Sputnik 1

Sputnik 1

Replica of Sputnik 1 in the Museum of Space and Missile Technology (Saint Petersburg)
Names	Спутник 1 Object PS (Prosteishiy Sputnik) Простейший Спутник-1 Elementary Satellite-1
Mission type	Technology demonstration
Operator	OKB-1
Harvard designation	1957 Alpha 2[1]
COSPAR ID	1957-001B
SATCAT no.	2[2] (The launch rocket has SATCAT no.1)
Mission duration	22 days (achieved)
Orbits completed	1440[3]
Spacecraft properties
Spacecraft	Sputnik-1
Manufacturer	OKB-1 Ministry of Radiotechnical Industry
Launch mass	83.6 kg (184 lb)
Dimensions	58 cm (23 in) diameter
Power	1 watt
Start of mission
Launch date	4 October 1957; 66 years ago (4 October 1957), 19:28:34 UTC
Rocket	Sputnik 8K71PS[4]
Launch site	Baikonur Cosmodrome Site 1/5[4]
Contractor	OKB-1
End of mission
Disposal	Atmospheric entry
Last contact	26 October 1957
Decay date	4 January 1958[4]
Orbital parameters
Reference system	Geocentric orbit[5]
Regime	Low Earth orbit
Semi-major axis	6,955.2 km
Eccentricity	0.05201
Perigee altitude	215 km (134 mi)
Apogee altitude	939 km (583 mi)
Inclination	65.10°
Period	96.20 minutes
Instruments
Radio transmitter 20.005 and 40.002 MHz
Sputnik program Sputnik 2 →

Sputnik 1 (/ˈspʌtnɪk, ˈspʊtnɪk/, Russian: Спутник-1, Satellite 1) was the first artificial Earth satellite. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957 as part of the Soviet space program. It sent a radio signal back to Earth for three weeks before its three silver-zinc batteries became depleted. Aerodynamic drag caused it to fall back into the atmosphere on 4 January 1958. The world's first observation was made at the school observatory in Rodawisch (Saxony).^[6]

It was a polished metal sphere 58 cm (23 in) in diameter with four external radio antennas to broadcast radio pulses. Its radio signal was easily detectable by amateur radio operators,^[7] and the 65° orbital inclination made its flight path cover virtually the entire inhabited Earth.

The satellite's success was unanticipated by the United States. This precipitated the American Sputnik crisis and triggered the Space Race, part of the Cold War. The launch was the beginning of a new era of political, military, technological and scientific developments.^[8] The word sputnik is Russian for satellite when interpreted in an astronomical context;^[9] its other meanings are spouse or traveling companion.^[10][11]

Tracking and studying Sputnik 1 from Earth provided scientists with valuable information. The density of the upper atmosphere could be deduced from its drag on the orbit, and the propagation of its radio signals gave data 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 known as the Baikonur Cosmodrome). The satellite traveled at a peak speed of about 8 km/s (18,000 mph), taking 96.20 minutes to complete each orbit. It transmitted on 20.005 and 40.002 MHz,^[12] which were monitored by radio operators throughout the world. The signals continued for 21 days until the transmitter batteries depleted on 26 October 1957. On 4 January 1958, after three months in orbit, Sputnik 1 burned up while reentering Earth's atmosphere, having completed 1,440 orbits of the Earth,^[3] and travelling a distance of approximately 70,000,000 km (43,000,000 mi).^[13]