Development of in-situ atmospheric Ne measurement on Mars using a polyimide membrane for Ne-Ar separation

Abstract

The compositions of planetary atmosphere inform us origin and evolution of the planets. Each of the planets has a unique atmosphere. Mras has CO₂-dominat atmosphere with the pressure of 1/160 of the terrestrial atmosphere at the surface. The isotopic compositions of H, N, O and Ar in the Martian atmosphere are heavier than those in the terrestrial atmosphere, indicating intense atmospheric escape for Mars (Kurokawa et al., 2020). The Martian atmosphere contains approx. 2.5 ppm of Ne (Owen et al., 1977), however, its isotopic composition is not known so far. Interference of ⁴⁰Ar⁺⁺ to ²⁰Ne⁺ during mass spectrometry is one of the problems to be addressed. In order to perform in-situ Ne isotope measurements on Mars, we are developing a system consisting of a mass spectrometer, a permeable membrane for Ne-Ar separation and purification line (e.g., Miura et al., 2020). In this presentation, results obtained for the permeation experiments using a polyimide sheet with 100 um thickness at low temperatures are reported and discussed.