page_title: Impact survival
section_title: Possible organisms on Earth
hierarchical_section_title: Impact survival / Possible organisms on Earth
caption_attribution_description: English: The Bacterium Bacillus subtilis taken with a Tecnai T-12 TEM. Taken by Allon Weiner, The Weizmann Institute of Science, Rehovot, Israel. 2006.
context_page_description: Impact survival is a theory that life, usually in the form of microbial bacteria, can survive under the extreme conditions they are exposed to during a major impact event, such as a meteorite striking the surface of a planet. This step is a necessity for the possibility of panspermia, for the microbial life must be able to survive both the escape out of the initial planetary atmosphere, likely due to a major impact, as well the reentry and collision with a second planetary body.
context_section_description: Recent experiments have found organisms that can survive both the acceleration and jerk involved in reaching escape velocity. A major impact event was simulated  using an air cannon to propel both ice and agar projectiles covered with chosen microorganisms to extreme speeds and then crashing the projectiles into a solid surface.  Two species of bacteria were tested - R. erythropolis and B. subtilis - and while survival rates were low, at 100 GPa of peak pressure there was still a survival rate of 3.9x10⁻⁵ in the B. subtilis. These findings have been replicated with other bacteria as well - D. radiodurans as well as when shot into liquid water - with similar low, but not zero, survival rates. Also, experimental methods have been varied, and survival rates have also been found when bacteria are subjected to acceleration at an extended time, through the use of a centrifuge as well as when shot into liquid water.  While very small, these finite results show that some lifeforms could survive the impact from a major impact event.
caption: The bacteria B. subtilis.
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