<?xml version="1.0" encoding="UTF-8"?>
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  <Version>2.2.6</Version>
  <Observatory>
    <ResourceID>spase://CDPP/Observatory/AMDA/PioneerVenusOrbiter</ResourceID>
    <ResourceHeader>
      <ResourceName>PVO</ResourceName>
      <AlternateName>Pioneer Venus Orbiter</AlternateName>
      <AlternateName>Pioneer 12</AlternateName>
      <AlternateName>1978-051A</AlternateName>
      <AlternateName>Pioneer Venus 1</AlternateName>
      <AlternateName>PVO</AlternateName>       
      <AlternateName>Pioneer Venus 1978 Orbiter</AlternateName>
      <ReleaseDate>2016-09-25T03:09:48Z</ReleaseDate>
      <Description>The Pioneer Venus Orbiter was 
        the first of a two-spacecraft orbiter-probe 
        combination designed to conduct a comprehensive investigation 
        of the atmosphere of Venus. The spacecraft was a solar-powered
        cylinder about 250 cm in diameter with its spin axis 
        spin-stabilized perpendicular to the ecliptic plane. 
        A high-gain antenna was mechanically despun to remain focused 
        on the earth. The instruments were mounted on a shelf within 
        the spacecraft except for a magnetometer mounted at the end 
        of a boom to ensure against magnetic interference from the 
        spacecraft. Pioneer Venus Orbiter measured the detailed 
        structure of the upper atmosphere and ionosphere of Venus, 
        investigated the interaction of the solar wind with the 
        ionosphere and the magnetic field in the vicinity of Venus, 
        determined the characteristics of the atmosphere and surface 
        of Venus on a planetary scale, determined the planet's 
        gravitational field harmonics from perturbations of the 
        spacecraft orbit, and detected gamma-ray bursts. 
        UV observations of comets have also been made. From Venus 
        orbit insertion on December 4, 1978 to July 1980 periapsis was
        held between 142 and 253 km to facilitate radar and 
        ionospheric measurements. Thereafter, the periapsis was 
        allowed to rise (to 2290 km at maximum) and then fall, to 
        conserve fuel. In 1991 the Radar Mapper was reactivated to 
        investigate previously inaccessible southern portions of the 
        planet. In May 1992 Pioneer Venus began the final phase of its
        mission, in which the periapsis was held between 150 and 250 
        km until the fuel ran out and atmospheric entry destroyed the 
        spacecraft the following August. The orbiter cost $125 million
        to build and operate for the first 10 years. For further
        details see Colin, L. and Hunten, D. M., Space Science 
        Reviews 20, 451, 1977.</Description>
      <Contact>        
        <PersonID>spase://SMWG/Person/Lawrence.Colin</PersonID>
        <Role>ProjectScientist</Role>
      </Contact>
      <InformationURL>
        <Name>NSSDC's Master Catalog</Name>
        <URL>http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1978-051A</URL>
        <Description>Information about the Pioneer Venus Orbiter mission</Description>
      </InformationURL>
    </ResourceHeader>    
    <Location>
      <ObservatoryRegion>Venus</ObservatoryRegion>
      <ObservatoryRegion>Heliosphere.Inner</ObservatoryRegion>
    </Location>
    <OperatingSpan>
      <StartDate>1978-12-05T07:20:07.282Z</StartDate>
      <StopDate>1992-10-08T16:30:39.579</StopDate>
      <!-- Note : if possible note large data gaps; multiple tags -->
    </OperatingSpan> 
  </Observatory>
</Spase>