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Venera 12
	Venera 12 model
Operator	Soviet Academy of Sciences
COSPAR ID	1978-086A; 1978-086C
SATCAT no.	11025; 12028
Mission duration	Travel: 3 months and 6 days; Lander: 110 minutes
Spacecraft properties
Spacecraft type	4V-1
Bus	4MV
Launch mass	4,457.9 kg (9,828 lb)
Dry mass	1,600 kg (3,500 lb)
Dimensions	2.3 m × 2.7 m × 5.7 m (7.5 ft × 8.9 ft × 18.7 ft)
Start of mission
Launch date	14 September 1978, 02:25:13 UTC
Rocket	Proton-K/D-1 8K82K
Launch site	Baikonur 81/23
End of mission
Last contact	18 April 1980
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Semi-major axis	6,569 kilometres (4,082 mi)
Perigee altitude	177 kilometres (110 mi)
Apogee altitude	205 kilometres (127 mi)
Inclination	51.5°
Flyby of Venus
Spacecraft component	Venera 12 flight platform
Closest approach	19 December 1978
Distance	~35,000 kilometers (22,000 mi)
Venus lander
Spacecraft component	Venera 12 descent craft
Landing date	21 December 1978, 03:30
Landing site	7°S 294°E / 7°S 294°E
	Venera ← Venera 11 Venera 13 →

The Venera 12 (Russian: Венера-12 meaning Venus 12) was an uncrewed Soviet space mission designed to explore the planet Venus. Venera 12 was launched on 14 September 1978 at 02:25:13 UTC.^[3]

After separating from its flight platform on 19 December 1978, the Venera 12 lander entered the Venus atmosphere two days later at 11.2 kilometres per second (7.0 mi/s). During its descent, the lander employed aerodynamic braking followed by parachute braking, ending with atmospheric braking. After a nearly one-hour descent, a soft landing was made at 06:30 Moscow time (0330 UT) on 21 December. Touchdown speed was 7–8 metres per second (23–26 ft/s); landing coordinates are 7°S 294°E / 7°S 294°E / -7; 294. Continuing for about 110 minutes after touchdown, the lander transmitted data to the flight platform for about 110 minutes until the flight platform, which remained in a heliocentric orbit, moved out of range. Venera 11 and 12 carried identical instruments.^[3]

Flight platform

The Venera 12 flight platform carried solar wind detectors, ionosphere electron instruments, and two gamma ray burst detectors – the Soviet-built KONUS and the French-built SIGNE 2. The SIGNE 2 detectors were simultaneously flown on Venera 12 and Prognoz 7 to allow for triangulation of gamma ray sources. Before and after the Venus flyby, Venera 11 and Venera 12 yielded detailed time-profiles for 143 gamma-ray bursts, resulting in the first ever catalog of such events. The last gamma-ray burst reported by Venera 12 occurred on 5 January 1980. Venera 12 used its ultraviolet spectrometer to study comet Bradfield (C/1979 Y1) on 13 February 1980, and reported spectrophotometric data until 19 March 1980.^[4]

The list of flight platform instruments and experiments are:^[5]

30–166 nm Extreme UV spectrometer
Compound plasma spectrometer
KONUS Gamma-ray burst detector
SNEG Gamma-ray burst detector
Magnetometer
4 Semiconductor counters
2 Gas-discharge counters
4 Scintillation counters
Hemispherical proton telescope

The active phase of the science mission for the flight platform ended in April 1980. Venera 12 is currently in heliocentric orbit, with perihelion of 0.69 AU, aphelion of 1.01 AU, eccentricity of 0.19, inclination of 2.3 degrees and orbital period of 284 days.

Lander

The Venera 12 descent craft carried instruments designed to study the detailed chemical composition of the atmosphere, the nature of the clouds, and the thermal balance of the atmosphere. These instruments included a gas chromatograph to measure the composition of the Venus atmosphere, instruments to study scattered solar radiation and soil composition, and a device named Groza which was designed to measure atmospheric electrical discharges. Results reported included evidence of lightning and thunder, a high ³⁶Ar/⁴⁰Ar ratio, and the discovery of carbon monoxide at low altitudes.

Each of the Venera 11 and Venera 12 included landers with a pair of cameras, each of which was designed for color imaging. A design flaw prevented the lens caps from separating, resulting in all cameras failing to capture and return images.^[6]

The list of lander experiments and instruments are:^[5]