Pioneer Venus Multiprobe
By Marty McDowell/NASA
On Aug 8, 1978, the United States launched Pioneer Venus 2. Three small
probes, one large probe, and the spacecraft bus entered the Venus
atmosphere on December 9, 1978.
The Pioneer Venus Multiprobe consisted of a bus which carried one large
and three small atmospheric probes. The large probe was released on
November 16, 1978 and the three small probes on November 20. All four
probes entered the Venus atmosphere on December 9, followed by the bus.
The Pioneer Venus large probe was equipped with 7 science experiments,
contained within a sealed spherical pressure vessel. This pressure vessel
was encased in a nose cone and aft protective cover. After deceleration
from initial atmospheric entry at about 11.5 km/s near the equator on the
Venus night side, a parachute was deployed at 47 km altitude. The large
probe was about 1.5 m in diameter and the pressure vessel itself was 73.2
cm in diameter. The science experiments were:
- a neutral mass spectrometer to measure the atmospheric composition
- a gas chromatograph to measure the atmospheric composition
- a solar flux radiometer to measure solar flux penetration in the
- an infrared radiometer to measure distribution of infrared radiation
- a cloud particle size spectrometer to measure particle size and
- a nephelometer to search for cloud particles
- temperature, pressure, and acceleration sensors
The three small probes were identical to each other, 0.8 m in diameter.
These probes also consisted of spherical pressure vessels surrounded by an
aeroshell, but unlike the large probe, they had no parachutes and the
aeroshells did not separate from the probe. Each small probe carried a
nephelometer and temperature, pressure, and acceleration sensors, as well
as a net flux radiometer experiment to map the distribution of sources and
sinks of radiative energy in the atmosphere. The radio signals from all
four probes were also used to characterize the winds, turbulence, and
propogation in the atmosphere. The small probes were each targeted at
different parts of the planet and were named accordingly. The North probe
entered the atmosphere at about 60 degrees north latitude on the day side.
The night probe entered on the night side. The day probe entered well into
the day side, and was the only one of the four probes which continued to
send radio signals back after impact, for over an hour.
The Pioneer Venus bus also carried two experiments, a neutral mass
spectromenter and an ion mass spectrometer to study the composition of the
atmosphere. With no heat shield or parachute, the bus survived and made
measurements only to about 110 km altitude before burning up. The bus was
a 2.5 m diameter cylinder weighing 290 kg, and afforded us our only direct
view of the upper Venus atmosphere, as the probes did not begin making
direct measurements until they had decelerated lower in the atmosphere.
Share Your Memories!
What do you remember about Pioneer Venus Multiprobe? Have you any compelling stories to share? Share your stories with the world! (We print the best stories right here!)
Space References (Books):
Dickinson, Terence. Nightwatch:
A Practical Guide to Viewing the Universe. Firefly Books, 1998.
Greene, Brian. Elegant
Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate
Theory. Vintage, 2000.
Hawking, Stephen. Illustrated
Brief History of Time, Updated and Expanded Edition. Bantam, 1996.
Hawking, Stephen. Theory
of Everything: The Origin and Fate of the Universe. New Millenium,
Hawking, Stephen. The
Universe in a Nutshell. Bantam, 2001.
Kaku, Michio. Hyperspace:
A Scientific Odyssey Through Parallel Universes, Time Warps and the Tenth
Kranz, Gene. Failure
Is Not an Option: Mission Control from Mercury to Apollo 13 and Beyond.
Berkley Pub Group, 2001.
Sagan, Carl; Druyan, Ann. Comet,
Revised Edition. Ballantine, 1997
Sagan, Carl. Cosmos,
Reissue Edition. Ballantine, 1993
Sagan, Carl. Pale
Blue Dot: A Vision of the Human Future in Space. Ballantine, 1997
Space References (Videos):
Hawking's Universe. PBS, 1997.
Beyond Earth PBS, 1999.
The Planets. BBC, 1999.
The Universe. A&E, 1996.
Artist's conception of probe courtesy of NASA
Courtesy of NASA
Launched: August 8, 1978
Arrival: December 9, 1978
Mission: Probing the atmosphere of Venus