Blasted off Mars, found in the Sahara: a 4.1-billion-year-old rock remembers a wetter world

A fist-sized rock found in pieces in Mali's Sahara Desert in 2022 turns out to be a visitor from Mars — and quite possibly the oldest of the 435 Martian meteorites known on Earth. Named Teghaza 001, it formed in the planet's crust at least 4.1 billion years ago, and its chemistry carries fingerprints of water moving through it as it cooled. That is fresh evidence that early Mars was warmer and wetter than the cold, dry world we see today — with conditions that could have suited microbial life. "A witness to a time when Mars was likely warmer and wetter than it has been for most of its history," says Yang Liu of NASA's Jet Propulsion Laboratory, lead author of the study in Science. Meteorites are the only pieces of Mars scientists can hold in a lab, and this one reaches back almost to the planet's birth.