The Pioneer mission to Venus consisted of two components, launched separately: an Orbiter and a Multiprobe.
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2 The Pioneer Venus Multiprobe 3 External links: |
The Pioneer Venus Orbiter
The Pioneer Venus Orbiter carried 17 experiments (with a total mass of 45 kg):
- a cloud photopolarimeter to measure the vertical distribution of the clouds
- a surface radar mapper to determine topography and surface characteristics
- an infrared radiometer to measure IR emissions from Venus' atmosphere
- an airglow ultraviolet spectrometer to measure scattered and emitted UV light
- a neutral mass spectrometer to determine the composition of the upper atmosphere
- 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 interactions
- an electron temperature probe to study the thermal properties of the ionosphere
- an ion mass spectrometer to characterize the ionospheric ion population
- a charged particle retarding potential analyzer 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 detector to record gamma ray burst events
The Pioneer Venus Multiprobe
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 atmosphere
- an infrared radiometer to measure distribution of infrared radiation
- a cloud particle size spectrometer to measure particle size and shape
- a nephelometer to search for cloud particles
- temperature, pressure, and acceleration sensors
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.
Large Probe | North Probe | Day Probe | Night Probe | Bus | |
---|---|---|---|---|---|
Entry Time (200 km) | 18:45:32 | 18:49:40 | 18:52:18 | 18:56:13 | 20:21:52 |
Impact Time | 19:39:53 | 19:42:40 | 19:47:59 | 19:52:05 | * |
Loss of Signal | 19:39:53 | 19:42:40 | 20:55:34 | 19:52:07 | 20:22:55 |
Impact Latitude | 4.4 N | 59.3 N | 31.3 S | 28.7 S | (37.9 S) |
Impact Longitude | 304.0 | 4.8 | 317.0 | 56.7 | (290.9) |
Solar Zenith Angle | 65.7 | 108.0 | 79.9 | 150.7 | 60.7 |
Local Venus Time | 7:38 | 3:35 | 6:46 | 0:07 | 8:30 |
All times in UT (= EST + 5 hours) on December 9, 1978