First results of the Perseverance rover on Mars: there was indeed a lake in the Jezero crater

The first results of rover Perseverance confirm how well the Jezero crater , where the mission landed on March , was promising. The rover’s landing site was a good home to a lake once, 3.6 billion years ago. This lake was 35 kilometers in diameter and several tens of meters deep. The announcement, relayed by the CNRS , is the subject of a publication in the journal Science on October 7, 2021.

“ Spacecraft observations orbitals have shown that the Jezero crater of Mars contains a prominent body of fan-shaped sedimentary rock deposited at its western margin ”, recall these scientists. The images of probes orbiting Mars foreshadowed the geological complexity and history of this basin. The interest of the area is now confirmed by the SuperCam instrument of the rover : the Jezero crater contained a lake fed by a river, via a delta (a triangular-shaped mouth).

The lake was 100 meters lower

“ Our rover images constrain the hydrological evolution of the Jezero crater and potentially the climate and the ability of the young Mar ”, write the researchers. The quality of the images taken by Perseverance made it possible to interpret the geology of the place. They were however taken at a distance, more than 2 kilometers from the geological formations studied.

The rover observed, after its arrival on the red planet in February 2021, “ a set of inclined sedimentary strata, sandwiched between horizontal strata ”, describes the CNRS in its press release . This geometry is similar to what we know of deltas on Earth and the team was able to use it to determine the shape of the lake, its altitude and the type of deposits.

Result: the height of the lake was 100 meters lower than suggested by the orbital data. Scientists were able to determine that it was a closed lake, the level of which fluctuated. An advantage of this enclosed lake structure is that the deposits that may have formed were undoubtedly well preserved. However, it is not excluded that we are therefore facing a less dynamic lake, with less hydrological activity, than an open lake.