NASA’s Curiosity rover has made two of its most important observations on Mars since arriving on the planet in 2012. First, the rover measured a spike in levels of the organic chemical methane in the local atmosphere of its Gale Crater research site.

The second big discovery came when the rover drilled into a rock dubbed “Cumberland.” Samples from the mudstone were analyzed by Curiosity’s Sample Analysis at Mars (SAM) instrument, and provided the first definitive detection of organic molecules on the martian surface.

Astrobiologists have been hunting for organic material on Mars for decades. Organic molecules are typically built from atoms of carbon and hydrogen, and they are often referred to as the ‘building blocks’ for life as we know it. However, there is not enough information to determine whether or not the martian organics found by Curiosity are biological or non-biological in origin. Many non-biological processes on Mars could have produced them, including the delivery of materials by meteorites or geological reactions in the rock.

Development of instruments on the Curiosity rover, including Sample Analysis at Mars (SAM) and Chemistry & Mineralogy (CheMin), was supported by the ASTID element of the NASA Astrobiology Program.