Sputnik, name of the first of several artificial satellites launched by the Soviet Union from 1957 to 1961. The goals of the Sputnik program included studying the earth’s upper atmosphere, observing animal survival in space flight, and testing Soviet rocket technology. The launch of the unmanned Sputnik 1 and of Sputnik 2, which carried a dog, spurred the United States to invest more money and resources into its fledgling space program, initiating a race between the two nations to land a person on the moon (see Space Exploration).
The Sputnik program began on October 4, 1957, with the launch of Sputnik 1, which weighed 83 kg (184 lb). The official name of the satellite was Iskustvennyi Sputnik Zemli (fellow world traveler of the earth). The launch vehicle was a test version of the Soviet intercontinental ballistic missile (see Guided Missiles). Sputnik 2 was launched on November 3, 1957, and weighed 508 kg (1100 lb). It carried a female dog named Laika. On-board instruments showed that Laika survived in space for several days until her oxygen supply was exhausted.
After failing in its first attempt, the United States launched its own satellite, Explorer 1, on January 31, 1958. The satellite weighed only 14 kg (31 lb), including its rocket motor. The Soviets responded by launching Sputnik 3, which weighed 1.3 metric tons, on May 15, 1958.
The first three Sputnik satellites each carried instruments to measure the temperature and density of the earth’s upper atmosphere, the electron density of the ionosphere, and the size and number of micrometeorites (tiny particles in space). In addition, Sputnik 3 carried the first space laboratory, a wide array of instruments that could transmit information about the environment outside the satellite. Solar energy was used for the first time by Sputnik 3 to power its instruments and transmitters.
From 1958 to 1959 the Soviet Union interrupted the Sputnik program to concentrate on the Luna series of vehicles that were sent toward the moon. The Sputnik program was resumed with Sputniks 5 through 10, which were launched from 1960 to 1961. Sputniks 5, 6, 9, and 10 all carried dogs, most of which reentered the earth’s atmosphere safely and were recovered. These satellites each weighed several thousand kilograms and were working models of the Vostok spacecraft, which would eventually carry the first human passenger, Yury Alekseyevich Gagarin, into space in April 1961. Sputniks 7 and 8, launched in February 1961, served as launching platforms for the Venera spacecraft, which were sent toward Venus. The Cosmos series of spacecraft carried on the work of the Sputnik program after 1961.
In addition to initiating the space race between the United States and the Soviet Union, the Sputnik series of spacecraft also had alarming military implications. The intercontinental ballistic missiles that were used to launch the Sputnik satellites were also capable of traveling from the Soviet Union to military targets in less than an hour-much less than the several hours required for conventional bomber aircraft. President Dwight D. Eisenhower of the United States reacted to the space race by signing the National Aeronautics and Space Act of 1958, which created the National Aeronautics and Space Administration (NASA). Eisenhower also established the Advanced Research Projects Agency (now the Defense Advanced Research Projects Agency), a division of the U.S. Department of Defense.