NASA thinks it might well have found signs of life on Mars after its Curiosity rover discovered some exciting supporting evidence.
New research has discovered that rocks collected by the rover contain organic carbon, which could have come from bugs that previously lived on Mars.
The space agency analysed sediments from six locations the rover had explored, including an exposed cliff, and found an ancient carbon cycle. It has suggested that the samples could have a ‘biological basis’, and resemble fossilised remains of microbial life in Australia that date back 2.7 billion years.
Carbon has two stable isotopes – 12 and 13 – and the amounts of these give an insight into its origin.
As per The Metro, Professor Christopher House, the lead author of the study from Penn State University in the US, explained, ‘The samples extremely depleted in carbon 13 are a little like samples from Australia taken from sediment that was 2.7 billion years old.’
He continued:
Those samples were caused by biological activity when methane was consumed by ancient microbial mats. But we can’t necessarily say that on Mars because it’s a planet that may have formed out of different materials and processes than Earth.
On Earth, this would indicate that past microbes consumed microbially-produced methane. Methane is the simplest organic molecule and is present in Mars’s atmosphere.
On ancient Mars, it means that large plumes of methane could have been being released from the subsurface, where production would have been energetically favourable.
The released methane would then either be consumed by microbes or react with ultraviolet light before being deposited directly on the surface.
The focus of the exploration has been around the Gale Crater, which is believed to have been a deep lake 3.5 billion years old and is said to contain complex organic molecules that are key raw materials for life as we know it.
House explained, ‘The amounts of carbon 12 and carbon 13 in our solar system are the amounts that existed at the formation of the solar system. Both exist in everything, but because carbon 12 reacts more quickly than carbon 13, looking at the relative amounts of each in samples can reveal the carbon cycle.’
Curiosity heated the samples to separate any chemicals, and scans showed that some of them were depleted in carbon 13, while others were enriched.
There are other theories as to why this might be, including a cosmic dust cloud or perhaps ultraviolet radiation breaking down carbon dioxide.
‘All three of these scenarios are unconventional – unlike processes common on Earth,’ concluded House.
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