Planetary protection

Planetary protection is a principle aiming to prevent biological contamination of a target body, such as Mars, or of Earth in the case of a return mission. As it is unknown if there is life on Mars, the subject of planetary protection is controversial. For the moment, as of 2020, it has been applied as a precautionary measure.

Mars colonization is probably incompatible with the concept of planetary protection as applied today. Mars settlements, no matter how well designed, will leak large amounts of air and water, that will carry out biological materials. Experience with the International Space station has shown that the station, despite being in vacuum, has its exterior contaminated with a number of different organisms(reference needed). The use of In_Situ materials from the Martian environment will create a reverse contamination path, from the exterior to the interior of a Martian settlement.

Both forward contamination (from Earth to Mars) and backward contamination (from Mars to Earth) planetary protection need to be evaluated.

The legal basis for planetary protection lies in Article IX of the Outer Space Treaty: "Article IX: .. States Parties to the Treaty shall pursue studies of outer space, including the Moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose...

However, some terms in this article lack definition. How do you define "harmful" contamination of the Moon and Mars? If there is no life on Mars, can the contamination be harmful? It is also unclear if present science still requires this protection, since extensive genomic knowledge should allow for easy distinction between terrestrial vs extraterrestrial organisms. This might not have been the case when the treaty was written. Harm to experiments on the search for life on Mars might not actually be possible, for example.

Private missions to Mars from nations that have not signed the Outer Space Treaty might render all of the requirements moot in the future.