Methane on Mars
ExoMars 2016 European Space Agency (Guest Investigator)
How to interpret methane in the atmosphere of Mars Understanding CH4 origin from ExoMars (Etiope, 2018, Planet.Space Sci.)
The enigma of methane on Mars: conflicting atmospheric measurements
Oehler D., Etiope G. (2021). Methane on Mars: subsurface sourcing and conflicting atmospheric measurements. In: Mars Geological Enigmas: From the Late Noachian Epoch to the Present Day, 1st Edition. Soare R., Conway S., Williams J.P., Oehler D. (Editors), Elsevier.
NEW DETECTION OF METHANE ON MARS!
A methane degassing event detected by the Mars Express orbiter
see the Nature Geoscience paper - Giuranna et al (2019)
https://www.nature.com/articles/s41561-019-0331-9
If you wish to know more about "Methane on Mars"
watch the talk at the SETI Institute (September 2016) Methane on Mars - SETI talk
or read the paper Oehler and Etiope (2017) "Methane on Mars: Where to look and why."