Radiative Habitable Zones in Martian Polar Environments

In this morning's astro-ph:

Paper: astro-ph/0507317
Title: Radiative Habitable Zones in Martian Polar Environments
Authors: C. Cordoba-Jabonero, M.-P. Zorzano, F. Selsis, M. R. Patel and C. S.
Cockell
Comments: 44 pages, 8 figures
Report-no: CAB-lcasat/04057
Journal-ref: Icarus 175 (2005) 360-371
DOI: 10.1016/j.icarus.2004.12.009

The biologically damaging solar ultraviolet (UV) radiation (quantified
by the DNA-weighted dose) reaches the Martian surface in extremely
high levels. Searching for potentially habitable UV-protected
environments on Mars, we considered the polar ice caps that consist of
a seasonally varying CO2 ice cover and a permanent H2O ice layer. It
was found that, though the CO2 ice is insufficient by itself to screen
the UV radiation, at 1 m depth within the perennial H2O ice the
DNA-weighted dose is reduced to terrestrial levels. This depth depends
strongly on the optical properties ofthe H2O ice layers (for instance
snow-lile layes). The Earth-like DNA-weighted dose and
Photosynthetically Active Radiation (PAR) requirements were used to
define the upper and lower limits of the nortern and southern polar
radiative habitable zone (RHZ) for which a temporal and spatial
mapping was performed. Based on these studies we conclude that
phtosynthetic life might be possible within the ice layers of the
polar regions. The thickness varies along each Martian polar spring
and summer between 1.5 m and 2.4 m for H2= ice-like layers, and a few
centimeters for snow-like covers. These Martian Earth-like radiative
habitable environments may be primary targets for future Martian
astrobiological missions. Special attention should be paid to
planetary protection, since the polar RHZ may also be subject to
terrestrial contamination by probes.

( http://arXiv.org/abs/astro-ph/0507317 , 888kb)

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