3 WHAT'S THERE? REMOTE SENSING

On a fall night in 1983, Lieutenant Colonel Stanislav Petrov was on duty at Serpukhov-15, a bunker where the Soviet Union monitored the satellite Oko. Oko's job was to detect nuclear missiles launched by the United States and its Cold War allies. Just after midnight, an alarm went off. This was not a rare instance; the system experienced occasional false alarms. This time, however, once the alarm sounded, it kept going. The Soviet satellite reported the United States had launched five ballistic missiles that would make impact in a matter of minutes.