|Mission type||Venus orbiter|
|Operator||NASA / ARC|
|Website||Pioneer Venus at NASA|
|Mission duration||14 years, 4 months, 18 days (from launch)|
13 years, 10 months, 4 days (at Venus)
|Launch mass||582 kg (1,283 lb)|
|Dry mass||517 kg (1,140 lb)|
|Dimensions||2.5 × 1.2 m (8.2 × 3.9 ft)|
|Start of mission|
|Launch date||May 20, 1978, 13:13:00UTC|
|Rocket||Atlas SLV-3D Centaur-D1AR|
|Launch site||Cape Canaveral LC-36A|
|End of mission|
|Last contact||October 8, 1992, 19:22UTC|
|Decay date||October 22, 1992|
|Semi-major axis||33,405.8 kilometres (20,757.4 mi)|
|Pericytherion altitude||181.6 kilometers (112.8 mi)|
|Apocytherion altitude||66,630 kilometers (41,400 mi)|
|Epoch||22 November 1979, 11:53:20 UTC|
|Orbital insertion||December 4, 1978|
The Pioneer Venus Orbiter, also known as Pioneer Venus 1 or Pioneer 12, was a mission to Venus conducted by the United States as part of the Pioneer Venus project. Launched in May 1978 atop an Atlas-Centaur rocket, the spacecraft was inserted into an elliptical orbit around Venus on December 4, 1978. It returned data on Venus until October 1992.
The Pioneer Venus Orbiter was launched by an Atlas SLV-3D Centaur-D1AR rocket, which flew from Launch Complex 36A at the Cape Canaveral Air Force Station. The launch occurred at 13:13:00 on May 20, 1978, and deployed the Orbiter into heliocentric orbit for its coast to Venus. Venus orbit insertion occurred on December 4, 1978.
Manufactured by Hughes Aircraft Company, the Pioneer Venus Orbiter was based on the HS-507 bus. The spacecraft was a flat cylinder, 2.5 meters (8.2 ft) in diameter and 1.2 meters (3.9 ft) long. All instruments and spacecraft subsystems were mounted on the forward end of the cylinder, except the magnetometer, which was at the end of a 4.7 meters (15 ft) boom. A solar array extended around the circumference of the cylinder. A 1.09 metres (3 ft 7 in) despun dish antenna provided S and X band communication with Earth. A Star-24 solid rocket motor was integrated into the spacecraft to provide the thrust to enter orbit around Venus.
From Venus orbit insertion to July 1980, periapsis was held between 142 and 253 kilometres (88 and 157 mi) (at 17 degrees north latitude) to facilitate radar and ionospheric measurements. The spacecraft was in a 24-hour orbit with an apoapsis of 66,900 kilometers (41,600 mi). Thereafter, the periapsis was allowed to rise to a maximum of 2,290 kilometres (1,420 mi) and then fall, to conserve fuel.
In 1991, the Radar Mapper was reactivated to investigate previously inaccessible southern portions of the planet, in conjunction with the recently arrived Magellan spacecraft. In May 1992, Pioneer Venus began the final phase of its mission, in which the periapsis was held between 150 and 250 kilometres (93 and 155 mi), until the spacecraft's propellant was exhausted, after which the orbit decayed naturally. The spacecraft continued to return data until 8 October 1992, with the last signals being received at 19:22 UTC. The Pioneer Venus Orbiter disintegrated upon entering the atmosphere of Venus on October 22, 1992.
The Pioneer Venus Orbiter carried 17 experiments with a total mass of 45 kilograms (99 lb):
|Name||Complete designation||Type||Manufacturer||Responsible scientist||Mass||Electrical consumption|
|OCPP||Orbiter Cloud Photopolarimeter||Photo polarimeter||GISS||J. Hansen||5 kg (11 lb)||5.4 W|
|ORAD||Orbiter Radar Mapper Instrument||Radar||MIT||G. Pettengill||9 kg (20 lb)||18 W|
|OIR||Orbiter Infrared Radiometer||Infrared radiometer||JPL||F. Taylor||5.9 kg (13 lb)||5.2 W|
|OUVS||Orbiter Ultraviolet Spectrometer||Ultraviolet spectrometer||LASP||A. Stewart||3.1 kg (6.8 lb)||1.7 W|
|ONMS||Orbiter Neutral Mass Spectrometer||Neutral mass spectrometer||GSFC||H. Neimann||3.8 kg (8.4 lb)||12 W|
|OPA||Orbiter Plasma Analyzer||Analzer plasma||ARC||J. Wolfe||3.9 kg (8.6 lb)||5 W|
|OMAG||Orbiter Magnetometer||Magnetometer||UCLA||C. Russell||2 kg (4.4 lb)||2.2 W|
|OEFD||Orbiter Electric Field Detector||Measure the electric fields of Venus||TRW||F. Scarf||0.8 kg (1.8 lb)||0.7 W|
|OETP||Orbiter Electron Temperature Probe||Electron temperature gauge||GSFC||L. Brace||2.2 kg (4.9 lb)||4.8 W|
|OIMS||Orbiter Ion Mass Spectrometer||Ion mass spectrometer||GSFC||H. Taylor||3 kg (6.6 lb)||1.5 W|
|ORPA||Orbiter Retarding Potential Analyzer||Ion charge meter||LPARL||W. Knudsen||2.8 kg (6.2 lb)||2.4 W|
|OGBD||Orbiter Gamma-Ray Burst Detector||Gamma-ray burst detector||LASL||W. Evans||2.8 kg (6.2 lb)||1.3 W|
|-||Venus (ORO)||Radio science||-||A. Kliore (JPL)||–||-|
|Orbiter Dual-Frequency Experiments (OGPE)||-||T. Croft (SRI)|
|Atmospheric and Solar Wind Turbulence Experiment (OTUR)||-||T. Croft (JPL)|
|Orbiter Atmospheric Drag Expe "nment (OAD)||-||G. Keating (LRC)|
|Orbiter Internal Density Distribution Experiment (OIDD)||-||R. Phillips (JPL)|
|Orbiter Celestial Mechanics Experiment (OCM)||-||I. Shapiro (MIT)|
|LASP: Laboratory for Atmospheric and Space Physics (University of Boulder, Colorado); UCLA: University of California in Los Angeles; JPL: Jet Propulsion Laboratory; MIT: Massachusetts Institute of Technology; GSFC: Goddard Space Flight Center GISS: Goddard Institute for Space Studies; LRC: Langley Research Center; ARC: Ames Research Center; LASL: Los Alamos National Laboratory; SRI: Stanford Research Institute|
The spacecraft conducted radar altimetry observations allowing the first global topographic map of the Venusian surface to be constructed.
From its orbit of Venus, the Pioneer Venus Orbiter was able to observe Halley's Comet when it was unobservable from Earth due to its proximity to the sun during February 1986. UV spectrometer observations monitored the loss of water from the comet's nucleus at perihelion on February 9.
|Wikimedia Commons has media related to Pioneer Venus 1.|