Distinguishing between shock-darkening and space-weathering trends in ordinary chondrite reflectance spectra

Tomas Kohout, Antti Penttilä, Paul Mann, Ed Cloutis, Jan Čuda, Jan Filip, Ondrej Malina, Vishnu Reddy, Victor I. Grokhovsky, Grigoriy A. Yakovlev, Patricie Halodova, Jakub Haloda

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Space-weathering as well as shock effects can darken meteorite and asteroid reflectance spectra. We present a detailed comparative study on shock-darkening and space-weathering using different lithologies of the Chelyabinsk LL5 chondrite. Compared to space-weathering, the shock processes do not cause significant spectral slope changes and are more efficient in attenuating the orthopyroxene 2 μm absorption band. This results in a distinct shock vector in the reflectance spectra principal component analysis, moving the shocked silicate-rich Chelyabinsk spectra from the S-complex space into the C/X complex. In contrast to this, the space-weathering vector stays within the S complex, moving from Q type to S type. Moreover, the 2 μm to 1μm band depth ratio (BDR) as well as the 2 μm to 1μm band area ratio (BAR) are not appreciably affected by shock-darkening or shock melting. Space-weathering, however, causes significant shifts in both BDR and BAR toward higher values. Application of the BDR method to the three distinct areas on the asteroid Itokawa reveals that Itokawa is rather uniformly space-weathered and not influenced by regolith roughness or relative albedo changes.

Original languageEnglish (US)
Article number37
JournalPlanetary Science Journal
Volume1
Issue number2
DOIs
StatePublished - Sep 2020
Externally publishedYes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Geophysics

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