Preliminary Planning for Mars Sample Return (MSR) Curation Activities in a Sample Receiving Facility

The Mars Sample Return Planning Group 2 (MSPG2) was tasked with identifying the steps that encompass all the curation activities that would happen within the MSR Sample Receiving Facility (SRF) and any anticipated curation-related requirements. An area of specific interest is the necessary analytical instrumentation. The SRF would be a Biosafety Level-4 facility where the returned MSR flight hardware would be opened, the sample tubes accessed, and the martian sample material extracted from the tubes. Characterization of the essential attributes of each sample would be required to provide enough information to prepare a sample catalog used in guiding the preparation of sample-related proposals by the world’s research community and informing decisions by the sample allocation committee. The sample catalog would be populated with data and information generated during all phases of activity, including data derived concurrent with Mars 2020 sample-collecting rover activity, sample transport to Earth, and initial sample characterization within the SRF. We conclude that initial sample characterization can best be planned as a set of three sequential phases, which we have called Pre-Basic Characterization (Pre-BC), Basic Characterization (BC), and Preliminary Examination (PE), each of which requires a certain amount of instrumentation. Data on specific samples and subsamples obtained during sample safety assessments and time-sensitive scientific investigations would also be added to the catalog. There are several areas where future work would be beneficial to prepare for the receipt of samples, which would include the design of a sample tube isolation chamber and a strategy for opening the sample tubes and removing dust from the tube exteriors

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

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

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

The NASA/ESA Mars Sample Return (MSR) Campaign seeks to establish whether life on Mars existed where and when environmental conditions allowed. Laboratory measurements on the returned samples are useful if what is measured is evidence of phenomena on Mars rather than of the effects of sterilization conditions. This report establishes that there are categories of measurements that can be fruitful despite sample sterilization and other categories that cannot. Sterilization kills living microorganisms and inactivates complex biological structures by breaking chemical bonds. Sterilization has similar effects on chemical bonds in non-biological compounds, including abiotic or pre-biotic reduced carbon compounds, hydrous minerals, and hydrous amorphous solids. We considered the sterilization effects of applying dry heat under two specific temperature-time regimes and the effects of γ-irradiation. Many measurements of volatile-rich materials are sterilization sensitive—they will be compromised by either dehydration or radiolysis upon sterilization. Dry-heat sterilization and γ-irradiation differ somewhat in their effects but affect the same chemical elements. Sterilization-sensitive measurements include the abundances and oxidation-reduction (redox) states of redox-sensitive elements, and isotope abundances and ratios of most of them. All organic molecules, and most minerals and naturally occurring amorphous materials that formed under habitable conditions, contain at least one redox-sensitive element. Thus, sterilization-sensitive evidence about ancient life on Mars and its relationship to its ancient environment will be severely compromised if the samples collected by Mars 2020 rover Perseverance cannot be analyzed in an unsterilized condition. To ensure that sterilization-sensitive measurements can be made even on samples deemed unsafe for unsterilized release from containment, contingency instruments in addition to those required for curation, time-sensitive science, and the Sample Safety Assessment Protocol would need to be added to the Sample Receiving Facility (SRF). Targeted investigations using analogs of MSR Campaign-relevant returned-sample types should be undertaken to fill knowledge gaps about sterilization effects on important scientific measurements, especially if the sterilization regimens eventually chosen are different from those considered in this report

Final Report of the MSR 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 will 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 can, 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

Evidence of martian perchlorate, chlorate, and nitrate in Mars meteorite EETA79001: Implications for oxidants and organics

The results from the Viking mission in the mid 1970s provided evidence that the martian surface contained oxidants responsible for destroying organic compounds. In 2008 the Phoenix Wet Chemistry Lab (WCL) found perchlorate (ClO4-) in three soil samples at concentrations from 0.5 to 0.7wt%. The detection of chloromethane (CH3Cl) and dichloromethane (CH2Cl2) by the Viking pyrolysis gas chromatograph-mass spectrometer (GC-MS) may have been a result of ClO4- at that site oxidizing either terrestrial organic contaminates or, if present, indigenous organics. Recently, the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) Curiosity directly measured the presence of CH3Cl, CH2Cl2 and, along with measurements of HCl and oxygen, indirectly indicate the presence of ClO4 However, except for Phoenix, no other direct measurement of the ClO4- anion in martian soil or rock has been made. We report here ion chromatographic (IC) and isotopic analyses of a unique sawdust portion of the martian meteorite EETA79001 that show the presence by mass of 0.6±0.1ppm ClO4-, 1.4±0.1ppm ClO3-, and 16±0.2ppm NO3- at a quantity and location within the meteorite that is difficult to reconcile with terrestrial contamination. The sawdust sample consists of basaltic material with a minor salt-rich inclusion in a mass ratio of ~300:1, thus the salts may be 300 times more concentrated within the inclusion than the whole sample. The molar ratios of NO3-:ClO4- and Cl-:ClO4-, are very different for EETA79001 at ~40:1 and 15:1, respectively, than the Antarctic soils and ice near where the meteorite was recovered at ~10,000:1 and 5000:1, respectively. In addition, the isotope ratios for EETA79001 with δ15N=-10.48±0.32‰ and δ18O=+51.61±0.74‰ are significantly different from that of the nearby Miller Range blue ice with δ15N=+102.80±0.14‰ and δ18O=+43.11±0.64‰. This difference is notable, because if the meteorite had been contaminated with nitrate from the blue ice, the δ15N values should be the same. More importantly, the δ15N is similar to the uncontaminated Tissint Mars meteorite with δ15N=-4.5‰. These findings suggest a martian origin of the ClO4-, ClO3- and NO3- in EETA79001, and in conjunction with previous discoveries, support the hypothesis that they are present and ubiquitous on Mars. The presence of ClO3- in EETA79001 suggests the accompanying presence of other highly oxidizing oxychlorines such as ClO2- or ClO-, produced both by UV oxidation of Cl- and γ- and X-ray radiolysis of ClO4 Since such intermediary species may contribute to oxidization of organic compounds, only highly refractory and/or well-protected organics are likely to survive. The global presence of ClO4-, ClO3-, and NO3-, has broad implications for the planet-wide water cycle, formation of brines, human habitability, organics, and life

Identification of the Perchlorate Parent Salts At the Phoenix Mars Landing Site and Possible Implications

In 2008 the Phoenix Mars lander Wet Chemistry Laboratory (WCL) measured 0.6wt% of perchlorate (ClO4-) in the martian soil. A crucial question remaining unanswered is the identity of the parent salt phase(s) of the ClO4 Due to the ClO4- ion\u27s high solubility and stability, its distribution, chemical forms, and interactions with water, could reveal much about the aqueous history of the planet. Until now, the presence of Ca(ClO4)2 as a parent salt has been considered unlikely because based on its eutectic point and model calculations, highly insoluble calcium carbonates and sulfates would serve as sinks for Ca2+ rather than Ca(ClO4)2. Thus, the dominant ClO4- parent salt has been assumed to be a hydrated form of Mg(ClO4)2. Here we report on the results of a new refined analysis of the Phoenix WCL sensor data, post-flight experiments run on a flight-spare WCL unit, and numerous laboratory analyses. The results show that the response of the Ca2+ sensor is extremely sensitive to the counter ion of the ClO4- salt, and that addition of martian soil to the Phoenix WCL that contained only Mg(ClO4)2 or Ca(ClO4)2 would have produced a very different response than what was observed on Mars. A series of analyses were run with Ca2+ sensors and calibration solutions identical to those used on Phoenix, and with a Mars simulant formulation known to give the same results as on Mars. The response of the Ca2+ sensor at various ratios of added Mg(ClO4)2 to Ca(ClO4)2 gave the best fit to the Phoenix data with a sample containing ~60% Ca(ClO4)2 and 40% Mg(ClO4)2. These results suggest that the Ca(ClO4)2 in the Phoenix soil has not been in contact with liquid water and thus did not form by evaporation or sublimation processes. Had the highly soluble Ca(ClO4)2 come into contact with liquid water, then the presence of soluble sulfates would have, on evaporation formed only CaSO4. The presence of Ca(ClO4)2 and Mg(ClO4)2 phases at roughly the CaCO3 to MgCO3 ratio suggests that since their production, the ClO4- phases have remained in a severely arid environment, with minimal or no liquid water interaction. The formation of the Ca(ClO4)2 and Mg(ClO4)2 is also consistent with the interaction of atmospherically deposited HClO4 with Ca- and Mg-carbonates and may also contribute to CO2 enrichment of 18O and may contribute in explaining why carbonates on the surface are at much lower levels than expected from an earlier global wet and warm period