Peculiar Oxygen Fluctuations on Mars are Inexplicable

​New data from Curiosity rover, currently exploring Mars, shows some peculiar changes occurring to the planet’s atmospheric gases. Not long ago, there was the mystery with the methane disappearing and reappearing, and now, oxygen levels have been spotted fluctuating as well.

The location of the weird changes is the Gale Crater, and the amounts seen rising and falling across the crater floor and up the foot of Mount Sharp don’t fit any familiar chemical process.

Peculiar Fluctuations

The rover is not only observing the rocks underneaths its strides, but it’s also registering the Martian atmosphere to calculate the seasonal atmospheric changes. It has been on the Red Planet for three years now – in Martian years – and six years in Earth years and researchers managing the data it sends back have observed that oxygen in the planet’s atmosphere is not acting as expected.

There is not much oxygen at all on Mars (0.16 percent), with the majority (95 percent) of its atmosphere made of carbon dioxide, molecular nitrogen (2.6 percent), argon (1.9 percent), and carbon monoxide (0.06 percent).

Atmospheric pressure on the Red Planet changes over the period of the year. On the winter hemisphere, CO2 freezes above the pole, making the pressure lower across the hemisphere. This leads to a hemisphere-to-hemisphere reallocation of gases to balance the pressure over the planet.

In spring, the opposite happens: pressure increases in that hemisphere then equalizes as gases are redistributed towards the winter hemisphere. Therefore, the fluctuations of the other gases are expected according to the CO2 levels.

This spring and summer, oxygen increased by approximately 30 percent, getting back to the normal levels in autumn. This took place every year without exceptions, but because the quantity by which the oxygen increases differs from year to year, it appears something is making the oxygen appear, then takes it away again.

There is no known chemical process that can make this happen.

Only Organic Processes Could Be the Cause

The first question for such a peculiar calculation was whether the Quadrupole Mass Spectrometer instrument or software broke. Numerous verification proved that it was functioning perfectly.

Another option was whether the oxygen could be generated by water or carbon dioxide scattering in some way in the atmosphere. That was rapidly eliminated as there is not sufficient water in the atmosphere of the Red Planet, and CO2 scatters too slowly to manage to create the observed fluctuations.

“We’re struggling to explain this,” said planetary scientist Melissa Trainer of NASA‘s Goddard Space Flight Center.

“The fact that the oxygen behavior 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.”

However, there is one possible answer: methane. This particular gas increases suddenly over Mars’ summer months, rising up to 60 percent. At times, the methane and oxygen levels even seem to increase at the same time. It is possible that the same cause that makes methane fluctuate is also behind the oxygen variations.

Even so, this is still a huge question. Both gases can only be generated through organic processes, which is life, and both can also be produced via geological processes. As of now, we have no evidence that there is life on the Red Planet, but it cannot be eliminated as a cause. However, the research team believes the occurrences are more probably to be geological.

The research has been published in the Journal of Geophysical Research: Planets.​

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