The Kosmos 954 was a satellite launched by the Soviet Union in 1977. It was part of a series of reconnaissance satellites meant to observe ocean traffic, including surface vessels and nuclear submarines, using active radar.
In mid-December, the North American Aerospace Defense Command noticed the satellite making erratic manoeuvres and changing altitude. All the while, its Soviet operators struggled to control their failing spacecraft.
In secret meetings, Soviet officials warned their U.S. counterparts that they had lost control over the vehicle, and that the system which was intended to propel the spent reactor core into a safe disposal orbit had failed.
At first the USSR claimed that the satellite had been completely destroyed during re-entry but later searches showed debris from the satellite had been deposited on Canadian territory, including portions of the Northwest Territories (some of which is now Nunavut), Alberta and Saskatchewan along a 600-kilometre (370 miles) path from Great Slave Lake to Baker Lake.
The effort to recover radioactive material from the satellite was dubbed Operation Morning Light. The joint Canadian-American team swept the area by foot and air, from January 24 to October 15, 1978. They were ultimately able to recover 12 larger pieces of the satellite. All but two fragments recovered were radioactive.
Under the terms of the 1972 Space Liability Convention, a state which launches an object into space is liable for damages caused by that object. For the recovery efforts, the Canadian government billed the Soviet Union $6,041,174.70 for actual expenses and additional compensation for future unpredicted expenses; the U.S.S.R. eventually paid the sum of C$3 million.
Richard Mingus worked at the U.S. Department of Energy‘s emergency command center in Las Vegas on January 24, 1978 at the time. His job was fielding calls at the command center, and to prevent Americans from panicking. All that the agency would report was that a “Space Aged Difficulty” had occurred. Nothing about a nuclear powered satellite with potential lethal fallout.