“It was only a few centuries ago that people began to realize that those points of light in the night sky were suns, like our Sun, and like our Sun, they might have planets around them. Many visionaries then dreamed and wrote of visiting those other planets in ships that traveled between the stars. Later, when astronomers were able to estimate the distance to the nearer stars, others concluded that, because interstellar distances were so immense and human life so short, interstellar travel was impossible.
“Travel to the stars will be difficult and expensive. It will take decades of time, gigawatts of power, kilograms of energy and trillions of dollars. Recently, however, some new technologies have emerged and are under development for other purposes, that show promise of providing propulsion systems that will make interstellar travel feasible within the forseeable future — if the world community decides to direct its energies and resources in that direction. Make no mistake — interstellar travel will always be difficult and expensive, but it can no longer be considered impossible.”
— Robert Forward, “Ad Astra!” Journal of the British Interplanetary Society Vol. 49, p. 23 (1996).
Centauri Dreams note: For just one example of Forward’s innovative work, see his “Roundtrip Interstellar Travel Using Laser-Pushed Lightsails,” Journal of Spacecraft and Rockets Vol. 21, Mar-Apr (1984), pp. 187-195. This seminal paper appeared two years after Forward’s novel Rocheworld, which illustrated the physics behind a manned, one-way mission to Barnard’s Star. Rocheworld was published in Analog Science Fiction/Science Fact in December of 1982, and was later released in a longer version as The Flight of the Dragonfly (New York: Timescape, 1984). A final, still longer version, once again titled Rocheworld, appeared in 1990 (New York: Baen Books).