The environmental changes of Gale Crater visible in the samples collected by the Mars Rover Curiosity

An area at the base of Mount Sharp (Image NASA/JPL-Caltech/MSSS)
An area at the base of Mount Sharp (Image NASA/JPL-Caltech/MSSS)

An article published in the journal “Earth and Planetary Science Letters” describes a study of the first samples taken in the lower layers of Mount Sharp on Mars by NASA’s Mars Rover Curiosity. A team of scientists in the ARES Division at NASA’s Johnson Space Center compared the minerals found in the first samples analyzed, which show the different environmental conditions that existed over time.

The Mars Rover Curiosity explored the layers at the base of Mount Sharp since September 2014 to continue in the following months, in 2015. Various samples were taken and analyzed, including some containing sediments that accumulated in ancient lakes about 3.5 billion years ago. Spectroscopic analyzes had already been carried out by space probes orbiting Mars with interesting results because they showed variations in minerals in the lower layers suggesting that there were changes in the area.

That and other characteristics of Mount Sharp made it the Curiosity mission’s first scientific target. This mountain is at the center of Gale Crater, where Curiosity landed in August 2012, which in a remote time was a lake. By the end of 2014, NASA presented evidence of the existence of that lake and that Mount Sharp was the result of progressive deposits of sediments in the lake bed over tens of millions of years.

The research continued with the addition of new data from the testing of the samples collected by the Mars Rover Curiosity over time. Now scientists in the Astromaterials Research and Exploration Science (ARES) Division at NASA’s Johnson Space Center studied the first samples taken in the lower layers of Mount Sharp to understand more about the changes in the conditions of that aquatic environment in the course of time.

The comparison showed that the environment has changed over time, so much that the scientists talk about different environments present in remote times in Gale Crater. This is consistent with the discoveries announced at the end of 2014, as the data also indicated a number of changes in the ecology of the area with repeated filling and subsequent evaporation of a lake over tens of millions of years.

The minerals show traces of water with different pH because in some cases minerals were found that dissolve at low pH and various oxidation conditions were detected. The rocks in the areas called “Pahrump Hills” and “Marias Pass” came from different regions, transported by water. In short, this is an environment that in a very ancient time was particularly dynamic and subject to various changes over time.

In the area called “Buckskin” tridymite was found, a discovery that was surprising. Quartz-like minerals were found at “Telegraph Peak”. At “Confidence Hills” and “Mojave” clay minerals were found, usually formed in the presence of water with a pH near the neutral. The last two samples contain traces of a salt that forms in acid solutions called jarosite and this indicates environmental changes. There are also iron oxides such as hematite and magnetite.

This comparative study of the results obtained by the Mars Rover Curiosity over the years provided more information about Gale Crater’s ancient environment and above all on its changes. It’s a type of study that will continue because Curiosity is slowly climbing Mount Sharp collecting new data about that environment.

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