Evrim Yazgin
Cosmos science journalist
Data from NASA’s Perseverance rover confirms that the Jezero Crater on Mars, where the robot landed in 2021, was once filled with water.
If life ever existed on Mars, the verification of an ancient lake at the site provides the best hope of finding signs of organisms having once inhabited the Red Planet.
Results confirming the presence of an ancient lake are published in the journal Science Advances.
The study shows that the crater was once filled with water before shrinking. Sediments carried into the lake by the river that fed the ancient body of water formed a massive delta. When the lake disappeared, it left behind the features visible today.
“From orbit we can see a bunch of different deposits, but we can’t tell for sure if what we’re seeing is their original state, or if we’re seeing the conclusion of a long geological story,” says Professor David Paige from the University of California, Los Angeles. “To tell how these things formed, we need to see below the surface.”
Perseverance has been studying the crater since 2021. Soil and rock samples collected by the rover will be brought back to Earth by a future mission and examined for evidence of life.
One of the rover’s scientific instruments is the Radar Imager for Mars’ Subsurface Experiment, or RIMFAX.
RIMFAX fired radar waves downward at 10-cm intervals on the rover’s journey from the crater floor onto the delta between May and December 2022. It then measured pulses reflected from depths of about 20 metres below the surface.
The images showed two distinct periods of sedimentation sandwiched between two periods of erosion.
The crater floor below the delta is not flat, suggesting erosion took place before sediments were deposited into the lake. The sediment layers are regular and horizontal – just like sediments deposited in lakes on Earth.
Previous studies suggested lake sediments, but this is the first confirmation that an ancient lake existed in the crater.
So far, we have only ever found evidence for life in one place in the universe: Earth. As far as we know, liquid water was critical to life evolving here. Confirming the existence of an ancient lake on Mars gives us our best opportunity to find life outside our planet.
