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��������’s Curiosity rover has tested a new technique for finding signs of alien life on Mars. Although the rover found no such evidence, it suggests that future missions to other worlds could use the same method.

In March 2017, the rover scooped material from the Bagnold Dunes, a band of sand dunes stretching tens of kilometres on the surface. In December 2017, Curiosity transferred some of this material into its Sample Analysis at Mars (SAM) instrument.

SAM has 74 “cups”, or holders, that are used to analyse Martian samples. Most are empty, with the samples in them heated by the rover to be studied, but nine contain solvents that can dissolve the samples, which allows us to better work out their compositions. The test in December 2017 saw some of these solvents used for the first time, to see whether this technique could be useful on other worlds.

The results showed it could. After years of careful work on Earth to understand what they were seeing, at Georgetown University in Washington DC and her colleagues found evidence for organic molecules in the samples that would have been missed by the rover’s regular analysis. While they didn’t find any concrete evidence of life, such as amino acids, the results showed the benefits of these so-called “wet chemistry derivatization” experiments.

“We have proved that this experiment can work,” says Millan. “That means we can do this same experiment again on different minerals like clay and sulphates that can better preserve organic molecules.”

That will include further studies on the surface of Mars by Curiosity in regions that are more conducive to life. Its sister rover, Perseverance, is also looking for signs of life, but doesn’t have the same “wet chemistry” equipment.

The technique will be used on future missions, such as Europe’s upcoming Rosalind Franklin Mars rover launching in 2022 and ��������’s Dragonfly mission, a drone that will explore the surface of Saturn’s moon Titan in 2036. “Now we know we’re able to make it work on the surface of another planet,” says Millan.

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