When radioactive debris from the Soviet Cosmos 954 ocean surveillance satellite was scattered along a path eight hundred kilometers long in the Canadian Northwest Territories, the remoteness of the region made search operations difficult, but the area’s low population minimized the hazard to humans.

When Cosmos 954 hit the dense region of Earth’s atmosphere at 6:53 a.m. eastern standard time, the spacecraft was heated rapidly by air friction and degenerated into a brilliant fireball, streaking across the sky as would a large meteor. The reentry was observed by witnesses on the ground in Yellowknife, Northwest Territories. Radar ocean reconnaissance satellites
Radar;satellite tracking

Later analysis of the debris indicated that the uranium core had begun to disintegrate at an altitude of about sixty-nine kilometers. The disintegration of the core was complete by the time the core reached fifty-six kilometers of altitude, over the west end of Great Slave Lake. The uranium core fragmented into pieces ranging from about one centimeter in size down to microscopic fragments. Many large pieces of the radioactive structure of the spacecraft survived reentry.

At 7:15 a.m., twenty minutes after the reentry, U.S. president Jimmy Carter telephoned Canadian prime minister Pierre Trudeau to inform him that Cosmos 954 had landed in Canada and to offer U.S. assistance in locating any debris. The Canadians accepted the offer, and the NEST teams were dispatched to the Canadian forces base in Edmonton, Alberta. Radar tracking indicated that the debris might be strewn anywhere along an 800-kilometer path from Yellowknife to Baker Lake in the Canadian Northwest Territories. The remoteness of the region would make search operations difficult, but the area’s low population minimized the hazard to humans.

The NEST team installed search equipment, which can detect the gamma rays emitted by some radioactive objects, in a Canadian Air Force C-130 aircraft. This plane departed on its first search mission at 3:15 a.m. on January 25. The aircraft flew a grid pattern over the presumed impact path. High readings on the gamma-ray detector were noted, and the positions were recorded so that helicopters could be dispatched to those sites for follow-up examination. As the data from this first flight were processed, a problem became apparent. The search area included natural uranium deposits that produce a gamma-ray signal similar to that expected from the satellite debris.

The first observation of Cosmos 954 debris was made by two campers, Mike Mobley Mobley, Mike and John Mordhurst, Mordhurst, John who saw some gray metal struts sticking up through the snow near Warden’s Grove on the Thelon River. They contacted the Yellowknife meteorological station by radio, and a helicopter was dispatched to the site. Radiation detectors measured from 10 to 100 milliroentgens per hour, well above background radiation levels but not consistent with the high readings expected from the uranium core. This indicated that the debris was likely to be part of the satellite structure. Mobley and Mordhurst were evacuated to Edmonton, where tests indicated their radiation exposure had been minimal, equivalent to no more than one or two medical X rays.

On February 1, 1978, the second major fragment of Cosmos 954, a large tube the size of a trash can, was sighted from the air about thirty-two kilometers north of Fort Reliance. It was not radioactive. A few kilometers away, a highly radioactive metal slab, measuring eight centimeters by twenty-five centimeters, was discovered. Persons in contact with this fragment, which was emitting 200 roentgens per hour, would receive the maximum allowable exposure for radiation workers within a few minutes. This find provided the first evidence that dangerous fragments of Cosmos 954 had indeed reached the ground. A specially shielded lead box was constructed at the University of Alberta to allow safe transport of this fragment. Other pieces of spacecraft structure, including disks, rods, and plates, were located near this site.

Cleanup efforts continued for nearly two months. Three major fields of debris were identified: one thirty-two kilometers northwest of Fort Reliance, a second thirty-two kilometers northeast of Fort Reliance, and the Thelon River site, where the first debris had been discovered.

The reactor and its fifty kilograms of enriched uranium 235 were determined to have broken up on reentry. The radioactive particles of debris were small and had drifted in the wind, falling onto Great Slave Lake and the snow-covered land to the south. Because the particles were so small, exposure to individual fragments was not deemed to be hazardous. Cleanup of these particles was accomplished by shoveling the contaminated snow into cans. Some of the smaller particles outside inhabited areas were left on the ground when it was determined that they did not result in a significant increase in the natural background radiation.

By March, the cleanup teams had recovered about one hundred pounds of debris, including about 10 percent of the uranium core. The recovered material was examined at the Whiteshell Atomic Energy Laboratory in Pinawa, Manitoba, before it was returned to the Soviet Union.

The 1972 Convention on International Liability for Damage Caused by Space Objects Convention on International Liability for Damage Caused by Space Objects (1972) obligates the launching nation to pay compensation for damage to Earth’s surface caused by space objects. The Canadian government presented the Soviet Union with a bill for $12 million to pay for the cost of the Cosmos 954 cleanup effort. After much negotiation, the Soviet Union paid about one-half that amount in compensation.

In response to the reentry of Cosmos 954, Carter called for a worldwide ban on nuclear reactors in space. The Soviet Union opposed this proposal. The United States, Canada, and Sweden pushed for U.N. action to prevent similar events in the future. Subsequent debate resulted in the adoption of a U.N. resolution permitting nuclear reactors in space but establishing guidelines to minimize the risk of large radioactive pieces reaching the surface intact.

The failure of Cosmos 954 resulted in a suspension of the RORSAT program while the nuclear reactor was redesigned. Cosmos 1176, launched on April 29, 1980, was the first test of the new design, in which the uranium core was separated from the reactor structure at the end of the operational phase of the flight. Separating the core from the reactor structure ensured that, even if the rocket engine failed to boost the core into the 600-kilometer-high parking orbit, the core would disintegrate on reentry.

Cosmos 1402, launched on August 30, 1982, provided a test of the new system. On January 5, 1983, the U.S. government announced that the booster rocket, designed to carry the Cosmos 1402 reactor and its radioactive support structure into high orbit, had failed, and the satellite was expected to reenter later in January. The concern was not with the uranium core, which was expected to disintegrate into small enough particles to pose no significant hazard, but with the structure made radioactive by its proximity to the core. The public was warned that if the satellite hit in their vicinity, they should not touch any fragments and should remain indoors.

Because a large fraction of Earth is covered by either water or sparsely populated regions, the likelihood of an impact in a region with a substantial population was low. The NEST team was alerted, and local emergency agencies were notified. On January 23, 1983, the final orbit of the major structure of Cosmos 1402 passed over the eastern United States, eastern Canada, the North Atlantic, Scandinavia, the Soviet Union, Iran, and the Indian Ocean, with reentry beginning over the island of Diego Garcia. Any debris that survived reentry plunged into the Indian Ocean about eighteen hundred kilometers southeast of Diego Garcia. Two weeks later, the nuclear core reentered over the South Atlantic between Brazil and Africa, and any surviving radioactive debris landed in the Atlantic Ocean.

The fear of radioactive debris has resulted in public protest demonstrations in the United States, such as the demonstration prior to the 1989 launching of the Galileo Galileo (spacecraft) interplanetary spacecraft. A court challenge to that launching, brought by citizens concerned with the environmental hazard to the east coast of Florida if the space shuttle carrying Galileo should explode during the launch phase of the flight, was not successful.

Between 1970 and 1988, the Soviet Union flew thirty-one RORSAT missions. In addition to the Cosmos 954 and Cosmos 1402 reactors, these RORSAT missions left twenty-nine nuclear reactors in high parking orbits. The major hazard posed by these reactors comes from collisions in space that could send radioactive debris onto paths reentering the atmosphere. Scientists disputed these alarmist claims, but protests by antinuclear activists continued. Disasters;radiation

• Aftergood, S., D. W. Hafemeister, O. F. Prilutsky, J. R. Primack, and S. N. Rodionov. “Nuclear Power in Space.” Scientific American 264 (June, 1991): 42-47. A discussion of the risks and benefits of nuclear power for Earth-orbiting satellites and interplanetary spacecraft. Includes color illustrations of the Cosmos 954 cleanup effort.
• Barrowman, Gerald L. “Operation Morning Light.” Spaceflight 21 (July, 1979): 302-307. A detailed account of the reentry and cleanup of Cosmos 954.
• Harland, David M., and Ralph D. Lorenz. Space Systems Failures: Disasters and Rescues of Satellites, Rockets and Space Probes. New York: Springer, 2005. A unique chronicle of the variety of space systems failures since the 1940’s.
• Heaps, Leo. Operation Morning Light. New York: Paddington Press, 1978. A detailed, well-illustrated account of the fall of Cosmos 954, the search for debris, and the cleanup effort. Based on interviews with the participants.
• Peebles, Curtis. Guardians: Strategic Reconnaissance Satellites. Novato, Calif.: Presidio Press, 1987. The chapter on ocean surveillance satellites focuses on the Cosmos 954 incident and the subsequent Cosmos 1402 failure. Footnotes, references.

Radioactive Cargo Sinks in the North Sea

Soviet Nuclear Submarine Sinks in the Atlantic