Sputnik 1 - Launch and Mission

Launch and Mission

The control system of the Sputnik rocket was tuned to provide an orbit with the following parameters: perigee height – 223 km (139 mi), apogee height – 1,450 km (900 mi), orbital period – 101.5 min. A rocket trajectory with these parameters was calculated earlier by Georgi Grechko, after completing the calculations over several nights on the USSR Academy of Sciences' mainframe computer.

The Sputnik rocket was launched at 19:28:34 UTC, on 4 October 1957, from Site No.1 at NIIP-5. Processing of the information, obtained from the "Tral" system showed that the side boosters separated 116.38 seconds into the flight and the second-stage engine was shut down 294.6 seconds into the flight. At this moment the second stage with PS-1 attached had a height of 223 km (139 mi) above Earth's surface, a velocity of 7,780 m/s (25,500 ft/s) and velocity vector inclination to the local horizon was 0 degrees 24 minutes. This resulted in an initial orbit with a perigee of 223 kilometres (139 mi), an apogee of 950 kilometres (590 mi), 65.1 degrees of inclination and a period of 96.2 minutes.

After 3.14 seconds PS-1 separated from the second stage and at the same moment at the small "Finnish house" of IP-1 station Junior Engineer-Lieutenant V.G. Borisov heard the "Beep-beep-beep" signals from the radio receiver R-250 (see ru:Р-250 (радиоприёмник)). Reception lasted for two minutes, while PS-1 was above the horizon. There were many people in the house, both military and civil, and they were probably the first to celebrate the event. After 325.44 seconds a corner reflector on the second stage was opened, that also allowed measurement of its orbit parameters – like the working "Tral" system did.

The designers, engineers and technicians who developed the rocket and satellite watched the launch from the range. After the launch they ran to the mobile radio station to listen to signals from the satellite. They waited about 90 minutes to ensure that the satellite had made one orbit and was transmitting, before Korolyov called Soviet premier Nikita Khrushchev. The downlink telemetry included data on temperatures inside and on the surface of the sphere.

On the first orbit the Telegraph Agency of the Soviet Union (TASS) transmitted: "As result of great, intense work of scientific institutes and design bureaus the first artificial Earth satellite has been built". The Sputnik 1 rocket booster (second stage of the rocket) also reached Earth orbit and was visible from the ground at night as a first magnitude object following the satellite. Korolyov had intentionally requested reflective panels placed on the booster in order to make it so visible. The satellite itself, a small but highly polished sphere, was barely visible at sixth magnitude, and thus more difficult to follow optically. Ahead of Sputnik 1 flew the third object – the payload fairing, 80 cm (31 in)-long cone, i.e. a little bit bigger than the satellite.

Sputnik 1 remained in orbit until 4 January 1958, when it decayed and reentered the atmosphere, having completed 1,440 orbits of the Earth.