THE United States plans a multi-decade, multi-billion-dollar cleanup of dirty nuclear facilities. The Soviet Union admits to an equally daunting problem with contaminated sites. It seems incredible that these two countries should continue to plan for orbiting nuclear reactors as they finally face up to the radioactive mess they have made on the ground. They should put such plans on hold and enter into serious negotiations to ban nuclear reactors in Earth orbit altogether.
Congress is considering legislation to nudge the Bush administration toward such negotiations. One proposal would also require the administration to report on the degree to which gamma rays leaking from orbiting reactors interfere with expensive astronomical satellites. The report would be due next April.
The administration should need no nudging. Nor do we need another study of the well-documented gamma ray leakage. The fact that putting nuclear reactors in orbit is at cross purposes with other important objectives is enough to justify starting the desired negotiations as soon as possible.
Making the most of astronomical satellites is one such purpose. Cosmic gamma rays have become a major source of information about the universe now that detectors can be orbited above the atmosphere which absorbs the rays. Leakage from Soviet satellite reactors interferes with this study. The leakage continues even when the reactor is shut down and put into a ``graveyard'' orbit.
Minimizing the build-up of space junk is another important objective. The junk cloud enveloping our planet is a hazard to manned and unmanned space craft in low Earth orbits. We don't need to add derelict reactors to this mix. If one of these reactors smashes up in a collision it would spread an especially nasty kind of debris.
Furthermore, we don't need the risk of a reactor accidently bringing its radioactive load back to Earth's surface. Two of the 30 or so reactors the Soviets have orbited have already done this. There will always be risk of contamination even with reactors designed to survive re-entry intact - as in the case of the space power reactor the United States is developing.
Having orbited one unit, the United States no longer uses reactor power in space. The Soviets do use reactors on radar reconnaissance satellites. Both countries are developing advanced space power reactors and the Soviet Union has already tested its model in orbit.
Such reactors would indeed provide abundant power for civilian and military satellites, especially for anti-missile weapons. But specific uses are only vaguely defined.
There is no urgent need for either country to develop and deploy a new design of space reactor. There are important reasons to refrain from putting such potentially dangerous power sources in Earth orbit. The Bush administration should recognize this and adopt a ban on orbiting reactors as one of its environmental objectives.