Following enormous collisions, such as asteroid impacts, some amount of material from an impacted world may be ejected into space. This matter can travel vast distances and for extremely long periods of time. In theory, this substance could contain direct or indirect signs of life from the host world, such as fossils of microorganisms. Such material could also be detectable by humans in the near future, or even now.
Click here for original story, Searching for life with space dust
Source: Phys.org