Sputnik 1 — the first artificial satellite

The original Object D was intended to be a large flying laboratory. Its development was slipping and rocket performance was limited. Korolev’s team therefore chose the small PS-1, the “simplest satellite”. It carried no camera or suite of scientific instruments. Its main tasks were to demonstrate orbital flight and emit a radio signal that could be tracked.

The transmitters operated at roughly one watt on 20.005 and 40.002 MHz. Their alternating pulses could be received with relatively simple amateur radio equipment. Pulse timing also conveyed information about conditions inside the sphere, especially temperature and pressure. Tracking the orbit and the propagation of radio waves yielded data about the upper atmosphere and ionosphere.

The satellite sat on an adapter at the top of the core stage. A short conical fairing protected it during flight through the dense atmosphere, with its antennas folded along the adapter. The 8K71PS had no third stage. Footage of later R-7 launches should therefore not automatically be presented as Sputnik 1’s actual launch.

The rocket lifted off from Tyuratam, today’s Baikonur, on 4 October 1957 at 19:28:34 UTC. Some engines were slow to build thrust and a fuel-control system failed during ascent. Nevertheless, the four boosters separated roughly 116 seconds after liftoff and the core continued climbing. Its engine shut down around T+295 seconds, slightly earlier than planned.

Sputnik travelled in an elliptical orbit inclined about 65.1°. Its initial low point was roughly 215–230 km above Earth and its high point around 940 km. One circuit took about 96.2 minutes. Changes in the orbit helped researchers estimate drag from the thin upper atmosphere.

The Soviet success was a scientific milestone and a political signal: a rocket that could reach orbit also demonstrated the potential of intercontinental technology. In the United States it triggered the “Sputnik crisis”. The Vanguard TV-3 launch attempt ended in an explosion on 6 December 1957; Juno I carried the first American satellite, Explorer 1, into orbit on 31 January 1958.

The batteries stopped powering the transmitters on 26 October 1957. The silent satellite continued around Earth until it re-entered the atmosphere on 4 January 1958. In about 92 days it completed roughly 1,440 orbits. The rocket core re-entered earlier, on 2 December 1957.