Sen— NASA's longest-running rover on Mars is studying a rock boundary that probably formed in wet conditions in the Red Planet's ancient past.
Lying at the foot of "Solander Point", scientists believe there are at least two layers present in this area: one that formed in acidic wet conditions, and another that formed in neutral water.
If the researchers can prove this point, this will add to the growing list of evidence that there was running water on the planet in the ancient past.
"We made it," stated Matt Golombek, Opportunity's project scientist at the NASA Jet Propulsion Laboratory.
"The drives went well, and Opportunity is right next to Solander Point. We know we could be on that north-facing slope with a one-day drive, but we don't need to go there yet. We have time to investigate the contact between the two geological units around the base of Solander Point. Geologists love contacts."
Opportunity's view of the boundary layer between the Burns Formation (the darker area) and Solander Point (the lighter area) on Mars. Credit: NASA/JPL-Caltech
Part of the team's motivation to bring Opportunity to this point is to provide a safe haven for the winter. As the rover is solar-powered, when winter falls on Mars it is important to put it in a position where its panels can collect as much of the weak sunlight as possible.
Opportunity will be put on the north-facing Solander slope before mid-December, where it will remain as the sunshine reaches a minimum in February 2014. The rover will receive enough sunlight to move throughout the worst of the winter, NASA stated.
The area is also rich from a geological perspective, however, providing motivation for Opportunity to drive some distance (2.4 kilometers) from its last location at Cape York to get here.
Cape York and Solander Point are "raised segments" of the west side of the 22-kilometer Endeavour Crater, with the flatter area in between called the Burns Formation. Since the rocks in Burns include sulfate, scientists believe that environment had sulfuric acid in the distant past.
There could be something different at this new boundary level, however. "From observations by Mars orbiters and from Opportunity's work on Cape York, researchers suspect these older rocks may contain minerals that formed under wet conditions that were not as acidic," NASA stated.
Opportunity has been working on Mars since January 2004, well beyond its design life of three months. While its twin, Spirit, ceased working in 2010 after falling into a sandtrap, Opportunity remains in good health despite aging signs such as stiffer joint motion.
The two rovers have found extensive evidence of rocks that may have formed in Martian water in the ancient past, with those finds forming part of the inspiration for the more robust NASA Curiosity rover to follow them to the Red Planet in August 2012.