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Pioneer Venus project

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Main articles:Pioneer Venus OrbiterandPioneer Venus Multiprobe
Arrival of the Pioneer Venus spacecraft at Venus

ThePioneer Venus projectwas part of thePioneer programconsisting of two spacecraft, thePioneer Venus Orbiterand thePioneer Venus Multiprobe,launched toVenusin 1978.[1]The program was managed byNASA'sAmes Research Center.

The Pioneer Venus Orbiter entered orbit around Venus on December 4, 1978, and performed observations to characterize theatmosphereand surface of Venus.[2]It continued to transmit data until October 1992.[1][3]

The Pioneer Venus Multiprobe deployed four small probes into the Venusian atmosphere on December 9, 1978.[1][3]All four probes transmitted data throughout their descent to the surface.[4]One probe survived the landing and transmitted data from the surface for over an hour.

Overview

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The Pioneer mission consisted of two components, launched separately: an orbiter and a multiprobe.

Orbiter

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Main article:Pioneer Venus Orbiter
Pioneer Venus Orbiter
Cloud structure inthe Venusian atmospherein 1979, revealed by ultraviolet observations byPioneer Venus Orbiter

The orbiter was launched on May 20, 1978 on anAtlas-Centaurrocket. The orbiter's mass was 517 kg (1,140 lb).[3]The Pioneer Venus Orbiter was inserted into an elliptical orbit around Venus on December 4, 1978. It carried 17 experiments (with a total mass of 45 kg):[3]

  • 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 the Venus atmosphere
  • an airglow ultraviolet spectrometer to measure scattered and emitted UV light
  • a neutral massspectrometerto determine the composition of the upper atmosphere
  • asolar windplasma analyzer to measure properties of the solar wind
  • amagnetometerto 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 theionosphere
  • an ionmass spectrometerto 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 recordgamma-ray burstevents

In May 1992 the orbiter 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 in August 1992.[3]

Multiprobe

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Main article:Pioneer Venus Multiprobe
Pioneer Venus Multiprobe bus and atmospheric probes
Pioneer Venus Multi-Probe

The Pioneer Venus Multiprobe was launched on August 8, 1978 on an Atlas-Centaur rocket. It consisted of a 290 kgbuswhich carried one large (315 kg) 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 about 1.5 m in diameter and equipped with 7 science experiments. After deceleration from initial atmospheric entry at about 11.5 km/s, a parachute was deployed at 47 km altitude. The probe stopped broadcasting when it impacted the surface.[4]The science experiments were:[3]

  • a neutralmass spectrometerto measure the atmospheric composition
  • agas chromatographto measure the atmospheric composition
  • asolar flux radiometerto 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
  • anephelometerto search for cloud particles
  • temperature, pressure, and acceleration sensors

The three small probes were identical to each other, 0.8 m in diameter and 90 kg each small probe.[3]The small probes were each targeted at different parts of the planet;[5]They had no parachutes and the aeroshells did not separate from the probe. Two of the small probes reached the surface, and one of these, the day probe, continued to broadcast for 67 minutes and 37 seconds after reaching the surface.[4]

The Pioneer Venusbusalso carried two experiments, a neutralmass spectrometerand an ion mass spectrometer to study the composition of the atmosphere. With no heat shield or parachute, the bus made measurements only to about 110 km altitude before burning up.[3]

See also

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References

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  1. ^abc"The Pioneer Venus Project".NASA.RetrievedMarch 26,2023.
  2. ^"Pioneer Venus 1".NASA Solar System Exploration.RetrievedMarch 26,2023.
  3. ^abcdefgh"Pioneer Venus Project Information".NASA Goddard Space Flight Center.RetrievedAugust 17,2016.
  4. ^abcNASA.Pioneer Venus 2,NASA Science: Solar System Exploration, February 3, 2021. Retrieved 24 April 2022.
  5. ^Pioneer Venus Probes.NASA Goddard Space Flight Center, 2005.
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