The Sputnik I was an artificial satellite put in orbit by the Soviet government in October 4, 1957. It was the first man-made satellite to orbit Earth in the history of mankind. The Sputnik was launched by the two-stage R-7 Semyorka rocket. Carrying two antennas designed by the Antenna Laboratory of OKB-1 led by M.V.Krayushkin, the Sputnik I was a 58.5 cm (23 in) diameter sphere, which was assembled from two hermetically-sealed hemispheres, having a mass of 83.6 kilograms (184 lb). The hemispheres were covered with a highly polished 1mm-thick heat shield made of aluminum-magnesium-titanium AMG6T alloy. Each antenna was made up of two whip-like parts: 2.4 and 2.9 m (7.9 and 9.5 ft) in length, and had an almost spherical radiation pattern, so that the satellite beeps were transmitted with equal power in all directions. The power supply of Sputnik I consisted of three silver-zinc batteries, developed at the All-Union Research Institute of Current Sources (VNIIT) under the leadership of N. S. Lidorenko. Two of them powered the radio transmitter and one powered the temperature regulation system. Sputnik I orbited the Earth until January 4, 1958, when it deteriorated and reentered the atmosphere, after 1,440 orbits around the Earth.
Sputnik I Documentary (Video)