Kosmos 954, the nuclear satellite that fell on Canada
The account
A fireball streaked across the Arctic sky and scattered mysterious pieces across the snow.
What investigators found
It was a Soviet spy satellite with a nuclear reactor, and its radioactive debris was recovered in a joint operation.
The story
In the early hours of January 24, 1978, the Soviet satellite Kosmos 954, which used a small nuclear reactor as its power source, reentered the atmosphere over northern Canada. Residents saw a light crossing the sky, and fragments were scattered along a long stretch of the Northwest Territories, near Great Slave Lake.
Canada and the United States mounted a large search operation called Morning Light and found radioactive pieces in the snow. The Canadian government billed the Soviet Union for the cleanup costs. The case is one of the best-known examples of an object falling from the sky that, far from being alien, revealed the risks of space junk.