Curation Protocol of Phobos Sample Returned by Martian Moon Exploration (MMX)

Abstract

The Martian Moons Exploration (MMX) aims to return the regolith samples from the Martian moon, Phobos. After the topographic and spectroscopic observation, the spacecraft will land on the surface of Phobos to conduct the sampling operation [1–2]. Pneumatic and coring samplers will collect ≥ 10 g Phobos grains from two different sites. The collected samples will be retrieved from the capsule and transferred to the curation facility in 2029. Sample analyses for the Phobos grains are the key to achieving the MMX mission goals [3]. The mineralogy, petrology, geochemistry and isotopic compositions (e.g. O and Cr) of bulk-scale Phobos grains will, define the origin of Martian moons. Chronology using noble gases and moderately volatile isotopes will determine the timing of geologic events on Phobos. Organic chemistry is also a powerful tool for the origin of small bodies in the case of capture origin. In addition, grains from Mars, possibly incorporated into the Phobos samples, may be the first Martian samples collected by sample return missions. The MMX’s Sample Analysis Working Team (SAWT) designed the flow of the sample analysis of Phobos samples [4]. Before the sample analysis, Phobos samples will be stored in a clean glove box under purified N2 condition, called the “clean chamber.” The operation phase of Phobos grains within the clean chamber is termed “curation.” The design of the curation protocol is critical for the sample allocation and subsequent sample analysis phase. Based on the knowledge of the preceding sample return mission of Hayabusa 2, MMX introduces a new concept of curation, that is, the cooperation of curation with the remote- sensing teams and interdisciplinary Science Strategy Teams (SSTs). This study reports the curation protocols and refined sample analysis flow defined by SAWT with the support of JAXA’s curation team and MMX remote-sensing instrument teams.