After 20.1 km and 2073 sols of driving and science operations we have reached the next milestone of the Mars Science Laboratory mission – the Clay Unit. The presence of clay was predicted from near infrared remote spectroscopy and was one of the key reasons for selection of Gale Crater as the landing site. The clay unit is likely to have been a trap for martian organics so we will be looking forward to drillholes and the subsequent gas chromatography and mass spectrometry results from SAM.
One of the key questions we have been addressing for the Gale Crater sediments is the nature of the crustal source materials that were eroded from the surrounding ancient highlands to form the sedimentary deposits. That gives us a window into the formation and evolution of the ancient igneous crust. In a paper recently published by one of our PhD students Candice Bedford (joint with the Open University) we demonstrate that prior to the effects of burial and alteration, the sedimentary material was a mixture of the expected basalt but also more differentiated, silica-rich crustal material. Gale Crater is revealing not just organics and clay but an unexpected history of the formation of the underlying Mars igneous crust.
Paper about source regions of Gale sediments