20-EPN2-048: Heating effects on the spectral reflectance properties of carbonaceous chondrite meteorites
Visit by Edward Cloutis, University of Winnipeg (Canada), to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 28 August – 2 September 2022
Report Summary: Carbonaceous chondrites are likely derived from dark (C-class) asteroids. Sample return missions to dark asteroids (JAXA Hayabusa-2, OSIRIS-REx) will allow us to link specific meteorites to these possible parent bodies. The compositions of the sample return target asteroids (Ryugu and Bennu) are currently unknown, as are the compositions of other dark asteroids. Dark asteroids are important scientific targets because they may have delivered prebiotic organic molecules to the early Earth.To help address how we can determine the compositions of dark asteroids, particularly whether they are primitive, aqueously-altered, and/or heated, we conducted a series of experiments at PSL designed to address this.
Specifically, we performed heating experiments, in vacuum, on clay minerals present in carbonaceous chondrite meteorites, and measured their subsequent spectral reflectance properties, as well as on samples heated in previous experiments (clays, carbonaceous chondrites, carbonaceous chondrite analogues), focusing on the most diagnostic spectral feature relevant to dark asteroids – the 3 micron region hydroxyl/water absorption band. The results are still being analysed, but it appears that heating in vacuum and exposure to vacuum cause changes in the depth and shape of this absorption feature, as well as the albedo, spectral slope, and appearance of additional absorption features. The results of this study will provide important constraints into the composition and history of dark asteroids.