Detecting Methane above the Clay Unit in Gale Crater Sol 2424

Around this locality in the Clay Unit of Gale Crater we have  been doing more methane measurements with the SAM instrument. This highlights the enigmatic nature of Mars’ atmospheric methane.  A couple of weeks ago we analysed a large spike at 20 parts per billion molecules.  Then a few a days to follow this up we returned to background levels at around 1 ppb. This may explain why Trace Gas Orbiter hasn’t yet identified any methane from orbit, it is transitory.  Formation of some clay-like phases (in particular serpentine) can release methane, so possibly ancient methane is being periodically released from the Clay Unit.  To get further information about biological or non biological origins – particularly isotopes of carbon and hydrogen – will need sample return, starting with the next NASA rover Mars2020.