In September 2023 NASA's Perseverance rover arrived at the inner margin of Jezero Crater on Mars, surprising the science team with what it encountered.
The studied region, known as the Margin Unit, follows the shoreline of an ancient lake. Scientists anticipated sedimentary rocks made of clay and silt layers, which on Earth are good at preserving signs of past microbial life.
Orbiter observations had previously detected strong carbonate signals in the area. On Earth such carbonates typically form in shallow lakes or oceans, environments that can support life.
The presence of both sedimentary deposits and carbonates suggests that Jezero Crater experienced at least three distinct periods with liquid water. These findings improve our understanding of Mars' ancient habitability.