NASA's Mars Species Analysis (SAM) instrument on NASA's Rover ios probe measures the seasonal changes in air-filling gases directly above the surface of the Gale Crater, and notes something confusing: oxygen behaves the way planetary scientists have done so far. cannot explain it by any known atmospheric or surface process.
For nearly five years (three years on Mars), the SAM instrument has been breathing in the Galate Crater's air and analyzing its composition.
The results confirmed the makeup of the Martian atmosphere on the surface: 95% by volume of carbon dioxide, 2.6% molecular nitrogen, 1.9% argon, 0.16% molecular oxygen and 0.06% carbon monoxide.
They also discovered how the molecules in the Martian air mix and circulate with changes in air pressure throughout the year.
These changes are caused when carbon dioxide freezes over the poles in winter, thereby reducing air pressure across the planet after redistribution to maintain pressure balance. When carbon dioxide evaporates in spring and summer and mixes across Mars, it increases air pressure.
Within this environment, researchers have found that nitrogen and argon follow a predictable seasonal pattern, targeting and decreasing concentrations of thieves throughout the year over how much carbon dioxide is in the air.
They were expecting oxygen to do the same. But that was not the case. Instead, the amount of gas in the air increased by as much as 30% during the spring and summer, and then dropped back to levels predicted by the famous chemistry in the fall.
This pattern was repeated every spring, though the amount of oxygen added to the atmosphere varied, meaning it produced something and then took it away.
"The first time we saw it, I had to wake up in my mind," said University of Michigan professor Susil Atrea.
Once scientists discovered the oxygen ecg, Mars experts tried to work on trying to explain it.
They first double and triple checked the accuracy of the SAM instrument they used to measure the gases: Quadrupole Mass Spectrometer. The instrument was fine.
They looked at the possibility of carbon dioxide or water molecules releasing oxygen when they decompose into the atmosphere, leading to short-term elevation. But it will take five times as much water over Mars to produce extra oxygen, and carbon dioxide decomposes too slowly to be generated in such a short time.
What about oxygen reduction? Can solar radiation break down the oxygen molecules into two atoms blown into space? No, the researchers concluded, because it will take at least 10 years for oxygen to disappear through this process.
"We are struggling to explain this. The fact that oxygen behavior is not perfectly repetitive every season has made us think that it is not a problem related to atmospheric dynamics. It has to be some chemical sources and sinks that we still can't count on, "said Dr. Melissa Trainer, a planetary scientist at NASA's Goddard Space Flight Center.
For planetary scientists, the story of oxygen is curiously similar to that of methane.
Methane is constantly in the air within Kate Gallee in such small quantities (on average 0.00000004%) that it is hardly noticeable even on the most sensitive instruments on Mars. However, it is measured by an adjustable SAM laser spectrometer.
The instrument found that as methane grows and falls seasonally, it increases in abundance by about 60% in the summer months for unexplained reasons.
With the new oxygen breakthroughs, the team wonders if chemistry similar to the natural seasonal variations of methane can also cause oxygen. At least occasionally, the two gases appear to be moving in tandem.
"We are starting to see this astonishing correlation between methane and oxygen for a good part of the year on Mars. I think there's something to it. I don't have the answers yet. Nobody does, "Professor Atrea said.
The team's paper was published in Crash for Geophysical Research: Planets.
Melissa G. trainer et al. Seasonal variations in atmospheric composition, as measured in the Galle Crater, Mars. Crash for Geophysical Research: Planets, posted online, 12.11.2019; doi: 10.1029 / 2019JE006175
This article is based on text provided by the National Air and Space Administration.