While the results obtained are not direct evidence for life, the presence of ancient organic molecules preserved in the soil of a dried up lake have bolstered the case that Mars was not always the lifeless place seen today.
“To understand Mars was habitable and the conditions for life could have been there – part of the jigsaw was organics,” Professor John Bridges, head of the Mars Science Laboratory at the University of Leicester, told The Independent.
The case was further supported by the presence of fluctuating clouds of methane, which itself could be evidence of microbe activity on the planet surface.
“We find remnants of organics in 3.2-3.8 billion year old rocks, and we find them in an environment we discovered was habitable around the same time,” Dr Inge Loes ten Kate, an astrobiologist at Utrecht University told The Independent.
“That means there could have been life.”
As these kind of substances can serve as “starter materials”, they are evidence that the arid planet could once have allowed life to flourish.
“This doesn’t say anything about life actually being present, but there are ingredients for life,” said Dr ten Kate.
However, as the organic materials and the methane could well be explained by geological processes, further exploration of the planet’s surface will be crucial to confirm the presence of alien life in our solar system.
The launch of ExoMars, a joint European-Russian programme that will take another rover to the planet’s surface, will take its cue from Curiosity’s latest findings.
“We are ramping up for ExoMars in 2020, and we will have a meeting in Leicester in November where we finally select the landing site,” said Professor Bridges.
“Nasa’s discovery will inform this decision.”
Other targets in the search for aliens, such as the moons Enceladus and Europa, are “just as valid”, according to Dr ten Kate.
The oceans found underneath the surface of these astronomical bodies seem promising potential homes for alien microbes, but the current case is nowhere near as strong as Mars.
“The thing with Europa and Enceladus is we don’t have this kind of detailed data yet – for Mars this is the closest we get.”
If life is ever found in other parts of our solar system, it will help scientists understand the origin of life on Earth as well. While Martians would support the idea of the first organisms emerging on the planet’s surface, Europa and Enceladus would suggest a deep-sea origin.
Finding organics on Mars is the culmination of years of frustration and false alarms, after the Viking programme failed to provide convincing evidence in the 1970s.
According to Professor Bridges, the latest news shows how far scientists’ knowledge of the red planet has advanced in recent years.
“If you look back before 2012, our view of Mars has really changed – we guessed there had been water and so on but we didn’t have the hard evidence there had been long-standing lakes and river systems,” he said.
“Now we know they are there – and now we know the mudstone in the lakes were organic-bearing. We’re piecing it all together.”
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