By Prarthana Mitra
A study published in Science on Thursday provided the first conclusive evidence for organic molecules on Mars, a pursuit that began with NASAs Viking landers in the 1970’s. NASA’s Mars rover Curiosity recently identified a variety of large carbon-based organic molecules, universally agreed upon as the building blocks of life, in martian rocks dating back to 3.5 billion years ago.
Let’s back up a bit
Earlier tests also hinted at the presence of organics, but traces of chlorine in martian dirt complicated those interpretations.
Kicking off a quest to determine the possibility of life on Mars, the Curiosity rover touched Martian soil in August 2012 and drilled into the red planet in 2014 and 2015. Curiosity mission scientists stationed near Mars’ huge Gale Crater, were quick in finding that Gale hosted a potentially habitable system, complete with a lake, billions of years ago. Supporting these claims were other organics, found near Curiosity’s landing site, using a Sample Analysis at Mars (SAM) instrument.
“We were a bit puzzled; we weren’t sure what those molecules really meant in the bigger picture of the search for life,” said biogeochemist at NASA Goddard and lead author of the study, Jennifer Eigenbrode. “But it gave us a lot of anticipation that, if we can find these molecules here, perhaps we’re going to come across other layers of rock that have more organics in them.”
New discoveries
The new observations have increased the inventory of known Mars organics and “are more consistent with what we would expect if the organics were from life, from meteorites or from geological processes,” Eigenbrode added.
There’s another intriguing possibility, that these rocks came from the bottom of a lake from a time when Mars was a warm and watery planet.
“These results do not give us any evidence of life,” stressed Eigenbrode. ”But there is a possibility that [the organics] are from an ancient life source; we just don’t know,” Eigenbrode told Space.com. “And even if life was never around, they [the molecules] tell us there was at least something around for organisms to eat.”
In addition to finding organic molecules in the rocks in Gale Crater, rover scientists have also reported the discovery of considerable amounts of methane, another organic molecule, in the Martian atmosphere.
However, all this does not prove that there is or ever was life on Mars. It merely signals to the possibility of life forms on the red planet, or there being conditions conducive to life, in the distant past.
Prarthana Mitra is a staff writer at Qrius