Peril Seen in Soviet Use of A-Reactors in Spy Satellites

The Soviet Union has launched more than 30 nuclear reactors into space in a program that threatens public safety and could disrupt a promising new type of astronomy, according to the first scientific reports on the subject.

The reactors, which supply on-board power to Soviet spy satellites, can pose a serious public health danger by reentering the Earth’s atmosphere and disintegrating, plunging highly radioactive materials to the ground. They have done that at least twice in the past when the Soviet Union was unable to boost them to higher, safer orbits after they had outlived their usefulness.

Furthermore, the space reactors raise the threat of weapons-grade uranium falling into the hands of terrorists, who could use the material to make nuclear weapons, according to reports published today in the journal Science.

The subject of orbiting reactors has been classified by the Pentagon for nearly a decade, but federal officials began releasing some details last year after a team of scientists from UC Riverside inadvertently detected four space reactors with a gamma-ray telescope suspended from a high-flying balloon.

Breaking Up

The United States’ only space reactor was launched in 1965 and is now inactive in orbit, although it is reportedly breaking up. The Soviets have since orbited more than 30 reactors to power their radar ocean reconnaissance satellites, which are used to track U.S. naval vessels, writes physicist Joel R. Primack of the Institute for Particle Physics at UC Santa Cruz.

The United States is developing a powerful space reactor as part of the Strategic Defense Initiative, known popularly as Star Wars, but the reactor has not.been launched.

In a interview, Primack said the Soviets use nuclear reactors because of the immense demand for power to run their satellite radar systems. The United States uses a variety of intelligence methods, including a far more sophisticated radar system that can be powered by solar panels at a much higher orbit, he said.

Primack and others fear that a launch failure could cause a satellite to plunge back to Earth even before its reactor was turned on, thus allowing enough weapons-grade uranium to reach the ground before the reactor created the lethal fission products that would make recovery extremely difficult. Thus, anyone who found it, including terrorists, would have enough uranium “to make several weapons.”

Plunged to Earth

According to Steven Aftergood, executive director of the Los Angeles-based Committee to Bridge the Gap, many nuclear-powered satellites have either failed to reach orbit or plunged back to Earth.

Aftergood, an electrical engineer, told Congress earlier this month that satellites powered by either nuclear reactors or radioactive materials used to generate energy have repeatedly failed and fallen to the Earth.

The U.S. government has used radioisotopes, but not reactors, on various satellites that journey too far into space for the dim rays from the sun to supply enough energy to operate on-board instruments. Radioisotopes are generally considered a less hazardous means of generating power for satellites.

“A striking 15% of all Soviet and U.S. nuclear-powered space missions have ended in failure,” Aftergood testified.

The disclosures in the four Science articles are so alarming that Primack and others are calling for a total ban on orbiting reactors. Last year, Frank von Hippel of the Federation of American Scientists and Roald Sagdeev of the Committee of Soviet Scientists for Peace also called for a ban. Rep. George E. Brown Jr. (D-Colton) has introduced legislation to do just that.

Violations of such a ban would be easy to detect, because orbiting nuclear reactors are very difficult to hide. That is due largely to a neophyte field of gamma-ray astronomy, which had promised to open an entirely new window on the universe.

Gamma rays, the most energetic rays in the electromagnetic spectrum, are emitted by a wide range of celestial events, many of which are otherwise hidden by interstellar dust. By lifting gamma-ray telescopes above the Earth’s atmosphere, scientists hope to be able to study such exotic objects as quasars and neutron stars. But gamma rays are also emitted by orbiting reactors.

The extent of the problem was discovered accidentally by a team of astrophysicists from UC Riverside last August. They attached a gamma-ray telescope to a balloon and lifted it high above the Earth over Australia, where the atmosphere is so thin that gamma rays reached the instrument.

While collecting data that would allow them to create images of the universe as it would appear if the eye were sensitive to gamma rays, the Riverside team was startled when an incredibly bright object suddenly raced across the heavens.

sh Very Bright

It was, they later determined, a Soviet reactor that “outshines the rest of the sky put together in terms of gamma rays,” astrophysicist Terrence O’Neill said in a telephone interview.

O’Neill, the lead author of the Riverside report, said the reactor was 50 times brighter than the brightest object in the heavens at gamma-ray wavelengths. That object, the Crab Nebula, dims in comparison to the reactor, which O’Neill likened to putting a light bulb in front of a telescope.

“We were surprised,” said astrophysicist Stephen White, another member of the Riverside group. “We didn’t know they (the reactors) were up there.”

The Riverside team began asking questions about the powerful gamma-ray source but was told that the answers were classified. But as a result of the discovery, the National Aeronautics and Space Administration subsequently revealed that the source was a Soviet satellite.

During a brief, 30-hour flight, the UC Riverside telescope detected four different orbiting reactors.

Filled Memory

The reactors were so bright that they essentially filled the memory of the telescope’s data banks for awhile, thus blocking out observations of celestial events.

The problem would be even more serious for a telescope in orbit because it would be so close to the reactors that the gamma-ray emissions would appear suddenly as short bursts, similar to celestial events, rather than as a bright object racing across the sky.

Next year, NASA plans to launch its Gamma Ray Observatory, a key component in a series of orbiting telescopes that are designed to study the universe at every wavelength.

Orbiting satellites, because of their closer proximity to the reactors, would be particularly vulnerable to the radiation released by the reactors.

“It can almost cripple a satellite,” O’Neill said.

According to White, gamma rays from the reactors also create positrons and electrons that “are temporarily trapped in the Earth’s radiation belt.”

sh Strike Skin

Since the observatory will be in the same general region of the sky, it will be periodically bombarded by the subatomic particles, which create gamma rays when they strike the skin of the satellite that will house the telescope. That, in turn, creates a cloud of gamma rays that would block out the natural bursts that the scientists are trying to study.

Thus, the reactors pose a serious threat to gamma-ray astronomy, and they have no immediate practical use beyond military applications.

“Only military uses are currently contemplated for space reactors for at least the next decade,” Primack writes in an analysis of the four research papers.

Shielding would make the reactors too heavy to launch, so they “are such strong sources of radiation that human presence anywhere near them is impossible,” he concludes, so there is no immediate need for them as part of the civilian space program.

That does not hold true for deep space probes that must travel to the darkened reaches of the solar system. Radioisotopes may be the most reliable source of energy for such missions, he notes.

The Voyager spacecraft, which is now nearing the planet Neptune, is powered by radioisotopes. Two other probes with similar power plants are scheduled to be launched soon from the space shuttle, one for NASA to study Saturn and one for the European Space Agency to study the sun.

Both of the probes will require White House approval prior to launch, and it is not clear yet whether the Science reports will have any affect on those missions.

There is one touch of irony in today’s disclosures. Three of the reports are based on data collected by NASA’s Solar Maximum Mission satellite, which the space agency has decided not to rescue from a deteriorating orbit.

In 1984, Solar Max, as it is usually called, became the only satellite to be repaired in orbit by astronauts. NASA said then the repair was worth the effort because of the scientific merit of the satellite.

But a Defense Department document obtained by Aftergood under the Freedom of Information Act suggests that there was another player in that drama. The document, dated Aug. 14, 1981, lays out the need to repair the satellite because of its value in tracking the Soviet Union’s orbiting reactors with its gamma-ray detector.