ATMOSPHERIC SIGNATURES OF SUBSURFACE MARTIAN
LIFE
A.H. Stevens1, M.R. Patel1, T.J. Ringrose1, S.R. Lewis1, M.R. Leese1
1
The Open University, Milton Keynes, UK
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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