Active Neutron Spectroscopy to Determine the Hydration of Low‐Mass, Sealed Mars Samples

Abstract Mars samples returned to Earth as part of the NASA Mars Sample Return program (MSR) will be subject to a wide range of scientific analyses, many of which will have important implications for the search for life/habitability and planetary evolution. Critical to both of these is the hydration state of the samples. But to ensure the most accurate results, the measurement of volatiles must be accomplished prior to extracting the samples from their sample tubes because significant water loss may occur in the extraction process or before subsequent measurements. Neutron spectroscopy is the only technique that can measure water abundances of sealed samples without altering isotopic abundances. Here we report on simulations of neutron spectroscopy measurements using MSR sample compositions with variable hydration. We show that the neutron count rates in our simulations are well correlated with our simulated sample hydration. We project that very good precisions of ±0.5 wt.% water-equivalent hydrogen can be achieved in measurements of 3–4 hr or less precise results of ±1.0 wt.% in ∼45 min.