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Tytuł pozycji:

Bacterial spores in granite survive hypervelocity launch by spallation: implications for lithopanspermia.

Tytuł :
Bacterial spores in granite survive hypervelocity launch by spallation: implications for lithopanspermia.
Autorzy :
Fajardo-Cavazos P; Department of Microbiology and Cell Science, University of Florida , Space Life Sciences Laboratory, Kennedy Space Center, Florida 32899, USA.
Langenhorst F
Melosh HJ
Nicholson WL
Pokaż więcej
Źródło :
Astrobiology [Astrobiology] 2009 Sep; Vol. 9 (7), pp. 647-57.
Typ publikacji :
Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.
Język :
Imprint Name(s) :
Original Publication: Larchmont, N.Y. : Mary Ann Liebert, Inc., c2001-
MeSH Terms :
Microbial Viability*
Bacillus subtilis/*physiology
Silicon Dioxide/*chemistry
Space Flight/*methods
Spores, Bacterial/*physiology
Bacillus subtilis/cytology ; Bacillus subtilis/ultrastructure ; DNA, Bacterial/analysis ; Microscopy, Video ; Polymerase Chain Reaction ; Pressure ; Quartz ; Space Simulation ; Spores, Bacterial/cytology ; Spores, Bacterial/isolation & purification ; Spores, Bacterial/ultrastructure
Substance Nomenclature :
0 (DNA, Bacterial)
0 (granite)
14808-60-7 (Quartz)
7631-86-9 (Silicon Dioxide)
Entry Date(s) :
Date Created: 20090926 Date Completed: 20100303 Latest Revision: 20090925
Update Code :
Czasopismo naukowe
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.

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