NASA: Even seeing high definition images of the planet Mars, sent by the Perseverance rover since February, some things still remain unclear on the red planet. One of those mysteries is why methane gas exists there. But before scientists look into the problem, there’s another one: why do some instruments “see” CH4 and others don’t?
Here on Earth, when we want to observe the production of methane, we just have to go somewhere that has cattle. The gas is the product of microbes that help different types of ruminants to digest plants. Called enteric methane, about 90% of the gas produced in the animal’s digestive system is expelled through the mouth and nostrils through belching.
Since there are no oxen belching on Mars, detecting methane on the planet becomes fascinating, as it means that the microbes that produce it were or are still living there. Of course, this is not a scientific certainty, as geological processes, which involve the interaction of rocks, water and heat, can also produce methane.
Trying to find methane on Mars to explain it
Before scientists can determine the source of this mysterious methane, there is another question to be answered: what methane? The Curiosity rover has detected the presence of methane several times above the surface of the crater Gale. But the European probe ExoMars Trace Gas Orbiter has not detected any trace of the gas in the planet’s atmosphere.
The accuracy of the instruments used is beyond suspicion. Curiosity’s Adjustable Laser Spectrometer (TLS) is capable of tracking microscopic levels of oxygen in astronaut suits. ExoMars is considered the “gold standard” for measuring both methane and any type of gas on the planet.
One of the theories for the discrepancy is that Curiosity’s TLS, which detects methane, only works at night, when the planet’s atmosphere is calmer. But the ExoMars orbiter’s gas detection only works with sunlight, about five kilometers above the surface, when minute levels of methane