Water on Mars of these salts". NASA also reported that Jake M rock, a rock encountered by "Curiosity" on the way to Glenelg, was a mugearite and very similar to terrestrial mugearite rocks. On December 9, 2013, NASA reported that Mars once had a large freshwater lake inside Gale Crater, that could have been a hospitable environment for microbial life. On December 16, 2014, NASA reported detecting an unusual increase, then decrease, in the amounts of methane in the atmosphere of the planet Mars; in addition, organic chemicals were detected in powder drilled from a rock by the "Curiosity" rover. Also, based on
Crewed Mars rover rovers, because they need to know at least roughly where they are and where they are going to get to a destination. Dead reckoning was the method used by the Mars Pathfinder rover "Sojourner" for navigation. A GPS satellite network for Mars would mean a constellation of satellites in Mars orbit, but one alternative would be a surface based pseudo-satellites array. These devices would have to be emplaced with high precision, unless they were self-calibrating. An example of criteria for humaned Mars surface rover was expressed by NASA in the surface variant of the aforementioned SEV, in development in during