Since the Mars rover Curiosity landed near Mount Sharp in 2012, features that might be caused by seasonal flows of water have been spotted on the peak’s slopes. Should we send Curiosity to take a closer look? NASA is considering this question now.

If temporary liquid water is present, it would make these places so-called “special regions”, which enjoy a higher status under planetary-protection guidelines. Only rovers and landers that have been rigorously sterilised, unlike Curiosity, are supposed to examine them, to avoid possible contamination from microbes that hitched a ride from Earth.

But does maintaining this rule make sense? NASA plans a series of human missions to Mars in the 2030s, which makes contamination ever more likely anyway. And those missions will aim to exploit water sources on the Red Planet, so shouldn’t we do all we can to find out what the first astronauts will encounter in such places?

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