NASA's Perseverance rover has found minerals and organic matter in rocks on mars that suggest the planet once had conditions suitable for life. These rocks come from Jezero crater, a wide basin that long ago held a large lake and river delta.
The new study, published in Nature, studied a rock layer using PIXL, a tool that detects elements with x-rays, and SHERLOC, a scanner that spots organic chemicals and minerals using light.
Researchers from Imperial College London helped map the rocks' layers and textures.
Unexpected lake discovery
The lake would have been a good habitat for simple life forms. The rover found areas rich in iron-phosphate and iron-sulfide minerals. These minerals formed through redox reactions, processes where electrons move between substances, possibly using organic carbon. On earth, similar features come from microbes breaking down food, so these could be a biosignature, a clue to past life. But they might also form without biology, through non-living chemistry.
“My group observed redox reactions in lab experiments where ferrihydrite containing oxidized iron was heated with organic compounds, including amino acids, to produce the mineral magnetite containing reduced iron,” says SETI Institute scientist Janice Bishop in a press release. "Spectral analyses of pure minerals and mineral mixtures in the laboratory are necessary for interpreting the spectral data collected at Mars."
The rover has already drilled a sample and stored it. This waits for the Mars Sample Return mission, a NASA-European Space Agency project to bring samples to earth in the 2030s. There, advanced labs will test for true signs of life.
Once the samples return to Earth, scientists will be able to study them and shed light on the potential for prebiotic - or even biological - chemistry beyond our own planet.
Imperial College researchers call this an exciting potential biosignature but stressed the need for earth analysis to confirm. The UK Space Agency notes it as promising evidence, though caution is needed.