Martian meteorite bulk chemistry dataset to aid in orbital gamma ray and neutron data interpretation of Phobos*

The Mars-moon Exploration with GAmma rays and NEutrons (MEGANE) instrument aboard the Martian Moons eXploration (MMX) spacecraft will travel to Phobos to take elemental measurements of the surface. This 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 of Phobos. The data from MEGANE 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. In all, we achieved a dataset that represents 32% of the martian meteorite clan. Within the dataset, 72% of the meteorites had two or more chemistries 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, we focused on the large variation in the chassignite group as well as the various petrologies of the shergottite subgroups. This was done to further condense the lithologies that may be on Phobos, if giant impact proves more likely.