What did NASA discover? They explain:
"Scientists theorize that in Mars' distant past its environment may have been quite different, with persistent water and a thicker atmosphere. NASA's Mars Atmosphere and Volatile Evolution, or MAVEN, mission will investigate possible losses from the upper atmosphere when it arrives at Mars in 2014.
With these initial sniffs of Martian atmosphere, SAM [Sample Analysis at Mars] also made the most sensitive measurements ever to search for methane gas on Mars. Preliminary results reveal little to no methane. Methane is of interest as a simple precursor chemical for life. On Earth, it can be produced by either biological or non-biological processes.
Dan Vergano (USA Today) explains, "Methane might have suggested that microbes lurk under the surface of Gale crater. The $2.5 billion rover landed on Mars on Aug. 6 on a mission to look for chemistry evidence of past habitable conditions on the Red Planet." But it's not over yet. Irene Klotz (Discovery News) reports the search continues, "Curiosity scientists said they plan to increase their experiments' sensitivity and keep looking."
And Curiosity's mission includes more than methane searches. Amina Khan (Los Angeles Times) notes, "Curiosity will continue to take lungfuls of air as it makes its way on its two-year mission toward Mt. Sharp, a 3-mile-high mound in the middle of Gale Crater whose layers may hold clues revealing whether Mars was hospitable to life."