Sputnik 1

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Organization: Council of Ministers of the USSR
Major contractors: OKB-1, Soviet Ministry of Radiotechnical Industry
Mission type: Atmospheric studies
Satellite of: Earth
Launch date: October 4, 1957, 19:28:34 UTC (22:28:34 MSK)
Launch vehicle: R-7
Decay: January 4, 1958
Mission duration: 3 months
NSSDC ID: 1957-001B
Webpage: NASA NSSDC Master Catalog
Mass: 83.6 kg (184.3 lb.)
Semimajor axis: 6,955.2 km (4,321.8 miles)
Eccentricity: .05201
Inclination: 65.1°
Orbital period: 96.2 minutes
Apoapsis: 939 km (583 miles)
Periapsis: 215 km (134 miles)
Orbits: 1,440

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Sputnik 1 (Russian: "Спутник-1", "Satellite-1", or literally "Co-traveler-1" byname ПС-1 (PS-1, i.e. "Простейший Спутник-1", or Elementary Satellite-1)) was the first artificial satellite to be put into geocentric orbit. Launched by the Soviet Union on October 4, 1957, it was the first satellite of the Sputnik program.

The big satellite helped to identify the density of high atmospheric layers by its orbit change and provided data on radio-signal distribution in the ionosphere. Because the satellite's body was filled with pressurized nitrogen, Sputnik 1 also provided the first opportunity for meteorite detection, as losses in internal pressure due to meteoroid penetration of the outer surface would have been evident in the temperature data. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War.

Sputnik-1 was set in motion during the International Geophysical Year from the 5th Tyuratam range in Kazakh SSR (now Baikonur Cosmodrome). The satellite travelled at 29,000 kilometers (18,000 mi) per hour and emitted radio signals at around 20.005 and 40.002 MHz[1] which were monitored by Amateur radio operators throughout the world. The signals continued for 22 days until the transmitter batteries ran out on October 26, 1957.[2] Sputnik 1 burned as it fell from orbit upon reentering Earth's atmosphere, after traveling about 60 million km (37 million miles) in orbit.

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Prior to launch

The history of the Sputnik 1 project dates back to May 27, 1954, when Sergei Korolev addressed Dmitry Ustinov, then Minister of Defense Industries, proposing development of an artificial satellite of the Earth and forwarding him a report by Mikhail Tikhonravov with an overview of similar projects abroad.[3] Tikhonravov emphasized that an artificial satellite is an inevitable stage in the development of rocket equipment, after which interplanetary communication would become possible. [4] On July 29, 1955 the U.S. President Dwight Eisenhower announced through his press secretary that the United States would launch an artificial satellite during the International Geophysical Year (IGY).[5] A week later, on August 8, the Presidium of the Central Committee of the CPSU approved the idea of creating an artificial satellite.[6] On August 30, Vasily Ryabikov, the head of the State Commission on R-7 rocket test launches, held a meeting where Korolev presented calculation data on the spacecraft to be sent to the Moon. They decided to develop a three-stage version of the R-7 rocket for satellite launches.[7]
On January 30, 1956, the Council of Ministers of the USSR approved practical work on an artificial satellite of the Earth. This satellite, named "Object D", was planned to be completed in 1957-58; it would have a mass of 1,000 to 1,400 kg (2,200 to 3,090 lb) and would carry 200 to 300 kg (440 to 660 lb.) of scientific instruments.[8] The first test launch of "Object D" was scheduled for 1957.[4] According to that decision, work on the satellite was divided between institutions as follows:[9]
•   USSR Academy of Sciences was responsible for the general scientific leadership and research instruments supply
•   Ministry of Defense Industry and its main executor OKB-1 were assigned a task of creating the satellite as a special carrier for scientific research instruments
•   Ministry of Radiotechnical Industry should develop the control system, radiotechnical instruments and the telemetry system
•   Ministry of Ship Building Industry should develop gyroscope devices
•   Ministry of Machine Building should develop ground launching, refueling and transportation means
•   Ministry of Defense was responsible for conducting launches

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By July 1956 the draft was completed and scientific tasks to be carried out by a satellite were defined. They should include measuring density of the atmosphere, its ion composition, corpuscular solar radiation, magnetic fields, cosmic rays, etc. Data valuable for creating future oriented satellites was also planned to be collected. Ground observational complex was developed, that should collect information transmitted by the satellite, should observe satellite's orbit and transmit commands to the satellite. Such complex should include up to 15 measurement stations. Due to the limited time frame, they should have means designed for rocket R-7 observations, observations were planned for only 7 to 10 days and orbit calculations were expected to be not quite accurate.[10]

Unfortunately, the complexity of the ambitious design and problems in following exact specifications meant that some parts of 'Object D', when delivered for assembly, simply did not fit with the others, causing costly delays. By the end of 1956 it became clear, that plans for 'Object D' were not to be fulfilled in time due to difficulties creating scientific instruments and low specific impulse of completed R-7 engines (304 sec instead of planned 309 to 310 sec), and the government re-scheduled its launch for April 1958.[4] Object D would later fly as Sputnik 3.

Fearing the U.S. would launch a satellite before the USSR, OKB-1 suggested to create and launch in April-May 1957, before the IGY should begin in July 1957, a new satellite that was simple, light (100 kg), and easy to construct, forgoing the complex, heavy scientific equipment in favour of a simple radio transmitter. On February 15, 1957 the Council of Ministers of the USSR approved this, providing for launching the simplest unoriented Earth satellite, designated 'Object PS' for checking the possibility of its observation in orbit and for receiving signals transmitted by the satellite.[11] Launch of two satellites PS-1 and PS-2 with two R-7 rockets (8K71) was allowed, but only after one or two successful R-7 test launches.[11]

The ground observational complex, completed by a group lead by Colonel Yu.A.Mozzhorin, was called "command-measurement complex" and consisted of the coordination center in NII-4 and seven ground tracking stations, situated along the line of the projection of the satellite orbit onto the Earth surface. The complex had a communication channel with the launching pad. Stations were equipped with radars, optical instruments and communication means. PS-1 was not designed to be controlled, it could only be observed. Data from stations was transmitted by telegraphs into NII-4 where ballistics specialists calculated orbit parameters. Such complex became an early prototype of the Soviet Mission Control Center [12]

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A picture of Sputnik 1 in the fall of 1957 as a technician puts finishing touches on it.

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Design

The Sputnik 1 satellite was a 585 mm (23 in) diameter sphere, made of highly polished 2 mm-thick aluminum AMG6T alloy,[13] carrying four whip-like antennas between 2.4 and 2.9 meters (7.9 and 9.5 ft) in length. The antennas resembled long "whiskers" pointing to one side. It had two radio transmitters (20.005 and 40.002 MHz) and is believed to have orbited Earth at a height of about 250 km (150 mi). Analysis of the radio signals was used to gather information about the electron density of the ionosphere. Temperature and pressure were encoded in the duration of radio beeps, which additionally indicated that the satellite had not been punctured by a meteorite. Sputnik 1 was launched by an R-7 rocket. It burned up upon re-entry on January 4, 1958.