Pioneer Venus Orbiter
By Marty McDowell/NASA
On May 20, 1978, the United States launched Pioneer Venus 1. This was
the first spacecraft to visit Venus with radar surfacing equipment (needed
to see through the dense Venusian atmosphere). It orbited the planet Venus
for 14 years until it entered the Venus atmosphere on October 8, 1992 and
The Pioneer Venus Orbiter was inserted into an elliptical orbit around
Venus on December 4, 1978. The Orbiter was a flat cylinder 2.5 m in
diameter and 1.2 m high. 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 m boom. A solar array extended around the
circumference of the cylinder. A 1.09 m despun dish antenna provided S and
X band communication with Earth.
The Pioneer Venus Orbiter carried 17 experiments (with a total mass of
- a cloud photopolarimeter to measure the vertical distribution of the
- a surface radar mapper to determine topography and surface
- an infrared radiometer to measure IR emissions from the Venus
- an airglow ultraviolet spectrometer to measure scattered and emitted
- a neutral mass spectrometer to determine the composition of the
- a solar wind plasma analyzer to measure properties of the solar wind
- a magnetometer to characterize the magnetic field at Venus
- an electric field detector to study the solar wind and its
- an electron temperature probe to study the thermal properties of the
- an ion mass spectrometer to characterize the ionospheric ion
- a charged particle retarding potential analyzer to study ionospheric
- two radio science experiments to determine the gravity field of
- 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 detector to record gamma ray burst events
From Venus orbit insertion to July 1980, periapsis was held between 142
and 253 km (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 km. 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
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Artist's conception of probe courtesy of NASA
Courtesy of NASA
Launched: May 20, 1978
Arrival: December 4, 1978
Mission: Orbit and mapping of Venus