Sputnik 1
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.
It was a polished metal sphere in diameter with four external radio antennas to broadcast radio pulses. Its radio signal was easily detectable by amateur radio operators, and the 65° orbital inclination made its flight path cover virtually the entire inhabited Earth.
The satellite's success was unanticipated by the United States. This precipitated the American Sputnik crisis and triggered the Space Race. The launch was the beginning of a new era of political, military, technological, and scientific developments. The word sputnik is Russian for satellite when interpreted in an astronomical context; its other meanings are spouse or travelling companion.
Tracking and studying Sputnik 1 from Earth provided scientists with valuable information. The density of the upper atmosphere could be deduced from its drag on the orbit, and the propagation of its radio signals gave data about the ionosphere.
Sputnik 1 was launched during the International Geophysical Year from Site No.1/5, at the 5th Tyuratam range, in Kazakh SSR. The satellite travelled at a peak speed of about, taking 96.20 minutes to complete each orbit. It transmitted on 20.005 and 40.002 MHz, which were monitored by radio operators throughout the world. The signals continued for 22 days until the transmitter batteries depleted on 26 October 1957. On 4 January 1958, after three months in orbit, Sputnik 1 burned up while reentering Earth's atmosphere, having completed 1,440 orbits of the Earth, and travelling a distance of approximately.
Etymology
Спутник-1, romanized as Sputnik-Odin, means 'Satellite-One'. The Russian word for satellite,, was coined in the 18th century by combining the prefix and , thereby meaning 'fellow-traveler', a meaning corresponding to the Latin root satelles, which is the origin of English satellite.Before the launch
Satellite construction project
On 17 December 1954, chief Soviet rocket scientist Sergei Korolev proposed a developmental plan for an artificial satellite to the Minister of the Defense Industry, Dimitri Ustinov. Korolev forwarded a report by Mikhail Tikhonravov, with an overview of similar projects abroad. Tikhonravov had emphasised that the launch of an orbital satellite was an inevitable stage in the development of rocket technology.On 29 July 1955, U.S. President Dwight D. Eisenhower announced through his press secretary that, during the International Geophysical Year, the United States would launch an artificial satellite. Four days later, Leonid Sedov, a leading Soviet physicist, announced that they too would launch an artificial satellite. On 8 August, the Politburo of the Communist Party of the Soviet Union approved the proposal to create an artificial satellite. On 30 August, Vasily Ryabikov—the head of the State Commission on the R-7 rocket test launches—held a meeting where Korolev presented calculation data for a spaceflight trajectory to the Moon. They decided to develop a three-stage version of the R-7 rocket for satellite launches.
File:Sputnik 1 Arming Key.jpg|right|thumb|Last remaining piece of Sputnik 1: metal arming key which prevented contact between batteries and transmitter prior to launch; on display at the Smithsonian National Air and Space Museum
On 30 January 1956, the Council of Ministers approved practical work on an artificial Earth-orbiting satellite. This satellite, named Object D, was planned to be completed in 1957–58; it would have a mass of and would carry of scientific instruments. The first test launch of "Object D" was scheduled for 1957. Work on the satellite was to be divided among institutions as follows:
- The USSR Academy of Sciences was responsible for the general scientific leadership and the supply of research instruments.
- The Ministry of the Defense Industry and its primary design bureau, OKB-1, were assigned the task of building the satellite.
- The Ministry of the Radio technical Industry would develop the control system, radio/technical instruments, and the telemetry system.
- The Ministry of the Ship Building Industry would develop gyroscope devices.
- The Ministry of the Machine Building would develop ground launching, refuelling, and transportation means.
- The Ministry of Defense was responsible for conducting launches.
By the end of 1956, it became clear that the complexity of the ambitious design meant that 'Object D' could not be launched in time because of difficulties creating scientific instruments and the low specific impulse produced by the completed R-7 engines. Consequently, the government rescheduled the launch for April 1958. Object D would later fly as Sputnik 3.
Fearing the U.S. would launch a satellite before the USSR, OKB-1 suggested the creation and launch of a satellite in April–May 1957, before the IGY began in July 1957. The new satellite would be simple, light, and easy to construct, forgoing the complex, heavy scientific equipment in favour of a simple radio transmitter. On 15 February 1957 the Council of Ministers of the USSR approved this simple satellite, designated 'Object PS', PS meaning "prosteishiy sputnik", or "elementary satellite". This version allowed the satellite to be tracked visually by Earth-based observers, and it could transmit tracking signals to ground-based receiving stations. The launch of two satellites, PS-1 and PS-2, with two R-7 rockets, was approved, provided that the R-7 completed at least two successful test flights.
Launch vehicle preparation and launch site selection
The R-7 rocket was initially designed as an intercontinental ballistic missile by OKB-1. The decision to build it was made by the Central Committee of the Communist Party of the Soviet Union and the Council of Ministers of the USSR on 20 May 1954. The rocket was the most powerful in the world; it was designed with excess thrust since they were unsure how heavy the hydrogen bomb payload would be. The R-7 was also known by its GRAU designation 8K71. At the time, the R-7 was known to NATO sources as the T-3 or M-104, and Type A.Several modifications were made to the R-7 rocket to adapt it to 'Object D', including upgrades to the main engines, the removal of a radio package on the booster, and a new payload fairing that made the booster almost four metres shorter than its ICBM version. Object D would later be launched as Sputnik 3 after the much lighter 'Object PS' was launched first. The trajectory of the launch vehicle and the satellite were initially calculated using arithmometers and six-digit trigonometric tables. More complex calculations were carried out on a newly-installed computer at the Academy of Sciences.
A special reconnaissance commission selected Tyuratam for the construction of a rocket proving ground, the 5th Tyuratam range, usually referred to as "NIIP-5", or "GIK-5" in the post-Soviet time. The selection was approved on 12 February 1955 by the Council of Ministers of the USSR, but the site would not be completed until 1958. Actual work on the construction of the site began on 20 July by military building units.
The first launch of an R-7 rocket occurred on 15 May 1957. A fire began in the Blok D strap-on almost immediately at liftoff, but the booster continued flying until 98 seconds after launch when the strap-on broke away and the vehicle crashed downrange. Three attempts to launch the second rocket were made on 10–11 June, but an assembly defect prevented launch. The unsuccessful launch of the third R-7 rocket took place on 12 July. An electrical short caused the vernier engines to put the missile into an uncontrolled roll which resulted in all of the strap-ons separating 33 seconds into the launch. The R-7 crashed about from the pad.
The launch of the fourth rocket, on 21 August at 15:25 Moscow Time, was successful. The rocket's core boosted the dummy warhead to the target altitude and velocity, reentered the atmosphere, and broke apart at a height of after travelling. On 27 August, the TASS issued a statement on the successful launch of a long-distance multistage ICBM. The launch of the fifth R-7 rocket, on 7 September, was also successful, but the dummy was also destroyed on atmospheric re-entry, and hence needed a redesign to completely fulfil its military purpose. The rocket, however, was deemed suitable for satellite launches, and Korolev was able to convince the State Commission to allow the use of the next R-7 to launch PS-1, allowing the delay in the rocket's military exploitation to launch the PS-1 and PS-2 satellites.
On 22 September a modified R-7 rocket, named Sputnik and indexed as 8K71PS, arrived at the proving ground and preparations for the launch of PS-1 began. Compared to the military R-7 test vehicles, the mass of 8K71PS was reduced from, its length with PS-1 was and the thrust at liftoff was.
Observation complex
PS-1 was not designed to be controlled; it could only be observed. Initial data at the launch site would be collected at six separate observatories and telegraphed to NII-4. Located back in Moscow, NII-4 was a scientific research arm of the Ministry of Defence that was dedicated to missile development. The six observatories were clustered around the launch site, with the closest situated from the launch pad.A second, nationwide observation complex was established to track the satellite after its separation from the rocket. Called the Command-Measurement Complex, it consisted of the coordination center in NII-4 and seven distant stations situated along the line of the satellite's ground track. These tracking stations were located at Tyuratam, Sary-Shagan, Yeniseysk, Klyuchi, Yelizovo, Makat in Guryev Oblast, and Ishkup in Krasnoyarsk Krai. Stations were equipped with radar, optical instruments, and communications systems. Data from stations were transmitted by telegraphs into NII-4 where ballistics specialists calculated orbital parameters.
The observatories used a trajectory measurement system called "Tral", developed by OKB MEI, by which they received and monitored data from transponders mounted on the R-7 rocket's core stage. The data were useful even after the satellite's separation from the second stage of the rocket; Sputnik's location was calculated from data on the location of the second stage, which followed Sputnik at a known distance. Tracking of the booster during launch had to be accomplished through purely passive means, such as visual coverage and radar detection. R-7 test launches demonstrated that the tracking cameras were only good up to an altitude of, but radar could track it for almost.
Outside the Soviet Union, the satellite was tracked by amateur radio operators in many countries. The booster rocket was located and tracked by the British using the Lovell Telescope at the Jodrell Bank Observatory, the only telescope in the world able to do so by radar. Canada's Newbrook Observatory was the first facility in North America to photograph Sputnik 1.