TY - JOUR
T1 - Fine-regolith production on asteroids controlled by rock porosity
AU - Cambioni, S.
AU - Delbo, M.
AU - Poggiali, G.
AU - Avdellidou, C.
AU - Ryan, A. J.
AU - Deshapriya, J. D.P.
AU - Asphaug, E.
AU - Ballouz, R. L.
AU - Barucci, M. A.
AU - Bennett, C. A.
AU - Bottke, W. F.
AU - Brucato, J. R.
AU - Burke, K. N.
AU - Cloutis, E.
AU - DellaGiustina, D. N.
AU - Emery, J. P.
AU - Rozitis, B.
AU - Walsh, K. J.
AU - Lauretta, D. S.
N1 - Funding Information:
Acknowledgements This material is based on work supported by NASA under contract NNM10AA11C issued through the New Frontiers Program. We are grateful to the entire OSIRIS-REx team for making the encounter with Bennu possible, to C. Wolner and F. Murphy for editorial help, and to the OPAL infrastructure of the Observatoire de la Côte d’Azur (CRIMSON) for providing computational resources and support. S.C. thanks the University of Arizona for supporting this study. M.D., C.A., J.D.P.D. and M.A.B. acknowledge the French space agency CNES. C.A. and M.D. acknowledge support from ANR “ORIGINS” (ANR-18-CE31-0014). C.A. was supported by the French National Research Agency under the project “Investissements d’Avenir” UCAJEDI ANR-15-IDEX-01. G.P. and J.R.B. were supported by Italian Space Agency grant agreement INAF/ASI number 2017-37-H.0. B.R. acknowledges financial support from the UK Science and Technology Facilities Council (STFC). E.C. thanks CSA, NSERC, CFI, MRIF and UWinnipeg for supporting this study.
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature Limited.
PY - 2021/10/7
Y1 - 2021/10/7
N2 - Spacecraft missions have observed regolith blankets of unconsolidated subcentimetre particles on stony asteroids1–3. Telescopic data have suggested the presence of regolith blankets also on carbonaceous asteroids, including (101955) Bennu4 and (162173) Ryugu5. However, despite observations of processes that are capable of comminuting boulders into unconsolidated materials, such as meteoroid bombardment6,7 and thermal cracking8, Bennu and Ryugu lack extensive areas covered in subcentimetre particles7,9. Here we report an inverse correlation between the local abundance of subcentimetre particles and the porosity of rocks on Bennu. We interpret this finding to mean that accumulation of unconsolidated subcentimetre particles is frustrated where the rocks are highly porous, which appears to be most of the surface10. The highly porous rocks are compressed rather than fragmented by meteoroid impacts, consistent with laboratory experiments11,12, and thermal cracking proceeds more slowly than in denser rocks. We infer that regolith blankets are uncommon on carbonaceous asteroids, which are the most numerous type of asteroid13. By contrast, these terrains should be common on stony asteroids, which have less porous rocks and are the second-most populous group by composition13. The higher porosity of carbonaceous asteroid materials may have aided in their compaction and cementation to form breccias, which dominate the carbonaceous chondrite meteorites14.
AB - Spacecraft missions have observed regolith blankets of unconsolidated subcentimetre particles on stony asteroids1–3. Telescopic data have suggested the presence of regolith blankets also on carbonaceous asteroids, including (101955) Bennu4 and (162173) Ryugu5. However, despite observations of processes that are capable of comminuting boulders into unconsolidated materials, such as meteoroid bombardment6,7 and thermal cracking8, Bennu and Ryugu lack extensive areas covered in subcentimetre particles7,9. Here we report an inverse correlation between the local abundance of subcentimetre particles and the porosity of rocks on Bennu. We interpret this finding to mean that accumulation of unconsolidated subcentimetre particles is frustrated where the rocks are highly porous, which appears to be most of the surface10. The highly porous rocks are compressed rather than fragmented by meteoroid impacts, consistent with laboratory experiments11,12, and thermal cracking proceeds more slowly than in denser rocks. We infer that regolith blankets are uncommon on carbonaceous asteroids, which are the most numerous type of asteroid13. By contrast, these terrains should be common on stony asteroids, which have less porous rocks and are the second-most populous group by composition13. The higher porosity of carbonaceous asteroid materials may have aided in their compaction and cementation to form breccias, which dominate the carbonaceous chondrite meteorites14.
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UR - http://www.scopus.com/inward/citedby.url?scp=85116484939&partnerID=8YFLogxK
U2 - 10.1038/s41586-021-03816-5
DO - 10.1038/s41586-021-03816-5
M3 - Article
C2 - 34616055
AN - SCOPUS:85116484939
SN - 0028-0836
VL - 598
SP - 49
EP - 52
JO - Nature
JF - Nature
IS - 7879
ER -