Panspermia is the hypothesis that life can survive the transfer between planetary bodies as a secondary path for life to get started on planets throughout a solar system. The discovery of extraterrestrial life on asteroids or within meteorites would have profound implications for understanding the origins and distribution of life in the universe.

Excitement turned to surprise when scientists studying asteroid Ryugu samples found elongated microorganisms. Were they alien life? Not quite. Despite rigorous handling, the samples were contaminated with Earth-based bacteria.