Towards Martian Moons Exploration: micro-Raman and VIS-MIR reflection spectroscopy of the Phobos surface simulants

Abstract

The Japan Aerospace Exploration Agency (JAXA)’ Martian Moons eXploration (MMX) remote sensing, robotic and sample return mission, scheduled to be launched in 2024 and to return in 2029, will have a strong focus on studying Phobos, including close-up surface analysis and collecting samples for Earth return. A rover, provided by CNES and DLR, will be deployed to Phobos. Its payload includes the Raman spectrometer (RAX) for in-situ characterization of the surface composition. Characterization of payload instrumentation by measurements of planetary simulants is a crucial test for performance and prediction of scientific yield. Controversial conclusions on similarity of infrared reflection and imaging of Phobos to those of low-albedo asteroids imply that combined optical spectroscopy studies will prepare a set of possible clues shortly before the MMX mission. Different Phobos simulants were selected and have been used for Raman and broad range (visible-to-mid-infrared) reflection spectroscopy in order to provide critical parameters on detectivity of mineral phases in the sample matrix as well as to compare the close-up spectroscopy with the known remote sensing of Phobos surface by previous Earth-based observatories and planetary missions.