Organic molecules of ‘unprecedented size’ have been discovered on Mars, adding further evidence that life may once have existed on the Red Planet.
Experts have found long carbon chains, containing up to 12 consecutive atoms, in samples of Martian rock which date back billions of years.
These organic molecules – the longest identified so far – could originate from fatty acids, which are the building blocks of fats and oils and are created on Earth through biological activity.
And scientists said the discovery is of ‘high interest’ in the search for potential signs of life.
The samples were collected by the ‘Sample Analysis at Mars’ (SAM) – one of the instruments on-board NASA’s Curiosity Rover which has been studying the Gale crater since 2012.
It has a gas chromatograph and mass spectrometer which allow it to identify molecules in samples.
Analysis revealed that the collected mudstone contains the organic molecules decane, undercane and dodecane.
The lack of geological activity and the cold, arid climate on Mars have helped preserve this invaluable organic matter for the past 3.7 billion years.
Organic molecules of ‘unprecedented size’ have been discovered on Mars, adding further evidence that life may once have existed on the Red PlanetÂ
It therefore dates from the period during which life first emerged on Earth, the experts said.
While fatty acids are an important component of living cells on Earth, they can also be formed by abiotic – physical, rather than biological – processes, they added.
Writing in the journal Proceedings of the National Academy of Sciences (PNAS) the team said their success paves the way for future missions in search of signs of complex, life-like chemistry.
‘Organic molecules preserved in ancient Martian rocks provide a critical record of the past habitability of Mars and could be chemical biosignatures’, they wrote.
‘The source of the long-chain alkanes remains uncertain; however, laboratory experiments support a source from the saturated form of straight-chain, primary carboxylic acids [fatty acids].
‘Although abiotic processes can form these acids, they are considered universal products of biochemistry – terrestrial, and perhaps Martian.
‘Thus, the provenance and distribution of these molecules are of high interest in the search for potential biosignatures on Mars.’
Searching for further life-like chemistry on Mars will be one of the goals of the European Space Agency’s upcoming ExoMars mission, set to launch in 2028.
The samples were collected by the ‘Sample Analysis at Mars’ (SAM) – one of the instruments on-board NASA’s Curiosity Rover which has been studying the Gale crater since 2012Â
Samples were collected by drilling into Martian rock (pictured with superimposed carbon molecules)
The same team involved in this study will build an instrument similar to SAM for Dragonfly – the drone that is due to explore the surface of Titan, Saturn’s largest satellite, from 2034 onwards.
A separate study recently concluded that Mars was once home to sun-soaked, sandy beaches with gentle, lapping waves.
Researchers discovered evidence of a ‘vacation-style’ environment on the Red Planet, despite there being no visible liquid on the surface of Mars today.
An international team of scientists used data from China’s Zhurong Mars rover to unearth hidden layers of rock underneath the planet’s surface that strongly suggest the presence of an ancient northern ocean.
The new research offers the clearest evidence yet that the planet once contained a significant body of water and a more habitable environment for life, the researchers said.