The Pioneer Venus project was part of the

Pioneer program The Pioneer programs were two series of United States lunar and planetary space probes exploration. The first program, which ran from 1958 to 1960, unsuccessfully attempted to send spacecraft to orbit the Moon, successfully sent one spacecraft to ...

consisting of two spacecraft, the

Pioneer Venus Orbiter The Pioneer Venus Orbiter, also known as Pioneer Venus 1 or Pioneer 12, was a mission to Venus conducted by the United States as part of the Pioneer Venus project. Launched in May 1978 atop an Atlas-Centaur rocket, the spacecraft was inserted i ...

and the Pioneer Venus Multiprobe, launched to

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...

in 1978. The program was managed by NASA's

Ames Research Center The Ames Research Center (ARC), also known as NASA Ames, is a major NASA research center at Moffett Federal Airfield in California's Silicon Valley. It was founded in 1939 as the second National Advisory Committee for Aeronautics (NACA) labor ...

. The Pioneer Venus Orbiter entered orbit around Venus on December 4, 1978, and performed observations to characterize the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

and surface of Venus. It continued to transmit data until October 1992. The Pioneer Venus Multiprobe deployed four small probes into the Venusian atmosphere on December 9, 1978. All four probes transmitted data throughout their descent to the surface. One probe survived the landing and transmitted data from the surface for over an hour.

Overview

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

Orbiter

The orbiter was launched on May 20, 1978 on an

Atlas-Centaur The Atlas-Centaur was a United States expendable launch vehicle derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station (CCAFS) in Florida. Early development Convair, th ...

rocket. The orbiter's mass was . 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): *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 mass spectrometer to determine the composition of the upper atmosphere *a

solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sol ...

plasma analyzer to measure properties of the solar wind *a

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, on ...

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 The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an im ...

*an ion

mass spectrometer Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is use ...

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 In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten millise ...

events 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.

Multiprobe

The Pioneer Venus Multiprobe was launched on August 8, 1978 on an Atlas-Centaur rocket. It consisted of a 290 kg

bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...

which 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. The science experiments were: *a neutral

to measure the atmospheric composition *a

gas chromatograph Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, ...

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 A nephelometer or aerosol photometer is an instrument for measuring the concentration of suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam (source beam) and a light dete ...

to 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. The small probes were each targeted at different parts of the planet;Pioneer Venus Probes
NASA Goddard Space Flight Center, 2005. 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.NASA.
Pioneer Venus 2
', NASA Science: Solar System Exploration, February 3, 2021. Retrieved 24 April 2022. The Pioneer Venus

also carried two experiments, a neutral

and 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.

References

External links

NASA: Pioneer Venus Project Information

Pioneer Venus Program Page
b
NASA's Solar System Exploration

NSSDC Master Catalog: Spacecraft Pioneer Venus Probe Bus
(Other components of the mission have their own pages at this site too.)

specifications at NASA *
The Pioneer Venus Orbiter: 11 years of data.
Results published on May 1, 1990.
Art for the mission
{{DEFAULTSORT:Pioneer Venus Missions to Venus Pioneer program 1978 in spaceflight Spacecraft launched in 1978

Overview

Orbiter

Multiprobe

See also

References

External links