Survival of lichens and bacteria exposed to outer space conditions – Results of the Lithopanspermia experiments
de la Torre, Rosa and Sancho, Leopoldo G. and Horneck, Gerda and de los Ríos, Asunción and Wierzchos, Jacek and Olsson-Francis, Karen and Cockell, Charles S. and Rettberg, Petra and Berger, Thomas and de Vera, Jean-Pierre P. and Ott, Sieglinde and Martinez Frías, Jesus and Gonzalez Melendi, Pablo and Lucas, Maria Mercedes and Reina, Manuel and Pintado, Ana and Demets, René (2010) Survival of lichens and bacteria exposed to outer space conditions – Results of the Lithopanspermia experiments. Icarus: International Journal of Solar System Studies, 208 (2), pp. 735-748. Elsevier. DOI: 10.1016/j.icarus.2010.03.010.
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In the space experiments Lithopanspermia, experimental support was provided to the likelihood of the lithopanspermia concept that considers a viable transport of microorganisms between the terrestrial planets by means of meteorites. The rock colonising lichens Rhizocarpon geographicum and Xanthoria elegans, the vagrant lichen Aspicilia fruticulosa, and endolithic and endoevaporitic communities of cyanobacteria and bacteria with their natural rock substrate were exposed to space for 10 days onboard the Biopan facility of the European Space Agency (ESA). Biopan was closed during launch and re-entry. In addition, in the Stone facility, one sample of R. geographicum on its natural granitic substrate was attached at the outer surface of the re-entry capsule close to the stagnation point, only protected by a thin cover of glass textolite. Post-flight analysis, which included determination of the photosynthetic activity, LIVE/DEAD staining, and germination capacity of the ascospores, demonstrated that all three lichen were quite resistant to outer space conditions, which include the full spectrum of solar extraterrestrial electromagnetic radiation or selected wavelength ranges. This high resistance of the lichens to space appears to be due to their symbiotic nature and protection by their upper pigmented layer, the cortex. In contrast, the rock- or halite-inhabiting bacteria were severely damaged by the same exposure. After atmospheric re-entry, the granite of the Stone sample was transformed into a glassy, nearly homogenous material, with several friction striae. None of the lichen cells survived this re-entry process. The data suggest that lichens are suitable candidates for testing the concept of lithopanspermia, because they are extremely resistant to the harsh environment of outer space. The more critical event is the atmospheric re-entry after being captured by a planet. Experiments simulating the re-entry process of a microbe-carrying meteoroid did not show any survivors.
|Title:||Survival of lichens and bacteria exposed to outer space conditions – Results of the Lithopanspermia experiments|
|Journal or Publication Title:||Icarus: International Journal of Solar System Studies|
|In Open Access:||No|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 735-748|
|Keywords:||Astrobiology, Exobiology, Meteorites, Solar radiation|
|HGF - Research field:||Aeronautics, Space and Transport|
|HGF - Program:||Space|
|HGF - Program Themes:||W FR - Forschung unter Weltraumbedingungen|
|DLR - Research area:||Space|
|DLR - Program:||W FR - Forschung unter Weltraumbedingungen|
|DLR - Research theme (Project):||W - Vorhaben Strahlenbiologie|
|Location:||Köln-Porz , Berlin-Adlershof|
|Institutes and Institutions:||Institute of Planetary Research|
Institute of Aerospace Medicine > Radiation Biology
|Deposited By:||Kerstin Kopp|
|Deposited On:||16 Jul 2010 09:22|
|Last Modified:||04 Apr 2013 16:22|
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