New hope for life on Mars brings more evidence of a life-sustaining environment on primordial Mars, in the form of ancient sediments that confirm Jezero crater was once a vast lake:

As Perseverance travels across the surface of Mars, the RIMFAX instrument sends radar waves downward at 4-inch (10-centimeter) intervals and measures pulses reflected from depths of about 65.6 feet (20 meters) below the surface to create a subsurface profile of the crater floor.

The RIMFAX data showed evidence of sediment deposited by water that once filled the crater. It’s possible that microbial life could have lived in the crater at this time and, if such life existed on Mars, sediment samples from this area would contain signs of their remains.

Two distinct periods of deposition occurred, creating layers of sediments on the crater floor that appear regular and horizontal, much like strata layers seen on Earth. Fluctuations in the lake’s water levels caused some of the sediment deposits to form an enormous delta, which Perseverance traversed between May and December 2022, according to the statement.