The Mars Curiosityrover has found evidence of ancient organic matter on Mars
NASA’s Curiosity rover has found evidence of complex organic matter on Mars.
The discovery provides the most compelling evidence yet that the Red Planet could have supported ancient life.
In a separate paper meanwhile, NASA scientists conclusively detected methane in the Martian atmosphere, noting that levels of the gas fluctuate depending on the season.
The discoveries will fuel speculation that there is – or once was life – on Mars, however the researchers have warned that there are other explanations for the finding.
“Are there signs of life on Mars?” said Michael Meyer, lead scientist for NASA's Mars Exploration Program. “We don’t know, but these results tell us we are on the right track.”
The Curiosity rover discovered the complex organic matter buried in ancient sediments that would have formed a lake bed on Mars more than €3bn years ago.
The molecules contain carbon and hydrogen and may also include oxygen, nitrogen and other elements – all essential building blocks of life.
The researchers have warned that, while the molecules are commonly associated with life, there are other explanations for their presence on Mars.
While they may be the remains of past organisms, they could also be the product of chemical reactions with rocks – or might have travelled to Mars on a comet, asteroid or meteor.
Either way the finding proves that if there was microbial life on Mars – it would not have gone hungry.
However, the fact that the samples were taken from an ancient lake-bed has added to the excitement surrounding the finding.
It means that, at one time, the lake held all the necessary ingredients for life - including water, chemical building blocks and energy sources.
“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA.
“I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”
There are a number of explanations for the seasonally fluctuating methane levels in the Martian atmosphere.
Methane is commonly viewed as a clear sign of life and the discovery will fuel speculation that the gas could be coming from microbes living deep underneath the Martian surface.
However, it could also be the result of chemical reactions between water and Martian rocks.
Researchers believe the seasonal changes in the gas levels could be the result of reservoirs of Methane deep under the surface.
If the gas was slowly leaking, it would stick to the Martian soil in winter before being released in greater quantities during the summer when the soil warms up.
Both papers are published in the latest edition of the journal Science.