Corinnguard
Hero
True. Then there is Embryonic Space Colonization. Embryo space colonization - WikipediaUnless you are talking about cryogenic hibernation or similar, I don't think such long journeys would be 2 way.
From Wikipedia:
Embryo space colonization is a theoretical interstellar space colonization concept that involves sending a robotic mission to a habitable terrestrial planet, dwarf planet, minor planet or natural satellite transporting frozen early-stage human embryos or the technological or biological means to create human embryos. The proposal circumvents the most severe technological problems of other mainstream interstellar colonization concepts. In contrast to the sleeper ship proposal, it does not require the more technically challenging 'freezing' of fully developed humans
This approach was used in Arthur C. Clarke's novel, The Songs of Distant Earth.
