This event marks the launch of the Sputnik 25 satellite on October 4th, 1962. This launch was a major milestone in the history of space exploration, as it was the first successful launch of a satellite by the Soviet Union. The satellite was designed to study the Earth's atmosphere and
From Wikipedia
Sputnik 1, often referred to as simply Sputnik, was the first artificial Earth satellite. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957 as part of the Soviet space program. It sent a radio signal back to Earth for three weeks before its three silver-zinc batteries became depleted. Aerodynamic drag caused it to fall back into the atmosphere on 4 January 1958.