Mars Sample Return: From collection to curation of samples from a habitable world

Abstract

NASA's Mars 2020 mission has initiated collection of samples from Mars' Jezero Crater, which has a wide range of ancient rocks and rock types from lavas to lacustrine sedimentary rocks. The Mars Sample Return (MSR) Campaign, a joint effort between NASA and ESA, aims to bring the Perseverance collection back to Earth for intense scientific investigation. As the first return of samples from a habitable world, there are important challenges to overcome for the successful implementation of the MSR Campaign from the point of sample collection on Mars to the long-term curation of the samples on Earth. In particular, the successful execution of planetary protection protocols adds well-warranted complexity to every step of the process from the two MSR Program flight elements to the ground element at the sample receiving facility (SRF). In this contribution, we describe the architecture of the MSR Campaign, with a focus on infrastructure needs for the curation (i.e., the clean storage, processing, and allocation) of pristine Martian samples. Curation is a science-enabling and planetary protection-enabling activity, and the curation practices described in this contribution for the SRF and any long-term curation facility will enable the sample safety assessment, initial scientific investigations of the samples, and establish the MSR collection as a scientific resource that will enable generations of science and discovery through studies of the returned Mars samples. The planetary protection and curation processes established for MSR will provide critical insights into potential future sample return missions from other habitable worlds like Enceladus and Europa.

Keywords: Jezero Crater; Martian; astrobiology; astromaterials; planetary protection.

Fig. 1.

Notional MSR Campaign architecture (Image Credit: Adapted with permission from ref. 26). The cartoon is intended to demonstrate functional steps for the MSR Campaign and, other than the Mars 2020 Mission, may not represent the final campaign mission architecture.

Fig. 2.

Airflow direction in various clean (positive pressure) and biosafety (negative pressure) laboratory settings. The legend refers to a plenum, which is a part of a building that facilitates air circulation through various pathways for airflow. Panels (A and B) include traditional airflow in cleanrooms and biosafety labs, respectively. Panels (C–E) illustrate various strategies for achieving clean high-containment environments that could be utilized for MSR in the SRF. The implementation choice for meeting clean and contained environmental requirements will be dictated by the level of high containment, the cleanliness requirements, and the necessary operations. (A) Typical cleanroom positive-pressure technology; (B) typical high-containment negative-pressure technology; (C) cleanroom within high-containment lab, operated by personnel in positive pressure suits (for activities with less stringent contamination control requirements and larger equipment); (D) specialized ultraclean isolator (for activities with more stringent contamination control requirements and for activities with inert gas requirement); (E) specialized isolator installed within a cleanroom in an overall contained space operated by personnel in cleanroom attire for nominal operations (for isolators, the negative versus positive pressure configuration is reversed to ensure planetary protection requirements are met).

Fig. 3.

The anticipated high-level concept of operations within the SRF is demonstrated in Stages 1 to 4. Infrastructural requirements within the high-containment portion of the SRF will be determined by the operational functions and the cleanliness requirements. The center of the circle represents the environment with the most stringent contamination control requirements, where the pristine samples are processed (Stage 3). Less stringent contamination control requirements are anticipated during hardware disassembly (Stage 1 and 2) and within analytical suites (Stage 4), therefore, this work is positioned closer to the border of the circle. The stages and activities highlighted represent notional examples and are not an exhaustive list of the potential activities or types of spaces that may be implemented within the SRF. Previously undefined acronyms in the figure include: STIC, sample tube isolation container; SOCC, secondary outer containment caps; SCV, secondary containment vessel; RSTA, returnable sample tube assemblies; Pre-BC, Pre-basic characterization; EEV, Earth entry vehicle.