NASA’s Perseverance rover has been searching for signs of life on Mars since it landed in an ancient lake on the Red Planet in February 2021. In a trio of new studies, scientists have revealed some details about the habitable conditions that once existed on Mars, while limiting the chances of finding Martian life in the future.

Mars is currently a cold and desiccated world hostile to life, but there is ample evidence that it was warmer, wetter, and friendlier many billions of years ago. Simple life forms could have arisen in the lakes and rivers that flowed in that ancient era, which is why NASA sent Perseverance to search for fossilized traces of any Martian microbes that once existed. The rover is also collecting samples from Jezero Crater, which the mission team hopes to pick up with a future spacecraft to bring back to Earth for closer study. The data for the new research was collected during nearly two years of extraterrestrial research.

The teams working on each of Perseverance’s specialized instruments have published a summary of their findings in a series of three studies. New research follows the August one, which reported an abundance of igneous (or volcanic) rocks in areas first explored by Perseverance, and offered more details about the rover’s new discoveries.

“What’s coming out now is the actual instrument documentation of all this evidence that we saw,” said Eva Scheller, a planetary scientist at the Massachusetts Institute of Technology who led the SHERLOC (Onboard Ultraviolet Spectrometer) study, which was published in the Science journal. “This is actually the first time we have used this kind of instrumentation in a planetary mission.So in itself, it is also a demonstration of a new engineering technique.”

SHERLOC detected two distinct periods when the crater was affected by the presence of water. Although it is difficult to determine the exact time span, the team estimates that the water in the area was around 3.8 billion years ago. More than a billion years later, the crater contained a saltier brine that produced chemicals called perchlorates, Scheller said.

“In that kind of environment, we’re seeing very, very strange chemistry which is not common on Earth at all, but seems to be more common on Mars because we’ve seen these kinds of materials in almost all the missions now,” she explained. “So there are two liquids from different rocks with two different ages with very different chemistry that [SHERLOC] was able to determine.”

The instrument was also able to detect organic molecules that are key ingredients for life, confirming that conditions suitable for life once existed in Jezero Crater.

The SHERLOC results help reconstruct the history of water and organics on Mars and confirm that Jezero Crater had the necessary conditions to support microbes, although this does not mean that life ever originated on the Red Planet.

In addition to SHERLOC, Perseverance also carries the PIXL X-ray spectrometer and the Mastcam-Z stereoscopic camera, which has a zoom function.

Meanwhile, the Mastcam-Z team reported that they found no conclusive evidence of lacustrine sedimentation in the crater floor regions, meaning the rover has yet to encounter sedimentary rocks that could preserve any ancient signs of life.

Together, the new research advances our understanding of a habitable version of Mars that existed billions of years ago.