Mars: the "leopard spots" of Cheyava Falls

The claim

"NASA's rover found the clearest sign of ancient life on Mars."

Where the idea comes from

Perseverance studied a rock called Cheyava Falls in an ancient river valley in July 2024; NASA announced the Nature paper on 10 September 2025.

What the evidence shows

1. The rock has small "leopard spots": light patches ringed by dark minerals rich in iron phosphate (vivianite) and iron sulfide (greigite).
2. On Earth, such reactions in mud are often driven by microbes feeding on organic matter, and organic molecules were detected in the rock.
3. NASA called the sample, "Sapphire Canyon", a potential biosignature: a feature that may have a biological origin but needs more study.
4. Chemistry without life could also produce the spots, for example at higher temperatures; the rover's instruments can't tell the difference.
5. In 2026 the Mars Sample Return mission was cancelled, so the sealed sample stays on Mars for now; China plans its own sample return (Tianwen-3).

What is still open

Only analysis in a laboratory on Earth could decide. This is NASA's strongest candidate for ancient life beyond Earth.

Our verdict

Worth watching A serious candidate, waiting for a lab that can't reach it.

Sources

• NASA says Mars rock is a potential biosignature (EarthSky)
• Unpacking the Cheyava Falls find (Planetary Society)
• Sample's uncertain future (CNN, 2026)

Checked 31 October 2026. Spotted a newer source? Tell us.