On any surface, if clay is found it indicates the presence of water nearby. Hence, finding clay on Mars is a very big thing. The historical, present water conditions of the planet are very crucial to understand the planet and to know if it supported life at any point. Currently, MSL Curiosity is present at Mt Sharp for inspection of the rocks and to find evidence of clay. Detecting evidence of clay at Mt Sharp was one of the main reasons for choosing Gale Crater as a landing site for MSL Curiosity.
Curiosity has sampled two rocks as a clay-bearing unit and it confirmed that clay is indeed present there. Among the rocks checked by Curiosity so far, these two rocks have the greatest clay concentration. The rocks are named as “Aberlady” and “Kilmarie“. They are situated at Mt Sharp’s lowest region, which has been the primary objective of the mission.
The height of Mt Sharp above the crater floor is 5.5kms, which means that it contains a layered record of the geology of Mars. With the passage of time, it was weathered down by winds and thus has been an easy target for Curiosity. Scientists have been interested in Mt Sharp which is also known as Aeolis Mons due to its formation. Gale Crater is an impact crater which was most probably filled with water, and according to scientists, the formation of Mt Sharp took place over 2 billion years with the deposition of the sediments at the bottom.
There are some doubts about the timeline of the formation of Mt Sharp. MSL Curiosity hopes to clear out this confusion. Mt Sharp appears as an eroded, sedimented mountain and scientists hope as the work of Curiosity continues a clearer view of its formation will be obtained.
It is being considered that the interaction of water and sediment at the bottom of the lake took place for the formation of clay. Since, a mountain has various layers containing different kinds of minerals, specific types of clay at given layers gives the information on the timeline of water on Mars. The layers above clay-containing layers have sulphur and above it, there are layers which contain minerals bearing oxygen.
There is also a river named Gediz Vallis Channel in Gale crater. It formed after the layers of clay and sulphur. It presents a different type of puzzle and the work of Curiosity is to collect all the clues of the puzzle, process it and generate the final information on Martian geology and history.