東京大学
東京大学
東京大学地震研究所
National Aeronautics and Space Administration (NASA)
宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)
東京大学
著者所属（英）
The University of Tokyo
The University of Tokyo
Earthquake Research Institute, The University of Tokyo
National Aeronautics and Space Administration (NASA)
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)
The University of Tokyo
We are developing a Ne isotope measurement system with a permeable membrane for a future Mars mission. A typical lightweight mass spectrometer with moderate mass resolution (m/Δm approximately 10(exp 2)), such as a quadrupole mass spectrometer (QMS), cannot distinguish Ar-40(++) from Ne-20(+) signal because the difference in their mass/charge ratios is very small (m/Δm = 1777). Thus, Ar needs to be removed from sample gas before mass spectrometric measurements. One approach to separate Ne and Ar is to use a permeable membrane. In this study, we experimentally investigate the difference in permeability of Viton sheets between Ar and Ne. Our experimental results indicate that a 1-mm Viton sheet can increase the abundance ratio of Ne to Ar from the atmospheric value of approximately 10(exp -3) to approximately 1. We also measured the ratio of Ar-40(++) to Ar-40(+) using a QMS with a typical ionization voltage (70V). The results indicate that Ar-40(++) is generated about 10% of that of Ar-40(+) during the ionization process in the QMS. These results suggest that the Ne isotope measurement with the uncertainty better than 10% can be performed by correcting for the contribution of Ar-40(++). Since Martian atmospheric pressure is about two orders of magnitude lower and Ne-20/Ar-40 ratio is about one order of magnitude lower, the separation efficiency could decrease compared to that at the Earth atmosphere. However, it has a room for significant improvement by optimization for various parameters, such as materials, thickness, and duration of permeation. These results suggest that measurements of Ne isotopic ratio in Martian atmosphere can be achieved with this approach after optimization.
内容記述
形態: カラー図版あり
内容記述（英）
Physical characteristics: Original contains color illustrations
火星探査におけるネオン測定に向けた分別膜の性能評価
AA1630044000.pdf
(1.92MB)
