The ratio of a heavier hydrogen isotope, deuterium, to the most common hydrogen isotope can provide a signature for comparison across different stages of a planetвЂ™s history. SAM analyzed hydrogen isotopes from water molecules that had been locked inside a rock sample for billions of years and were freed when SAM heated it, yielding information about the history of martian water. Researchers also reported that CuriosityвЂ™s taste of martian water, bound into lakebed minerals in the Cumberland rock more than 3 billion years ago, indicates the planet lost much of its water before that lakebed formed and continued to lose large amounts after. The challenge now is to find other rocks on Mount Sharp that might have different and more extensive inventories of organic compounds.вЂќ In turn, this is informative about Earth-Mars differences and whether or not particular environments represented by Gale Crater sedimentary rocks were more or less favorable for accumulation of organic materials. вЂњOrganics are important because they can tell us about the chemical pathways by which they were formed and preserved. вЂњThis first confirmation of organic carbon in a rock on Mars holds much promise,вЂќ said Roger Summons of the Massachusetts Institute of Technology in Cambridge. When heated inside SAM, the perchlorates alter the structures of the organic compounds, so the identities of the martian organics in the rock remain uncertain. Identifying which specific martian organics are in the rock is complicated by the presence of perchlorate minerals in martian rocks and soils. However, extensive testing and analysis yielded confidence in the detection of martian organics. CuriosityвЂ™s SAM lab detected in several samples some organic carbon compounds that were, in fact, transported from Earth inside the rover. Researchers worked many months to determine whether any of the organic material detected in the Cumberland sample was truly martian. вЂњCan we learn more about the active chemistry causing such fluctuations in the amount of methane in the atmosphere? Can we choose rock targets where identifiable organics have been preserved?вЂќ вЂњWe will keep working on the puzzles these findings present,вЂќ said John Grotzinger from the California Institute of Technology in Pasadena. CuriosityвЂ™s findings from analyzing samples of atmosphere and rock powder do not reveal whether Mars has ever harbored living microbes, but the findings do shed light on a chemically active modern Mars and on favorable conditions for life on ancient Mars.

Organic molecules, which contain carbon and usually hydrogen, are chemical building blocks of life, although they can exist without the presence of life.

These martian organics could either have formed on Mars or been delivered to Mars by meteorites. Before and after that, readings averaged only one-tenth that level.Д¬uriosity also detected different martian organic chemicals in powder drilled from a rock dubbed Cumberland, the first definitive detection of organics in surface materials of Mars. During two of those months, in late 2013 and early 2014, four measurements averaged seven parts per billion. Researchers used CuriosityвЂ™s onboard Sample Analysis at Mars (SAM) laboratory a dozen times in a 20-month period to sniff methane in the atmosphere.

вЂњThere are many possible sources, biological or non-biological, such as interaction of water and rock.вЂќ вЂњThis temporary increase in methane - sharply up and then back down - tells us there must be some relatively localized source,вЂќ said Sushil Atreya of the University of Michigan in Ann Arbor. NASAвЂ™s Mars Curiosity rover has measured a tenfold spike in methane, an organic chemical, in the atmosphere around it and detected other organic molecules in a rock-powder sample collected by the robotic laboratoryвЂ™s drill.

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