The result of this careful analysis is that scientists have conclusively found thiophenic, aromatic, and aliphatic organic compounds on Mars. These results are reported Thursday in a new paper in Science, of which Eigenbrode is the lead author. She was especially intrigued by the discovery of sulfur within the organic molecules, which probably helps explain how the organic molecules were preserved on the surface of Mars for a long period of time despite the harsh radiation.
With this analysis, scientists searching for indications of past life on Mars are really pushing the suite of instruments on Curiosity pretty far. But this won’t be the last opportunity to search for organic molecules on Mars. In July 2020, the European Space Agency and Russia’s Roscosmos will launch the ExoMars rover to Mars. That summer, NASA also plans to launch the Mars 2020 rover, which should be able to perform additional observations.
The ExoMars rover is particularly tantalizing to scientists because it will have both an instrument to detect organics like the SAM on Curiosity, as well as the capacity to go significantly deeper below the surface of Mars to get samples, perhaps as far as two meters. Although scientists are not sure, they suspect the organic molecules at this depth, if they were indeed produced by biological processes long ago, would stand a much better chance of being protected from radiation on the surface.
And what if microorganisms did, in fact, exist on Mars billions of years ago? Confirming it would involve a pretty in-depth analysis of rocks on Mars, which is probably beyond the capability of any of these rovers. One option is to return samples, which may happen in the 2020s. The other option is to send humans.