Nasa Mars rover: How Perseverance will hunt for signs of past life

A survey of the minerals in Jezero Crater by Dr Briony Horgan of Purdue University, Dr Melissa Rice of Western Washington University (both scientists on the mission) and colleagues, revealed carbonate deposits at the western edge of the ancient shore. These "marginal carbonates" were likened to a bathtub ring - the build-up of soap scum that's left after the water is drained.