The Precautionary Principle and Space Exploration

The Precautionary Principle (PP) is the principle following which one should act only when there is scientific proof that no harmful consequences will result from their acting; or, said differently, “better safe than sorry”. The PP has applications in many fields such as policy decision, science, engineering or technology. But if the PP is taken into consideration in these fields, it is often seen as vague, unclear, or an obstacle to development. In the case of the colonization of Mars, there are of course numerous risks (the trip, the settlement of a colony, the distance with Earth, the dangerous radiations, etc.). Given the PP, what should be done (or not done) in the colonization of Mars? What are the values hidden behind the evaluation of these risks? And what are the values guiding the colonization of Mars, for scientists as well as for private investors?