The Curiosity rover detects oxygen behaving strangely on MarsAshley Strickland-Profile-Image
By Ashley Strickland, CNN
Updated 5:17 PM ET, Tue November 12, 2019
https://www.cnn.com/2019/11/12/world/curiosity-rover-oxygen-scn/index.html?no-st=1574038955(CNN)Since it landed in Gale Crater in 2012, the Curiosity rover has been studying the Martian surface beneath its wheels to learn more about the planet's history. But Curiosity also stuck its nose in the air for a big sniff to understand the Martian atmosphere.
So far, this sniffing has resulted in some findings that scientists are still trying to understand.
Earlier this year, the rover's tunable laser spectrometer, called SAM, which stands for Sample Analysis at Mars, detected the largest amount of methane ever measured during its mission.
SAM has also found that over time, oxygen behaves in a way that can't be explained by any chemical process scientists currently understand.
SAM has had plenty of time -- about six years -- to sniff and analyze the atmospheric composition on Mars. The data revealed that at the surface, 95% of the atmosphere is carbon dioxide, followed by 2.6% molecular nitrogen, 1.9% argon, 0.16% oxygen and 0.06% carbon monoxide.
Like Earth, Mars goes through its seasons; over the course of a year, the air pressure changes. This happens when the carbon dioxide gas freezes in winter at the poles, causing the air pressure to lower. It rises again in the spring and summer, redistributing across Mars as the carbon dioxide evaporates.
In relation to the carbon monoxide, nitrogen and argon also follow similar dips and peaks. But oxygen didn't.
Surprisingly, the oxygen actually rose by a peak increase of 30% in the spring and summer before dropping back to normal in the fall.
Given the amount of time Curiosity has been monitoring the atmosphere, it was able to detect that this pattern repeated, albeit with varying amounts of oxygen.
The variation suggests that the oxygen is being created by something, then taken away.
So why is this unusually large amount of methane so interesting? On Earth, microbial life is a key source of methane. But NASA also warned that expectations of life should be managed due to the fact that interactions between rocks and water can also create methane, and Mars has water and an abundance of rocks.
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"We're beginning to see this tantalizing correlation between methane and oxygen for a good part of the Mars year," Atreya said. "I think there's something to it. I just don't have the answers yet. Nobody does."
The origin of the methane or oxygen won't be evident because the rover doesn't have any instruments that can trace or determine the source. And while both oxygen and methane can be created from biological sources, they can also arise due to chemistry, like the interaction of water and rocks.
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