Planning Implications Related to Sterilization-Sensitive Science Investigations Associated with Mars Sample Return (MSR)

Multi-Technique Characterization of 3.45 Ga Microfossils on Earth: A Key Approach to Detect Possible Traces of Life in Returned Samples from Mars

The NASA Mars 2020 Perseverance rover is actively exploring Jezero crater to conduct analyses on igneous and sedimentary rock targets from outcrops located on the crater floor (Máaz and Séítah formations) and from the delta deposits, respectively. The rock samples collected during this mission will be recovered during the Mars Sample Return mission, which plans to bring samples back to Earth in the 2030s to conduct in-depth studies using sophisticated laboratory instrumentation. Some of these samples may contain traces of ancient martian life that may be particularly difficult to detect and characterize because of their morphological simplicity and subtle biogeochemical expressions. Using the volcanic sediments of the 3.45 Ga Kitty's Gap Chert (Pilbara, Australia), containing putative early life forms (chemolithotrophs) and considered as astrobiological analogues for potential early Mars organisms, we document the steps required to demonstrate the syngenicity and biogenicity of such biosignatures using multiple complementary analytical techniques to provide information at different scales of observation. These include sedimentological, petrological, mineralogical, and geochemical analyses to demonstrate macro- to microscale habitability. New approaches, some unavailable at the time of the original description of these features, are used to verify the syngenicity and biogenicity of the purported fossil chemolithotrophs. The combination of elemental (proton-induced X-ray emission spectrometry) and molecular (deep-ultraviolet and Fourier transform infrared) analyses of rock slabs, thin sections, and focused ion beam sections reveals that the carbonaceous matter present in the samples is enriched in trace metals (e.g., V, Cr, Fe, Co) and is associated with aromatic and aliphatic molecules, which strongly support its biological origin. Transmission electron microscopy observations of the carbonaceous matter documented an amorphous nanostructure interpreted to correspond to the degraded remains of microorganisms and their by-products (extracellular polymeric substances, filaments…). Nevertheless, a small fraction of carbonaceous particles has signatures that are more metamorphosed. They probably represent either reworked detrital biological or abiotic fragments of mantle origin. This study serves as an example of the analytical protocol that would be needed to optimize the detection of fossil traces of life in martian rocks.

DNA sequencing at the picogram level to investigate life on Mars and Earth

DNA is an incontrovertible biosignature whose sequencing aids in species identification, genome functionality, and evolutionary relationships. To study life within the rocks of Earth and Mars, we demonstrate, in an ISO5 clean room, a procedure based on nanopore technology that correctly identifies organisms at picogram levels of DNA without amplification. Our study with E. coli and S. cerevisiae DNA samples showed that MinION sequencer (Oxford Nanopore Technologies) can unequivocally detect and characterise microbes with as little as 2 pg of input with just 50 active nanopores. This result is an excellent advancement in sensitivity, immediately applicable to investigating low biomass samples. This value is also at the level of possible background contamination associated with the reagents and the environment. Cultivation of natural and heat-treated Martian analogue (MMS-2) regolith samples, exposed to atmospheric water vapour or in increasing water concentrations, led to the extraction of 600-1000 pg of DNA from 500 mg of soil. Applying the low detectability technology enabled through MinION sequencer for a natural low biomass setting, we characterised the dry MMS-2 and found few soil-related organisms and airborne contaminants. The picogram detection level and the procedure presented here, may be of interest for the future Mars sample Return program, and the life research and planetary protection studies that will be implemented through the sample safety assessment.

Science and Curation Considerations for the Design of a Mars Sample Return (MSR) Sample Receiving Facility (SRF)

The most important single element of the "ground system" portion of a Mars Sample Return (MSR) Campaign is a facility referred to as the Sample Receiving Facility (SRF), which would need to be designed and equipped to receive the returned spacecraft, extract and open the sealed sample container, extract the samples from the sample tubes, and implement a set of evaluations and analyses of the samples. One of the main findings of the first MSR Sample Planning Group (MSPG, 2019a) states that "The scientific community, for reasons of scientific quality, cost, and timeliness, strongly prefers that as many sample-related investigations as possible be performed in PI-led laboratories outside containment." There are many scientific and technical reasons for this preference, including the ability to utilize advanced and customized instrumentation that may be difficult to reproduce inside in a biocontained facility, and the ability to allow multiple science investigators in different labs to perform similar or complementary analyses to confirm the reproducibility and accuracy of results. It is also reasonable to assume that there will be a desire for the SRF to be as efficient and economical as possible, while still enabling the objectives of MSR to be achieved. For these reasons, MSPG concluded, and MSPG2 agrees, that the SRF should be designed to accommodate only those analytical activities that could not reasonably be done in outside laboratories because they are time- or sterilization-sensitive, are necessary for the Sample Safety Assessment Protocol (SSAP), or are necessary parts of the initial sample characterization process that would allow subsamples to be effectively allocated for investigation. All of this must be accommodated in an SRF, while preserving the scientific value of the samples through maintenance of strict environmental and contamination control standards. Executive Summary The most important single element of the "ground system" portion of a Mars Sample Return (MSR) Campaign is a facility referred to as the Sample Receiving Facility (SRF), which would need to be designed and equipped to enable receipt of the returned spacecraft, extraction and opening of the sealed sample container, extraction of the samples from the sample tubes, and a set of evaluations and analyses of the samples-all under strict protocols of biocontainment and contamination control. Some of the important constraints in the areas of cost and required performance have not yet been set by the necessary governmental sponsors, but it is reasonable to assume there will be a desire for the SRF to be as efficient and economical as is possible, while still enabling the objectives of MSR science to be achieved. Additionally, one of the main findings of MSR Sample Planning Group (MSPG, 2019a) states "The scientific community, for reasons of scientific quality, cost, and timeliness, strongly prefers that as many sample-related investigations as possible be performed in PI-led laboratories outside containment." There are many scientific and technical reasons for this preference, including the ability to utilize advanced and customized instrumentation that may be difficult to reproduce inside a biocontained facility. Another benefit is the ability to enable similar or complementary analyses by multiple science investigators in different laboratories, which would confirm the reproducibility and accuracy of results. For these reasons, the MSPG concluded-and the MSR Science Planning Group Phase 2 (MSPG2) agrees-that the SRF should be designed to accommodate only those analytical activities inside biocontainment that could not reasonably be done in outside laboratories because such activities are time-sensitive, sterilization-sensitive, required by the Sample Safety Assessment Protocol (SSAP), or are necessary parts of the initial sample characterization process that would allow subsamples to be effectively allocated for investigation. All activities within the SRF must be done while preserving the scientific value of the samples through maintenance of strict environmental and contamination control standards. The SRF would need to provide a unique environment that consists of both Biosafety Level 4 (BSL-4) equivalent containment and a very high level of contamination control. The SRF would also need to accommodate the following activities: (1)Receipt of the returned spacecraft, presumably in a sealed shipping container (2)De-integration (i.e., disassembly) and assessment of the returned system, beginning with the spacecraft exterior and ending with accessing and isolating all Mars material (gas, dust, regolith, and rock) (3)Initial sample characterization, leading to development of a sample catalog sufficient to support sample allocation (see Tait et al., 2022) (4)Science investigations necessary to complete the SSAP (see Kminek et al., 2021) (5)Certain science investigations that are both time- and sterilization-sensitive (see Tosca et al., 2022; Velbel et al., 2022) (6)A managed transition to post-SRF activities that would include analysis of samples (either sterilized or not) outside biocontainment and the transfer of some or all samples to one or more uncontained curation facilities The MSPG2 has produced a compilation of potential design requirements for the SRF, based on the list of activities noted above, that can be used in cost and schedule planning. The text of this report is meant to serve as an overview and explanation of these proposed SRF Design Requirements that have been compiled by the MSPG2 SRF Requirements Focus Group (Supplement 1). Summary of Findings FINDING SRF-1: The quality of the science that can be achieved with the MSR samples will be negatively impacted if they are not protected from contamination and inappropriate environmental conditions. A significant amount of SRF infrastructure would therefore be necessary to maintain and monitor appropriate levels of cleanliness, contamination control, and environmental conditions. FINDING SRF-2: Although most MSR sample investigations would take place outside of the SRF, the SRF needs to include significant laboratory capabilities with advanced instruments and associated sample preparation systems to enable the MSR science objectives to be successfully achieved. FINDING SRF-3: Preliminary studies of different operational scenarios should be started as soon as possible to enable analysis of the trade-offs between the cost and size of the SRF and the amount of time needed to prepare the samples for allocation and analysis. FINDING SRF-4: The ability to add additional analytical capabilities within biocontainment should be preserved to address the contingency scenario in which unsterilized material is not cleared to be analyzed outside of biocontainment. If potential evidence of martian life were to be detected in the samples, for example, it would be a high priority to conduct further investigations related to any putative lifeforms, as well as to enable other sterilization-sensitive science investigations to be conducted in biocontainment.

COSPAR Sample Safety Assessment Framework (SSAF)

The Committee on Space Research (COSPAR) Sample Safety Assessment Framework (SSAF) has been developed by a COSPAR appointed Working Group. The objective of the sample safety assessment would be to evaluate whether samples returned from Mars could be harmful for Earth's systems (e.g., environment, biosphere, geochemical cycles). During the Working Group's deliberations, it became clear that a comprehensive assessment to predict the effects of introducing life in new environments or ecologies is difficult and practically impossible, even for terrestrial life and certainly more so for unknown extraterrestrial life. To manage expectations, the scope of the SSAF was adjusted to evaluate only whether the presence of martian life can be excluded in samples returned from Mars. If the presence of martian life cannot be excluded, a Hold & Critical Review must be established to evaluate the risk management measures and decide on the next steps. The SSAF starts from a positive hypothesis (there is martian life in the samples), which is complementary to the null-hypothesis (there is no martian life in the samples) typically used for science. Testing the positive hypothesis includes four elements: (1) Bayesian statistics, (2) subsampling strategy, (3) test sequence, and (4) decision criteria. The test sequence capability covers self-replicating and non-self-replicating biology and biologically active molecules. Most of the investigations associated with the SSAF would need to be carried out within biological containment. The SSAF is described in sufficient detail to support planning activities for a Sample Receiving Facility (SRF) and for preparing science announcements, while at the same time acknowledging that further work is required before a detailed Sample Safety Assessment Protocol (SSAP) can be developed. The three major open issues to be addressed to optimize and implement the SSAF are (1) setting a value for the level of assurance to effectively exclude the presence of martian life in the samples, (2) carrying out an analogue test program, and (3) acquiring relevant contamination knowledge from all Mars Sample Return (MSR) flight and ground elements. Although the SSAF was developed specifically for assessing samples from Mars in the context of the currently planned NASA-ESA MSR Campaign, this framework and the basic safety approach are applicable to any other Mars sample return mission concept, with minor adjustments in the execution part related to the specific nature of the samples to be returned. The SSAF is also considered a sound basis for other COSPAR Planetary Protection Category V, restricted Earth return missions beyond Mars. It is anticipated that the SSAF will be subject to future review by the various MSR stakeholders.

Final Report of the Mars Sample Return Science Planning Group 2 (MSPG2)

The Mars Sample Return (MSR) Campaign must meet a series of scientific and technical achievements to be successful. While the respective engineering responsibilities to retrieve the samples have been formalized through a Memorandum of Understanding between ESA and NASA, the roles and responsibilities of the scientific elements have yet to be fully defined. In April 2020, ESA and NASA jointly chartered the MSR Science Planning Group 2 (MSPG2) to build upon previous planning efforts in defining 1) an end-to-end MSR Science Program and 2) needed functionalities and design requirements for an MSR Sample Receiving Facility (SRF). The challenges for the first samples brought from another planet include not only maintaining and providing samples in pristine condition for study, but also maintaining biological containment until the samples meet sample safety criteria for distribution outside of biocontainment. The MSPG2 produced six reports outlining 66 findings. Abbreviated versions of the five additional high-level MSPG2 summary findings are: Summary-1. A long-term NASA/ESA MSR Science Program, along with the necessary funding and human resources, will be required to accomplish the end-to-end scientific objectives of MSR. Summary-2. MSR curation would need to be done concurrently with Biosafety Level-4 containment. This would lead to complex first-of-a-kind curation implementations and require further technology development. Summary-3. Most aspects of MSR sample science could, and should, be performed on samples deemed safe in laboratories outside of the SRF. However, other aspects of MSR sample science are both time-sensitive and sterilization-sensitive and would need to be carried out in the SRF. Summary-4. To meet the unique science, curation, and planetary protection needs of MSR, substantial analytical and sample management capabilities would be required in an SRF. Summary-5. Because of the long lead-time for SRF design, construction, and certification, it is important that preparations begin immediately, even if there is delay in the return of samples.

Rationale and Proposed Design for a Mars Sample Return (MSR) Science Program

The Mars Sample Return (MSR) Campaign represents one of the most ambitious scientific endeavors ever undertaken. Analyses of the martian samples would offer unique science benefits that cannot be attained through orbital or landed missions that rely only on remote sensing and in situ measurements, respectively. As currently designed, the MSR Campaign comprises a number of scientific, technical, and programmatic bodies and relationships, captured in a series of existing and anticipated documents. Ensuring that all required scientific activities are properly designed, managed, and executed would require significant planning and coordination. Because there are multiple scientific elements that would need to be executed to achieve MSR Campaign success, it is critical to ensure that the appropriate management, oversight, planning, and resources are made available to accomplish them. This could be achieved via a formal MSR Science Management Plan (SMP). A subset of the MSR Science Planning Group 2 (MSPG2)-termed the SMP Focus Group-was tasked to develop inputs for an MSR Campaign SMP. The scope is intended to cover the interface to the Mars 2020 mission, science elements in the MSR flight program, ground-based science infrastructure, MSR science opportunities, and the MSR sample and science data management. In this report, a comprehensive MSR Science Program is proposed that comprises specific science bodies and/or activities that could be implemented to address the science functionalities throughout the MSR Campaign. The proposed structure was designed by taking into consideration previous management review processes, a set of guiding principles, and key lessons learned from previous robotic exploration and sample return missions. Executive Summary The Mars Sample Return (MSR) Campaign represents one of the most ambitious scientific endeavors ever undertaken. Analyses of the martian samples would offer unique science benefits that cannot be attained through orbital or landed missions that rely only on remote sensing and in situ measurements, respectively. Ensuring that all required scientific activities are properly designed, managed, and executed would require significant planning and coordination. As currently designed, the MSR Campaign comprises a number of scientific, technical, and programmatic bodies and relationships, captured in a series of existing and anticipated documents. Because there are so many scientific elements that would need to be executed to achieve MSR Campaign success, it is critical to ensure that the appropriate management, oversight, planning, and resources are made available to accomplish them. To date, however, no dedicated budget lines within NASA and ESA have been made available for these purposes, and no formal MSR Science Management Plan (SMP) has yet been established. It is thus evident that: A joint ESA/NASA MSR Science Program, along with the necessary funding and resources, will be required to accomplish the end-to-end scientific objectives of MSR. To aid in planning, the MSR Science Program requires an overarching SMP to fully describe how it could be implemented to meet the MSR scientific objectives and maximize the overall science return. A subset of the MSR Science Planning Group 2 (MSPG2)-termed the SMP Focus Group-was tasked to develop inputs for the MSR Campaign SMP. The scope covers the interface to the Mars 2020 mission, science elements in the MSR flight program, ground-based science infrastructure, MSR science opportunities, and the MSR sample and science data management. Some of the required bodies and activities already exist; the remainder require definition. In this report, a comprehensive MSR Science Program is proposed, comprising specific science bodies and/or activities that could be implemented to address the science functionalities throughout the MSR Campaign. The proposed structure was designed by taking into consideration previous management review processes, a set of guiding principles, and key lessons learned from previous robotic exploration and sample return missions. While we acknowledge that the proposal is non-unique, that is, other implementations could meet the overall needs of the MSR Campaign, we have striven to optimize efficiencies and eliminate unnecessary overlap wherever possible to reduce the potential cost and complexity of the MSR Science Program. Many elements of the proposed Science Program are interdependent, as the decision to trigger certain bodies or activities depend on reaching key milestones throughout the MSR Campaign. Although the timing of certain elements may be flexible depending on the anticipated date of samples arriving on Earth, it is crucial that others are implemented as soon as is feasible. As a first step, formalizing the Science Program's management structure as soon as possible would ensure that impending time-sensitive trades are conducted, and the resulting decisions are made with adequate scientific input. Summary of Findings FINDING SMP-1: A joint science management structure and documented agreements among the MSR Partners are required to coordinate the MSR Science Program elements that are not currently defined in existing structures or documents. FINDING SMP-2: A long-term ESA/NASA MSR Science Program, along with the necessary funding and human resources, will be required to accomplish the end-to-end scientific objectives of MSR. FINDING SMP-3: The MSR Science Management Plan should be linked to, but not encompass, other required functionalities within the MSR Campaign. Input will be needed to produce formal plans for (at a minimum) curation, planetary protection, data management, and public engagement. FINDING SMP-4: The guiding principles proposed in the MSR Science Planning Group (MSPG) Framework document (2019c) remain appropriate and relevant and should be utilized in drafting the MSR Science Memorandum of Understanding (MOU) and Science Management Plan. FINDING SMP-5 (a): MSR scientific return would be maximized if participation in the MSR Science Program is not limited to scientists sponsored by existing MSR Partners; rather, opportunities should be provided to scientists from around the world. (b) All programmatic decision-making power (e.g., selection of competitive proposals) would still rest with the Partners. FINDING SMP-6: At the implementation level, the MSR Science Program should, wherever possible, leverage structures, programs, and lessons-learned from previous mission organization to benefit from their experiences to engender familiarity among both decision-makers and the science community. FINDING SMP-7: The MSR Science Program requires the establishment of scientific bodies to meet management, science operations, and public participation needs. These bodies require dedicated funding, addressing scientific functionalities that span the entirety of the MSR Campaign. FINDING SMP-8: Some elements of the MSR Science Program cannot be delayed in the event of an MSR Program schedule delay, as they are linked to key decisions or operations of the Mars 2020 mission.