• Dirk Schulze-Makuch

Returning Samples Collected by the Perseverance Rover from Mars to Earth

The Design and Construction of the Sample Receiving Facility must start now.

The Mars 2020 Perseverance rover, the first phase of the Mars Sample Return mission.

After the recent successful collection of the first Martian samples by the Perseverance rover, detailed planning is on the way for returning these and additional samples, collected during the coming months, back to Earth. The Mars sample return effort and its associated preparations and investigations have been reported in a just-released set of articles published in the journal Astrobiology.

The Perseverance rover is collecting Martian samples and depositing them into tubes. These will then be transferred into sampling containers, which will later be picked up by a sample retrieval mission, probably sometime between 2028 and 2031. The retrieval mission will transport the samples to Earth and drop them off in a specially designed Sample Receiving Facility. The facility will be equipped to receive the returning spacecraft, open the sealed sample containers, extract the samples from the tubes, and conduct at least some initial analyses of the sediments and gases collected.

Due to planetary protection guidelines and concerns that Martian life may be “hiding” within the samples, the Sample Receiving facility will have the highest biosafety level, which is 4. A Biosafety Level 4 laboratory deals with highly dangerous and contagious microbes and viruses, including pathogens transmitted through aerosols.

I think that the danger from the Mars sample return to any life on Earth would be minimal. If microbial life from Mars has been collected as part of the samples, it is unlikely to survive several years of being stored in a container on Mars, in addition to being transported through space. Further, even if some of the microbial life survives, any indigenous Martian life would be adapted to Mars, not Earth’s environment or its species, and would most likely not present any danger.

Nevertheless, this is our home planet, and we are unsure what to expect, so utmost caution should be exercised and safety protocols rigorously followed. Mission scientists will be under pressure from the scientific community to release samples as soon as they are deemed safe. Investigators outside the facility will want to use their high-tech tools in their labs for analyses, which are likely more powerful than equipment available within the facility under the given biosafety restrictions. One option to deal with the demand would be to sterilize the samples upon arrival and distribute them quickly to individual scientists. Only by doing that we could lose the most interesting information the samples may hold – data related to possible biology.

Personally, I think that one opportunity has already been missed. I advocated previously that the collected samples should be analyzed before they are collected and stored. Sure, the instrumentation that could be used on a rover for in-situ screening would be limited and less sophisticated than the instruments we can use back on Earth. Still, it could provide us with a way of optimizing how we conduct the analyses once the samples arrive on Earth.

But even with that opportunity missed, the Mars Sample Return mission is still a once in a lifetime opportunity for planetary scientists and astrobiologists to gain invaluable insights. I can only second the statement by the Mars Science Planning Group 2 (MSPG2), headed by Michael Meyer from NASA headquarters, that because of the long lead-time for the design, construction, and certification of the Sample Return Facility, preparations must begin immediately. This should be the case even if there is a delay in returning the collected samples. Once the samples from Mars return, the Sample Receiving Facility should be available and ready to provide – under safest handling conditions and quarantine measures – the biggest scientific return possible.

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