Towards Calibrating the Vestan Regolith: Correlating the Petrology, Chemistry and Spectroscopy of Howardites

[摘要] The Dawn spacecraft carries a visible and infrared mapping spectrometer (VIR) [1] that has acquired spectra for the wavelength range 0.25-5.0 m at various spatial resolutions covering much of the vestan surface [2]. Through comparison of VIR spectra with laboratory spectra of howardite, eucrite and diogenite meteorites, the distribution of more diogenite-rich and more eucrite-rich terranes on Vesta have been mapped [3], but these maps are qualitative in nature. The available laboratory spectra are not well-integrated with detailed sample petrology or composition limiting their utility for lithologic mapping. Importantly, howardites are now recognized to come in two subtypes, regolithic and fragmental [4]. The former are breccias assembled in part from true regolith, while the latter have had much less exposure to the space environment. We are attempting to develop a more quantitative basis for mapping the distribution of lithologic types on Vesta through acquiring laboratory spectra on splits of howardites that have been petrologically and chemically characterized [5]. Noble gas analyses have been done on some allowing identification of those howardites that have been exposed in the true regolith of Vesta [6].

[发布日期] 2013-07-29

[学科分类] 地质物理学