Reacción a "Mars ice could support photosynthetic life, study finds"

The paper argues that it is possible that there are areas on Mars where ultraviolet radiation destructive to organic molecules, such as nucleic acids (DNA), is sufficiently attenuated by layers of ice and dust, yet still allows the light needed for photosynthesis to penetrate.

Such areas, located at mid-latitudes where there is exposed ice on the surface, could be favourable for photosynthetic organisms, which could be a guide for future exploration. There may be microenvironments similar to those found in some terrestrial glaciers, where photosynthetic life could occur.

For me this work has many limitations. Although it is robust and the complex models used make the results clear, it is after all based on terrestrial life and in particular on cyanobacteria, terrestrial photosynthetic bacteria. The model is based on the assumption that potential Martian life could have evolved in the same way as on Earth, with photosynthetic mechanisms, DNA and resistance to ultraviolet radiation similar to that of terrestrial life. Moreover, it is highly unlikely that there is life on Mars today, so if any photosynthetic life existed, it is likely to have been in the distant past, under very different environmental conditions, and it could have evolved differently from terrestrial photosynthesis.

The work is purely theoretical, based on a terrestrial analogue, so exploration could show that such a model is not really possible on Mars. Moreover, they do not seem to have taken into account effects such as the sublimation of ice at low Martian pressure.

Because of the limitations I have discussed, it does not seem that the implications of this work will be very significant, although these calculations should be taken into account in future Mars exploration, particularly in relation to the presence of exposed or very shallow ice.