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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Sputnik 1 | 5/8 | https://en.wikipedia.org/wiki/Sputnik_1 | reference | science, encyclopedia | 2026-05-05T13:23:17.580301+00:00 | kb-cron |
The control system of the Sputnik rocket was adjusted to an intended orbit of 223 by 1,450 km (139 by 901 mi), with an orbital period of 101.5 minutes. The trajectory had been calculated earlier by Georgi Grechko, using the USSR Academy of Sciences' mainframe computer. The Sputnik rocket was launched on 4 October 1957 at 19:28:34 UTC (5 October at the launch site) from Site No.1 at NI P-5. Telemetry indicated that the strap-ons separated 116 seconds into the flight and the core stage engine shut down 295.4 seconds into the flight. At shutdown, the 7.5-tonne core stage (with PS-1 attached) had attained an altitude of 223 km (139 mi) above sea level, a velocity of 7,780 m/s (25,500 ft/s), and a velocity vector inclination to the local horizon of 0 degrees 24 minutes. This resulted in an initial elliptical orbit of 223 km (139 mi) by 950 km (590 mi), with an apogee approximately 500 km (310 mi) lower than intended, and an inclination of 65.10° and a period of 96.20 minutes. Several engines did not fire on time, almost aborting the mission. A fuel regulator in the booster also failed around 16 seconds into launch, which resulted in excessive RP-1 consumption for most of the powered flight and the engine thrust being 4% above nominal. Core stage cutoff was intended for T+296 seconds, but the premature propellant depletion caused thrust termination to occur one second earlier when a sensor detected overspeed of the empty RP-1 turbopump. There were 375 kg (827 lb) of LOX remaining at cutoff. At 19.9 seconds after engine cut-off, PS-1 separated from the second stage and the satellite's transmitter was activated. These signals were detected at the IP-1 station by Junior Engineer-Lieutenant V.G. Borisov, where reception of Sputnik 1's "beep-beep-beep" tones confirmed the satellite's successful deployment. Reception lasted for two minutes, until PS-1 passed below the horizon. The Tral telemetry system on the R-7 core stage continued to transmit and was detected on its second orbit. The designers, engineers, and technicians who developed the rocket and satellite watched the launch from the range. After the launch they drove to the mobile radio station to listen for signals from the satellite. They waited about 90 minutes to ensure that the satellite had made one orbit and was transmitting before Korolev called Soviet premier Nikita Khrushchev. 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 R-7 core stage, with a mass of 7.5 tonnes and a length of 26 metres, also reached Earth orbit. It was a first magnitude object following behind the satellite and visible at night. Deployable reflective panels were placed on the booster in order to increase its visibility for tracking. A small highly polished sphere, the satellite was barely visible at sixth magnitude, and thus harder to follow optically. The batteries ran out on 26 October 1957, after the satellite completed 326 orbits. The core stage of the R-7 remained in orbit for two months until 2 December 1957, while Sputnik 1 orbited for three months, until 4 January 1958, having completed 1,440 orbits of the Earth. It is presumed Sputnik 1 may have broken up above the Western United States. A man in Encino, CA, woke up one morning and noticed something glowing in his backyard. Upon inspection, it proved to be plastic tubing of the type used in Sputnik. No one has been able to prove whether this in fact was part of the satellite.
== Reception ==
Organised through the citizen science project Operation Moonwatch, teams of visual observers at 150 stations in the United States and other countries were alerted during the night to watch for the satellite at dawn and during the evening twilight as it passed overhead. The USSR requested amateur and professional radio operators to tape record the signal being transmitted from the satellite. One of the first observations of it in the western world was made at the school observatory in Rodewisch (Saxony).