The noted physicist Freeman Dyson identified comets, rather than planets, as the major potential habitat of life in space. It is thought that several trillion comets or iceteroids exist outside the orbit of Neptune. These may harbour all the ingredients for life (water ice and organic compounds) including significant amounts of deuterium, tritium, and helium-3. Estimates indicate the ratio of deuterium to standard hydrogen in the comets to be about 1 part per 10,000 to 100,000, which would provide around 50 to 100 kilotonnes of deuterium in an average comet, which may be used as fusion fuel to provide sufficient power to a comet colony for thousands of years. Two astrophysicists have also proposed that an average comet may include enough aluminum to create a solar power collector with a radius in the thousands of kilometers, which could collect starlight from the brightest star even when the comet is deep into the Oort Cloud or interstellar space, to provide enough indefinitely sustainable power for a colonized comet with around 500 colonists. Colonies sent to these far flung worldlets could build rotating habitats or live in dug-out spaces and light them with fusion reactors for thousands or millions of years before moving on. It is envisaged that over the eons humanity could migrate to neighbouring star systems, which may have similar clouds, without the need for large interstellar starships, by using comets as slow interstellar vessels with substantial natural resources; and that such interstellar comet colonies could also serve as way-stations for faster, smaller interstellar ships. The Artemis Project designed a plan to colonize Europa. ... No solid plans or studies have been made regarding manned missions to Titan, or colonization of that world, at least not outside of science fiction. ... This article does not cite its references or sources. ... Freeman John Dyson (born December 15, 1923) is a British-born American physicist and mathematician, famous for his work in quantum mechanics, solid-state physics, nuclear weapons design and policy, and for his serious theorizing in futurism and science fiction concepts, including the search for extraterrestrial intelligence. ... Comet Hale-Bopp Comet McNaught as seen from Swifts Creek, Victoria, Australia on 23 January 2007 A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail â€” both primarily from the effects of... The eight planets and three dwarf planets of the Solar System. ... Comet Hale-Bopp Comet McNaught as seen from Swifts Creek, Victoria, Australia on 23 January 2007 A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail â€” both primarily from the effects of... Note: This article contains special characters. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of planet Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... Tritium (symbol T or 3H) is a radioactive isotope of hydrogen. ... Helium-3 is a non-radioactive and light isotope of helium. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of planet Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... Interstellar Space was one of the last albums recorded before the death of John Coltrane in 1967. ...

Links

• http://www.orbitalvector.com/Interstellar%20Flight/Stepping%20Stone/Stepping%20Stone.htm

Works Cited

• ^ Freeman Dyson, "The World, the Flesh, and the Devil", Third J.D. Bernal Lecture, May 1972, reprinted in Communication with Extraterrestrial Intelligence, Carl Sagan, ed., MIT Press, 1973, ISBN 0-262-69037-3
• ^ Richard P. Terra, "Islands in the Sky: Human Exploration and Settlement of the Oort Cloud", in Islands in the Sky: Bold New Ideas for Colonizing Space, Stanley Schmidt and Robert Zubrin, eds. Wiley, 1996, ISBN 0-471-13561-5
• ^ Ben R. Finney and Eric M. Jones, eds., Interstellar Migration and the Human Experience, University of California Press, 1986, ISBN 0-520-05898-4
• ^ David G. Stephenson, "Comets and Interstellar Travel", in Journal of the British Interplanetary Society, 36, 1983, pp. 210-214.