The Pioneer Venus Orbiter, also known as Pioneer Venus 1 or Pioneer 12, was a mission 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 ...
conducted by the United States as part of the
Pioneer Venus project
The Pioneer Venus project was part of the Pioneer program consisting of two spacecraft, the Pioneer Venus Orbiter and the Pioneer Venus Multiprobe, launched to Venus in 1978. The program was managed by NASA's Ames Research Center.
The Pione ...
. Launched in May 1978 atop 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, ...
rocket, the spacecraft was inserted into an elliptical orbit around Venus on December 4, 1978. It returned data on Venus until October 1992.
Launch and arrival at Venus
![Pioneer Venus 1 orbit attitude](https://upload.wikimedia.org/wikipedia/commons/f/f4/Pioneer_Venus_1_orbit_attitude.gif)
The Pioneer Venus Orbiter was launched by an
Atlas SLV-3D Centaur-D1AR rocket, which flew from
Launch Complex 36A at the
Cape Canaveral Air Force Station
Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida.
Headquartered at the nearby Patrick Space Force Base, the statio ...
. The launch occurred at 13:13:00 on May 20, 1978, and deployed the Orbiter into
heliocentric orbit
A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun i ...
for its coast to Venus. Venus orbit insertion occurred on December 4, 1978.
Spacecraft
![Pioneer Venus 1 at KSC](https://upload.wikimedia.org/wikipedia/commons/6/6a/Pioneer_Venus_1_at_KSC.jpg)
Manufactured by
Hughes Aircraft Company
The Hughes Aircraft Company was a major American aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of Hughes Tool Company. The company was known for producing, among other produ ...
, the Pioneer Venus Orbiter was based on the HS-507
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 ...
.
The spacecraft was a flat cylinder, in diameter and long. All instruments and spacecraft subsystems were mounted on the forward end of the cylinder, except the
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, o ...
, which was at the end of a boom. A
solar array
A photovoltaic system, also PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and ...
extended around the circumference of the cylinder. A despun dish
antenna
Antenna ( antennas or antennae) may refer to:
Science and engineering
* Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves
* Antennae Galaxies, the name of two collid ...
provided
S and
X band
The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxim ...
communication with
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. A
Star-24 solid rocket motor
A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder; they were used in warfare by the Arabs, Chinese, Persia ...
was integrated into the spacecraft to provide the thrust to enter orbit around Venus.
From Venus orbit insertion to July 1980,
periapsis
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary (astronomy), primary body. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two ...
was held between (at 17 degrees north latitude) to facilitate radar and ionospheric measurements. The spacecraft was in a 24-hour orbit with an
apoapsis
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two apsides in any ellip ...
of . Thereafter, the periapsis was allowed to rise to a maximum of and then fall, to conserve fuel.
In 1991, the Radar Mapper was reactivated to investigate previously inaccessible southern portions of the planet, in conjunction with the recently arrived
Magellan
Ferdinand Magellan ( or ; pt, Fernão de Magalhães, ; es, link=no, Fernando de Magallanes, ; 4 February 1480 – 27 April 1521) was a Portuguese people, Portuguese explorer. He is best known for having planned and led the Magellan expeditio ...
spacecraft. In May 1992, Pioneer Venus began the final phase of its mission, in which the periapsis was held between , until the spacecraft's propellant was exhausted, after which the orbit
decayed naturally. The spacecraft continued to return data until 8 October 1992, with the last signals being received at 19:22 UTC.
The Pioneer Venus Orbiter disintegrated upon
entering the
atmosphere of Venus
The atmosphere of Venus is the layer of gases surrounding Venus. It is composed primarily of supercritical carbon dioxide and is much denser and hotter than that of Earth. The temperature at the surface is 740 K (467 °C, 872 ° ...
on October 22, 1992.
Experiments
![Venus map with labels](https://upload.wikimedia.org/wikipedia/commons/d/dd/Venus_map_with_labels.jpg)
The Pioneer Venus Orbiter carried 17 experiments with a total mass of :
![Venus clouds seen by Pioneer Venus Orbiter](https://upload.wikimedia.org/wikipedia/commons/6/64/Venus_clouds_seen_by_Pioneer_Venus_Orbiter.jpg)
*a cloud photo-polarimeter (OCPP) to measure the vertical distribution of the
cloud
In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may co ...
s, similar to
Pioneer 10
''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...
and
Pioneer 11
''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...
imaging photo-polarimeter (IPP)
*a surface radar mapper (ORAD) to determine topography and surface characteristics. Observations could only be conducted when the probe was closer than 4700 km over the planet. A 20 watt
S-band
The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional ...
signal (1.757
gigahertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one h ...
) was sent to the surface that reflected it, with the probe analyzing the echo. Resolution at
periapsis
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary (astronomy), primary body. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two ...
was 23 x 7 km.
*an infrared radiometer (OIR) to measure
IR emissions from
Venus' atmosphere
*an airglow
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
spectrometer (OUVS) to measure scattered and emitted UV light
*a neutral
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 used ...
(ONMS) 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 sola ...
plasma
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
analyzer (OPA) to measure properties of the solar wind
*a magnetometer (OMAG) to characterize the
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
at Venus
*an electric field detector (OEFD) to study the solar wind and its interactions
*an
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no kn ...
temperature (OETP) 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 ...
*an ion mass spectrometer (OIMS) to characterize the ionospheric ion population
*a charged particle retarding potential analyzer (ORPA) to study ionospheric particles
*two
radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
science experiments to determine the
gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
field of Venus
*a
radio occultation
Radio occultation (RO) is a remote sensing technique used for measuring the physical properties of a planetary atmosphere or ring system.
Atmospheric radio occultation
Atmospheric radio occultation relies on the detection of a change in a radio ...
experiment to characterize the atmosphere
*an atmospheric drag experiment to study the upper atmosphere
*a radio science atmospheric and solar wind
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
experiment
*a
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 milli ...
(OGBD) detector to record gamma ray burst events
![Pioneer-Venus-Trajectories](https://upload.wikimedia.org/wikipedia/commons/a/a2/Pioneer-Venus-Trajectories.png)
The spacecraft conducted
radar altimetry
A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it t ...
observations allowing the first global topographic map of the Venusian surface to be constructed.
Observations of Halley's Comet
From its orbit of Venus, the Pioneer Venus Orbiter was able to observe
Halley's Comet
Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the o ...
when it was unobservable from Earth due to its proximity to the sun during February 1986. UV spectrometer observations monitored the loss of water from the comet's nucleus at perihelion on February 9.
See also
*
Pioneer Venus Multiprobe
The Pioneer Venus Multiprobe, also known as Pioneer Venus 2 or Pioneer 13, was a spacecraft launched in 1978 to explore Venus as part of NASA's Pioneer program. This part of the mission included a spacecraft bus which was launched from Earth car ...
*
List of missions to Venus
There have been 46 (including gravity-assist flybys) space missions to the planet Venus. Missions to Venus constitute part of the exploration of Venus.
List
As of 2020, the Soviet Union, United States, European Space Agency and Japan have con ...
*
Timeline of artificial satellites and space probes
This Timeline of artificial satellites and Space probe
A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby ...
References
External links
NASA: Pioneer Venus Project InformationPioneer Venus Program Pageb
NASA's Solar System ExplorationKasprzak, W. T – The Pioneer Venus Orbiter: 11 years of data. (May 1, 1990) – NASA
Science Magazine in year 1979 issue 4401
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
{{Orbital launches in 1978
1978 in spaceflight
Missions to Venus
Pioneer program
Spacecraft launched by Atlas-Centaur rockets
Destroyed space probes
Spacecraft launched in 1978