blobrana wrote:
My question is `What took then so long?`...
I expect it's the concentrations we are dealing with. 10 ppb is very small and only very sensetive spectrometers are likely to spot methane absorption/emission spectra at that concentration. Just think of the signal to noise ration alone...
Erring on the side of caution, there is the possibility that perhaps these emissions are not from living organisms but perhaps once living ones. After all, natural gas occasionally finds it's way from deep underground to vent into the atmosphere here. If there was ever a martian carboniferous period, perhaps it has various petrochemical deposits underground too.
