curiosity rover

Nasa’s Curiosity finds strongest evidence yet of alien life on Mars

Image credit: nasa

Nasa’s Curiosity rover has detected organic compounds on the surface of Mars which offers some of the strongest evidence yet that the Red Planet may once have harboured life.

The rover found organic molecules preserved in 3.5 billion-year-old bedrock in Gale Crater, believed to have once contained a shallow lake the size of Florida’s Lake Okeechobee.

The molecules suggest that conditions back then may have been conducive to life and leaves open the possibility that micro-organisms once populated our planetary neighbour and might still exist there.

“The Martian surface is exposed to radiation from space and harsh chemicals that break down organic matter, so finding ancient organic molecules in the top five centimetres, from a time when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper,” said Nasa’s Jen Eigenbrode, lead author on a new paper about the findings.

Organic molecules contain carbon and hydrogen and can include oxygen, nitrogen and other elements.

Organic compounds are commonly associated with life, although they can be created by non-biological processes as well, processes referred to as abiotic organic chemistry. There is no way for Curiosity to determine if the materials it found came from ancient Martian life or not, according to Eigenbrode.

Sedimentary rocks (mudstones) were drilled from four areas at the base of Mount Sharp, the central mound in Gale crater. Although the surface of Mars is inhospitable today, there is evidence that in the distant past, the Martian climate allowed the presence of liquid water - an essential ingredient for life - at the surface.

Curiosity also confirmed sharp seasonal increases of methane in the Martian atmosphere and researchers said they cannot rule out a biological source.

Most of Earth’s atmospheric methane comes from animal and plant life, as well as the environment itself.

In a companion article, an outside expert describes the findings as “breakthroughs in astrobiology”.

“The question of whether life might have originated or existed on Mars is a lot more opportune now that we know that organic molecules were present on its surface at the time,” wrote Inge Loes ten Kate, an astrobiologist at the Utrecht University of the Netherlands.

Kirsten Siebach, a Rice University geologist, is equally excited. She said the discoveries break down some of the strongest arguments put forward by life-on-Mars sceptics, herself included.

“The big takeaway is that we can find evidence. We can find organic matter preserved in mudstones that are more than three billion years old,” she said.

“And we see releases of gas today that could be related to life in the subsurface or at the very least are probably related to warm water or environments where Earth life would be happy living.”

The methane observations provide “one of the most compelling” cases for present-day life, she said.

Scientists agree more powerful spacecraft - and, ideally, rocks returned to Earth from Mars - are needed to prove whether tiny organisms like bacteria ever existed on the Red Planet.

Last week, Dennis Muilenburg, CEO of Boeing, said he believes the first person to walk on Mars would be sent on a Boeing spacecraft.  

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