confidently measure Bennu's surface. Accurate calibration is critical not only for establishing a global understanding of Bennu, but also for enabling analyses of potential sampling locations and for providing scientific context for the returned sample.
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Affiliation(s)
- D R Golish
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | | | - B Rizk
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - D N DellaGiustina
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - P H Smith
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - K Becker
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - N Shultz
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - T Stone
- United States Geological Survey Astrogeology Science Center, Flagstaff, AZ USA
| | - M K Barker
- 3Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD USA
| | - E Mazarico
- 3Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD USA
| | - E Tatsumi
- 4Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
| | - R W Gaskell
- 5Planetary Science Institute, Tucson, AZ USA
| | - L Harrison
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - C Merrill
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - C Fellows
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - B Williams
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - S O'Dougherty
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - M Whiteley
- 6Space Dynamics Laboratory, Utah State University, Logan, UT USA
| | - J Hancock
- 6Space Dynamics Laboratory, Utah State University, Logan, UT USA
| | - B E Clark
- 7Department of Physics and Astronomy, Ithaca College, Ithaca, NY USA
| | - C W Hergenrother
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - D S Lauretta
- 1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
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10
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Golish DR, Drouet d’Aubigny C, Rizk B, DellaGiustina DN, Smith PH, Becker K, Shultz N, Stone T, Barker MK, Mazarico E, Tatsumi E, Gaskell RW, Harrison L, Merrill C, Fellows C, Williams B, O’Dougherty S, Whiteley M, Hancock J, Clark BE, Hergenrother CW, Lauretta DS. Ground and In-Flight Calibration of the OSIRIS-REx Camera Suite. Space Sci Rev 2020; 216:12. [PMID: 32025061 PMCID: PMC6979463 DOI: 10.1007/s11214-019-0626-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 11/27/2019] [Indexed: 05/18/2023]
Abstract
The OSIRIS-REx Camera Suite (OCAMS) onboard the OSIRIS-REx spacecraft is used to study the shape and surface of the mission's target, asteroid (101955) Bennu, in support of the selection of a sampling site. We present calibration methods and results for the three OCAMS cameras-MapCam, PolyCam, and SamCam-using data from pre-flight and in-flight calibration campaigns. Pre-flight calibrations established a baseline for a variety of camera properties, including bias and dark behavior, flat fields, stray light, and radiometric calibration. In-flight activities updated these calibrations where possible, allowing us to confidently measure Bennu's surface. Accurate calibration is critical not only for establishing a global understanding of Bennu, but also for enabling analyses of potential sampling locations and for providing scientific context for the returned sample.
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Affiliation(s)
- D. R. Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | | | - B. Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | | | - P. H. Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - K. Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - N. Shultz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - T. Stone
- United States Geological Survey Astrogeology Science Center, Flagstaff, AZ USA
| | - M. K. Barker
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD USA
| | - E. Mazarico
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD USA
| | - E. Tatsumi
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
| | | | - L. Harrison
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - C. Merrill
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - C. Fellows
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - B. Williams
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - S. O’Dougherty
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - M. Whiteley
- Space Dynamics Laboratory, Utah State University, Logan, UT USA
| | - J. Hancock
- Space Dynamics Laboratory, Utah State University, Logan, UT USA
| | - B. E. Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY USA
| | | | - D. S. Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
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11
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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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12
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Hergenrother CW, Maleszewski CK, Nolan MC, Li JY, Drouet d'Aubigny CY, Shelly FC, Howell ES, Kareta TR, Izawa MRM, Barucci MA, Bierhaus EB, Campins H, Chesley SR, Clark BE, Christensen EJ, DellaGiustina DN, Fornasier S, Golish DR, Hartzell CM, Rizk B, Scheeres DJ, Smith PH, Zou XD, Lauretta DS. The operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations. Nat Commun 2019; 10:1291. [PMID: 30890725 PMCID: PMC6425024 DOI: 10.1038/s41467-019-09213-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 02/26/2019] [Indexed: 11/17/2022] Open
Abstract
During its approach to asteroid (101955) Bennu, NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft surveyed Bennu's immediate environment, photometric properties, and rotation state. Discovery of a dusty environment, a natural satellite, or unexpected asteroid characteristics would have had consequences for the mission's safety and observation strategy. Here we show that spacecraft observations during this period were highly sensitive to satellites (sub-meter scale) but reveal none, although later navigational images indicate that further investigation is needed. We constrain average dust production in September 2018 from Bennu's surface to an upper limit of 150 g s-1 averaged over 34 min. Bennu's disk-integrated photometric phase function validates measurements from the pre-encounter astronomical campaign. We demonstrate that Bennu's rotation rate is accelerating continuously at 3.63 ± 0.52 × 10-6 degrees day-2, likely due to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, with evolutionary implications.
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Affiliation(s)
- C W Hergenrother
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - C K Maleszewski
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M C Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J-Y Li
- Planetary Science Institute, Tucson, AZ, USA
| | | | - F C Shelly
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E S Howell
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - T R Kareta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M R M Izawa
- Institute for Planetary Materials, Okayama University-Misasa, Misasa, Tottori, Japan
| | - M A Barucci
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France
| | | | - H Campins
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - S R Chesley
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - B E Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - E J Christensen
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - S Fornasier
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France
| | - 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
| | - B Rizk
- 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
| | - X-D Zou
- Planetary Science Institute, Tucson, AZ, USA
| | - D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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13
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Meech KJ, Ageorges N, A'Hearn MF, Arpigny C, Ates A, Aycock J, Bagnulo S, Bailey J, Barber R, Barrera L, Barrena R, Bauer JM, Belton MJS, Bensch F, Bhattacharya B, Biver N, Blake G, Bockelée-Morvan D, Boehnhardt H, Bonev BP, Bonev T, Buie MW, Burton MG, Butner HM, Cabanac R, Campbell R, Campins H, Capria MT, Carroll T, Chaffee F, Charnley SB, Cleis R, Coates A, Cochran A, Colom P, Conrad A, Coulson IM, Crovisier J, deBuizer J, Dekany R, de Léon J, Dello Russo N, Delsanti A, DiSanti M, Drummond J, Dundon L, Etzel PB, Farnham TL, Feldman P, Fernández YR, Filipovic MD, Fisher S, Fitzsimmons A, Fong D, Fugate R, Fujiwara H, Fujiyoshi T, Furusho R, Fuse T, Gibb E, Groussin O, Gulkis S, Gurwell M, Hadamcik E, Hainaut O, Harker D, Harrington D, Harwit M, Hasegawa S, Hergenrother CW, Hirst P, Hodapp K, Honda M, Howell ES, Hutsemékers D, Iono D, Ip WH, Jackson W, Jehin E, Jiang ZJ, Jones GH, Jones PA, Kadono T, Kamath UW, Käufl HU, Kasuga T, Kawakita H, Kelley MS, Kerber F, Kidger M, Kinoshita D, Knight M, Lara L, Larson SM, Lederer S, Lee CF, Levasseur-Regourd AC, Li JY, Li QS, Licandro J, Lin ZY, Lisse CM, LoCurto G, Lovell AJ, Lowry SC, Lyke J, Lynch D, Ma J, Magee-Sauer K, Maheswar G, Manfroid J, Marco O, Martin P, Melnick G, Miller S, Miyata T, Moriarty-Schieven GH, Moskovitz N, Mueller BEA, Mumma MJ, Muneer S, Neufeld DA, Ootsubo T, Osip D, Pandea SK, Pantin E, Paterno-Mahler R, Patten B, Penprase BE, Peck A, Petitas G, Pinilla-Alonso N, Pittichova J, Pompei E, Prabhu TP, Qi C, Rao R, Rauer H, Reitsema H, Rodgers SD, Rodriguez P, Ruane R, Ruch G, Rujopakarn W, Sahu DK, Sako S, Sakon I, Samarasinha N, Sarkissian JM, Saviane I, Schirmer M, Schultz P, Schulz R, Seitzer P, Sekiguchi T, Selman F, Serra-Ricart M, Sharp R, Snell RL, Snodgrass C, Stallard T, Stecklein G, Sterken C, Stüwe JA, Sugita S, Sumner M, Suntzeff N, Swaters R, Takakuwa S, Takato N, Thomas-Osip J, Thompson E, Tokunaga AT, Tozzi GP, Tran H, Troy M, Trujillo C, Van Cleve J, Vasundhara R, Vazquez R, Vilas F, Villanueva G, von Braun K, Vora P, Wainscoat RJ, Walsh K, Watanabe J, Weaver HA, Weaver W, Weiler M, Weissman PR, Welsh WF, Wilner D, Wolk S, Womack M, Wooden D, Woodney LM, Woodward C, Wu ZY, Wu JH, Yamashita T, Yang B, Yang YB, Yokogawa S, Zook AC, Zauderer A, Zhao X, Zhou X, Zucconi JM. Deep Impact: observations from a worldwide Earth-based campaign. Science 2005; 310:265-9. [PMID: 16150977 DOI: 10.1126/science.1118978] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.
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Affiliation(s)
- K J Meech
- Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
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Gladman B, Kavelaars JJ, Holman M, Nicholson PD, Burns JA, Hergenrother CW, Petit JM, Marsden BG, Jacobson R, Gray W, Grav T. Discovery of 12 satellites of Saturn exhibiting orbital clustering. Nature 2001; 412:163-6. [PMID: 11449267 DOI: 10.1038/35084032] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The giant planets in the Solar System each have two groups of satellites. The regular satellites move along nearly circular orbits in the planet's orbital plane, revolving about it in the same sense as the planet spins. In contrast, the so-called irregular satellites are generally smaller in size and are characterized by large orbits with significant eccentricity, inclination or both. The differences in their characteristics suggest that the regular and irregular satellites formed by different mechanisms: the regular satellites are believed to have formed in an accretion disk around the planet, like a miniature Solar System, whereas the irregulars are generally thought to be captured planetesimals. Here we report the discovery of 12 irregular satellites of Saturn, along with the determinations of their orbits. These orbits, along with the orbits of irregular satellites of Jupiter and Uranus, fall into groups on the basis of their orbital inclinations. We interpret this result as indicating that most of the irregular moons are collisional remnants of larger satellites that were fragmented after capture, rather than being captured independently.
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Affiliation(s)
- B Gladman
- Observatoire de la Côte d'Azur, B.P. 4229, 06304 Nice Cedex 4, France.
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