5

Planetary Protection Challenges from the Human Exploration of Mars

CURRENT INTEREST IN HUMAN MISSIONS TO MARS

In addition to robotic missions to Mars, NASA has stated its intent to send humans to the Red Planet.¹ At least two private-sector enterprises, Lockheed Martin and Space Exploration Technologies (SpaceX), have also started developing plans for sending humans to Mars (see Table 5.1). Likely new international relationships, new non-government players, and a potentially potent new contamination source (i.e., humans) will, in the committee’s view, affect the processes for planetary protection policy development.

PLANETARY PROTECTION AND HUMANS ON MARS

NASA planetary protection documents acknowledge that NASA does not have a policy for human exploration on the surface of Mars and mostly call for a significant number of tests and experiments before sending humans there.² Current Committee on Space Research (COSPAR) principles and guidelines for human missions to Mars (see Box 5.1) state that “the intent of this planetary protection policy is the same whether a mission to Mars is conducted robotically or with human explorers . . . even if specific implementation requirements must differ.”³ Implementing the current COSPAR principles and guidelines may be impossible in any practical manner for human missions. Living quarters and spacesuits are imperfect, and leaks will contaminate the immediate martian environment with biological and chemical matter from Earth. Furthermore, waste from human presence will present even bigger contamination challenges. Human presence on Mars would, thus, raise serious planetary protection challenges and questions not confronted before, including (but not limited to) what “harmful contamination” of Mars means in terms U.S. obligations under the Outer Space Treaty (OST).

The planetary protection challenges generated by human missions to Mars will require policy makers to adapt existing approaches and develop new strategies. For example, rather than thinking about forward contamination in terms of an entire body, assessing the effects of human presence on local and regional scales might be more

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¹ For a possible human Mars architecture see, for example, H. Price, J. Baker, and F. Naderi, A minimal architecture for human journeys to Mars, New Space 3:73-81, 2015.

² Planetary Protection Requirements for Human Extraterrestrial Missions NPI 8020.7 and NPD 8020.7G.

³ G. Kminek, C. Conley, V. Hipkin, and H. Yano, COSPAR Planetary Protection Policy, Space Research Today, No. 200, December 2017, pp. 12-24.

TABLE 5.1 Private-Sector Interest in Human Missions to Mars

¹ T. Cichan, S.A. Bailey, T. Antonelli, S.D. Jolly, R.P. Chambers, B. Clark, and S.J. Ramm, Mars base camp: An architecture for sending humans to Mars, New Space 5:203-217, 2017.

² E. Musk, Making humans a multi-planetary species, New Space 5:46-61, 2017; and E. Musk, Making life multi-planetary, New Space 6:2-11, 2018.

effective. Similarly, the NASA Human Exploration and Operations Mission Directorate (HEOMD) is studying and developing a so-called exploration zone approach that would define the locus of a human landing site, in situ resource areas, and scientific regions of interest (see Figure 5.1). These ideas heighten the need for policies that address planetary protection at varying spatial scales.

Adapted and new approaches will also create novel planetary protection and other policy challenges. For example, the establishment of an exploration zone or regions of interest on Mars by the United States would raise questions about whether such an act violated the OST’s prohibition of national appropriation of part of a celestial body.⁴ If a nation or a private-sector entity wishes to protect a limited region temporarily without exercising any claim of ownership, how can a planetary protection policy be developed for that purpose? International discussions can resolve such questions.⁵

In addition, human missions to Mars would also raise potential back contamination problems. NASA’s Chief Medical Officer, J.D. Polk, told the committee that he was less worried about back contamination from Mars microbes than he was concerned about return of microorganisms carried by the crew from Earth to Mars and back.⁶ If those organisms experienced mutation through prolonged exposure to the space environment during the mission, such microbes might pose a health risk to returning crew as well as the public on Earth. As with the first Apollo astronauts, NASA expects to quarantine the crew until proven safe from returned risks.⁷ Appropriate experiments on radiation mutation of Earth microbes may be needed to establish new policy.

DEVELOPMENT PROCESS FOR A NEW PLANETARY PROTECTION POLICY

Except for the so-called Mars Special Regions, current planetary protection requirements treat the planet globally (i.e., as a single monolithic entity).⁸ Given that Mars has approximately 80 distinct geological regions, such a blanket treatment may be unwarranted. It is reasonable to expect that the modification of planetary protection requirements to enable human exploration will have an impact on future science investigations, the magnitude of

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⁴ Outer Space Treaty, Article II.

⁵ For example, the states parties to the agreement on the International Space Station agreed that the operation of the station did not constitute an appropriation of low-Earth orbit space even though the station has been using the same orbit path for approximately 20 years. See “Agreement Among the Government of Canada, Governments of the Member States of the European Space Agency, the Government of Japan, the Government of the Russian Federation, and the Government of the United States of America Concerning Cooperation On the Civil International Space Station,” ftp://ftp.hq.nasa.gov/pub/pao/reports/1998/IGA.html.

⁶ Personal communication from J.D. Polk to J.A. Alexander, July 28, 2017. See, for example, P.W. Taylor, Impact of space flight on bacterial virulence and antibiotic susceptibility, Infection and Drug Resistance 8:249-262, 2015.

⁷ See “The Apollo Experience” in Chapter 2.

⁸ See, for example, J.D. Rummel, D.W. Beaty, M.A. Jones, C. Bakermans, et al., A new analysis of Mars “Special Regions”: Findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2), Astrobiology 14:887-968, 2014.

which cannot be known at this time. However, existing planetary protection requirements imposed on the robotic science missions would become irrelevant only if future human missions exceed the current levels of contamination on a planet-wide basis. Therefore, the processes for selecting a human exploration strategy and for developing planetary protection policy are inextricably linked.

As NASA begins to develop a planetary protection policy that will encompass future human missions, policy makers will need to consider all the potential approaches for human missions. An illustrative list of these approaches might include the following:

1. Require human spaceflight missions to follow the same standards as robotic science missions (i.e., follow the current COSPAR guideline). If humans cannot meet the standards, they cannot go; implying that scientific investigation has greater importance than human exploration. This alternative is, of course, completely incompatible with plans for human presence on Mars.
2. Promulgate a policy that terminates or eliminates all forward biological contamination planetary protection requirements for all types of missions for Mars. This approach effectively assumes that the period of

3. protected biological exploration for Mars has ended. Science missions would still need to be cleaned based on the contamination control requirements imposed by the missions’ science instruments.

4. Establish exploration zones (perhaps through an international process) where humans are allowed to explore based on scientific and engineering studies that establish zone extent and perhaps even duration (see Figure 5.1). Set requirements for human missions that are relaxed from current COSPAR standards based on realistic engineering considerations and the outcome of the research and technologies studies addressing specific items in Box 5.1 above. As noted in the discussion below of future studies, this alternative assumes exploration activities can protect large parts of Mars for scientific study and that contamination from the human habitats will not expand into these other regions of interest.
5. Delineate, via international agreement, areas of scientific interest that cannot be accessed by human missions. Ensure that these zones have sufficient buffers to protect the scientific endeavors from human contamination. The process will have to acknowledge that non-access is by mutual agreement to serve scientific research and is not intended to abrogate the OST’s provisions.⁹

Alternative four is not in conflict with option three above, and some combination of three and four may be optimum. The process by which a new planetary protection policy for human exploration of Mars is developed will need to provide for international discussions of, and choices amongst, alternatives such as these.

FUTURE STUDIES REQUIRED TO DEVELOP THE NEXT HUMAN EXPLORATION POLICY

The feasibility and limitations of a policy that allows for protected science zones or unprotected human exploration zones depend on the extent to which contaminants can be transported across Mars. After many decades of intensive scientific Mars exploration, the only known truly global phenomena are dust storms. While some dust storms occur on a part of the planet every year, there are occasionally extreme events that cover the entire planet. Mars scientists have concluded, therefore, that the surface dust of Mars is “well-mixed.”¹⁰ It is conceivable that some release of contaminants might be (or might have been in the past) carried a significant distance by those dust storms. The committee hastens to add that the Mars atmosphere is very thin, mostly carbon dioxide with a pressure about that of Earth at an altitude of 30 km. Thus even at the highest velocities measured by landers (~130 km per hour) the force exerted is extremely small; about like a puff of your breath. Only because martian dust is extremely fine, like flour or talcum powder, can it be moved by such small forces. However, microorganisms are also tiny and have low mass so it is conceivable they might be blown by those forces as well.

There are several questions that require further research in order to provide a scientific basis on which to develop new policy. The following are examples:¹¹

1. Because some releases of gases, dust, or other emissions from a human base are inevitable, how far would such contamination travel in the very thin atmosphere of Mars? Would it be diluted extensively and/or sterilized before reaching the science region of interest?
2. If a human habitat on Mars were to suffer a catastrophic blowout event and release microbes from the astronauts, how far would the contamination travel and what effect could it have on the science regions?

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⁹ Article I of the Outer Space Treaty ensures that “The exploration and use of outer space . . . shall be free for exploration and use by all States without discrimination of any kind”; Article II specifies that outer space “is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means”; and Article XII ensures that “[a]ll stations, installations, equipment and space vehicles on the moon and other celestial bodies shall be open to representatives of other States Parties to the Treaty on a basis of reciprocity.” The U.S. negotiator for the OST explained at the time that this provision “does not confer, or imply the existence of any right or power to veto proposed visits to other countries’ facilities on a celestial body” (see S. Hobe, B. Schmidt-Tedd, K.-U. Schrogl, and G.M. Goh, eds., Cologne Commentary on Space Law, Heymanns, Cologne, Germany, Volume 1, 2009. p. 10).

¹⁰ H. Wang and M.I. Richardson, The origin, evolution, and trajectory of large dust storms on Mars during Mars years 24-30 (1999-2011), Icarus 251:112-127, 2015.

¹¹ A recent NASA-sponsored workshop (Dust in the Atmosphere of Mars and Its Impact on Human Exploration, June 13-15, 2017) addressed some of the same issues as those below, but the committee believes that a further consideration of such topics is warranted.

3. Using the current knowledge of Mars and modern biological expertise, is there credible evidence that any terrestrial microbes would survive in the harsh radiation and very dry oxidizing conditions on the surface of Mars?
4. To what extent might modern genomic techniques be applied to assessing contamination and possibly even eliminate the need for some contamination control requirements?

The committee believes that to formulate new policy, research is essential to develop advanced biological contamination measurement techniques and instrumentation. For example, DNA (deoxyribonuclic acid) sequencing to identify possible contaminants is not incompatible with options number 3 and 4 above and could be an enabling technology. However, the most important current contaminant requirement for the Mars 2020 mission is considered to be the total organic carbon burden, which may not be able to be addressed by genomic techniques. There are also capabilities such as highly sophisticated computational fluid dynamics analysis, the use of wind tunnels, and other ground-based simulations and experiments that could be carried out prior to any space-based project in order to bound the problem. The important point is that modern existing tools, knowledge, and facilities need to be used to assess the risks and, thereby, provide scientific information to inform policy decisions.

Finding: Although NASA is planning for human missions to Mars in the 2030s, NASA does not currently have an adequate planetary protection policy for human exploration and activities on Mars. In addition, neither NASA nor the Department of State have crafted strategies for productive international dialog on developing policy for planetary protection and for other issues, such as the relationship between exploration zones on Mars and the OST’s prohibition on national appropriation of parts of celestial bodies, associated with human missions to Mars.

Recommendation 5.1: NASA’s process for developing a human Mars exploration policy should include examination of alternative planetary protection scenarios and should have access to the necessary research that informs these alternatives. It should also include plans to engage with other nations on the policy and legal implications of missions to Mars.