Atmospheric signatures of subsurface martian life

Stevens, Adam; Patel, Manish; Lewis, Stephen; Ringrose, Tim and Leese, Mark (2013). Atmospheric signatures of subsurface martian life. In: 5th UK Astrobiology Society of Britain Conference, 17-19 Apr 2013, UK Centre for Astrobiology, Edinburgh.


The martian subsurface is the most likely environment on the planet to find life, as it is protected from the hostile ultraviolet [1] and ionising radiation [2] environment of the surface and provides conditions more conducive to the presence of liquid water [3]. However, we currently have no access to the subsurface, and sampling at the depths that life might exist would require significant technological advances [4].
We can gain information about this subsurface life by looking for products of their metabolisms in the atmosphere [5]. For example, colonies of methanogenic organisms have been proposed as a putative source for the methane observed in the martian atmosphere [6]. If these colonies exist, the methane produced would have to travel through kilometres of megaregolith before entering the atmosphere.
Although the structure of the martian subsurface is poorly known, this transport can be modelled using carefully chosen parameters and a modified form of Fick’s laws [7]. This modelling can help to characterise potential atmospheric biomarkers in terms of their abundance and timescales of release. Here we present preliminary findings from such modelling.
Combining the results of these models with data from future missions such as the ExoMars Trace Gas Orbiter will allow constraints to be placed on the potential sources of methane and other trace gases observed in the martian atmosphere

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