Microchemical and structural evidence for space weathering in soils from asteroid Itokawa

Michelle S. Thompson, Roy Christoffersen, Thomas J. Zega, Lindsay P. Keller

Research output: Contribution to journalLetterpeer-review

32 Scopus citations

Abstract

Here we report microchemical and microstructural features indicative of space weathering in a particle returned from the surface of asteroid Itokawa by the Hayabusa mission. Space weathering features include partially and completely amorphous rims, chemically and structurally heterogeneous multilayer rims, amorphous surface islands, vesiculated rim textures, and nanophase iron particles. Solar-wind irradiation is likely responsible for the amorphization as well as the associated vesiculation of grain rims. The multilayer rims contain a nanocrystalline outer layer that is underlain by an amorphous inner layer, and both have compositions that are distinct from the underlying, crystalline orthopyroxene grain. The multilayer rim features could be derived from either radiation-induced sputter deposition or vapor deposition from micrometeorite impact events. The amorphous islands on grain surfaces have a distinctive morphology and composition suggesting that they represent surface deposits of melt derived from micrometeorite impact events. These observations indicate that both irradiation damage and micrometeorite impacts play a role in surface modification and space weathering on asteroid Itokawa.

Original languageEnglish (US)
Article number89
JournalEarth, Planets and Space
Volume66
Issue number1
DOIs
StatePublished - 2014

Keywords

  • Airless body
  • Hayabusa
  • Irradiation
  • Itokawa
  • Micrometeorite impact
  • Sample return analysis
  • Space weathering
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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