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Pioneer Venus 1, Orbiter and Multiprobe spacecraft (included NASA Ames partnership)
03.23.07
 
Pioneer Venus consisted of two spacecraft launched separately to study Venus: the orbiter and the multiprobe. The Pioneer Venus 1 orbiter was launched May 20, 1978, from the Kennedy Space Center aboard an Atlas-Centaur rocket. The Pioneer Venus multiprobe was launched on Aug. 8, 1978. It encountered Venus on Dec. 9, 1978. It consisted of five separate probes. The Sounder was released from the ‘Bus’ on Nov. 15, 1978; three small probes were released on Nov. 19, 1978.

Overview:

Pioneer Venus consisted of two spacecraft launched separately to study Venus: the orbiter and the multiprobe. The latter divided into five separate vehicles near Venus.

The Pioneer Venus 1 (also known as 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 orbiter spacecraft was launched May 20, 1978. The spacecraft was a solar-powered cylinder about 8.3 feet (250 centimeters) in diameter.

It went into orbit around Venus on Dec. 4, 1978. The orbiter peered through the clouds and produced the first radar topographic map of most of the surface, at a resolution of 47 miles (75 kilometers). It found a relatively smooth planet, with the highest point, Maxwell Montes, at about seven miles (11 kilometers) above the surface. The orbiter’s cameras also detected continuous lightning.

The Pioneer Venus multiprobe was launched on Aug. 8, 1978. It encountered Venus on Dec. 9, 1978. It consisted of five separate probes: the probe transporter (referred to as the Bus), a large atmospheric entry probe (called Sounder), and three identical small probes (called North, Day and Night). The Sounder released from the Bus on Nov. 15, 1978; the three small probes released on Nov. 19, 1978. All probes entered the venusian atmosphere within 11 minutes of each other, and descended toward the surface over approximately an hour-long period, sending back data to the Earth. Two of the probes survived impact, and one of them transmitted data for 67 minutes before being crushed. These probes confirmed clouds composed mainly of sulfuric acid droplets.

The 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. It also made UV observations of comets.

A high-gain antenna was mechanically de-spun 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.

From Venus orbit insertion on Dec. 4, 1978, to July 1980, periapsis (the point closest to the gravitational center of Venus) was held between 89 and 158 miles (142 and 253 kilometers) to facilitate radar and ionospheric measurements. Thereafter, the periapsis was allowed to rise to 1,431 miles (2,290 kilometers) 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 94 and 156 miles (150 and 250 kilometers) until the fuel ran out and atmospheric entry destroyed the spacecraft in August 1992. The orbiter cost $125 million to build and operate for the first 10 years.

Key Mission People
Mr. Richard O. Fimmel, project manager, NASA Ames Research Center, Moffett Field, Calif.
http://quest.nasa.gov/sso/cool/pioneer10/graphics/fimmel/index.html

Dr. Lawrence Colin, project scientist, NASA Ames Research Center, Moffett Field, Calif.

In the early 1980s, Ames presented to NASA Headquarters a suite of concepts for Pioneer-class missions to the outer and inner planets, under the leadership of Dr. Larry Colin, chief of the Space Science Division at NASA Ames. Among these were probe missions to Saturn, Uranus and Neptune. This suite of small, focused missions presaged what became a NASA-wide emphasis on "faster, better, cheaper" missions by more than a decade.

John W. Dyer, NASA Ames Research Center, Moffett Field, Calif.

Robert W. Jackson, NASA Ames Research Center, Moffett Field, Calif.


Related links:

The Pioneer Mission

Pioneer Venus Mission Section
Pioneer Venus Project Information
Pioneer Venus Orbiter
Goddard Pioneer Venus Mission Overview