Sputnik 1

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Major contractors	OKB-1, Soviet Ministry of Radiotechnical Industry
Mission type	Atmospheric studies
Satellite of	Earth
Orbits	1,440
Launch date	19:28:34, October 4, 1957 (UTC) (1957-10-04T19:28:34Z) (22:28:34 MSK)
Launch vehicle	Sputnik Rocket
Mission duration	3 months
Orbital decay	4 January 1958
COSPAR ID	1957-001B
Home page	NASA NSSDC Master Catalog
Mass	83.6 kg (184.3 lb)
Orbital elements
Semimajor axis	6,955.2 km (4,321.8 mi)
Eccentricity	0.05201
Inclination	65.1°
Orbital period	96.2 minutes
Apoapsis	7,310 km (4,540 mi) from centre, 939 km (583 mi) from surface
Periapsis	6,586 km (4,092 mi) from centre, 215 km (134 mi) from surface

This metal arming key is the last remaining piece of the first Sputnik satellite. It prevented contact between the batteries and the transmitter prior to launch. Currently on display at the National Air and Space Museum.

Sputnik 1 (Russian: "Спутник-1" Russian pronunciation: [ˈsputnʲɪk], "Satellite-1", ПС-1 (PS-1, i.e. "Простейший Спутник-1", or Elementary Satellite-1)) was the first Earth-orbiting artificial satellite. It was launched into a low altitude elliptical orbit by the Soviet Union on 4 October 1957, and was the first in a series of satellites collectively known as the Sputnik program. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the Space Race within the Cold War.

Apart from its value as a technological first, Sputnik also helped to identify the upper atmospheric layer's density, through measuring the satellite's orbital changes. It also provided data on radio-signal distribution in the ionosphere. Pressurized nitrogen, in the satellite's body, provided the first opportunity for meteoroid detection. If a meteoroid penetrated the satellite's outer hull, it would be detected by the temperature data sent back to Earth.

Sputnik-1 was launched during the International Geophysical Year from Site No.1, at the 5th Tyuratam range, in Kazakh SSR (now at the Baikonur Cosmodrome). The satellite traveled at 29,000 kilometres (18,000 mi) per hour, taking 96.2 minutes to complete an orbit, and emitted radio signals at 20.005 and 40.002 MHz^[1] which were monitored by amateur radio operators throughout the world.^[2] The signals continued for 22 days until the transmitter batteries ran out on 26 October 1957.^[3] Sputnik 1 burned up on 4 January 1958 as it fell from orbit upon reentering Earth's atmosphere, after traveling about 60 million km (37 million miles) and spending 3 months in orbit.^[4]