NASA’s Curiosity rover has many months of arduous travel ahead of it before it reaches the base of Mount Sharp, its geologically vibrant final destination on Mars. However, NASA is savoring the rover’s journey, using it as an opportunity to visit numerous other intriguing locations with clues to Mars’ distant, more hospitable past.
According to a Jet Propulsion Laboratory press release, Curiosity’s next stop is a spot known as “the Kimberley”. The Curiosity team chose this site for a visit based upon orbital images that showed four different types of terrain with different textures intersecting. As Curiosity approaches the Kimberley, it is gaining a fuller picture of the rocks, which appear to be different sandstone layers with different textures and resistance to weathering. This suggests that the different sandstones, although superficially similar, actually were deposited in different environments.
The outcrops in question are 282 feet south of Curiosity’s current position. Once the rover arrives, it might have time to use its drill to collect rock samples for analysis with its internal laboratory instruments. So far, Curiosity’s most exhaustive studies have been on finer-grained mudstones, including a site called “Yellowknife Bay”; Curiosity’s analyses there showed that the site was once a lakebed setting suitable for microbial life.
The Kimberley will be the first chance Curiosity has had to sink its teeth into sandstones. The four different layers visible at the site differ in their durability, their resistance to erosion. These differences are attributable to variation in the cements, the material that fills the spaces between grains in a sandstone. The softness or hardness of a cement, and thus of the sandstone containing it, is affected by the conditions in which the sandstone formed. Scientists hope that the Kimberley sandstones will reveal variability in the wetter environments in the site’s geological history.
Examination of variation in sandstone durability could also explain the landscape through which Curiosity is trundling. Harder sandstones form caprocks on the tops of mesas and buttes, and might even play a role in why Mount Sharp exists in the center of Gale Crater. Being able to distinguish the hard caprocks can also help the Curiosity team plan routes that minimize damage to the rover’s aluminum wheels.