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Pioneer Venus Orbiter

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Pioneer Venus Orbiter
Artist's impression of Pioneer 12 in orbit above Venus
NamesPioneer Venus 1
Pioneer 12
Mission typeVenus orbiter
OperatorNASA / Ames
COSPAR ID1978-051A Edit this at Wikidata
SATCAT no.10911
Websitescience.nasa.gov
Mission durationTotal:
14 years, 4 months and 18 days
Science phase:
13 years, 10 months and 4 days
Spacecraft properties
BusHS-507
ManufacturerHughes
Launch mass582 kg (1,283 lb)[1]
Dry mass517 kg (1,140 lb)
Dimensions2.5 × 2.5 × 1.2 m (8.2 × 8.2 × 3.9 ft)
Power312 watts
Start of mission
Launch dateMay 20, 1978, 13:13:00 (1978-05-20UTC13:13Z) UTC [1]
RocketAtlas SLV-3D Centaur-D1AR (AC-50)
Launch siteCape Canaveral LC-36A
End of mission
DisposalDecommissioned
Last contactOctober 8, 1992, 19:22 (1992-10-08UTC19:23Z) UTC
Decay dateOctober 22, 1992[2]
Orbital parameters
Reference systemCytherocentric
Semi-major axis33,405.8 km (20,757.4 mi)
Eccentricity0.842
Pericytherion altitude181.6 km (112.8 mi)
Apocytherion altitude66,630 km (41,400 mi)
Inclination105 degrees
Period24 hours
Epoch22 November 1979, 11:53:20 UTC[3]
Venus orbiter
Orbital insertionDecember 4, 1978

The Pioneer Venus Orbiter, also known as Pioneer Venus 1 or Pioneer 12, was a mission to Venus conducted by NASA 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 from Venus until October 1992.[2][4]

Launch and arrival at Venus

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Orbit attitude of Pioneer Venus 1 between 1978–1980 and 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 (8:13 a.m. local time) on May 20, 1978, and deployed the Orbiter into heliocentric orbit for its coast to Venus. Venus orbit insertion occurred on December 4, 1978.

Spacecraft

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Pioneer Venus 1 at KSC.

Manufactured by Hughes Aircraft Company, the Pioneer Venus Orbiter was based on the HS-507 bus.[5] 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.[5]

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.[4] The Pioneer Venus Orbiter disintegrated upon entering the atmosphere of Venus on October 22, 1992.[2]

Instruments

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A map of Venus produced from Pioneer data

The Pioneer Venus Orbiter carried 17 experiments with a total mass of 45 kilograms (99 lb):[6]

An image of Venus in ultraviolet light by the Pioneer Venus Orbiter
  • a cloud photo-polarimeter (OCPP) to measure the vertical distribution of the clouds, similar to Pioneer 10 and Pioneer 11 imaging photo-polarimeter (IPP)
  • a surface radar mapper (ORAD) to determine topography and surface characteristics. Observations could only be conducted when the probe was closer than 4,700 kilometres (2,900 mi) over the planet. A 20-watt S-band signal (1.757 gigahertz) was sent to the surface that reflected it, with the probe analyzing the echo. Resolution at periapsis was 23 by 7 kilometres (14.3 mi × 4.3 mi).
  • an infrared radiometer (OIR) to measure IR emissions from Venus' atmosphere
  • an airglow ultraviolet spectrometer (OUVS) to measure scattered and emitted UV light
  • a neutral mass spectrometer (ONMS) to determine the composition of the upper atmosphere
  • a solar wind plasma analyzer (OPA) to measure properties of the solar wind
  • a magnetometer (OMAG) to characterize the magnetic field at Venus
  • an electric field detector (OEFD) to study the solar wind and its interactions
  • an electron temperature probe (OETP) to study the thermal properties of the ionosphere
  • an ion mass spectrometer (OIMS) to characterize the ionospheric ion population
  • a charged particle retarding potential analyzer (ORPA) to study ionospheric particles
  • two radio science experiments to determine the gravity field of Venus
  • a radio occultation experiment to characterize the atmosphere
  • an atmospheric drag experiment to study the upper atmosphere
  • a radio science atmospheric and solar wind turbulence experiment
  • a gamma ray burst (OGBD) detector to record gamma ray burst events
Orbit of the spacecraft Pioneer Venus Orbiter.
Launch of Pioneer Venus Orbiter with Atlas-Centaur rocket.
Trajectory of Pioneer Venus Orbiter.
Instrument details
Name Complete designation Type Manufacturer Responsible scientist Mass Electrical consumption
OCPP Orbiter Cloud Photopolarimeter Photo polarimeter GISS J. Hansen (later L. Travis) 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.I.F. 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 (later A. Barnes) 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 Experiment (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.

The instruments can also be classified by what they are meant to measure or analyze:[7]

  • Composition and structure of the atmosphere
    • Large Probe Mass Spectrometer (LNMS)
    • Large Probe Gas Chromatograph (LGC)
    • Bus Neutral Mass Spectrometer (BNMS)
    • Orbiter Neutral Mass Spectrometer (ONMS)
    • Orbiter Ultraviolet Spectrometer (OUVS)
    • Large/Small Probe Atmosphere Structure (LAS/SAS)
    • Atmospheric Propagation Experiments (OGPE)
    • Orbiter Atmospheric Drag Experiment (OAD)
  • Clouds
    • Large/Small Probe Nephelometer (LN/SN)
    • Large Probe Cloud Particle Size Spectrometer (LCPS)
    • Orbiter Cloud Photopolarimenter (OCPP)
  • Thermal balance
    • Large Probe Solar Flux Radiometer (LSFR)
    • Large Probe Infrared Radiometer (LIR)
    • Small Probe Net Flux Radiometer (SNFR)
    • Orbiter Infrared Radiometer (OIR)
  • Dynamics
    • Differential Long Baseline Interferometry (DLBI)
    • Doppler Tracking of Probes (MWIN)
    • Atmospheric Turbulence Experiments (MTUR/OTUR)
  • Solar wind and ionosphere
    • Bus Ion Mass Spectrometer (BIMS)
    • Orbiter Ion Mass Spectrometer (OIMS)
    • Orbiter Electron Temperature Probe (OETP)
    • Orbiter Retarding Potential Analyzer (ORPA)
    • Orbiter Magnetometer (OMAG)
    • Orbiter Plasma Analyzer (OPA)
    • Orbiter Electric Field Detector (OEFD)
    • Orbiter Dual-Frequency Occultation Experiments (ORO)
  • Surface and interior
    • Orbiter Radar Mapper (ORAD)
    • Orbiter Internal Density Distribution Experiments (OIDD)
    • Orbiter Celestial Mechanics Experiments (OCM)
  • High-energy astronomy
    • Orbiter Gamma Burst Detector (OGBD)

Observations of Comets

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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.[8]

The extended mission allowed the spacecraft controllers to make several comet observations that were never part of the original mission objectives. The tilt of the spacecraft was altered during these comet observations so that the Ultraviolet Spectrometer (OUVS) could view the comets rather than Venus. Comets Encke (April 13–16, 1984), Giacobini-Zinner (September 8–15, 1985), Halley (December 27, 1985 - March 9, 1986), Wilson (March 13 - May 2, 1987), NTT (April 8, 1987), and McNaught (November 19–24, 1987) were all observed in this way.[7]

See also

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References

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  1. ^ a b "Pioneer Venus Orbiter/Pioneer Venus 1/Pioneer 12". NASA's Solar System Exploration website. Retrieved December 1, 2022.
  2. ^ a b c McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Archived from the original on 2003-10-11.
  3. ^ "NASA - NSSDCA - Spacecraft - Trajectory Details". nssdc.gsfc.nasa.gov. Retrieved 2018-05-02.
  4. ^ a b "Pioneer Venus 1". Solar System Exploration. NASA. Archived from the original on 2006-10-04. Retrieved 2013-08-16.
  5. ^ a b Krebs, Gunter. "Pioneer 12 (Pioneer Venus Orbiter, PVO)". Gunter's Space Page. Archived from the original on 2005-01-12.
  6. ^ "Pioneer Venus Project Information". NASA Goddard Space Flight Center. Retrieved 2016-08-17.
  7. ^ a b "PVO Mission Document". NASA.
  8. ^ Russell, C.T.; Luhmann, J.G.; Scarf, F.L. (1985). "Pioneer Venus Observations during Comet Halley's Inferior Conjunction" (PDF). University of California, Los Angeles. Archived from the original (PDF) on 2009-02-27. Retrieved 2013-08-16.

Bibliography

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