Mars Sample Handling and Requirements Panel (MSHARP) Final Report
Michael H. Carr, et. al., NASA, Jet Propulsion Lab, Pasadena, CA, NASA TM-1999-209145 (1999). (pdf)
Charter: In anticipation of the return of samples from Mars, NASA’s Office of Space Sciences chartered a panel to examine how Mars samples should be handled. The panel was to make recommendations in three areas: 1) sample collection and transport back to Earth; 2) certification of the samples as non-hazardous; and 3) sample receiving, curation, and distribution. This report summarizes the findings of that panel.
Background: The samples should be treated as hazardous until proven otherwise. They are to be sealed within a canister on Mars, and the canister is not to be opened until within a Biosafety Hazard Level 4 (BSL-4) containment facility here on Earth. This facility must also meet or exceed the cleanliness requirements of the Johnson Space Center (JSC) facility for curation of extraterrestrial materials. A containment facility meeting both these requirements does not yet exist. Hazard assessment and life detection experiments are to be done at the containment facility, while geochemical characterization is being performed on a sterilized subset of the samples released to the science community. When and if the samples are proven harmless, they are to be transferred to a curation facility, such as that at JSC.
Summary and Conclusions:
- The search for evidence of life, particularly past life, is a primary objective of the Mars exploration program. Parallel and intimately connected goals are determination of the planet’s climate and of the planet’s geologic histories.
- Many of the outstanding biologic, climatologic, and geologic issues with respect to Mars are unlikely to be resolved until we have a variety of resumed samples.
- The present martian surface is very hostile to life because of its low temperatures, the lack of liquid water, the high UV flux, the presence of oxidants, and the scarcity of organics.
- The chances of finding extant life in samples returned from the martian surface are very low, and even if extant life were present, it would be unlikely to have significant ecological impact or other harmful effects on the Earth. The risk is not zero, however.
- Because we cannot demonstrate that the risk is zero, the returned samples should be assumed to be potentially harmful until proven otherwise. They should be placed in sealed containers on Mars, and the containers should be opened only in a BSL4 containment facility here on Earth. No samples should leave BSL4 containment unless sterilized or proven to be harmless.
- Return of samples to the International Space Station is impractical and is likely to be more risky than returning them to Earth.
- Sterilizing samples at Mars is not advocated because sterilization would be difficult to accomplish and verify remotely on Mars, and sterilization would destroy much of the biologic and climatologic information in the samples.
- We endorse the current Athena sample acquisition plan to use a rover to acquire primarily rock cores, with a few additional soil samples. We strongly advocate acquisition of a contingency sample by the lander, although this need not be returned if the rover mission is successful.
- The sampling strategy should be aimed at acquiring the maximum variety of samples from the sites visited.
- Contamination of the samples with terrestrial materials is of considerable concern because it could compromise the science results from the samples. Also, any false positives on hazard assessment and life detection tests would confuse interpretation of analytical results from the samples and could significantly delay release of unsterilized samples from BSL4 containment for distribution to the science community.
- All components that land on the martian surface must be cleaned to at least Pathfinder levels of cleanliness.
- All spacecraft components that touch the samples must be sterilized and cleaned to significantly higher standards than Pathfinder.
- Recognizing that some contamination of the samples could occur, we strongly advocate the use of tracers, witness plates, and assays to help identify adventitious contaminants. We do not, however, advocate deliberately impregnating the drill bits with tracers because of concerns that contamination of the samples by the tracers would be significant and would interfere with sample analysis.
- The sample canister must be sealed before leaving the martian surface, and the integrity of the seal should be confirmed either before leaving the martian surface or while in orbit at Mars.
- The sample canister must be transferred to the Earth Return Vehicle (ERV) in such a way that the only martian materials on the ERV are those sealed within the sample canister.
- Insofar as it is practical during return to Earth, the samples should be maintained at temperatures no higher than 240 K, the maximum temperature they are likely to have experienced on Mars. It is especially desirable that the samples not be allowed to experience temperatures above 270 K.
- We recommend that introduction of unsterilized material into the Earth’s environment be kept to a very low probability, mainly by system design, such as by multiple seals and interleaved filters, rather than through monitoring containment and incorporating various contingency responses into the design. We believe the most likely times of containment failure are at the surface of Mars, when a decision could be made not to return the samples, and during entry and landing at Earth, when monitoring has little value. Limited resources are better used by designing against failure rather than by monitoring and contingency mechanisms.
- After reaching Earth, the sample canister must be opened in a sample receiving facility (SRF) with the equivalent of BSL4 containment. The facility must also meet the cleanliness standard used for handling extraterrestrial materials at JSC. To our knowledge, no such facility now exists.
- We view the SRF as primarily a service facility for the science community, rather than a research facility. The facility will make an early inventory of the samples, do some preliminary hazard assessment and life detection testing, and sterilize a subset of the samples for distribution to the science community for geochemical characterization.
- Early distribution of a subset of sterilized samples is an essential element in both scientific analysis of the samples and in assessing their potential for harm. The geologic and geochemical characteristics of the samples, such as the presence and nature of any organics, will be important for deciding what hazard and life detection testing needs to be done. Geochemical characterization is most reliably and comprehensively done by the at-large science community. Radiation sterilization is the method of choice because of its minimal effects on the geochemical character of the samples. Allocation of the distributed samples should be by the normal NASA Research Announcement (NRA) Peer Review process.
- Some hazard assessment and life-detection experiments must be done in the SRF. We think it premature to advise how these might best be done, given that technologies will likely evolve considerably between now and 2008 when the first samples return, but we suspect that hazard assessment will primarily involve tissue-cell culture testing rather than tests on whole organisms.
- Some of the hazard assessment and life-detection experiments could be done at containment facilities other than the SRF by distributing unsterilized samples to other containment facilities using well established procedures for handling and transporting biohazardous materials.
- The SRF can be scaled, built, and configured in a variety of ways, depending on such factors as what testing is to be done in the facility, as opposed to testing elsewhere, whether the facility is for Mars samples only or for extraterrestrial materials in general, and how long the Mars sample return program is to last. We believe that an SRF built from modular, modest-sized, commercially available, biosafety laboratories is appropriate for the early sample returns. Should life be detected and/or the samples prove to be hazardous, then more elaborate alternatives could be built.
- The SRF should be built, staffed, and operational 1-2 years before receipt of the samples.
- If and when the samples are found to be non-hazardous, the samples should be transferred to a curation facility such as that at Johnson Space Center (JSC).