It’s not the smoking gun which proves that there is still life on Mars - but it’s certainly a new gas mystery from the Red Planet.
NASA’s Mars Curiosity Rover spotted rising and falling oxygen levels on Mars - and the amounts don’t fit what we know about Mars.
During spring and summer on Mars, oxygen levels rise by up to 30%, and it’s a figure that the NASA team are still struggling to explain.
Melissa Trainer of NASA's Goddard Space Flight Center said, "We're struggling to explain this.
"The fact that the oxygen behaviour isn't perfectly repeatable every season makes us think that it's not an issue that has to do with atmospheric dynamics.
“It has to be some chemical source and sink that we can't yet account for."
Methane on Mars also rises in the summer months, and scientists now think there might be a connection.
The instrument revealed that while methane rises and falls seasonally, it increases in abundance by about 60% in summer months for inexplicable reasons. (In fact, methane also spikes randomly and dramatically. Scientists are trying to figure out why.)
With the new oxygen findings in hand, Trainer’s team is wondering if chemistry similar to what’s driving methane’s natural seasonal variations may also drive oxygen’s. At least occasionally, the two gases appear to fluctuate in tandem.
Sushil Atreya, professor of climate and space sciences at the University of Michigan “We’re beginning to see this tantalizing correlation between methane and oxygen for a good part of the Mars year.
"I think there’s something to it. I just don’t have the answers yet. Nobody does.”