Gale Crater, home of NASA's Curiosity Rover, is approximately 150 km in diameter and located near the boundary between the southern highlands and northern lowlands of Mars. The crater contains a massive central mound that contains a kilometres-thick layered sequence of sedimentary rocks that provide evidence for a changing climate over the planet’s history. Studies indicate that it transitioned from wetter conditions in which water-bearing minerals formed, to the drier climate conditions observed today.
The exposed layers seen in this image, taken by the CaSSIS camera onboard the ESA/Roscosmos ExoMars Trace Gas Orbiter, are located on the west side of the Gale crater central mound. This section belongs to the so-called ‘Lower Formation’, which is characterised by abundant signatures of the presence of water as observed by the CRISM imaging spectrometer onboard NASA’s Mars Reconnaissance Orbiter. These transition from sulphate-bearing, to clay-sulphate mixtures, to sulphate-bearing rocks in the highest parts of the formation. The transitions are reflected here in the changing colours observed by CaSSIS.
The image is centred at 5.2ºS/137.2ºE and was taken on 20 July 2019. North is up.