AGU: Geophysical Research Letters

 

Editors' Highlight

Astrobiology and the Martian radiation environment

Although the surface of Mars is currently barren, evidence exists that past Martian environments were warmer, wetter, and possibly able to sustain life. Modern Mars, however, lacks a global magnetic field or thick atmosphere, and the surface is exposed to high levels of cosmic radiation. To determine whether life can survive today, Dartnell et al. (2007) modeled the propagation of solar energetic protons and galactic cosmic rays through the Martian atmosphere and through different surface scenarios. Their results show that the ionizing radiation environment on or beneath the Martian surface is never lethal to even radiosensitive bacteria, assuming potential life on Mars is similar to that on Earth. However, the authors noted that freezing conditions on Mars' surface imply that cells must be dormant. Because radiation will eventually deactivate dormant cells, the sampling of surviving life requires that near-subsurface cells must either periodically revive to repair radiation damage and reproduce and or be excavated from sufficient depths. Deep rock layers impart their own radiation environments, so promising candidates for such excavation include frozen crater lakes or the putative frozen sea at Elysium.

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