Examining initial samples of rocks collected by NASA's Mars Curiosity rover, scientists have found a wide diversity of minerals in the lower-most layers of Mount Sharp mountain, suggesting that conditions changed in the water environments on the Red Planet over time.
Curiosity landed near Mount Sharp in Gale Crater in August 2012. It reached the base of the mountain in 2014. Layers of rocks at the base of Mount Sharp accumulated as sediment within ancient lakes around 3.5 billion years ago.
Orbital infrared spectroscopy had shown that the mountain's lower-most layers have variations in minerals.
"We went to Gale Crater to investigate these lower layers of Mount Sharp that have these minerals that precipitated from water and suggest different environments," said Elizabeth Rampe of NASA's Johnson Space Center in Houston who is the first author of the study.
"These layers were deposited about 3.5 billion years ago, coinciding with a time on Earth when life was beginning to take hold. We think early Mars may have been similar to early Earth, and so these environments might have been habitable," Rampe added.
The minerals found in the four samples drilled near the base of Mount Sharp suggest several different environments were present in ancient Gale Crater, according to the study published in the journal Earth and Planetary Science Letters.
At the base are minerals from a primitive magma source; they are rich in iron and magnesium, similar to basalts in Hawaii, the data showed.
Moving higher in the section, scientists saw more silica-rich minerals.
In the "Telegraph Peak" sample, scientists found minerals similar to quartz. In the "Buckskin" sample, scientists found tridymite.
Tridymite is found on Earth in rocks that formed from partial melting of the Earth's crust or in the continental crust -- a strange finding because Mars never had plate tectonics.
In the "Confidence Hills" and "Mojave 2" samples, scientists found clay minerals, which generally form in the presence of liquid water with a near-neutral pH, and therefore could be good indicators of past environments that were conducive to life.