Image above: The Trace Gas Orbiter (TGO), our European satellite with highly sensitive Belgian spectrometers from NOMAD.
Source Article: https://aeronomie.be/nl/nieuws/2025/methaan-mars-louter-illusie
One of the fascinating mysteries that has occupied Mars researchers for years is about the detection of methane. The Curiosity rover (NASA) has measured multiple methane spikes in surface air samples in the Gale crater. So the surprise was great when our European TGO satellite became active from 2018 and could not make any measurements of methane at all. The spectrometer aboard the TGO (Belgian aircraft NOMAD) is very sensitive and would immediately detect methane spikes as measured by Curiosity should there be any. But in all these years, the satellite has not measured any methane at all, not even near the Gale crater. The independent Russian ACS instrument on board TGO also did not measure any methane. Explanations were sought, for example: there could be a hitherto unknown mechanism that causes methane escaping from the soil to break down quasi immediately, so that it is no longer detectable after a few minutes.
Now the Royal Belgian Institute for Space Aeronomy (BIRA) comes up with another explanation: the methane measured by Curiosity probably came from the craft itself, and not from the Martian air. Presumably it is caused by contamination from the pre-option chamber just next to the sample cell where the Martian air is measured. It could also partly be due to the way the TLS team carried out the analyses of the measurement data, namely by measuring each separate spectral line of methane first separately and then averaging the three spectral lines. This allows the measurement to be positive even if not all three methane spectral lines are positive.
So there was probably no methane emission at all on the Martian surface during the period of the measurements! Not even just above the NASA rover. A punishing claim, based on the detailed study of the detection device TLS (Tunable Laser SPectrometer) aboard the Curiosity rover. To be fair, this statement does satisfy. But it does, of course, dismiss the small possibility of methane-producing underground bacteria allegedly causing the emissions.
Read BIRA’s statement for yourself at this link.