Ever since a Soviet nuclear-powered satellite broke apart over a remote region of northern Canada in 1978, the use of atomic reactors in space has been highly controversial. Once again the debate over nukes in orbit has heated up. Last April the Soviets lost control of another nuclear satellite, raising fears that it would fall to earth before they managed to boost the reactor into a safer, high-altitude orbit. Then, at a scientific conference in New Mexico last month, the Soviets said they had begun putting a new generation of powerful reactors in space and were even interested in selling them to the West.
The news has upset antinuclear activists and raised questions about American + plans for nukes in space. The U.S. has not launched a nuclear satellite since 1977, relying instead mostly on solar-powered models. But Pentagon officials are planning the eventual use of atomic spacecraft in the Strategic Defense Initiative, the Government's proposed space-based defense system. To prevent that idea from going any further, U.S. Representative George Brown, a California Democrat, introduced a bill in Congress last week that would bar American nuclear-power sources from space -- on the unlikely condition that the Soviets do so first. The only exceptions: projects like moon bases or trips to other planets.
The Soviets have launched some three dozen nuclear satellites over the past two decades. Altogether they contain almost 3,500 lbs. of radioactive fuel. The only way to halt that proliferation would be to make space nukes an issue in U.S.-Soviet arms-control talks. Warns Brown: "If we don't stop the use of nuclear-power sources traveling over our heads, we're likely to wake up one day with a nuclear reactor landing on our heads."
That nearly happened in 1978, when the Soviets' Cosmos 954 fell from orbit and burned on re-entry, showering northern Canada with radioactive debris. The only reason no one was hurt was that the impact site was virtually unpopulated. The incident persuaded the Soviets to design more effective safety devices into their nuclear satellites.
Those safeguards were put to a test last September, when the nuclear-powered Cosmos 1900, containing about 70 lbs. of radioactive fuel, began falling out of orbit. But before the satellite re-entered the atmosphere, an automated safety system kicked in. The reactor was separated from the satellite and shot into a higher orbit. If, however, the reactor should collide with a defunct satellite or some other piece of debris left from more than 30 years of human activity in space, it could be knocked out of orbit anyway. Says Daniel Hirsch, director of the Stevenson Program on Nuclear Policy at the University of California at Santa Cruz: "The probability of a collision with space debris is unacceptably high."
While not admitting that any of their nuclear satellites are dangerous, the Soviets boast that their new type of space reactor, called Topaz, is especially safe. Topaz can produce up to 10,000 watts of power, about ten times as much as previous models. That enables Topaz-powered satellites to fly at such high altitudes, say Soviet scientists, that they will remain safely in orbit for up to 350 years, long enough to lose most of their radioactivity.