In July 2024, Perseverance drilled into an arrowhead-shaped rock in an ancient Martian riverbed. What came out of it, a year of peer review later, is the strongest potential biosignature ever found on Mars — and a sample that may never make it home to prove it.
Perseverance's selfie beside Cheyava Falls, July 23, 2024. Credit: NASA/JPL-Caltech/MSSS
Video via YouTube — NASA/JPL-Caltech, official Sept. 10, 2025 briefing on the Cheyava Falls finding.
An arrowhead-shaped rock in Neretva Vallis, a dry river channel that once fed Jezero Crater — covered in millimeter-scale "leopard spots" where mineral rings meet.
SHERLOC detected organic carbon; PIXL found vivianite and greigite — iron-bearing minerals that, on Earth, often form through reactions microbes use for energy.
Non-biological explanations haven't been ruled out. Confirming it either way needs lab equipment no rover carries — the sample has to come home.
Mars Sample Return — the mission that would fly Sapphire Canyon and Perseverance's other tubes back to Earth for lab analysis — had already faced years of cost and schedule pressure. In January 2026, a spending package passed by the House of Representatives effectively cancelled its funding. Barring a reversal, the rock many scientists consider the best evidence yet for ancient Martian life may stay exactly where it is: sealed in a titanium tube, on Mars, unconfirmed.
While Sapphire Canyon waits, the search for organic chemistry on Mars keeps producing new evidence elsewhere. NASA announced this year that a rock Curiosity drilled in 2020 — thousands of miles from Cheyava Falls — contains the most diverse collection of organic molecules ever found on Mars: 21 carbon-containing compounds, seven detected on the planet for the first time. NASA also released two new 360-degree panoramas from the rovers: Curiosity's 1.5-billion-pixel view of ancient "boxwork" ridges carved by long-vanished groundwater, and Perseverance's panorama of some of the oldest exposed rock anywhere in the solar system, on the rim of Jezero Crater.