Credit: NASA

A NASA-funded study makes the case for making it simpler to send spacecraft to some areas of Mars while still protecting the planet from Earth-based contamination.

The just-issued study could allow robotic missions to certain locations on Mars to be carried out with less restrictive “bioburden” requirements designed to prevent harmful contamination by Earth-based microbes at Mars.

The Committee on Planetary Protection, a standing committee of the National Academies Space Studies Board, was tasked by NASA to write the report discussing criteria that could be used to designate regions on Mars where missions can land with less stringent bioburden requirements than currently in place.

This map of Mars shows locations where ice is potentially located within 1 meter of the surface, based on neutron spectroscopy data (Mars Odyssey) or thermal infrared (IR) spectra (Mars Climate Sounder), and includes known subsurface access points from the Mars Candidate Cave Catalog. The gray regions are those lacking IR data and yielding water equivalent hydrogen (WEH) contents less than 10% from neutron spectroscopy. In the gray areas, closed-system ice or brine could potentially be present in the top 1 meter, but it is likely to be low in abundance and patchy in distribution. Gray regions may be appropriate for missions planning subsurface activities (as deep as 1 meter) with reduced bioburden requirements, if landing sites are a conservative buffer distance from subsurface access points.
Credit: A. Deanne Rogers, Stony Brook University, The State University of New York.

Imposing, costly, complex

Amanda Hendrix, a Planetary Science Institute senior scientist and co-chair of the committee said: “Currently, meeting planetary protection requirements – for instance, using rigorous sterilization techniques – can be seen as imposing, costly and complex, and it could be that these restrictions can be simplified and modernized, in some cases, which can help make some areas of Mars more accessible.”

The Committee’s findings,” Hendrix said, “can lead to making portions of Mars more accessible to both commercial and government endeavors by relaxing planetary protection requirements while remaining careful about access to potential habitable zones.”

“Biocidal” UV environment

The newly-issued report, for example, notes that for missions that do not access the subsurface, such regions could include a significant portion of the surface of Mars, because the UV environment is so biocidal that terrestrial organisms are, in most cases, not likely to survive more than one to two sols, or Martian days.

Location of candidate caves in the Tharsis region on Mars.
Credit: USGS

Furthermore, for missions that access the subsurface (down to 1 meter), regions on Mars expected to have patchy or no water ice below the surface might also be visited by spacecraft with more relaxed bioburden requirements, because such patchy ice is likely not conducive to the proliferation of terrestrial microorganisms.

Cave openings: keep your distance

The report also found that it is imperative that any mission sent to Mars with reduced bioburden requirements remain some conservative distance from any subsurface access points, such as cave openings.

Though less stringent than current requirements, these missions with relaxed bioburden requirements would still need some level of cleanliness, which could be achieved for instance using standard aerospace cleanliness practices.

The committee’s findings apply specifically to missions for which NASA has responsibility for planetary protection. For commercial missions in which NASA has no role or connection, the U.S. government still needs to designate a regulatory agency to authorize and continually supervise space activities in accordance with the Outer Space Treaty, the report explains.

To access the full report — Evaluation of Bioburden Requirements for Mars Missions – go to:

https://www.nap.edu/download/26336

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