Survivability of bacteria in hypervelocity impacts on ice

As part of the arrival stage of the Panspermia process, organisms must endure a hypervelocity impact either into the atmosphere or onto the surface of the destination planet. The impacts associated with this arrival stage are studied in this paper. To this end, the two-stage light gas gun at the University of Kent has been used to fire bacteria-laden projectiles, at velocities of approximately 5 km s(-1), onto semi-solid nutrient medium, and solid and porous ice targets, representing planetary oceans and icy surfaces. The targets were then analysed to investigate whether the bacteria survived the impacts. It was found that bacteria can survive hypervelocity impacts at 5 km s(-1), with a survival rate of I per 3.5 million using targets of nutrient gel. With ice targets no survival has been found yet with a limit on survival of less than I per 0.4 million.