Planetary protection and the search for extraterrestrial life

Abstract

One of the main goals of space exploration is to search for signs of life beyond Earth. Planetary protection measures play a crucial role in preserving the integrity of these investigations. Planetary protection aims to prevent the contamination of extraterrestrial environments of astrobiological interest with terrestrial organisms and complex organics and protect Earth from potential extraterrestrial biological contamination. Planetary protection implementation guidelines have been developed by the Committee on Space Research (COSPAR). The measures differ depending on the type of mission, the target in our solar system and the mission objective. They have been implemented since the Viking missions to Mars in the 1970s. With the recent remarkable advances in the detection of microorganisms with molecular techniques the addition of metagenomics to the cultivation-based assays used to date will enable a targeted detection of those microorganisms which are relevant for the respective planet or moon. While the focus of planetary protection has primarily been on robotic missions, future crewed missions to Mars will require supplementary planetary protection measures because human activities will inadvertently introduce terrestrial microorganisms to the martian environment. In addition, it is necessary to ensure the health of the crew through systematic microbial monitoring.