Noble Gas Cosmochemistry
William Cassata | 22-FS-038
Noble gases trapped in meteorites contain information on the age, history, and origins of planetary materials. The objective of this one-year feasibility study was to explore several distinct topics in cosmochemistry. The two main efforts pursued were the evolution of atmospheric neon (Ne) on Mars and better constraining the isotopic compositions of krypton (Kr) and xenon (Xe) on Mars. Knowledge of the Ne isotopic composition of the Martian atmosphere can help constrain the extent to which atmospheric escape processes have modified Mars' atmosphere over time. Measurements of Kr and Xe isotopes on Mars have the potential to shed light on timescales over which (and processes by which) Mars acquired its volatiles. Both efforts focused on measurement of gases trapped in Martian meteorites.
The primary technical finding of this project was that Kr and Xe in the Martian mantle are isotopically distinct from the Sun and volatile rich meteorites, but similar to that of Earth. These data are consistent with a scenario in which volatiles (including water) in the planetary interiors of Earth and Mars are primarily derived from inner solar system material, not volatile-rich asteroids from the outer solar system.
The project has impacted LLNL's mission through (1) a manuscript that provides novel insights into planetary volatile reservoirs that can form the basis for program development, (2) supporting engagement with the academic and broader national laboratory communities that is important for staff recruitment, (3) development of a data-analysis capability that could be used to meet future national security challenges, and (4) development of measurement routines that applicable to future work in the noble gas mass spectrometry lab.