Just over a year ago, Nasa made a remarkable announcement. The Perseverance rover had found potential signs of ancient life on Mars. Now, the technical details behind that discovery have been published in a Nature paper that, despite its rather modest wording, may ultimately prove to be among the most significant in the history of science.

The bottom line is this: it might be life, but we won’t know for sure until we return the samples to Earth. Perseverance has already collected a fragment of the relevant rock — we just have to go and get it.

Indeed, Nasa has been working with the European Space Agency on a mission to go to Mars, retrieve the samples of rock collected by Perseverance and deliver them to Earth. This would include the sample from the rock that’s the subject of the Nature study. However, the mission, known as Mars Sample Return, has run into trouble because of rising costs.

In mid-2024, the Perseverance rover encountered a block of ancient mudstone, nicknamed Cheyava Falls, distinguished by its........

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