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Planetary Protection

The possibility of life beyond Earth imposes significant ethical and practical considerations on planetary exploration.

Guidelines

As humanity gains greater ability to explore the Solar System, it is necessarily to consider the ethical principles that apply to doing so, as well as the risks of introducing life forms to other planets (forward contamination), or life from other planets to Earth (backward contamination). Currently, all spacefaring nations are governed by the following guidelines of the Committee on Space Research (COSPAR), implemented by the Outer Space Treaty.

Planetary Protection Policy
GroupingDescriptionExample Missions CoveredRegulations
Category INo interest to the origins or development of lifeMetamorphosed asteroids, Io, Sun, MercuryNone
Category IIDestination of interest to life, but remote chance of contaminationMoon, Venus, comets, carbonaceous asteroids, gas giants, Titan, Triton, Kuiper Belt objects (including Pluto/Charon), CeresDocumentation
Category IIIFly-by's and orbiters with significant chance of contaminationMars, Europa, EnceladusDocumentation, spacecraft assembled in cleanroom, possible bioburden reduction
Category IVProbes and landers with significant chance of contaminationMars, Europa, EnceladusExtensive documentation, trajectory biasing, cleanrooms, bioburden reduction, possible partial sterilization of the direct contact hardware and a bioshield for that hardware as appropriate
Category V, unrestrictedEarth-return missions from destinations not of interest for lifeSame restrictions as previous categories for outbound phase
Category V, restrictedEarth-return missions from destinations of interest for lifeStrict containment procedures for all unsterilized material

Source: COSPAR 1.

The Outer Space Treaty takes an anthropocentric view of planetary protection, seeking to avoid forward contamination to preserve the possibility of scientific exploration, and to prevent backward contamination to protect humans from possibly dangerous outbreaks 2. The Moon Treaty, which few nations have ratified, has a more ecocentric ethos, seeking to preserve planets for their own sake 2. It is also debated whether non-biotic extraterrestrial sites should be perserved, and to what extent 3.

Experiments have suggested that microbial life could indeed be transmitted between planets inadvertently via spacecraft 4,5. It may also be possible for life to travel between planets naturally via panspermia, which is the transportation of microbial life by rocks that are knocked to escape velocity by asteroids or some other means 6,7,8.

Problem:
Risk of Planetary Contamination
Solution:
Better Quantify the Contamination Risk

Planetary Parks

A planetary park, analogous to a national park, is an extraterrestrial region intended to be kept free of industrialization or settlement. The designation of planetary parks has been proposed for Mars 9, the Moon 10, and other extraterrestrial bodies 11 well in advance of these bodies being feasibly industrialized or settled. These parks are envisioned to protect natural features of extraterrestrial environments for intrinsic reasons, as well as for instrumental reasons.

References

  1. Kminek, G., Conley, C., Hipkin, V., Yano, H. "COSPAR’s Planetary Protection Policy". December 2017. ↩

  2. Arnould, J., Debus, A. "An ethical approach to planetary protection". Advances in Space Research 42, pp. 1089-1095. 2008. ↩ ↩2

  3. Schwartz, J. "Where no planetary protection policy has gone before". International Journal of Astrobiology 18(4), pp. 353-361. August 2019. ↩

  4. Horneck, G., Moeller, R., Cadet, J., Douki, T., Mancinelli, R., Nicholson, W., Panitz, C., Rabbow, E., Rettberg, P., Spry, A., Stackebrandt, E., Vaishampayan, P., Venkateswaran, K. "Resistance of Bacterial Endospores to Outer Space for Planetary Protection Purposes—Experiment PROTECT of the EXPOSE-E Mission". Astrobiology 12(5), pp. 445-456. May 2012. ↩

  5. Moissl-Eichinger, C. "Archaea in artificial environments: Their presence in global spacecraft clean rooms and impact on planetary protection". The ISME journal 5(2), pp. 209-219. February 2011. ↩

  6. Horneck, G., Rettberg, P., Reitz, G., Wehner, J., Eschweiler, U., Strauch, K., Panitz, C., Starke, V., Baumstark-Khan, C. "Protection of Bacterial Spores in Space, a Contribution to the Discussion on Panspermia". Origins of life and evolution of the biosphere 31, pp. 527-547. December 2001. ↩

  7. Nicholson, W., Schuerger, A. "Bacillus subtilis Spore Survival and Expression of Germination-Induced Bioluminescence After Prolonged Incubation Under Simulated Mars Atmospheric Pressure and Composition: Implications for Planetary Protection and Lithopanspermia". Astrobiology 5(4), pp. 536-544. August 2005. ↩

  8. Tauscher, C., Schuerger, A., Nicholson, W. "Survival and Germinability of Bacillus subtilis Spores Exposed to Simulated Mars Solar Radiation: Implications for Life Detection and Planetary Protection". Astrobiology 6(4), pp. 592-605. August 2006. ↩

  9. Cockell, C., Horneck, G. "A Planetary Park system for Mars". Space Policy 20(4), pp. 291-295. November 2004. ↩

  10. Cockell, C., Horneck, G. "A Planetary Park system for the Moon and beyond". 38th COSPAR Scientific Assembly. Held 18-15 July 2010, in Bremen, Germany, p.3. July 2010. ↩

  11. Cockell, C., Horneck, G. "Planetary parks—formulating a wilderness policy for planetary bodies". Space Policy 22(4), pp. 256-261. November 2006. ↩