Directed panspermia from Earth to new solar systems has been proposed to expand life in the Universe. For example, microbial payloads launched by solar sails at speeds up to 0.0001 c (30,000 m/s) would reach targets at 10 to 100 light-years in 0.1 million to 1 million years. Fleets of microbial capsules can be aimed at clusters of new stars in star-forming clouds where they may land on planets, or captured by asteroids and comets and later delivered to planets. Payloads may contain extremophiles for diverse environments and cyanobacteria similar to early microorganisms. Hardy multicellular organisms (rotifer cysts) may be included to induce higher evolution. (Mautner, M. N. (1997), "Directed panspermia. 3. Strategies and motivation for seeding star-forming clouds", J. British Interplanetary Soc.)
There is a chance that humans, at some point in our space explorations, may unintentionally transport microorganisms on manned craft or unmanned probes to other other planetary bodies. Contamination such as this distorting data is a concern among space researchers seeking to find extraterrestrial life. Even the best sterilization techniques can not guarantee that organic materials will not be unintentionally spread.
Deliberate directed panspermia by humans would seed planetary bodies, securing the of future life. This intentional action would need to be balanced against interference with the quest to find extraterrestrial life. This interference can be minimized by targeting remote solar systems where life would not have evolved yet. Seeding a few hundred young solar systems would secure future life while leaving billions of stars pristine for exploration.