NASA's Perseverance rover is the first mission to collect and store Martian rocks and regolith.
NASA/JPL-Caltech
On Mars, it’s the little things that hint at a past life. In 2025, tiny details in rocks on the surface of Mars revealed some of the most interesting clues that microbial life may once have existed there.
They come from analysis of samples collected by NASA's Perseverance rover, which has begun to provide evidence for the existence of life. last year: Perseverance came across rocks with tiny spots, each only a millimeter wide, with a ring of dark material around it. These spots, dubbed “leopard spots,” are similar to features we see on Earth associated with microbial fossils.
This year, Joel Hurowitz of Stony Brook University in New York state and his colleagues conducted a more detailed analysis of leopard spots, finding forms of iron and sulfur that often arise from chemical reactions involving microbes. “I think this is much more promising [an indication of life] more than anything I’ve seen in the last 20 years,” says Hannah Sizemore at the Planetary Science Institute in Arizona.
Previous discoveries hinting at life on Mars have included unexpected changes in methane levels on the planet, as well as fossil-like structures in Martian meteorites. “I'm more excited about these discoveries than any of them,” Sizemore says. “It was all on the wrong physical scale.” On the other hand, leopard spots are about the right size to be caused by germs, she says.
The same is true for other potential biosignatures A persistence discovered this year: tiny greenish nodules of minerals that on Earth are typically associated with microbial life. “It was always obvious that life was not obvious there. These are not herds of wildebeest sweeping majestically across the plain,” he says Andrew Steele at Carnegie Science in Washington, D.C., who was part of the team that developed the science targets for Perseverance. “Whatever these signs are, they will be subtle, and we need the best tools available to us to find them.”
The Perseverance rover took a photo of a rock with characteristic “leopard spots.”
NASA/JPL-Caltech/MCSS
Perseverance has a sophisticated array of scientific instruments, but if we want to definitively determine whether these rocks contain signs of past life, we will have to bring samples back to Earth for testing in laboratories here. The plan was always that Perseverance would store the samples and a future mission would pick them up and bring them back.
“These samples represent the best chance to take the next step in analyzing whether there is [or has been] life on Mars—we just need to bring them back,” Steele says.
Unfortunately, this prospect is looking less and less likely. Mars sample return project marked for cancellation by Trump administration proposed NASA budget for 2026; if this budget is approved, there will be no plan to collect the samples that Perseverance has so carefully collected.
Indeed, it is quite possible that we have found signs of life on Mars and will never know about it. “We continue to make significant progress, but our overall picture of Mars habitability continues to remain stagnant,” says Sizemore. “We are on the brink – we can't ignore it and we can't prove it. Only missions on the ground will change that.”
Astronomy capital of the world: Chile.
Explore the astronomical sights of Chile. Visit some of the most technologically advanced observatories in the world and gaze at the stars under some of the clearest skies on Earth.
Topics:
