Sampling and curation of volatile elements in the new era of sample return missions
Guillaume Avice1, Frédéric Moynier1, C. Mustin2, Jean Duprat3
Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, France
2
IMPMC, Muséum National d’Histoire Naturelle, Sorbonne Université, CNRS, Paris, France
3
Centre National D’Etudes Spatiales (CNES), France1

The scientific community has been entering a new era of sample return missions with the successful Hayabusa 1&2 (JAXA) andfuture OSIRIS-REx (NASA) missions, the future missions of samples return from Mars (Mars Sample Return mission, NASAand ESA) and its moon Phobos (MMX, JAXA). Other than their inner scientific values, sample return missions are of key
scientific importance as they trigger the development of suites of state-of-the-art analytical techniques in terrestrial laboratories
to conduct exhaustive characterization of the returned samples (petrography, mineralogy, chemical analyses etc.). Among theseinvestigations, measuring the elemental and isotopic composition of volatile elements in extraterrestrial samples is a high priority
scientific target as they can be used to understand the origin of planetary atmospheres and of water in terrestrial planets (e.g.,[1]). More broadly, such measurements could provide answers to the question: Why is the Earth habitable? Such investigations
rely on the ability to conduct a proper curation of the samples containing volatile elements. A recent study highlighted the needfor developing advanced curation techniques for volatile-rich samples [2] and a recent experiment developed by US-based
scientists opened lunar core containers returned to Earth by the Apollo astronauts in order to sample volatile elements (see ref. 3).
Developing new curation techniques is also one of the goals of the future curation center CENAME (a Center National for
Extraterrestrial Materials) which will be built at the French Musée National d'Histoire Naturelle (MNHN, Paris, France) incollaboration with the Institut de physique du globe de Paris (IPGP, France) (see J. Duprat et al., this meeting). This is also one
goal of the project MARCUS led by CNES (PI. C. Mustin) and which is part of the new French initiative PEPR Origins: fromplanets to life.
In 2019, the Hayabusa2 mission successfully sampled over 5 grams of solid samples from the surface and subsurface of theasteroid Ryugu. The preliminary scientific investigations revealed that Ryugu samples are similar to primitive carbonaceous
material similar to Ivuna-type meteorites but with less alteration than identified in these meteorites [4]. Having pristine samples
from carbon-rich asteroids also allows to put new constraints on the role of these bodies in the delivery of volatile elements toEarth [5]. Recent measurements of the D/H ratio of hydrogen contained in Ryugu samples revealed that carbonaceous-typematerial could have delivered up to 3% of Earth's water [6]. Importantly, the sealing technique adopted for closing the sample
capsule consisted in an aluminum metal seal [7], maximizing the chances to retain extraterrestrial volatile-rich elements such as
noble gases. A quick recovery of the sample capsule followed by careful onsite curation protocols [8] allowed to recover the gas
originally contained in the sample capsule. Results obtained by a preliminary study reveal that, despite a certain degree ofcontamination by the Earth's atmosphere, the gas sampled during the mission is extraterrestrial with a clear contribution fromsolar-wind derived gases [9]. Investigations also revealed that the Al-seal partially re-opened during Earth’s entry due to thestrong deceleration when the parachute deployed.
The technical developments and sample handling protocols used before, during and after the return of samples by the Hayabusa2
mission are the best and most recent examples of advanced curation techniques for volatile-rich elements collected during space
missions [8,9]. Therefore, they represent a reference starting point for improving the current curation protocols and developing
new solutions. Ryugu samples are thus providing perfect opportunity to assess the quality of the current techniques of curationof volatile-rich extraterrestrial samples. In this presentation we will show how Hayabusa2 samples have the potential to provide
key information on the state-of-the-art of curation techniques and possible improvements.
Gas samples from Ryugu allocated by the JAXA curation center will be delivered to IPGP in fall 2023. Noble gases (Ne, Ar, Krand Xe) elemental and isotopic composition will be immediately measured in order to : i) evaluate if the different samplesprepared by the curation team have the same composition (NT1 vs NT2 sample) ; ii) compare with published data (e.g., [9]) forNT1 sample and evaluate if the composition of the gas has evolved since the preliminary investigations. Samples will then be
stored in distinct conditions (closed and exposed to room pressure and temperature for one sample, closed and attached to a turbo
molecular pumping station for another sample, closed and exposed to moderate vacuum for another sample). New measurements
will then be conducted after 6-9 months to assess which storage conditions is the most appropriate. Results will be shared anddiscussed with the JAXA curation team the international community concerned on this aspect of the curation of extraterrestrialsamples.

Figure 1: Summary of the sample allocated by the JAXA curation center. The original samples NT1, NT2 and NT5(bottles, ref. 8) are identified as well as the three different pipettes to be drawn from the bottle by the JAXA curation
team. Samples will be measured at different times and stored in different conditions to evaluate curation techniques.

In this presentation we will also describe future long-term developments for the curation of volatile-rich samples. One
development will involve testing new materials for the sample containers (e.g., TiN covered Titanium coupons used for thepreparation of Perseverance sample tubes and gently provided by colleagues from JPL). We will also improve curation protocols(short- and long-term monitoring) and develop new solutions for vacuum containers.
References[1] Avice G. & Marty B. 2020. Space Science Reviews 216:36. [2] McCubbin et al. 2019. Space Science Reviews 215:48. [3]Parai et al. 2022. Apollo 17 – ANGSA Workshop, LPI Contrib. N°2704:2028. [4] Yokoyama et al. 2022. Science379:eabn7850. [5] Paquet et al. 2023. EPSL 611:118126. [6] Piani et al. 2023. Astrophysical Journal Letters 946:L43.
[7] Okazaki et al. 2017. Space Science Reviews 208:107-124. [8] Miura et al. 2022. Earth Planets Space 74:76. [9] Okazaki etal. 2023. Science 379:eabo0431.