Panspermina Revisited: Astrophysical and Biological Constraints

Abstract

AbstractWe have carried out a series of calculations involving bacteria and viruses embedded in dust grains that are ejected from our solar system by radiation pressure, and travel through space to other star systems. Under many conditions, this kind of panspermia is impractical, mainly because the ultraviolet radiation of the present Sun kills the micro-organisms. However, if the organisms are shielded by an absorbing material like carbon and if ejection takes place in the late-Sun (red giant) phase, there is a significant probability that these micro-organisms can reach another star system alive. In addition to panspermia with living micro-organisms, we note that it is possible to seed the Galaxy with dead ones, whose DNA fragments might provide the initial information necessary to start biological evolution in favorable environments.