Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Bennu’s near-Earth lifetime of 1.75 million years inferred from craters on its boulders

Nature volume 587, pages 205–209 (2020)Cite this article

Subjects

Abstract

An asteroid’s history is determined in large part by its strength against collisions with other objects1,2 (impact strength). Laboratory experiments on centimetre-scale meteorites3 have been extrapolated and buttressed with numerical simulations to derive the impact strength at the asteroid scale4,5. In situ evidence of impacts on boulders on airless planetary bodies has come from Apollo lunar samples6 and images of the asteroid (25143) Itokawa7. It has not yet been possible, however, to assess directly the impact strength, and thus the absolute surface age, of the boulders that constitute the building blocks of a rubble-pile asteroid. Here we report an analysis of the size and depth of craters observed on boulders on the asteroid (101955) Bennu. We show that the impact strength of metre-sized boulders is 0.44 to 1.7 megapascals, which is low compared to that of solid terrestrial materials. We infer that Bennu’s metre-sized boulders record its history of impact by millimetre- to centimetre-scale objects in near-Earth space. We conclude that this population of near-Earth impactors has a size frequency distribution similar to that of metre-scale bolides and originates from the asteroidal population. Our results indicate that Bennu has been dynamically decoupled from the main asteroid belt for 1.75 ± 0.75 million years.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Craters are observed on Bennu’s boulders in images and laser altimetry data.
Fig. 2: The maximum crater size on a boulder depends on boulder strength.
Fig. 3: Bennu’s boulders are relatively weak and have short lifetimes in the main asteroid belt.
Fig. 4: The surface exposure age of Bennu’s metre-size boulders is ~1.75 Myr.

Similar content being viewed by others

Data availability

OCAMS images and OLA data from the Orbital A, Detailed Survey and Orbital B phases of the OSIRIS-REx mission are available in the Planetary Data System at https://sbn.psi.edu/pds/resource/orex/. Measured dimensions and locations of craters and host boulders are available in Extended Data Tables 1, 2 and Supplementary Table 1.

Code availability

The Small Body mapping tool is available at http://sbmt.jhuapl.edu/.

References

  1. Michel, P. et al. Collisions and gravitational reaccumulation: forming asteroid families and satellites. Science 294, 1696–1700 (2001).

    ADS  CAS  PubMed  Google Scholar 

  2. Bottke, W. F. et al. Linking the collisional history of the main asteroid belt to its dynamical excitation and depletion. Icarus 179, 63–94 (2005).

    ADS  CAS  Google Scholar 

  3. Flynn, G. J. et al. Physical properties of the stone meteorites: implications for the properties of their parent bodies. Chem. Erde 78, 269–298 (2018).

    CAS  Google Scholar 

  4. Benz, W. & Asphaug, E. Catastrophic disruptions revisited. Icarus 142, 5–20 (1999).

    ADS  Google Scholar 

  5. Jutzi, M. et al. Fragment properties at the catastrophic disruption threshold: the effect of the parent body’s internal structure. Icarus 207, 54–65 (2010).

    ADS  Google Scholar 

  6. Grün, E. et al. Collisional balance of the meteoritic complex. Icarus 62, 244–272 (1985).

    ADS  Google Scholar 

  7. Nakamura, A. M. et al. Impact process of boulders on the surface of asteroid 25143 Itokawa—fragments from collisional disruption. Earth Planets Space 60, 7–12 (2008).

    ADS  Google Scholar 

  8. Golish, D. R. et al. Ground and In-Flight Calibration of the OSIRIS-REx Camera Suite. Space Sci. Rev. 216, 12 (2020).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  9. DellaGiustina, D. N. et al. Overcoming the challenges associated with image-based mapping of small bodies in preparation for the OSIRIS-REx mission to (101955) Bennu. Earth Space Sci. 5, 929–949 (2018).

    ADS  Google Scholar 

  10. Daly, M. G. et al. The OSIRIS-REx Laser Altimeter (OLA) investigation and instrument. Space Sci. Rev. 212, 899–924 (2017).

    ADS  Google Scholar 

  11. Murakami, Y. et al. Collisional disruption of highly porous targets in the strength regime: effects of mixture. Planet. Space Sci. 182, 104819 (2020).

    Google Scholar 

  12. Housen, K. Cumulative damage in strength-dominated collisions of rocky asteroids: rubble piles and brick piles. Planet. Space Sci. 57, 142–153 (2009).

    ADS  Google Scholar 

  13. Macke, R. J., Consolmagno, G. J. & Britt, D. T. Density, porosity, and magnetic susceptibility of carbonaceous chondrites. Meteorit. Planet. Sci. 46, 1842–1862 (2011).

    ADS  CAS  Google Scholar 

  14. Holsapple, K. A. & Schmidt, R. M. Point source solutions and coupling parameters in cratering mechanics. J. Geophys. Res. 92, 6350–6376 (1987).

    ADS  Google Scholar 

  15. Housen, K. R. & Holsapple, K. A. Ejecta from impact craters. Icarus 211, 856–875 (2011).

    ADS  Google Scholar 

  16. Nakamura, A. M. et al. Size dependence of the disruption threshold: laboratory examination of millimeter-centimeter porous targets. Planet. Space Sci. 107, 45–52 (2015).

    ADS  Google Scholar 

  17. Sugita, S. et al. The geomorphology, color, and thermal properties of Ryugu: implications for parent-body processes. Science 364, eaaw0422 (2019).

    Article  CAS  Google Scholar 

  18. Yasui, M. Effects of oblique impacts on the impact strength of porous gypsum and glass spheres: implications for the collisional disruption of planetesimals in thermal evolution. Icarus 335, 113414 (2020).

    CAS  Google Scholar 

  19. Holsapple, K. A. On the “strength” of the small bodies of the solar system: a review of strength theories and their implementation for analyses of impact disruptions. Planet. Space Sci. 57, 127–141 (2009).

    ADS  Google Scholar 

  20. Grott, M. et al. Low thermal conductivity boulder with high porosity identified on C-type asteroid (162173) Ryugu. Nat. Astron. 3, 971–976 (2019).

    ADS  Google Scholar 

  21. Jenniskens, P. et al. Radar-enabled recovery of the Sutter’s Mill meteorite, a carbonaceous chondrite regolith breccia. Science 338, 1583–1587 (2012).

    ADS  CAS  PubMed  Google Scholar 

  22. Brown, P. G. et al. An entry model for the Tagish Lake fireball using seismic, satellite and infrasound records. Meteorit. Planet. Sci. 37, 661–675 (2002).

    ADS  CAS  Google Scholar 

  23. Brown, P. et al. The flux of small near-Earth objects colliding with the Earth. Nature 420, 294–296 (2002).

    ADS  CAS  PubMed  Google Scholar 

  24. Avdellidou, C. & Vaubaillon, J. Temperatures of lunar impact flashes: mass and size distribution of small impactors hitting the Moon. Mon. Not. R. Astron. Soc. 484, 5212–5222 (2019).

    ADS  CAS  Google Scholar 

  25. Kawamura, T. et al. Cratering asymmetry on the Moon: new insight from the Apollo Passive Seismic Experiment. Geophys. Res. Lett. 38, 15201 (2011).

    ADS  Google Scholar 

  26. Hörz, F. et al. Catastrophic rupture of lunar rocks: a Monte Carlo simulation. Moon 13, 235–258 (1975).

    ADS  Google Scholar 

  27. Pokorný, P. & Brown, P. G. A reproducible method to determine the meteoroid mass index. Astron. Astrophys. 592, A150 (2016).

    ADS  Google Scholar 

  28. Delbo, M. et al. Thermal fatigue as the origin of regolith on small asteroids. Nature 508, 233–236 (2014).

    ADS  CAS  PubMed  Google Scholar 

  29. Moorhead, A. V. Deconvoluting measurement uncertainty from the meteor speed distribution. Meteorit. Planet. Sci. 53, 1292–1298 (2018).

    ADS  CAS  Google Scholar 

  30. Nesvorný, D. et al. Cometary origin of the zodiacal cloud and carbonaceous micrometeorites. Implications for hot debris disks. Astrophys. J. 713, 816–836 (2010).

    ADS  Google Scholar 

  31. Michel, P. & Delbo, M. Orbital and thermal evolutions of four potential targets for a sample return space mission to a primitive near-Earth asteroid. Icarus 209, 520–534 (2010).

    ADS  Google Scholar 

  32. Molaro, J. L. et al. In situ evidence of thermally induced rock breakdown widespread on Bennu’s surface. Nat. Commun. 11, 2913 (2020).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  33. Walsh, K. J. et al. Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface. Nat. Geosci. 12, 242–246 (2019); publisher correction 12, 399 (2019).

    ADS  CAS  Google Scholar 

  34. Britt, D. T. et al. Simulated asteroid materials based on carbonaceous chondrite mineralogies. Meteorit. Planet. Sci. 54, 2067–2082 (2019).

    ADS  CAS  Google Scholar 

  35. Nakamura, A. M. Impact cratering on porous targets in the strength regime. Planet. Space Sci. 149, 5–13 (2017).

    ADS  Google Scholar 

  36. Jutzi, M., Benz, W. & Michel, P. Numerical simulations of impacts involving porous bodies. I. Implementing sub-resolution porosity in a 3D SPH hydrocode. Icarus 198, 242–255 (2008).

    ADS  Google Scholar 

  37. Avdellidou, C. et al. Very weak carbonaceous asteroid simulants I: mechanical properties and response to hypervelocity impacts. Icarus 341, 113648 (2020).

    Google Scholar 

  38. Poelchau, M. H. et al. The MEMIN research unit: scaling impact cratering experiments in porous sandstones. Meteorit. Planet. Sci. 48, 8–22 (2013).

    ADS  CAS  Google Scholar 

  39. Housen, K. R. & Holsapple, K. A. On the fragmentation of asteroids and planetary satellites. Icarus 84, 226–253 (1990).

    ADS  Google Scholar 

  40. Housen, K. R. & Holsapple, K. A. Scale effects in strength-dominated collisions of rocky asteroids. Icarus 142, 21–33 (1999).

    ADS  Google Scholar 

  41. Holsapple, K. A. On the existence and implications of coupling parameters in cratering mechanics. In Lunar and Planetary Science Conference Vol. 14, 319–320 (Lunar and Planetary Institute, 1983).

  42. Holsapple, K. A. The scaling of impact processes in planetary sciences. Annu. Rev. Earth Planet. Sci. 21, 333–373 (1993).

    ADS  Google Scholar 

  43. Holsapple, K. A. & Housen, K. R. Craters from impacts and explosions. V2.2.1 http://keith.aa.washington.edu/craterdata/scaling/theory.pdf (Washington Univ., 2017).

  44. Holsapple, K. A. Catastrophic disruptions and cratering of solar system bodies: a review and new results. Planet. Space Sci. 42, 1067–1078 (1994).

    ADS  Google Scholar 

  45. Suzuki, A. I. et al. Increase in cratering efficiency with target curvature in strength-controlled craters. Icarus 301, 1–8 (2018).

    ADS  Google Scholar 

  46. Leinhardt, Z. M. & Stewart, S. T. Collisions between gravity-dominated bodies. I. Outcome regimes and scaling laws. Astrophys. J. 745, 79 (2012).

    ADS  Google Scholar 

  47. Leliwa-Kopystyński, J. et al. Impact cratering and break up of the small bodies of the Solar System. Icarus 195, 817–826 (2008).

    ADS  Google Scholar 

  48. Schenk, P. et al. The geologically recent giant impact basins at Vesta’s south pole. Science 336, 694–697 (2012).

    ADS  CAS  PubMed  Google Scholar 

  49. Walsh, K. J. Rubble pile asteroids. Annu. Rev. Astron. Astrophys. 56, 593–624 (2018).

    ADS  Google Scholar 

  50. Bennett, C. et al. A high-resolution global basemap of (101955) Bennu. Icarus (in the press).

  51. Barnouin, O. S. et al. Shape of (101955) Bennu indicative of a rubble pile with internal stiffness. Nat. Geosci. 12, 247–252 (2019); author correction https://doi.org/10.1038/s41561-020-0643-9 (2020).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  52. Ernst, C. M. et al. The Small Body Mapping Tool (SBMT) for accessing, visualizing, and analyzing spacecraft data in three dimensions. In Lunar and Planetary Science Conference Vol. 49, 1043 (Lunar and Planetary Institute, 2018).

  53. Lauretta, D. S. et al. OSIRIS-REx: sample return from asteroid (101955) Bennu. Space Sci. Rev. 212, 925–984 (2017).

    ADS  Google Scholar 

  54. Barnouin, O. S. et al. Digital terrain mapping by the OSIRIS-REx mission. Planet. Space Sci. 180, 104764 (2020).

    Google Scholar 

  55. Seabrook, J. A. et al. Global shape modeling using the OSIRIS-REx scanning Laser Altimeter. Planet. Space Sci. 177, 104688 (2019).

    Google Scholar 

  56. Farrance, I. & Frankel, R. Uncertainty of measurement: a review of the rules for calculating uncertainty components through functional relationships. Clin. Biochem. Rev. 33, 49–75 (2012).

    PubMed  PubMed Central  Google Scholar 

Download references

Acknowledgements

We thank D. P. Hamilton, K. A. Holsapple and P. Pravec for insights and feedback. This material is based upon 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. M.D., C.A. and P.M. 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. P.M. acknowledges funding support from the European Union’s Horizon 2020 research and innovation program under grant agreement number 870377 (project NEO-MAPP) and from Academies of Excellence: Complex Systems and Space, Environment, Risk, and Resilience, part of the IDEX JEDI of Université Côte d’Azur. M.P. was supported by the Italian Space Agency (ASI) under ASI-INAF agreement number 2017-37-H.0. S.R.S. is supported by contract number 80NSSC18K0226 as part of the OSIRIS-REx Participating Scientist Program.

Author information

Authors and Affiliations

  1. Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA

    R.-L. Ballouz, D. N. DellaGiustina, E. Asphaug, C. A. Bennett, H. C. Connolly Jr, D. R. Golish, M. C. Nolan, B. Rizk, S. R. Schwartz, C. W. V. Wolner & D. S. Lauretta

  2. Southwest Research Institute, Boulder, CO, USA

    K. J. Walsh & W. F. Bottke

  3. The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA

    O. S. Barnouin & R. T. Daly

  4. University of British Columbia, Vancouver, British Columbia, Canada

    M. Al Asad

  5. Smithsonian Institution, Washington, DC, USA

    E. R. Jawin

  6. York University, Toronto, Ontario, Canada

    M. G. Daly

  7. Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France

    P. Michel, C. Avdellidou & M. Delbo

  8. Lockheed Martin Space, Littleton, CO, USA

    E. B. Bierhaus

  9. Department of Geology, Rowan University, Glassboro, NJ, USA

    H. C. Connolly Jr

  10. Planetary Science Institute, Tucson, AZ, USA

    J. L. Molaro

  11. INAF-Astronomical Observatory of Padova, Padua, Italy

    M. Pajola

  12. HIGP/University of Hawaii at Mānoa, Honolulu, HI, USA

    D. Trang

Authors
  1. R.-L. Ballouz
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. K. J. Walsh
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. O. S. Barnouin
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. D. N. DellaGiustina
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. M. Al Asad
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. E. R. Jawin
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. M. G. Daly
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. W. F. Bottke
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. P. Michel
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. C. Avdellidou
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. M. Delbo
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. R. T. Daly
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. E. Asphaug
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. C. A. Bennett
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. E. B. Bierhaus
    View author publications

    You can also search for this author in PubMed Google Scholar

  16. H. C. Connolly Jr
    View author publications

    You can also search for this author in PubMed Google Scholar

  17. D. R. Golish
    View author publications

    You can also search for this author in PubMed Google Scholar

  18. J. L. Molaro
    View author publications

    You can also search for this author in PubMed Google Scholar

  19. M. C. Nolan
    View author publications

    You can also search for this author in PubMed Google Scholar

  20. M. Pajola
    View author publications

    You can also search for this author in PubMed Google Scholar

  21. B. Rizk
    View author publications

    You can also search for this author in PubMed Google Scholar

  22. S. R. Schwartz
    View author publications

    You can also search for this author in PubMed Google Scholar

  23. D. Trang
    View author publications

    You can also search for this author in PubMed Google Scholar

  24. C. W. V. Wolner
    View author publications

    You can also search for this author in PubMed Google Scholar

  25. D. S. Lauretta
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

R.-L.B. led the conceptualization of the study, the images and OLA data analysis, construction of the analytical formalism to measure boulder impact strength from crater sizes, the interpretation of results, and manuscript preparation efforts. K.J.W. contributed to the conceptualization of the study, the interpretation of results, and manuscript preparation efforts. O.S.B. created OLA DTMs of boulders, measured crater dimensions with these products, contributed to the interpretation of results and the preparation of the manuscript. D.N.D., E.R.J. and C.A.B. provided GIS guidance and expertise, contributed to the image analysis, interpretation of the results and the preparation of the manuscript. M.A.A., M.G.D. and R.T.D. contributed to the OLA data analysis, interpretation of the results and the preparation of the manuscript. W.F.B., P.M., C.A., M.D., J.L.M., E.A., E.B.B., M.C.N., M.P., H.C.C. Jr, S.R.S., D.T. and C.W.V.W. contributed to the interpretation of the results and the preparation of the manuscript. B.R. and D.R.G. processed the PolyCam images presented in the manuscript. D.S.L. leads the mission and contributed to the analysis and writing.

Corresponding author

Correspondence to R.-L. Ballouz.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Dan Britt and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Examples of boulders with craters and OLA profiles of the craters.

Boulders are outlined with dashed orange polygons. Craters are outlined with dashed white circles. The crater profile shown below each image corresponds to the dashed yellow line, with the letters A (start) and B (end) in the image indicating the direction of the corresponding profile (from left to right). a, Boulder 1 (image 20190328T191143S208_pol) has a circle-equivalent diameter of 2.9 m and an OLA-measured crater diameter of 1.21 ± 0.09 m. b, Boulder 2 (image 20190328T182010S618_pol) has a circle-equivalent diameter of 3.06 m and an OLA-measured crater diameter of 1.24 ± 0.07 m. c, Boulder 3 (image 20190329T205259S821_pol) has a circle-equivalent diameter of 4.24 m and an OLA-measured crater diameter of 1.60 ± 0.13 m. d, Boulder 4 (image 20190321T185825S567_pol) has a circle-equivalent diameter of 11.3 m and an OLA-measured crater diameter of 4.18 ± 0.47 m.

Extended Data Table 1 Summary of OLA crater profile measurements for a subset of boulders with crater size close to the maximum allowable before disruption
Full size table
Extended Data Table 2 Locations of boulders with flat faces that exhibit multiple impact craters on their surface
Full size table

Supplementary information

41586_2020_2846_MOESM1_ESM.pdf

Supplementary Table 1 Dimensions of craters and their host boulders. We tabulate the locations of boulders with craters and their dimensions based on shape model–projected images with pixel scales of 5 cm. We measure their largest crater radius \({R}_{{\rm{c}}}\), the boulder areal extent \({A}_{{\rm{b}}}\), and the ratio of the crater radius to the host boulder circle-equivalent radius \({R}_{{\rm{c}}}/{R}_{{\rm{t}}}\). We assume 3-pixel uncertainties (15 cm) for these measurements.

Peer Review File

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Ballouz, RL., Walsh, K.J., Barnouin, O.S. et al. Bennu’s near-Earth lifetime of 1.75 million years inferred from craters on its boulders. Nature 587, 205–209 (2020). https://doi.org/10.1038/s41586-020-2846-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-020-2846-z

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing