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Paper No. 101-4
Presentation Time: 8:00 AM-5:30 PM
MARTIAN METEORITE BULK CHEMISTRY DATASET TO AID IN ORBITAL GAMMA RAY AND NEUTRON DATA INTERPRETATION OF PHOBOS
The Mars-Exploration with GAmma rays and NEutrons (MEGANE) instrument aboard the Martian Moons eXploration (MMX) spacecraft will travel to Phobos and Deimos, the two martian moons, to take elemental measurements of both bodies. This international mission led by the Japan Aerospace Exploration Agency (JAXA) aims to determine the origin of the martian moons (giant impact vs. captured asteroid) via sample return and orbital measurements. The data from MEGANE (orbital gamma ray and neutron detector) requires a robust geochemical library of martian meteorites to aid data interpretation. This study conducted an in-depth literature review to compile bulk chemistries from a variety of martian meteorite petrologies. Specific focus was given to acquiring chemistries from several aliquots of each meteorite, as chemistry from single sub gram aliquots are not representative. The data from each meteorite was then averaged and used to calculate various neutron measurables MEGANE will detect on Phobos. In all, we achieved a dataset that represents 32% of the martian meteorite clan, and within the dataset, 72% of the meteorites had two or more chemistries that were averaged together. Several recorded meteorite pairs were also incorporated into the dataset, further expanding the number of single meteorites that had more than one compositional analysis.
Through the course of this work, a Fe-poor/Mg-rich composition for chassignite (NWA 2737) was incorporated, establishing a broader compositional range for that petrologic group. The variation in NWA 2737 is due to olivine composition, not abundance. Hence this sample has lower Fe but similar Si to the rest of the group. This finding is significant as both Si and Fe are MEGANE measurables. We also subdivided the shergottite group into petrologic subgroups (e.g. basaltic, olivine-phyric, etc.), allowing for discrimination of shergottite sub lithologies on Phobos, if present and if resolvable by MEGANE.