Mars probe discovers ancient rock with 'possible biosignature'

It is unclear whether there was ever life on Mars. However, NASA's Perseverance rover has found something on Mars that may include Earth biology.

Ancient life on Mars? Maybe, maybe, maybe. But you’ll have to take a closer look. That’s the brief message from NASA, which announced Thursday (July 25) that its Perseverance rover has found a rock containing compelling evidence of organic molecules and striking signs that, if seen on Earth, would indicate past biological activity.

The announcement came with warning labels. Organic matter can have both biological and non-biological origins, a fact confirmed by NASA scientists. Mars rocks have fooled scientists before.

But they are excited about this veined rock, which they have dubbed “Chiava Falls.” NASA said the rock was taken July 21 from the edge of a vast ancient river valley carved by water in Jezero Crater long ago, before Mars lost most of its atmosphere and surface water and became a cold, dry world with dust storms and no signs of life.

A possible biosignature has been discovered on Mars, and the discovery may have biological origins.

“We can’t say we’ve discovered life on Mars yet,” said Katie Stack Morgan, deputy project scientist. “But what we can say is that we have a potential biosignature, a set of features that could have a biological origin but still need further investigation and require more data.”

The reddish rocks are covered in white spots known as “tiger spots.” These spots are created by chemical reactions often associated with biological activity on Earth, Stack Morgan said. “If you find these types of features on Earth, there’s a good chance that there’s life there,” she said. At the same time, these are chemical reactions that don’t require life.

Cost overruns have made a Mars sample return less likely.

The rover crossed an ancient river delta in Jezero Crater and collected rock and soil samples as part of the ambitious but troubled Mars Sample Return mission. Chiava Falls is an arrow-shaped rock measuring 3.2 feet by 2 feet, named after a waterfall in the Grand Canyon, according to NASA.

The rover has taken a sample of the rock, and the 22nd sample has been recovered so far. The general plan is to send another spacecraft to the surface of Mars, which Perseverance will pick up to transport the samples. The new lander will then bring the material into Earth orbit, where it will be delivered to another spacecraft — one provided by the European Space Agency — for the return trip to Earth.