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Distinctive space weathering on Vesta from regolith mixing processes

Abstract

The surface of the asteroid Vesta has prominent near-infrared absorption bands characteristic of a range of pyroxenes, confirming a direct link to the basaltic howardite–eucrite–diogenite class of meteorites1,2,3. Processes active in the space environment produce ‘space weathering’ products that substantially weaken or mask such diagnostic absorption on airless bodies observed elsewhere4,5, and it has long been a mystery why Vesta’s absorption bands are so strong. Analyses of soil samples from both the Moon6 and the asteroid Itokawa7 determined that nanophase metallic particles (commonly nanophase iron) accumulate on the rims of regolith grains with time, accounting for an observed optical degradation. These nanophase particles, believed to be related to solar wind and micrometeoroid bombardment processes, leave unique spectroscopic signatures that can be measured remotely8,9,10 but require sufficient spatial resolution to discern the geologic context and history of the surface, which has not been achieved for Vesta until now. Here we report that Vesta shows its own form of space weathering, which is quite different from that of other airless bodies visited. No evidence is detected on Vesta for accumulation of lunar-like nanophase iron on regolith particles, even though distinct material exposed at several fresh craters becomes gradually masked and fades into the background as the craters age. Instead, spectroscopic data reveal that on Vesta a locally homogenized upper regolith is generated with time through small-scale mixing of diverse surface components.

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Figure 1: The optical properties across a typical area on Vesta as measured by Dawn.
Figure 2: Diverse material exposed at fresh craters in a well-developed regolith on Vesta.
Figure 3: The Canuleia region mapped at different spatial resolutions by Dawn’s two optical instruments.
Figure 4: Spectroscopic comparisons of Vesta soils with similar materials on the Moon.

References

  1. De Sanctis, M. C. et al. Spectroscopic characterization of mineralogy and its diversity across Vesta. Science 336, 697–700 (2012)

    Article  ADS  CAS  Google Scholar 

  2. Reddy, V. et al. Color and albedo heterogeneity of Vesta from Dawn. Science 336, 700–704 (2012)

    Article  ADS  CAS  Google Scholar 

  3. McCord, T. B., Adams, J. B. & Johnson, T. V. Asteroid Vesta: spectral reflectivity and compositional implications. Science 168, 1445–1447 (1970)

    Article  ADS  CAS  Google Scholar 

  4. Pieters, C. M. et al. Space weathering on airless bodies: resolving a mystery with lunar samples. Meteorit. Planet. Sci. 35, 1101–1107 (2000)

    Article  ADS  CAS  Google Scholar 

  5. Hapke, B. Space weathering from Mercury to the asteroid belt. J. Geophys. Res. 106, 10039–10073 (2001)

    Article  ADS  CAS  Google Scholar 

  6. Keller, L. P. & McKay, D. S. The nature and origin of rims on lunar soil grains. Geochim. Cosmochim. Acta 61, 2331–2341 (1997)

    Article  ADS  CAS  Google Scholar 

  7. Noguchi, T. et al. Incipient space weathering observed on the surface of Itokawa dust particles. Science 333, 1121–1125 (2011)

    Article  ADS  CAS  PubMed Central  Google Scholar 

  8. Sasaki, S., Nakamura, K., Hamabe, Y., Kurahashi, E. & Hiroi, H. Production of iron nanoparticles by laser irradiation in a simulation of lunar-like space weathering. Nature 410, 555–557 (2001)

    Article  ADS  CAS  PubMed Central  Google Scholar 

  9. Marchi, S., Brunetto, R., Magrin, S., Lazzarin, M. & Gandolfi, D. Space weathering of near-Earth and main belt silicate-rich asteroids: observations and ion irradiation experiments. Astron. Astrophys. 443, 769–775 (2005)

    Article  ADS  CAS  Google Scholar 

  10. Noble, S. K., Pieters, C. M. & Keller, L. P. An experimental approach to understanding the optical effects of space weathering. Icarus 192, 629–642 (2007)

    Article  ADS  CAS  Google Scholar 

  11. Adams, J. B. & McCord, T. B. Alteration of lunar optical properties: age and composition effects. Science 171, 567–571 (1971)

    Article  ADS  CAS  PubMed Central  Google Scholar 

  12. Hiroi, T., Pieters, C. & Takeda, H. Grain size of the surface regolith of asteroid 4 Vesta estimated from its reflectance spectrum in comparison with HED meteorites. Meteoritics 29, 394–396 (1994)

    Article  ADS  Google Scholar 

  13. Pieters, C. M. et al. in Asteroids, Comets, and Meteors 273–288 (Cambridge Univ. Press, 2006)

    Google Scholar 

  14. Matson, D. L., Johnson, T. V. & Veeder, G. J. Soil maturity and planetary regoliths: the Moon, Mercury, and the asteroids. Proc. Lunar Sci. Conf. 8, 625–627 (1977)

    Google Scholar 

  15. Clark, B. E., Hapke, B., Pieters, C. & Britt, D. in Asteroids III (eds Bottke, W. F., Cellino, A., Paolicchi, P. & Binzel, R. P.) 585–599 (Univ. Arizona Press, 2002)

    Google Scholar 

  16. Chapman, C. R. Space weathering of asteroid surfaces. Annu. Rev. Earth Planet. Sci. 32, 539–567 (2004)

    Article  ADS  CAS  Google Scholar 

  17. Trombka, J. et al. The elemental composition of asteroid 433 Eros: results of the NEAR-Shoemaker X-ray spectrometer. Science 289, 2101–2105 (2000)

    Article  ADS  CAS  PubMed Central  Google Scholar 

  18. Clark, B. E. et al. Space weathering on Eros: constraints from albedo and spectral measurements of Psyche crater. Meteorit. Planet. Sci. 36, 1617–1637 (2001)

    Article  ADS  CAS  Google Scholar 

  19. Nakamura, T. et al. Itokawa dust particles: a direct link between S-type asteroids and ordinary chondrites. Science 333, 1113–1116 (2011)

    Article  ADS  CAS  Google Scholar 

  20. Binzel, R. P. et al. MUSES-C target asteroid (25143) 1998 SF36: a reddened ordinary chondrite. Meteorit. Planet. Sci. 36, 1167–1172 (2001)

    Article  ADS  CAS  Google Scholar 

  21. Hiroi, T. et al. Developing space weathering on the asteroid 25143 Itokawa. Nature 443, 56–58 (2006)

    Article  ADS  CAS  PubMed Central  Google Scholar 

  22. McCord, T. et al. Dark material on Vesta from the infall of carbonaceous volatile-rich material. Nature http://dx.doi.org/10.1038/nature11561 (this issue)

  23. Li, J.-Y. et al. Investigating the origin of bright materials on Vesta: synthesis, conclusions, and implications. Proc. Lunar Planet. Sci. Conf. 43, abstr. 2381. (2012)

  24. Jaumann, R. et al. Vesta’s shape and morphology. Science 336, 687–690 (2012)

    Article  ADS  CAS  Google Scholar 

  25. Pieters, C. M. et al. The Moon Mineralogy Mapper (M3) on Chandrayaan-1. Curr. Sci. 96, 500–505 (2009)

    CAS  Google Scholar 

  26. Noble, S. K. & Keller, L. P. &. Pieters, C. M. Evidence of space weathering in regolith breccias II: asteroidal regolith breccias. Meteorit. Planet. Sci. 45, 2007–2015 (2010)

    Article  ADS  CAS  Google Scholar 

  27. Britt, D. & Pieters, C. M. Darkening in black and gas-rich ordinary chondrite meteorites: the spectral effects of opaque morphology and distribution. Geochim. Cosmochim. Acta 58, 3905–3919 (1994)

    Article  ADS  CAS  Google Scholar 

  28. Marchi, S. et al. The violent collisional history of asteroid 4 Vesta. Science 336, 690–694 (2012)

    Article  ADS  CAS  PubMed Central  Google Scholar 

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

    Article  ADS  CAS  PubMed Central  Google Scholar 

  30. Bottke, W. F. & Nolan, M. C. Greenberg, R. & Kolvoord, R. A. Velocity distributions among colliding asteroids. Icarus 107, 255–268 (1994)

    Article  ADS  Google Scholar 

  31. Russell, C. T. et al. Dawn at Vesta: testing the protoplanetary paradigm. Science 336, 684–686 (2012)

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We acknowledge the Dawn Instrument, Flight and Operations teams for the successful development, cruise, orbital insertion and operations of the Dawn spacecraft at Vesta. US team members are supported by the NASA Discovery Program through contract NNM05AA86C to the University of California, Los Angeles and by the NASA Dawn participating scientist programme.

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Contributions

C.M.P., D.T.B., M.C.D.S., S.M., L.A.M., D.W.M., V.R. and C.T.R. contributed to writing and improving the manuscript. E.A., L.L.C. and A.N. provided calibrated Dawn data. E.P. provided data searches. All authors contributed to discussion of the results.

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Correspondence to C. M. Pieters.

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The authors declare no competing financial interests.

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Pieters, C., Ammannito, E., Blewett, D. et al. Distinctive space weathering on Vesta from regolith mixing processes. Nature 491, 79–82 (2012). https://doi.org/10.1038/nature11534

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