Nasa rover finds rocks on Mars with potential signs of past life

Unusual rocks discovered on Mars contain the most tantalizing evidence of potential past life on the Red Planet.

Mudstones found in a dusty riverbed by NASA's Perseverance rover are dotted with intriguing markings called leopard spots and poppy seeds.

Scientists believe these formations contain minerals produced by chemical reactions that may be related to ancient Martian microbes.

The minerals may have formed through natural geological processes, but at a press conference NASA said the features may be the clearest signs of life ever discovered.

The results are significant enough to meet NASA's criteria for what it calls “potential biosignatures.”

This means they require further investigation to determine whether they are biological in origin.

“We haven't had anything like this before, so I think it's very important,” said Professor Sanjeev Gupta, a planetary scientist at Imperial College London and one of the study's authors. study which was published in the journal Nature.

“We found features in the rocks that, if you saw them on Earth, could be explained by biology – a microbial process. So we're not saying we've found life, but we're saying it does give us something to chase.”

“It looks like the remains of a fossil. Maybe it was leftover food, or maybe it was food that was excreted from the body, and that's what we're seeing here,” Dr. Nicola Fox, associate administrator for NASA's Science Mission Directorate, said at a news conference.

The only way to fully confirm that minerals were created by microbes is to return the rocks to Earth for analysis.

A Mars sample return mission has been proposed by NASA and the ESA, but its future looks very uncertain. The US Space Agency's science budget is facing huge cuts proposed in President Trump's 2026 budget, and the sample return mission is one of those that could be cancelled.

Today, Mars is a cold and arid desert. But billions of years ago, there is evidence that it had a dense atmosphere and water, making it a promising place to search for past life.

The Perseverance rover, which landed on the surface of Mars in 2021, was sent to search for signs of biology. He has spent the last four years exploring a region called Jezero Crater, which was once an ancient lake with a river flowing into it.

Last year, the rover found leopard print rocks at the bottom of a river-carved canyon in an area called the Bright Angel Formation. They are about 3.5 billion years old and are a rock called mudstone, which is a fine-grained rock formed from clay.

“We kind of knew right away that there was some interesting chemistry going on in these rocks, so we were immediately very excited,” said Joel Hurowitz of Stony Brook University in New York, who is also a Perseverance mission scientist and lead author of the paper.

The rover used several instruments in its onboard laboratory to analyze minerals in rocks. This data was then sent back to Earth for scientists to study.

“We think that what we found is evidence of a series of chemical reactions that occurred in the mud that was deposited on the bottom of the lake – and these chemical reactions seemed to occur between the mud itself and the organic matter – and these two ingredients reacted to form new minerals,” Dr. Hurowitz explained.

Under similar conditions on Earth, the chemical reactions that form minerals are usually caused by microbes.

“This is one possible explanation for how these features appeared in these stones,” Dr. Hurowitz said. “This looks like the most compelling potential biosignature detection we've ever seen.”

Scientists also examined how minerals could have formed without microbes, and concluded that natural geological processes may also be behind the chemical reactions.

However, this will require high temperatures, and the stones do not look like they have been heated.

“We found some difficulties with nonbiological pathways, but we can't completely rule them out,” Dr. Hurowitz said.

During its exploration of Mars, Perseverance collected samples, including rocks found in the Bright Angel Formation. They were stored in containers and will be placed on the surface of Mars to await a mission that can return them.

NASA's plans for such a project are hanging in the balance due to the threat of budget cuts, but China is also pursuing a sample return mission that could begin in 2028.

While this decision is being debated, scientists are desperately trying to get to the stones with gloves.

“We need to see these samples on Earth,” Professor Gupta said.

“I think to be truly sure, most scientists would like to see and study these rocks on Earth – it's one of our high priority samples to get back.”