NASA persistence finds first possible hint of ancient life on Mars

NASA’s Persistence rover has uncovered the first trace of ancient microbes on Mars.

“We’re not able to say that this is a sign of life,” says Persistence deputy project scientist Katie Stack Morgan of NASA’s Jet Propulsion Laboratory in Pasadena, California. “But this is the most compelling sample we’ve found so far.”

The rover retrieved the sample on July 21 from a reddish rock, named Cheyava Falls after a feature in the Grand Canyon. It is the first part of Mars that Perseverance has examined that contains organic molecules, the building blocks of life, project scientist Ken Farley of Caltech reported July 25 at the 10th International Conference on Mars in Pasadena.

This isn’t the first sign of organics on Mars – the Curiosity rover detected organic molecules in a region called Gale Crater in 2014 (SN: 16/12/14). But scientists have struggled to identify organics since Perseverance landed in an ancient dried-up lake called Jezero Crater in 2021, says Stack Morgan (SN: 17.2.21).

Adding to the excitement, the reddish rock is speckled with tiny white dots with black edges. “They look like a three-color leopard spot,” says Stack Morgan.

Perseverance examined the stains with instruments that can identify their chemical content and discovered that the lips contain iron phosphate molecules. On Earth, rings with similar structure and chemistry are associated with ancient microbial life. The chemical reactions that create the rings can be a source of energy for the microbes.

“They don’t REQUIRING life, of course, and that’s an important caveat,” says Stack Morgan. “But based on our experience with similar things on Earth, there is a possibility that life may have been involved and these may have a biological origin.”

The rock has other confusing features that cloud the picture of how it formed, says Stack Morgan. It is crossed with white veins of calcium sulfate. These veins are filled with millimeter-sized crystals of olivine, a mineral that forms from magma. The inclusion of both points and these volcanic features in the same rock is “a bit mysterious,” says Stack Morgan, as they indicate different origins. Understanding how the rock formed could help tell how likely the right conditions and temperatures were to host biology.

Planetary scientist Paul Byrne thinks we should be cautious about the discovery.

“Could this really be a biological signature? yes. And if it is, then it’s really the kind of society-changing discovery that the discovery of truly extraterrestrial life would be,” says Byrne, of Washington University in St. But it’s also possible that the stains came from something other than life, “in which case the whole thing is an interesting example of water-rock chemistry.”

The only way to find out for sure is to bring the rock home. A big part of Perseverance’s mission is to collect samples of interesting rocks for a future spacecraft to return to Earth, where they can be studied in more sophisticated laboratories than a rover can carry on its back. Persistence has thrown everything it has at this rock already, says Stack Morgan.

But funding uncertainty has recently put the program, known as Mars Sample Return, on hold (SN: 5/8/24).

“With this sample, the rationale for MSR is strengthened even more, and I should hope to motivate NASA to commit to this project sooner rather than later,” says Byrne.

Stack Morgan says the rover team is pushing ahead despite budget uncertainty.

“We have a mission to perform and a job to do: collecting compelling samples,” says Stack Morgan. “It can only be our hope that the samples we collect will be convincing enough to justify the cost of returning the sample to Mars. I think with this exciting sample, it really hits that home.”