Twenty-first century starflight

Abstract

By the end of the twenty-first century we will have imaged Earth-like planets (if these worlds exist) orbiting nearby stars, and our probes will have reached the heliosphere at, at least, the inner fringes of the Oort Cloud. Fission propulsion will probably be incapable of carrying humans to these beckoning new worlds; fusion-pulse may remain politically and socially unacceptable, solar-sailing is too slow, and antimatter is too expensive. This will be a time of vast change on Earth as our population peaks and nation states begin to give way to a true global civilization. Is there any hope, then, for a propulsion system that could take at least a few humans to habitable worlds orbiting nearby stars, on missions that begin late in the twenty-first century?

Looking out from the continent-sized cities and vast game preserves that may be our future on this planet, youngsters will dream that when they are grown, if they are very lucky, they will catch the night freight to the stars.

Carl Sagan, The Cosmic Connection (1973)