Degradation of Cyanobacterial Biosignatures by Ionizing Radiation

• DOI: 10.1089/ast.2011.0663
• Publication Date: 2011-12-09T16:27:04Z
• Authors: Lewis R. Dartnell; Michael C. Storri...; Conrad W. Mullineaux; Alexander V. Ruban; Gary Wright; Andrew D. Griffiths; Jan-Peter Muller; John M. Ward
• Keywords: 0301 basic medicine; 03 medical and health sciences; Spectrometry, Fluorescence; 13. Climate action; Radiation, Ionizing; Exobiology; Synechocystis; Mars; Biomarkers

Primitive photosynthetic microorganisms, either dormant or dead, may remain today on the martian surface, akin to terrestrial cyanobacteria surviving endolithically in analog sites Earth such as Antarctic Dry Valleys and Atacama Desert. Potential markers of photoautotrophs include red edge chlorophyll reflectance spectra fluorescence emission from systems light-harvesting pigments. Such biosignatures, however, would be modified degraded by long-term exposure ionizing radiation unshielded cosmic ray flux onto surface. In this initial study into issue, three analytical techniques—absorbance, reflectance, spectroscopy—were employed determine progression radiolytic destruction cyanobacteria. The pattern signal loss for reflection several biomolecules is characterized quantified after increasing exposures gamma radiation. This allows estimation degradation rates cyanobacterial biosignatures surface identification promising detectable fluorescent break-down products. Key Words: Mars—Life-detection instruments—Spectroscopic biosignatures—Photosynthesis—Endoliths. Astrobiology 11, 997–1016.