Oxygen fluctuations on Mars a mystery for Scientists to solve

Published: 15 November 2019

New research results show that the amount of oxygen on Mars varies over time in a way that current models cannot explain. Why is a mystery yet to be solved.
– There are still photochemistry processes in the atmosphere of Mars that are unknown, says Javier Martin-Torres, Professor of Atmospheric Science at Luleå University of Technology.

Over the course of nearly six years, an instrument at NASA’s Mars Science Laboratory Curiosity rover has acquired atmospheric composition measurements of the air of Gale Crater on Mars.

The results from the study has been published in the Journal of Geophysical Research: Planets. Two of the authors are Luleå University of Technology’s Professors of Atmospheric Science, Javier Martin-Torres and Maria-Paz Zorzano.

According to the study, the amount of oxygen added to the Martian atmosphere varied, implying that something was producing it and then taking it away. There is a “significant seasonal and interannual variability, suggesting an unknown atmospheric or surface process at work”.

Barometric pressure varies

The atmosphere on Mars is made up of primarily carbon dioxide (95%) but also consists of nitrogen, argon, oxygen and carbon monoxide. During the martian year the barometric pressure is known to cycle up and down substantially as the carbon dioxide freezes out and then is re‐released from polar caps. Nitrogen and argon follow the pressure changes with a delay, and the scientists expected it to be the same with oxygen. Instead, the amount of oxygen rose throughout spring and summer by as much as 30%.

– We do not know what is producing the excess of oxygen in the spring and summertime. Currently, the most likely source of this excess is the Martian soil, but even if this is the case we have no idea what in the soil is releasing so much oxygen into the atmosphere, says Javier-Martin Torres, adding:

– The most fascinating thing to me is that the in-situ observations with Curiosity are showing us that there are some things that we do not know about the photochemistry processes in the atmosphere of Mars. That happened with the observations of the behavior of methane and now with these observations of oxygen.

Interaction of surface and atmosphere

The new data can be used to better understand how the surface and atmosphere interact which is important in the search for signs of habitability on Mars.

– From the habitability point of view both oxygen and methane can be produced biologically and geologically, but we do not really have enough information to tell at this point, says Javier Martin-Torres.

– For me this is telling us, one more time, that we need to send more in-situ instruments to the surface of Mars before we send astronauts to the planet. If you send your children to an excursion you want to know very well where they are going. We need to have a very good characterization of the Mars environment before we send humans to Mars. I would bet for a deployment of many environmental stations on Mars before exploring it.

Luleå University of Technology's research group in Atmospheric Science has developed the instrument  HABIT, that will be sent to Mars next year with the ESA expedition ExoMars 2020. HABIT will be the first Swedish instrument to operate on the surface of Mars. It will, among other things, be able to investigate and quantify the landing area's three most critical environmental parameters for life as we know it: ultraviolet radiation, thermal ranges, and access to water.

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