Pioneer 6, 7, 8 and 9
Encyclopedia
Pioneer 6, 7, 8, and 9 were space probes in the Pioneer program
. Together, they formed a series of solar-orbiting, spin-stabilized, solar-cell and battery-powered satellites designed to obtain measurements on a continuing basis of interplanetary phenomena from widely separated points in space. They were also known as Pioneer A, B, C, and D. The fifth (Pioneer E) was lost in a launch accident.
, solar magnetic field
and cosmic ray
s. They were designed to measure large scale magnetic phenomena and particles and fields in interplanetary space. Data from the vehicles has been used to better understand stellar processes and the structure and flow of the solar wind. The vehicles also acted as the world's first space-based solar weather network, providing practical data on solar storm
s which impact communications and power on Earth.
The experiments studied the positive ion
s (cations) and electron
s in the solar wind, the interplanetary electron density (radio propagation
experiment), solar and galactic cosmic rays, and the Interplanetary Magnetic Field
.
0.94 m diameter × 0.81 m tall cylinders with a 1.8 m long magnetometer boom and solar panels mounted around the body.
The main antenna
was a high-gain
directional antenna. The spacecraft were spin-stabilized at about 1 Hz
, and the spin axis
was perpendicular
to the ecliptic plane
and pointed toward the south ecliptic
pole.
Instruments:
s, one of four data formats, and one of four operating modes could be selected. The five bit rates were 512, 256, 64, 16, and 8 bit/s. Three of the four data formats contained primarily scientific data and consisted of 32 seven-bit words per frame. One scientific data format was for use at the two highest bit rates. Another was for use at the three lowest bit rates. The third contained data from only the radio propagation
experiment. The fourth data format contained mainly engineering data.
The four operating modes were: real time, telemetry store, duty cycle store, and memory readout. In the real-time mode, data were sampled and transmitted directly (without storage) as specified by the data format and bit rate selected. In the telemetry store mode, data were stored and transmitted simultaneously in the format and at the bit rate selected. In the duty-cycle store mode, a single frame of scientific data was collected and stored at a rate of 512 bit/s. The time interval between the collection and storage of successive frames could be varied by ground command between 2 and 17 min to provide partial data coverage for periods up to 19 hours, as limited by the bit storage capacity. In the memory readout mode, data were read out at whatever bit rate was appropriate to the satellite distance from Earth.
, Pioneer 6 is still described as "extant", and is the oldest operating space probe. It is also believed that contact is still possible with Pioneers 7 and 8. Only Pioneer 9 is definitely dead.
Launched at 07:31:00 UTC from Cape Canaveral to a circular solar orbit with a mean distance of 0.8 AU.
December 1995
The prime TWT failed some time after December 1995.
July 1996
Spacecraft commanded to the backup TWT.
October 6, 1997
Tracked with the 70 meter Deep Space Station 43 in Australia.
The MIT and ARC Plasma Analyzers as well as the cosmic ray detector from University of Chicago were turned on and working.
December 8, 2000
Successful telemetry contact for about two hours.
Launched from Cape Canaveral into solar orbit with a mean distance of 1.1 AU.
March 20, 1986
Flew within 12.3 million kilometers of Halley's Comet and monitored the interaction between the cometary hydrogen tail and the solar wind. It discovered He+ plasma produced by charge exchange of solar wind He++ with neutral cometary material.
March 31, 1995
Tracked successfully. The spacecraft and one of the science instruments were still functioning.
Launched at 14:08:00 UTC from Cape Canaveral into solar orbit with a mean distance of 1.1 AU from the Sun.
August 22, 1996
The spacecraft commanded to switch to the backup TWT. Downlink signal was re-acquired, one of the science instruments again functioning.
Launched at 09:46:00 UTC from Cape Canaveral into solar orbit with a mean distance of 0.8 AU.
1983
Spacecraft failed.
Launched at 21:59:00 UTC from Cape Canaveral. The launch vehicle was destroyed by range safety
after hydraulics in the first stage failed.
Pioneer program
The Pioneer program is a series of United States unmanned space missions that was designed for planetary exploration. There were a number of such missions in the program, but the most notable were Pioneer 10 and Pioneer 11, which explored the outer planets and left the solar system...
. Together, they formed a series of solar-orbiting, spin-stabilized, solar-cell and battery-powered satellites designed to obtain measurements on a continuing basis of interplanetary phenomena from widely separated points in space. They were also known as Pioneer A, B, C, and D. The fifth (Pioneer E) was lost in a launch accident.
Purpose
Pioneers 6, 7, 8, and 9 were created to make the first detailed, comprehensive measurements of the solar windSolar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
, solar magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
and cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
s. They were designed to measure large scale magnetic phenomena and particles and fields in interplanetary space. Data from the vehicles has been used to better understand stellar processes and the structure and flow of the solar wind. The vehicles also acted as the world's first space-based solar weather network, providing practical data on solar storm
Solar storm
Solar storm can refer to:*Solar flare, a large explosion in the Sun's atmosphere*Coronal mass ejection , a massive burst of solar wind associated with solar flares*Geomagnetic storm, the interaction of the Sun's outburst with Earth's magnetic field...
s which impact communications and power on Earth.
The experiments studied the positive ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s (cations) and electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s in the solar wind, the interplanetary electron density (radio propagation
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...
experiment), solar and galactic cosmic rays, and the Interplanetary Magnetic Field
Interplanetary Magnetic Field
The interplanetary magnetic field is the term for the solar magnetic field carried by the solar wind among the planets of the Solar System....
.
Vehicle description
Each craft was identical, with an on-orbit dry mass of 146 kg. They were spin-stabilizedSpin-stabilized satellite
A spin-stabilized satellite is a satellite which has the motion of one axis held fixed by spinning the satellite around that axis, using the gyroscopic effect.The attitude of a satellite or any rigid body is its orientation in space...
0.94 m diameter × 0.81 m tall cylinders with a 1.8 m long magnetometer boom and solar panels mounted around the body.
The main antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
was a high-gain
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...
directional antenna. The spacecraft were spin-stabilized at about 1 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
, and the spin axis
Rotation
A rotation is a circular movement of an object around a center of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...
was perpendicular
Perpendicular
In geometry, two lines or planes are considered perpendicular to each other if they form congruent adjacent angles . The term may be used as a noun or adjective...
to the ecliptic plane
Plane of the ecliptic
The plane of the ecliptic is the plane of the Earth's orbit around the Sun. It is the primary reference plane when describing the position of bodies in the Solar System, with celestial latitude being measured relative to the ecliptic plane. In the course of a year, the Sun's apparent path through...
and pointed toward the south ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
pole.
Instruments:
- Solar Wind Plasma Faraday Cup (6,7)
- Cosmic-Ray Telescope (6,7)
- Electrostatic Analyzer (6,7,8)
- Superior Conjunction Faraday Rotation (6,7)
- Spectral Broadening (6)
- Relativity Investigation (6)
- Uniaxial Fluxgate Magnetometer (6)
- Cosmic-Ray Anisotropy (6,7,8,9)
- Celestial Mechanics (6,7,8,9)
- Two-Frequency Beacon Receiver (6,7,8,9)
- Single-Axis Magnetometer (7,8)
- Cosmic Dust Detector (8,9)
- Cosmic Ray Gradient Detector (8,9)
- Plasma Wave Detector (8)
- Triaxial Magnetometer (9)
- Solar Plasma Detector (9)
- Electric Field Detector (9)
Communications
By ground command, one of five bit rateBit rate
In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
s, one of four data formats, and one of four operating modes could be selected. The five bit rates were 512, 256, 64, 16, and 8 bit/s. Three of the four data formats contained primarily scientific data and consisted of 32 seven-bit words per frame. One scientific data format was for use at the two highest bit rates. Another was for use at the three lowest bit rates. The third contained data from only the radio propagation
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...
experiment. The fourth data format contained mainly engineering data.
The four operating modes were: real time, telemetry store, duty cycle store, and memory readout. In the real-time mode, data were sampled and transmitted directly (without storage) as specified by the data format and bit rate selected. In the telemetry store mode, data were stored and transmitted simultaneously in the format and at the bit rate selected. In the duty-cycle store mode, a single frame of scientific data was collected and stored at a rate of 512 bit/s. The time interval between the collection and storage of successive frames could be varied by ground command between 2 and 17 min to provide partial data coverage for periods up to 19 hours, as limited by the bit storage capacity. In the memory readout mode, data were read out at whatever bit rate was appropriate to the satellite distance from Earth.
Time line and current status
The Pioneer 6–9 program has been touted as one of the least expensive of all NASA spacecraft programs in terms of scientific results per dollar spent. Although the spacecraft have not been regularly tracked for science data return in recent years, a successful telemetry contact with Pioneer 6 was made on December 8, 2000 to celebrate 35 years of continuous operation since launch. Its original design life expectancy was only 6 months., Pioneer 6 is still described as "extant", and is the oldest operating space probe. It is also believed that contact is still possible with Pioneers 7 and 8. Only Pioneer 9 is definitely dead.
Pioneer 6
December 16, 1965Launched at 07:31:00 UTC from Cape Canaveral to a circular solar orbit with a mean distance of 0.8 AU.
December 1995
The prime TWT failed some time after December 1995.
July 1996
Spacecraft commanded to the backup TWT.
October 6, 1997
Tracked with the 70 meter Deep Space Station 43 in Australia.
The MIT and ARC Plasma Analyzers as well as the cosmic ray detector from University of Chicago were turned on and working.
December 8, 2000
Successful telemetry contact for about two hours.
Pioneer 7
August 17, 1966Launched from Cape Canaveral into solar orbit with a mean distance of 1.1 AU.
March 20, 1986
Flew within 12.3 million kilometers of Halley's Comet and monitored the interaction between the cometary hydrogen tail and the solar wind. It discovered He+ plasma produced by charge exchange of solar wind He++ with neutral cometary material.
March 31, 1995
Tracked successfully. The spacecraft and one of the science instruments were still functioning.
Pioneer 8
December 13, 1967Launched at 14:08:00 UTC from Cape Canaveral into solar orbit with a mean distance of 1.1 AU from the Sun.
August 22, 1996
The spacecraft commanded to switch to the backup TWT. Downlink signal was re-acquired, one of the science instruments again functioning.
Pioneer 9
November 8, 1968Launched at 09:46:00 UTC from Cape Canaveral into solar orbit with a mean distance of 0.8 AU.
1983
Spacecraft failed.
Pioneer E
August 27, 1969Launched at 21:59:00 UTC from Cape Canaveral. The launch vehicle was destroyed by range safety
Range Safety Officer
In the field of rocketry, Range Safety Officer is a generic term referring to an individual who monitors the performance of rockets in flight, and who is responsible for their remote destruction if it should be judged that they pose a hazard...
after hydraulics in the first stage failed.
External links
- Pioneer Project Page
- Pioneer 6 Profile by NASA's Solar System Exploration
- Pioneer 7 Profile by NASA's Solar System Exploration
- Pioneer 8 Profile by NASA's Solar System Exploration
- Pioneer 9 Profile by NASA's Solar System Exploration
- NSSDC Master Catalog: Spacecraft Pioneer 6
- NSSDC Master Catalog: Spacecraft Pioneer 7
- NSSDC Master Catalog: Spacecraft Pioneer 8
- NSSDC Master Catalog: Spacecraft Pioneer 9
- NSSDC Master Catalog: Spacecraft Pioneer-E