Testing the Lithopanspermia Theory in the Foton-M3 Mission: Simulation of Interplanetary Transfer and Re-entry Process of Epi- and Endolithic Microbial Communities with the Lithopanspermia Experiment

摘要

After flight (10 days exposure to harsh space conditions in low Earth orbit at about 300 km altitude) and recovery, the survival capacity of themicrobial communities has been assayed. First analyses have confirmed a fast recovery of the biological activity (chlorophyll a-fluorescence) of the lichen (epilithic and vagrant lichen), similar as the pre-flight activity, comparative to the high survival rates observed in the experiment Lichens onboard of the Foton-M2 mission (de la Torre et al. 2007; Sancho et al., 2007). First results of Confocal Scanning Laser Microscopy have shown maintenance of the vitality of epilithic samples..Ultrastructural changes are being analyzed by Transmission Electron Microscopy and cryoscanning. Furthermore, concerning the germination capacity of ascospores of Xanthoria elegans stimulation seems to have occurred. The epilithic cyanobacteria community did not survive the harsh conditions; however, the resting state cells of Anabaena did. Step 3 of Lithopanspermia has been tested with Rhizocarpon geographicum on its granite rock substrate, integrated in the thermal protection shield of the Foton capsule by use of the STONE facility, thereby simulating the external layer of a meteorite. The lichen did not survive this re-entry process. Mineralogical and petrologic studies have shown compositional and structural changes of the granite.