Nukes in Space: Scientists Debate U.S. Plan to Orbit Russian Reactor

January 24, 1993|By DOUGLAS BIRCH

COLLEGE PARK — And now, from the people who brought you Chernobyl: Nukes in space.

The University of Maryland College Park last week staged what physicist Roald Sagdeev, the former head of the Soviet space program now on the faculty at College Park, called "one of the most unusual meetings in the post-Cold War era."

Russian scientists, Pentagon and NASA officials, satellite designers and astronomers gathered in a windowless classroom for a sometimes-emotional debate over Department of Defense plans to launch a nuclear reactor, built by the former Soviet government, into orbit.

Americans argued with Americans, Russians disagreed with Russians, and scientists disputed data. "You're saying that your science is more important than our science! That's inflammatory!" one researcher snapped.

It was like a mixed-doubles tennis game without a net, and it might have made some nostalgic for the simpler days of superpower stalemate.

Last year, the Pentagon bought a couple of tepee-shaped Topaz II reactors from the Russian government for $13 million and is arranging to purchase four more -- the last four in existence.

To buyer and seller, the Topaz sale seemed like a sweet deal.

Strategic Defense Initiative officials have talked about using reactors to power anti-missile satellites, and they are eager to test prototype engines. The price was right. Former Soviet scientists were desperate for the income. And America hadn't built a space reactor of its own in almost 30 years.

During the same period, the Soviet Union launched dozens of them, including 31 aboard its RORSAT naval spy satellites.

The United States plans to use a U.S. rocket to lift a Topaz-equipped satellite, to be built by Johns Hopkins University's Applied Physics Laboratory, into orbit in late December 1995.

There the liquid metal-cooled reactor is supposed to begin splitting atoms and producing electricity to power several prototype plasma engines. The point of the experiment is to test both the reactor and the engines over two or three years. During that time, the $150 million satellite is supposed to gradually spiral up from its initial 1,000-mile orbit to a 22,000-mile orbit.

The Pentagon insists that Topaz II won't pose any significant risk to civilians. Uranium oxide, scientists say, is considered only moderately radioactive compared to the plutonium 238 used on some deep-space probes -- such as the Galileo mission to Jupiter and the Ulysses mission to explore the sun's polar regions.

The reactor won't be turned on and start producing highly radioactive byproducts until it reaches orbit. And if the satellite is disabled in its initial 1,000-mile orbit, it will take several centuries to fall back to Earth.

So far the Topaz flight, still almost three years away, seems to have drawn little opposition from anti-nuclear groups.

Some former Soviet scientists and their American colleagues have called for banning all space reactors from orbit, saying that even in high orbits satellites might be hit by debris and sent spinning toward Earth.

They point out that reactors aboard Soviet spy satellites in low orbits have twice accidentally re-entered the atmosphere in 1978 and 1983. In the 1978 incident, Cosmos 954 disintegrated and scattered radioactive debris over northwestern Canada. The Soviets later paid $2 million in compensation and damages.

But the most vocal critics of Topaz II are astronomers. Their concern is what Topaz II might do to their orbiting X-ray and gamma-ray telescopes.

Once the reactor is turned on in orbit, the lightly-shielded Topaz II will begin spewing clouds of high-energy particles -- electrons, positrons and neutrons. (To protect sensitive instruments, the reactor will be separated from the main body of the satellite by a 26-foot boom.)

Topaz II's particle clouds will be quickly trapped in the bands of the Earth's magnetic fields. "It's kind of like a magnetic bottle that holds these charged particles in place," said Dr. Barry H. Mauk, who is working on the project at the Applied Physics Laboratory.

In low orbits, some astronomers say, these clouds could persist for anywhere from a few seconds to up to 90 minutes.

Astronomers worry that ricocheting electrons -- the particles that surround the nucleus of an atom -- will trigger false readings on X-ray and gamma-ray detectors that cross their path. Positrons, which are the anti-matter counterparts of electrons, will create gamma-rays when they strike metal satellites -- confusing any gamma-ray detectors aimed at the stars.

In 1987 and early 1988, Soviet spy satellites powered by Topaz I reactors interrupted research with NASA's Solar Maximum Mission satellite an average of eight times a day. Gerry Share, an astronomer with the Naval Research Laboratory in Washington, said the radiation created "significant" problems for the satellite's study of the center of the Milky Way galaxy.

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