The Mars Curiosity rover has detected a mysterious spike in the organic molecule methane — one that could be a sign of life.
That’s according to a team of NASA scientists at a press conference at this year’s meeting of the American Geophysical Union.
“That we detect methane in the atmosphere on Mars is not an argument that we have found evidence of life on Mars, but it is one of the few hypothesis that we can propose that we must consider as we go forward in the future,” said NASA Curiosity Project Scientist John Grotzinger, of the California Institute of Technology, said during the press conference.
So, the find isn’t a smoking gun of life on the Red planet, but it is a good sign.
Methane on Mars
Curiosity’s Sample Analysis at Mars (SAM) laboratory has been sniffing the Martian atmosphere for the last 20 months. Over that period, SAM detected an unusually high amount of methane in the air a total of four different times.
The high levels of the gas were ten times stronger than the average amount of methane Curiosity has detected during its time on Mars, as shown in the graph below:
On average, the amount of methane in the Martian atmosphere is less than one part per billion, but SAM sniffed levels as high as 7 parts per billion on four different occasions since late last year.
In the past, instruments like the European Space Agency’s Mars Express spacecraft have measured even higher levels of atmospheric methane from 15 parts per billion all over the planet up to 45 parts per billion near the north pole, explains reporter Alex Witze in Nature. These measurements are taken farther up in the atmosphere than Curiosity, which is sitting on the surface. That difference could play a role in why the concentration fluctuates.
Scientists have failed to explain the different patterns and varying levels of methane gas in the Martian atmosphere, and Curiosity’s latest results just add more to the mystery.
“This temporary increase in methane — sharply up and then back down — tells us there must be some relatively localised source,” said Sushil Atreya in a statement. Atreya is a scientist based at the University of Michigan, Ann Arbor, and is a member of the Curiosity rover science team. “There are many possible sources, biological or non-biological, such as interaction of water and rock.”
The Curiosity team doesn’t know whether the methane is making its way into the air from sources that are above the surface, below the surface, or perhaps wafted from somewhere else entirely.
As shown in the graphic below, there are three primary sources that the scientists are exploring:
- Comets, which contain methane, could be the source upon impacting the Martian surface.
- Geological processes could have produced pockets of methane underground that are now being released near Curiosity’s location.
- Or the most exciting prospect could be that the methane is a byproduct from bacteria.
“We will keep working on the puzzles these findings present,” said Grotzinger in a press release. “Can we learn more about the active chemistry causing such fluctuations in the amount of methane in the atmosphere? Can we choose rock targets where identifiable organics have been preserved?”
Although the news is an exciting step forward in determining whether Mars once harbored life, it’s going to take more than a rover to make any final conclusions, according to some listening in on today’s press conference.
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