An analysis is carried out of the survival fraction of micro-organisms exposed to extreme shock pressures. A variety of
data sources are used in this analysis. The key findings are that survival depends on the behaviour of the cell wall. Below
a critical shock pressure there is a relatively slow fall in survival fraction as shock pressures increase. Above the critical
threshold survival starts to fall rapidly as shock pressure increases further. The critical shock pressures found here are in
the range 2.4 to 20 GPa, and vary not only from organism to organism, but also depend on the growth stage of given
organisms, with starved (i.e., no growth) states favoured for survival. At the shock pressures typical of those involved in
interplanetary transfer of rocky materials, the survival fractions are found to be small but finite. This lends credence to
the idea of Panspermia, i.e. life may naturally migrate through space. Thus for example, Martian meteorites should not a
prior be considered as sterile due to the shock processes they have undergone, but their lack of viable micro-organisms
either reflects no such life being present at the source at the time of departure or the influence of other hazardous
processes such as radiation in space or heating of surfaces during entry into a planetary atmosphere.
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