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Does the Mars atmosphere contain methane or not?
This is a question that planetary scientists have been asking for years, and the infuriating answer is: Yes. No, maybe. Well…
The question is actually quite important. Methane is a simple molecule (a carbon atom with four hydrogen atoms, if we keep track of it), and can be made in many different ways. However, it comes down to two big things: Methane is made either geologically or biologically. In other words, it can be destroyed by volcanoes or chimneys, or literally by life. Think of cows, bacteria, decaying plants. Martian insects.
On Earth, one or the other of these methods would not be surprising. On Mars, one or both would have be. The question of whether Mars is still geologically active is interesting. its surface is dotted with ancient volcanoes, probably extinct, including Olympus Mons, the largest of all the solar system. Some volcanoes were active hundreds of millions of years ago, but today? This is not clear.
As for life … well, the question is pretty obvious. There is no guarantee that Mars has living creatures on it and even if it did, there is no guarantee that these little creatures would erode methane. But methane is made by life here on Earth, so it's a good place to start thinking about it.
The search for Martian methane is therefore important. We had to find one first, then try to understand where it came from.
The problem is that if he is there, there will be no a lot The. Some detections were made in 2003 with the help of Earth observations, but they were at the limit of what telescopes could do here. It was therefore difficult to confirm. These observations indicated that there were plumes of gas, probably gusty, but again, it was hard to say.
Then, in 2013, the Curiosity rover detected a methane spike in Gale Crater, the huge impact it explores. The next day, this peak was confirmed by the Mars Express orbiter of ESA on the same site. This clearly shows that Mars definitely has methane, even if it is very little; the peak was seen only 15 parts per billion methane compared to the rest of the atmosphere.
Hurray!
But not so much!
Observer Exomars Trace Gas Orbiter (or TGO) from ESA, which has been monitoring Mars since 2016, is a good way to partner with all of this. It is also equipped with instruments capable of searching for methane. And what he found was … nothing. No methane. And the observations were very sensitive. they would have seen less than 1% methane compared to what Curiosity and Mars Express saw!
Arrrrrg. So, does Mars have methane or not?
Main events in the detection and non-detection of methane in the atmosphere of Mars. Credit: ESA
There are obviously tensions between these observations, but they do not necessarily contradict each other. For example, TGO is sensitive to the atmosphere well above the surface, about 5 km in height, while Curiosity sure the surface itself. Maybe the methane was lower.
Or maybe there is a process that quickly removes methane from the atmosphere, enough so that it is visible soon after it is released, but then disappears – by breaking it down or by breaking it down. sequestering (by storing it in one way or another). Theoretically, sunlight on Mars should dissolve methane in a few centuries. This process should therefore be new. Chemistry on Mars is different here on Earth; For example, the surface contains a lot of perchlorates, a chemical that breaks down organic molecules quickly. It may not be the culprit here; I just point out that the environment of Mars is different. Maybe there is an action on methane that we have not thought about yet.
Yet it is frustrating. Some scientists are still skeptical, but methane has been detected positively, and even though at the amount must be very small and disappear quickly. In any case, we are missing something.
I would like to have a better and more satisfying conclusion for you here, but hey, science. It is not a goal, but a process. Maybe something will happen soon, a new idea or a different / better detection. Or maybe this paradoxical Schrödinger methane will continue to exist simultaneously and will not exist for a while.
We will have an answer … finally. Until then, we keep our eyes on Mars and try to understand what we are trying to tell ourselves.
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