Mars Analogue Sample Library

Introduction:  Samples collected by NASA’s Mars 2020 Perseverance rover that are intended for return to Earth would be analyzed based on the highest priority recommendations of the international science community. The samples collected at Jezero crater by Perseverance consist of a variety of rocks (e.g., sedimentary and volcanic), regolith, and atmospheric gas [1-4]. With each additional sample, the potential cache continues to become more scientifically valuable. Regardless of the additional samples, even the current suite of samples represents a scientifically return-worthy cache [5].

Before these precious samples are investigated in state-of-the-art laboratories on Earth, extensive testing of analogues is necessary to fully prepare for engineering, science, curation, and planetary protection needs. Therefore, multiple teams branching from the Mars Sample Return (MSR) Campaign Science Group (MCSG) have been chartered to strategically select natural samples from the field that best represent discrete components of the Jezero samples. Collectively, these samples make up the Analogue Sample Library (ASL), set up to support MSR, and jointly hosted by NASA and ESA. The ASL is designed to serve as a resource for preparations to receive and analyse returned samples and support the broader scientific community in research, communication and outreach. Samples in the ASL collection are curated at and distributed from the Natural History Museum in Oslo in collaboration with the University of Oslo (UiO). This activity is supported by the Norwegian Space Agency (NOSA) and ESA.

Current ASL Collection:  In late 2022 an external expert science group, the ‘Rock Sample Team’ was appointed by the MSR Joint Science Office for various project needs. They were tasked to identify terrestrial analogue sites for four different lithologies based on the samples placed in the first sample depot on Mars at Three Forks.

These samples include (letters correlate to Fig. 1): (A) holocrystalline basalts, both aphyric and plagioclase-phyric, from Oregon, USA, (B) carbonate cemented and (C) carbonate-gypsum cemented fine sandstones/siltstones from California, and (D) eolian volcanic sands from Iceland, and (E) olivine cumulates from Scotland. The Rock Sample Team solicited input from the community and developed an extensive list of potential analogues before narrowing down to five candidates [6]. With field teams built from both NASA and ESA representatives, local geologists, as well as members from the Mars 2020 Science team, the first samples for the ASL were collected during the field campaign 2023 (Fig. 1).

Figure 1. Map displaying the sites of the field campaign 2023 (red stars) and newly proposed field sites (yellow stars; [7]). Pictures from the field teams of each field site are shown in inserts A-E.

Allocation of analogue samples: On November 14th, 2024, the ASL was officially opened at the Natural History Museum, Oslo. Analogue samples can be requested from the ASL. Proposals for allocation are evaluated according to priority of the proposed activity, which are (1) preparatory work for sample receiving, (2) the scientific community, and (3) public relations and outreach. The sample allocation process is managed by the NASA-ESA MSR Analogue Sample Allocation Panel (ASAP, Fig.2). Requests for analogue samples can be made via a web-interface (sample request) and are processed in a timely manner. The ASL also includes comprehensive baseline sample characterization by the Norwegian Geotechnical Institute (NGI), with reports available to the community.

Figure 2. Organizational flowchart for ASL sample management from collection and sample characterization to allocation and curation [6,7].

Ongoing and future work:  The MCSG chartered a new sub-team, the MCSG Analogue Team, which is tasked to critically evaluate the current collection and identifying any areas that need to be supplemented. One of the first tasks of the Analogue Team was to reevaluate the sedimentary analogue samples and subsequently, two new field sites were identified in Italy and Iceland (Fig. 1) to collect (1) a sandstone with basaltic provenance and (2) sandstone to pebble conglomerates with an ultramafic provenance. These analogues will be collected during the 2025 field campaign, funded by ESA and NASA. Their addition to the ASL will make the analogue collection more comprehensive. The Analogue Team also plans to re-examine both the igneous and regolith sample analogs. Finally, the team plans to continuously build the ASL as the Perseverance rover continues to diversify its cache.

The ASL represents a key resource for the preparation to study returned samples from Mars, as it enables wide availability of terrestrial analogue samples that are strategically selected to best represent the properties of diverse Mars samples at Jezero crater and collected by the Perseverance Rover.

Acknowledgments: The authors would like to thank the members of the “Rock Sample Team” for their recommendations on terrestrial analogue sample. We also would like to thank the members of the field campaign 2023 for their effort to collect the analogue samples.

 Disclaimer: The decision to implement Mars Sample Return will not be finalized until NASA’s completion of the National Environmental Policy Act (NEPA) process. This document is being made available for informational purposes only.