"Kosmos 954 (Russian: \u041A\u043E\u0441\u043C\u043E\u0441 954) was a reconnaissance satellite launched by the Soviet Union in 1977. A malfunction prevented safe separation of its onboard nuclear reactor; when the satellite reentered the Earth's atmosphere the following year, it scattered radioactive debris over northern Canada, prompting an extensive cleanup operation."@en . . .