Lichens, cyanobacteria and molds growing in humidity of simulated Martian atmosphere: Difference between revisions
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==Lichens surviving in Mars surface conditions== |
==Lichens surviving in Mars surface conditions== |
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The Martian surface has high levels of UV, higher than found anywhere on Earth. Most lichens do not survive prolonged exposure to Mars surface conditions. However lichens at high altitudes and in polar regions need protection from high levels of UV too, if not quite as high as on Mars. The lichens studied in these experiments have special pigments to protect them, found only found in lichens, such as parietin. They also have protective antioxidants such as b-carotene. They |
The Martian surface has high levels of UV, higher than found anywhere on Earth. Most lichens do not survive prolonged exposure to Mars surface conditions. However lichens at high altitudes and in polar regions need protection from high levels of UV too, if not quite as high as on Mars. The lichens studied in these experiments have special pigments to protect them, found only found in lichens, such as parietin. They also have protective antioxidants such as b-carotene. They are epilithic - grow on rock, and in our closet analogues to Mars conditions, for instance growing on rocks at high altitudes in Antarctica, they huddle in cracks with not much exposure to direct sunlight. |
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It turns out that all this gives them enough protection to tolerate the light levels in conditions of partial shade in the simulation chambers and make use of the light to photosynthesize. UV protection pigments that help them to survive such conditions have been suggested as potential biomarkers to search for on Mars.<ref>"Solar radiation is the primary energy source for surface planetary life, so that pigments are fundamental components of any surface-dwelling organism. They may therefore have evolved in some form on Mars as they did on Earth." {{cite journal | doi = 10.1017/S1473550402001039 | volume=1 | pages=39 | title=Pigmentation as a survival strategy for ancient and modern photosynthetic microbes under high ultraviolet stress on planetary surfaces | year=2002 | journal=International Journal of Astrobiology | last1 = Wynn-Williams | first1 = D.D. | last2 = Edwards | first2 = H.G.M. | last3 = Newton | first3 = E.M. | last4 = Holder | first4 = J.M.| bibcode=2002IJAsB...1...39W }}</ref> |
It turns out that all this gives them enough protection to tolerate the light levels in conditions of partial shade in the simulation chambers and make use of the light to photosynthesize. UV protection pigments that help them to survive such conditions have been suggested as potential biomarkers to search for on Mars.<ref>"Solar radiation is the primary energy source for surface planetary life, so that pigments are fundamental components of any surface-dwelling organism. They may therefore have evolved in some form on Mars as they did on Earth." {{cite journal | doi = 10.1017/S1473550402001039 | volume=1 | pages=39 | title=Pigmentation as a survival strategy for ancient and modern photosynthetic microbes under high ultraviolet stress on planetary surfaces | year=2002 | journal=International Journal of Astrobiology | last1 = Wynn-Williams | first1 = D.D. | last2 = Edwards | first2 = H.G.M. | last3 = Newton | first3 = E.M. | last4 = Holder | first4 = J.M.| bibcode=2002IJAsB...1...39W }}</ref> |
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