Advances in Planetary Protection Ahead of the “Journey to Mars”

Since the dawn of the Space Age, spacefaring nations have committed to protecting solar system objects from harmful contamination carried by interplanetary spacecraft. This is so that the scientific interrogation of such places can proceed without being compromised by terrestrial contamination. As we consider sample return missions, especially those involving human crew, the even greater importance of protecting the Earth from the potential release of an extra-terrestrial organism in a returned extra-terrestrial sample comes to the fore. Planetary protection policies to achieve these protection goals are relatively mature for missions performing robotic exploration of Mars. They have been informed and refined over time to reflect our increasing knowledge about the martian environment from successive orbiter and lander missions as well as our growing understanding of the limits and capabilities of terrestrial life on Earth.

When considering the future human exploration of Mars (e.g., NASA’s Journey to Mars), it is clear that the bioburden requirements historically used for robotic missions (e.g., <5x10e5 microbial spores/mission) are not directly applicable to a crewed mission (~1x10e14 microorganisms/astronaut in a dynamic community). However, if human missions undertaken to search for life on Mars are to succeed, the intent to prevent contamination and loss of martian science becomes all the more important, and the safeguarding of Earth from potential backward contamination continues to be the highest priority.

The challenge for the space exploration community is to determine how such contamination is to be prevented in future exploration scenarios. In this paper, we will outline the plans and progress towards development of executable planetary protection policy concepts, based on the output of the 2015 workshop on Planetary Protection Knowledge Gaps for Human Extraterrestrial Missions. Paths forward towards figures of merit for inclusion in a potential future NASA Program Requirements document (NPR) will also be described.