NASA’s Curiosity rover has again found evidence that Mars was potentially capable of hosting life.
As detailed in a new Science paper, “Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars”, some of the soil samples Curiosity took from the bottom of Gale Crater turned up molecules of “thiophenes, benzene, toluene, and small carbon chains, such as propane or butene.”
As some of those molecules are often fragments of kerogens – organic molecules known to be the residue of living matter – the paper’s authors cautiously suggest the Martian finds could suggest biological processes once took place on Mars.
There's also excitement because Curiosity found this stuff without having to look very hard: the organics turned up in some mud that looked likely. Also pleasing is that the presence of chlorine and sulphur, which both preserve organics, suggests the presence of many more deposits from which to learn more about Mars' past and possible ecosystems.
But the boffins are far from certain the the organic molecules or methane that Curiosity turned up have anything to do with life. As NASA put it, Water-rock chemistry might have generated the methane, but scientists cannot rule out the possibility of biological origins.”
But it’s getting easier to hypothesise that Mars once harboured life, because Curiosity’s extended trundling on Mars has shown evidence of liquid water on the surface and found plenty of the chemicals that you’d expect as pre-cursors to, or by-products of, life. We also know that Mars was once warmer and had a denser atmosphere, important requirements for life as we know it.
The agency and the paper’s authors said these new finds suggest we need to keep looking, rather than representing a smoking gun.
We are therefore still alone, but our imaginary bacterial buddies are less far-fetched. ®