How habitable was Mars in the past? Since the Curiosity rover touched down on Mars in August 2012, it has helped answer a few of these questions in the area surrounding its equatorial landing site of Gale Crater.
Most notably, in March 2013, Curiosity investigators announced extensive evidence of a lake bed or river system in a region that NASA dubs ‘Yellowknife Bay.’ The environment, which could be a favorable spot for microbes, includes minerals such as clays that are formed in waters that once existed there. The waters themselves were probably not too salty or acidic, geologic evidence shows, which gives further credence that life could have been possible on the Red Planet.
Curiosity is now preparing to ascend its prime target — Mount Sharp (Aeolis Mons). NASA isn’t going to stop there, however. The agency is readying a successor rover to follow on the heels of Curiosity.
Mars 2020, as it’s currently called, will have improved instruments over Curiosity. The new rover is heavily based on the Curiosity design, and as with its predecessor it will be able to search for habitable environments.
But Mars 2020 would also look directly for evidence of life, something Curiosity was not designed to do. This will make choosing a landing site crucial, since it would involve finding a spot where water or volcanic activity was present in the past. These processes provide energy for microbes.