April 2004
- 2004 Ernest Lilley / SFRevu
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Interstellar Travel and Multi-Generation Space Ships by Yoji Kondo (ed), Frederick Bruhweiler (ed), John Moore (ed), Charles Sheffield (ed,) John Moore (ed )
Apogee Books HCVR: ISBN 1896522998 PubDate: 06/01/03
Review by Alexis Gilliland

128 pgs. List price $ 24.95
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This is a series of articles looking at interstellar travel written by people who are strongly in favor of it. Much of it is technical, and some of the technology is highly speculative, such as the Bussard ramjet, leading Charles Sheffield to conclude: "Star travel is not impossible, It may not even be difficult. The fact that it seems difficult or impossible is merely a measure of the state of our science and technology." Well, yes. It is proper that one should walk before running, and in this context, walking would necessarily include living in space, since an interstellar and multi-generation ship would surely require mastery of such an art.

 The book also includes the only vehicle possible with 1950's technology, the Dyson Orion interstellar rocket, a 400,000 ton spaceship with a payload of 20,000 tons, "which could accommodate a crew of hundreds." (editor's note: Poul Anderson spun a fine yarn with this technology at the center in his "Orion Shall Rise") After 10 days of 1 gee acceleration, caused by exploding one atom bomb every three seconds, it would be traveling at tree percent of the speed of light, and would reach Alpha Centauri in 140 years.

Here is what Joe Haldeman says about that: "If you postulate a completely efficient closed ecology, everything recycled, then the mass associated with life support is constant for a given population, no matter how long the voyage. The energy to kindle photo­synthesis also requires expenditure of mass . . . ." We note that nuclear reactors running on E = Mc2 are far more massive than the mass they convert to energy, as are spare fuel rods, shielding and so forth. How much of that payload of 20,000 tons will be taken up by a nuclear reactor that will run for hundreds of years to provide artificial sunlight to drive the biosphere of which the human crew is a part? At a guess, 5,000 tons.

This will support "hundreds" of people, say 300, massing maybe 20 tons, but the crew does not exist in isolation, it is part of the ship's biosphere. Figure that each trophic level masses ten times as much as the trophic level that feeds on it. How far down on the food chain is the crew eating? We grow algae, and feed it to a fish, such as tilapia. We feed our wastes to bacteria that are fed in turn to clams and oysters, filterfeeders. Two trophic levels is the minimum for a human diet, which means that 20 tons of people are eating at the top of a food chain consisting of 2000 tons of bacteria and algae and 200 tons of tilapia and filter feeders. Which have their own requirements, such as adequate water to live in, and the aquarium support machinery. Maybe 20,000 tons, altogether, and we are already over the weight limit. Travelling with a self-contained biosphere means you are hauling around the farm, farmyard, crops, cows and sewage treatment plant, not to mention that massive power plant keeping everything working.

As Sheffield suggests, star travel may not even be difficult. However, current technology is not up to it.

- 2004 Ernest Lilley / SFRevu
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