One year after the Mir space station power-dived into the Pacific, speculation continues about the exact nature of the microorganisms that chewed up metal and corroded windows. More to the point, could any of the critters have survived re-entry? Nobody knows, and nobody really wants to find out either. The bottom line: partially sterilized spacecraft + a 16 year bath in cosmic radiation = angry bugs
“Throughout Mir’s life in space, the number of microorganisms grew continuously, one generation replacing another every 20-30 minutes. If in 1990 there were registered 94 species, in 2001 they numbered 140. But the real problem was not the species increasing in number but their growing aggressiveness: each new generation seemed to be more ferocious than the last.”