Bacterial Spores in Granite Survive Hypervelocity Launch by Spallation: Implications for Lithopanspermia
- 1 September 2009
- journal article
- research article
- Published by Mary Ann Liebert Inc in Astrobiology
- Vol. 9 (7), 647-657
- https://doi.org/10.1089/ast.2008.0326
Abstract
Bacterial spores are considered good candidates for endolithic life-forms that could survive interplanetary transport by natural impact processes, i.e., lithopanspermia. Organisms within rock can only embark on an interplanetary journey if they survive ejection from the surface of the donor planet and the associated extremes of compressional shock, heating, and acceleration. Previous simulation experiments have measured each of these three stresses more or less in isolation of one another, and results to date indicate that spores of the model organism Bacillus subtilis can survive each stress applied singly. Few simulations, however, have combined all three stresses simultaneously. Because considerable experimental and theoretical evidence supports a spallation mechanism for launch, we devised an experimental simulation of launch by spallation using the Ames Vertical Gun Range (AVGR). B. subtilis spores were applied to the surface of a granite target that was impacted from above by an aluminum projectile fired at 5.4 km/s. Granite spall fragments were captured in a foam recovery fixture and then recovered and assayed for shock damage by transmission electron microscopy and for spore survival by viability assays. Peak shock pressure at the impact site was calculated to be 57.1 GPa, though recovered spall fragments were only very lightly shocked at pressures of 5–7 GPa. Spore survival was calculated to be on the order of 10−5, which is in agreement with results of previous static compressional shock experiments. These results demonstrate that endolithic spores can survive launch by spallation from a hypervelocity impact, which lends further evidence in favor of lithopanspermia theory. Key Words: Bacillus subtilis—Ballistics—Lithopanspermia—Spallation—Spores. Astrobiology 9, 647–657.Keywords
This publication has 41 references indexed in Scilit:
- Role of DNA Protection and Repair in Resistance of Bacillus subtilis Spores to Ultrahigh Shock Pressures Simulating Hypervelocity ImpactsApplied and Environmental Microbiology, 2008
- On the Survivability and Detectability of Terrestrial Meteorites on the MoonAstrobiology, 2008
- Testing interplanetary transfer of bacteria between Earth and Mars as a result of natural impact phenomena and human spaceflight activitiesActa Astronautica, 2007
- Experimental evidence for the potential impact ejection of viable microorganisms from Mars and Mars-like planetsIcarus, 2007
- Bacillus Endospores Isolated from Granite: Close Molecular Relationships to Globally Distributed Bacillus spp. from Endolithic and Extreme EnvironmentsApplied and Environmental Microbiology, 2006
- Ejection of Martian meteoritesMeteoritics & Planetary Science, 2005
- Rummaging through Earth's Attic for Remains of Ancient LifeIcarus, 2002
- Refugia from asteroid impacts on early Mars and the early EarthJournal of Geophysical Research, 1998
- The role of volatiles and lithology in the impact cratering processReviews of Geophysics, 1980
- TRANSFORMATION OF BIOCHEMICALLY DEFICIENT STRAINS OF BACILLUS SUBTILIS BY DEOXYRIBONUCLEATEProceedings of the National Academy of Sciences of the United States of America, 1958