Venera 1 (Russian: Венера-1 meaning Venus 1), also known as Venera-1VA No.2 and occasionally in the West as Sputnik 8 was the first spacecraft to perform an interplanetary flight and the first to fly past Venus, as part of the Soviet Union's Venera programme.^[1] Launched in February 1961, it flew past Venus on 19 May of the same year; however, radio contact with the probe was lost before the flyby, resulting in it returning no data.

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Venera 1

Mockup of the Venera 1 spacecraft
Mission type	Venus impactor
Operator	OKB-1
Harvard designation	1961 Gamma 1
COSPAR ID	1961-003A
SATCAT no.	80
Mission duration	7 days
Spacecraft properties
Spacecraft	1VA No.2
Manufacturer	OKB-1
Launch mass	6,424.0 kilograms (14,162.5 lb)
Dry mass	643.5 kilograms (1,419 lb)
Start of mission
Launch date	February 12, 1961, 00:34:36 (1961-02-12UTC00:34:36Z) UTC
Rocket	Molniya 8K78
Launch site	Baikonur 1/5
End of mission
Last contact	19 February 1961 (1961-02-20)
Orbital parameters
Reference system	Heliocentric
Eccentricity	0.173
Perihelion altitude	0.718 AU
Aphelion altitude	1.019 AU
Inclination	0.58°
Period	311 days
Flyby of Venus
Closest approach	19 May 1961
Distance	100,000 km (62,000 mi)
Venera ← Tyazhely Sputnik Venera 2MV-1 No.1 →

Close

Venera 1 was a 643.5-kilogram (1,419 lb) probe consisting of a cylindrical body 1.05 metres (3 ft 5 in) in diameter topped by a dome, totalling 2.035 metres (6 ft 8.1 in) in height. This was pressurized to 1.2 standard atmospheres (120 kPa) with dry nitrogen, with internal fans to maintain even distribution of heat.^{[citation needed]} Two solar panels extended from the cylinder, charging a bank of silver-zinc batteries. A 2-metre (6 ft 7 in) parabolic wire-mesh antenna was designed to send data from Venus to Earth on a frequency of 922.8 MHz. A 2.4-metre (7 ft 10 in) antenna boom was used to transmit short-wave signals during the near-Earth phase of the mission. Semidirectional quadrupole antennas mounted on the solar panels provided routine telemetry and telecommand contact with Earth during the mission, on a circularly-polarized decimetre radio band.

The probe was equipped with scientific instruments including a flux-gate magnetometer attached to the antenna boom, two ion traps to measure solar wind, micrometeorite detectors, and Geiger counter tubes and a sodium iodide scintillator for measurement of cosmic radiation. An experiment attached to one solar panel measured temperatures of experimental coatings. Infrared and/or ultraviolet radiometers may have been included. The dome contained a KDU-414 engine used for mid-course corrections. Temperature control was achieved by motorized thermal shutters.

During most of its flight, Venera 1 was spin stabilized. It was the first spacecraft designed to perform mid-course corrections, by entering a mode of 3-axis stabilization, fixing on the Sun and the star Canopus. Had it reached Venus, it would have entered another mode of 3-axis stabilization, fixing on the Sun and Earth, and using for the first time a parabolic antenna to relay data.

Venera 1 was the second of two attempts to launch a probe to Venus in February 1961, immediately following the launch of its sister ship Venera-1VA No.1,^[2] which failed to leave Earth orbit.^[3] Soviet experts launched Venera-1 using a Molniya carrier rocket from the Baikonur Cosmodrome. The launch took place at 00:34:36 GMT on 12 February 1961.^[4]

The spacecraft, along with the rocket's Blok-L upper stage, was initially placed into a 229-by-282-kilometre (142 mi × 175 mi) low Earth orbit,^[1] before the upper stage fired to place "Venera 1" into a heliocentric orbit, directed towards Venus. The 11D33 engine was the world's first staged-combustion-cycle rocket engine, and also the first use of an ullage engine to allow a liquid-fuel rocket engine to start in space.

Three successful telemetry sessions were conducted, gathering solar-wind and cosmic-ray data near Earth, at the Earth's Magnetopause, and on February 19 at a distance of 1,900,000 km (1,200,000 mi). After discovering the solar wind with Luna 2, Venera 1 provided the first verification that this plasma was uniformly present in deep space. Seven days later, the next scheduled telemetry session failed to occur. On May 19, 1961, Venera 1 passed within 100,000 km (62,000 mi) of Venus. With the help of the British radio telescope at Jodrell Bank, some weak signals from Venera 1 may have been detected in June. Soviet engineers believed that Venera 1 failed due to the overheating of a solar-direction sensor.^[5]

• List of missions to Venus
• Mariner 2
• Timeline of planetary exploration