Bungling (笨手笨脚的) space organizations apart, the only mode of travel open to microbes seems to be meteorites (流星). Most of these are small bits of junk from the asteroid (小行星) belt that have gone off course. But some are rocks that have been flung into space from the surfaces of planets as a result of those planets having been struck by even larger bits of rock—decent-sized asteroids or comets.