Sputnik 1

Sputnik 1 (/ˈspʌtnɪk/; Russian: Спутник-1 [ˈsputnʲɪk] "Satellite-1", or ПС-1 ["PS-1", i.e. Russian: Простейший Спутник-1 "Elementary Satellite 1"]) was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957. It was a 58 cm (23 in) diameter polished metal sphere, with four external radio antennae to broadcast radio pulses. It was visible all around the Earth and its radio pulses were detectable. This surprise success precipitated the American Sputnik crisis and triggered the Space Race, a part of the larger Cold War. The launch ushered in new political, military, technological, and scientific developments.

Sputnik itself provided scientists with valuable information, even though it was not equipped with scientific instruments. The density of the upper atmosphere could be deduced from its drag on the orbit, and the propagation of its radio signals gave information 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 (now at the Baikonur Cosmodrome). The satellite travelled at about 29,000 kilometres per hour (18,000 mph; 8,100 m/s), taking 96.2 minutes to complete each orbit. It transmitted on 20.005 and 40.002 MHz which were monitored by amateur radio operators throughout the world. The signals continued for 21 days until the transmitter batteries ran out on 26 October 1957.Sputnik 1 burned up on 4 January 1958, as it fell from orbit upon reentering Earth's atmosphere, after travelling about 70 million km (43.5 million miles) and spending three months in orbit.

Satellite

In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as Earth's Moon.

The world's first artificial satellite, the Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth. Some satellites, notably space stations, have been launched in parts and assembled in orbit. Artificial satellites originate from more than 40 countries and have used the satellite launching capabilities of ten nations. About a thousand satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A few space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, Vesta, Eros, Ceres, and the Sun.

Satellites are used for a large number of purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.

Soviet Union

The Union of Soviet Socialist Republics (Russian: Сою́з Сове́тских Социалисти́ческих Респу́блик, tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik; IPA: [sɐˈjus sɐˈvʲɛtskʲɪx sətsɨəlʲɪsˈtʲitɕɪskʲɪx rʲɪˈspublʲɪk]) abbreviated to USSR (Russian: СССР, tr. SSSR) or shortened to the Soviet Union (Russian: Сове́тский Сою́з, tr. Sovetskij Soyuz; IPA: [sɐ'vʲetskʲɪj sɐˈjʉs]), was a Marxist–Leninist state on the Eurasian continent that existed between 1922 and 1991. A union of multiple subnational Soviet republics, its government and economy were highly centralized. The Soviet Union was a one-party state, governed by the Communist Party with Moscow as its capital.

1957

1957 (MCMLVII) was a common year starting on Tuesday (dominical letter F) of the Gregorian calendar, the 1957th year of the Common Era (CE) and Anno Domini (AD) designations, the 957th year of the 2nd millennium, the 57th year of the 20th century, and the 8th year of the 1950s decade.

Events

January

Geocentric orbit

A geocentric orbit involves any object orbiting the Earth, such as the Moon or artificial satellites. In 1997 NASA estimated there were approximately 2,465 artificial satellite payloads orbiting the Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. Over 16,291 previously launched objects have decayed into the Earth's atmosphere.

List of terms and concepts

Geocentric orbit types

The following is a list of different geocentric orbit classifications.

Altitude classifications

Inclination classifications

Eccentricity classifications

Directional classifications

Geosynchronous classifications

Special classifications

Non-geocentric classifications

Tangential velocities at altitude

See also

References

External links