Contextualizing Sample Return from Comets and Mars Using Multispectral Imaging, Terrestrial Analogs, and Orbital Remote Sensing
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Understanding how we fit into the puzzle of the universe is a resounding theme of humanity. While questions such as "How did life ever arise?" and "Are we alone in the universe?" were once challenged by our limited access to other worlds, we now have many tools to attempt to answer these questions including ground-based observations, space missions, meteor analysis, analog research and even sample return from other worlds. Of these, sample return missions aim to provide unprecedented laboratory access to extraterrestrial worlds. Two possible sample return missions, Comet Astrobiology Exploration Sample Return (CAESAR) and Mars Sample Return (MSR), can address our questions on life from different angles. As comets contain pre-solar grains, organics and less-processed materials from the early solar system, comet sample return can provide insights into the origins of Earth’s oceans, how pre-biotic chemistry arises, and the evolution of the early solar system. Mars Sample Return, on the other hand, can help us to understand if life ever took place on another world, and if so, what conditions were allowed life to take hold. While the eventual return of these cannot be guaranteed, we continue to prepare for their eventual return. As planetary samples can be greatly expanded by detailed contextual geologic information, we provide vital context to interpret future return samples from comets and Mars. We do so by 1) synthesizing the sediment transport pathways on comet 67P/Churyumov-Gerasimenko, 2) characterizing a Mastcam-Z Analog Spectral Imager using this imager to highlight the spectral effects of dust on Mastcam-Z spectra, 3) interpreting oxidation and hydration trends in the crater floor using in-situ and terrestrial analog multispectral data, and 4) expanding our analysis of oxidation and hydration-driven spectral effects across Jezero Crater. To synthesize trends in sediment transport on comet 67P, we selected 619 OSIRIS Narrow Angle Camera Images, then projected, co-registered and searched each image for changes in smooth terrain morphologies. In doing so, we found inter and intra-regional transport of smooth terrain materials with due to both insolation and local topography, as well as evidence for cold trap regions of limited smooth terrain deliverability and escape on the top of each lobe. In order to contextualize possible Mars return samples, we characterize the Mastcam-Z Analog Spectral Imager (MASI), highlighting the similarity of its spectral products to Mastcam-Z and well-characterized field spectrometers. We then compare terrestrial analog spectra collected using MASI and an ASD Visible/Infrared field spectrometer to Mastcam-Z and Supercam spectra from Jezero's crater floor to quantify correlated oxidation-driven spectral parameters, and show stratigraphic trends in oxidation. Finally, we extend our stratigraphic analysis of oxidation and hydration trends using Matscam-Z and SuperCam spectra to encompass Jezero Crater from the Crater Floor to the Crater Rim. Indoingso, we find spectral evidence that oxidation and hydration trends are correlated in Jezero Crater, and highlight variable aqueous alteration within Jezero Crater.