Instead of trying to blast our way across the stars in one lifetime, some plans imagine a longer process. Sleeper and generation ships imagine a crew either in suspended animation or with successive generations serving as its stewards.
Another vision proposes having frozen embryos on a kind of “seeder” ship to deliver the settlers. While there are still many unknowns and technical hurdles in the way (setting aside for the moment the ethical questions and philosophical debates which we love so much), recent research is taking us closer to making this old SF thought experiment a reality.
A Japanese team sent freeze dried mouse sperm up to the international space station to see how it would react after nine months. One purpose of the experiment was to determine how resilient DNA is in the face of intense space radiation. Although some damage was done, the sperm still proved healthy enough to fertilize mouse eggs which became viable embryos.
Fleets of seeder”ships might bring frozen sperm/egg or embryos to life sustaining worlds in the future. It might be used to colonize planets or as a back-up plan to avoid human extinction. Will machines serve as nannies and surrogate parents for the first babies born on alien worlds? If we ever learn how to “upload’ and download our consciousness like software can we grow duplicate bodies and transmit our minds to other worlds? What if humans accidentally seed a planet that already has intelligent life on it?