Survivability of Bacteria in Hypervelocity Impact

Bacteria belonging to the genus Rhodococcus have been tested for their survivability in hypervelocity impacts at 5.1 +/- 0.1 km s(-1). This is similar to the martian escape velocity for example but is slower than the mean velocities typical of impacts from space on planets like Mars (typically 14 km s(-1)) and Earth (typically 2025 km s(-1)). The bacteria fired were loaded on a projectile using a two-stage light-gas gun. The targets were plates of nutrient media. Analysis techniques including pyrolysis mass spectrometry and selective growth in acetonitrile confirmed that the bacterium grown on a target plate after a shot was the original strain. The indication is that, if fired on a projectile, bacteria can survive a hypervelocity impact and subsequently grow. This holds implications for the study of possible natural migration of life around the Solar System on minor bodies which end up impacting target planets, thus transferring life if the bacteria can survive the resulting hypervelocity impact. (C) 2001 Elsevier Science (USA).