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Sputnik was the first Soviet spacecraft series. The project dates back to the early 1950s to studies carried out at the NII-4, a military research institution under the aegis of the Ministry of Defense's Chief Artillery Directorate (GAU). On 16 September 1953, the NII-4 began official research on satellite studies under the leadership of M. K. Tikhonravov, a senior scientist at the institute. This initial work led to a report which was eventually modified by engineers and scientists from several different institutions including Chief Designer S. P. Korolev's OKB-1 (then a part of the NII-88) and the Department of Applied Mathematics of the V. A. Steklov Mathemtics Institute of the USSR Academy of Sciences. On 27 May 1954, Korolev sent the NII-4 report to the Soviet government requesting permission to develop and launch a 3,000 kilogram scientific satellite into Earth orbit using the R-7 ICBM.

Unfortunately, the government had a lukewarm response. It took another year of lobbying and also the U.S. announcement in July 1955 of plans to launch a satellite during the International Geophysical Year (IGY) before a concrete response. On 30 August 1955, the Soviet Military-Industrial Commission (then simply called the Special Committee) provisionally approved Korolev and Tikhonravov's satellite project. By then the satellite mass had been reduced to 1,000-1,400 kilograms. The USSR Council of Ministers officially approved the satellite project, by then named the Object D, on 30 January 1956. The decree also approved initial exploratory studies on military variants of the Object D named the Object OD-1 and OD-2.

The Object D (also known as the D-1) was so named because it was the fifth type of payload planned for the R-7 missile. The first four letters of the cyrrilic alphabet, A, B, V, and G, were used to denote different warhead containers for the ICBM. The massive scientific observatory, which would carry 200-300 kilograms of scientific gear, was planned for launch in 1957 at the beginning of the IGY. Korolev formally signed off on the "draft plan," i.e. the paper design, for the satellite on 24 July 1956, allowing construction to begin soon after.

To launch the Object D, Korolev's engineers began the design of a modified R-7 booster named the 8A91. There were five main changes to the R-7 to convert it to the 8A91:

  1. throttle the engines of the central core at the moment of launch to a level of 60 tons from 73 tons;
  2. throttle the engines of the strapons down to 75% of nominal thrust from 17 seconds before separation of the stages;
  3. introduce a special muffler to reduce reactive forces on the auxiliary nozzles of the oxygen tanks;
  4. rework the separation system of the payload block to ensure the release of the fairing;
  5. remove the radio compartment to the core.

On 20 September 1956, the U.S. Army launched a Jupiter C missile (no. RTV-1) on a ballistic flight over a distance of 5,300 kilometers. If the missile had been equipped with a live third stage, the booster could have probably inserted a tiny satellite into Earth orbit. News of this launch reached the USSR in a garbled manner. Korolev sincerely believed that the launch was a secret U.S. Army attempt to launch an artificial satellite which had failed. In the meantime there were problems in developing the 8A91 booster, in particular insufficient specific impulse to launch a satellite with a mass of 1.4 tons. There were also major delays in the delivery of subsystems for the Object D satellite. In this climate, Korolev and Tikhonravov were seriously concerned that the Americans would preempt the launch of Object D. To preclude such a possibility, the two men decided, in November 1956, to introduce a more modest satellite project while concurrently proceeding with the Object D effort.

On 5 January 1957, Korolev sent an official letter to the Military-Industrial Commission asking for permission to launch two small satellites, each about 100 kilograms in mass, before the beginning of the IGY. These were the Simple Satellites (PS), PS-1 and PS-2. Korolev believed that if he could launch PS-1 and PS-2 before the start of the IGY he would be able to preempt any U.S. attempt planned for the IGY. By 25 January 1957, Korolev approved the preliminary design of the two small satellites. On 15 February (some sources say 7 February), the Soviet government formally approved the new plan.

Since the 8A91 launcher was not ready, the OKB-1 implemented some rudimentary changes to the basic R-7 ICBM to launch the new small satellites. This interim version was called the 8K71PS. The changes implemented included removing the radiopackage from the core booster and modifying the firing regime of both the core and strapon engines.

PS-1 was eventually launched on 4 October 1957 and named "Sputnik."

On 12 October 1957, just a week after Sputnik, the OKB-1 received an order to launch a second satellite in time for the 40th anniversary of the Great October Revolution in early November 1957. Thus, the original PS-2, with the addition of a container modified from the payload of the R-2A scientific rocket, was launched on 3 November 1957 and named "Sputnik-2." The container carried Layka, the first living being to enter orbit around the Earth.

At least two models of the Object D satellite were built, both of which were launched. One of these did not reach orbit. The second, which reached orbit, was named "Sputnik-3."

There appear to have been plans to launch further variants of the Object D as part of the IGY, including a version of the Object OD. These plans were obviously never implemented. The OD program later served as the basis for both the Vostok (piloted) and Zenit (photo-reconnaissance) satellite projects.

Launch History:

Name OKB Name Vehicle
Serial Number
Launch Time
(Moscow Time)
Launch Date Launch Vehicle Launcher
Serial Number
Sputnik PS-1 - 2228:34 Oct 4 1957 8K71PS M1-1PS Jan 4 1958
Sputnik-2 PS-2 - 0530:42 Nov 3 1957 8K71PS M1-2PS Apr 14 1958
- D-1 1 1201 Apr 27 1958 8A91 b1-2 FTO
Sputnik-3 D-1 2 1000:35.5 May 15 1958 8A91 b1-1 Apr 6 1960



  1. K. V. Gerchik, ed., Nezabyvayemyy Baykonur (Moscow: Interregional Council of Veterans of the Baykonur Cosmodrome, 1998).
  2. M. V. Keldysh, ed., Tvorcheskoye naslediye Akademika Sergeya Pavlovicha Koroleva: izbrannyye trudy i dokumenty (Moscow: Nauka, 1980).
  3. Yu. P. Semenov, ed., Raketno-Kosmicheskaya Korporatsiya "Energiya" imeni S. P. Koroleva (Korolev: RKK Energiya named after S. P. Korolev, 1996).