 Artist's conception of thePioneer 6–9 spacecraft. | |
| Mission type | Interplanetary space |
|---|---|
| Operator | NASA |
| COSPAR ID |
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| SATCATno. |
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| Mission duration |
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| Spacecraft properties | |
| Manufacturer | TRW |
| Launch mass |
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| Power | 79 W |
| Start of mission | |
| Launch date |
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| Rocket | |
| Launch site |
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| End of mission | |
| Last contact |
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| Orbital parameters | |
| Reference system | Heliocentric |
| Perihelion altitude | between 0.75 to 1AU |
| Aphelion altitude | between 0.99 to 1.2 AU |
Pioneer 6,7,8, and9 werespace probes in thePioneer program, launched between 1965 and 1969. They were 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.[5] They were also known asPioneer A,B,C, andD. The fifth (Pioneer E) was lost in a launch accident, and therefore did not receive a numerical designation.
Pioneers 6,7,8, and9 were created to make the first detailed, comprehensive measurements of thesolar wind, solarmagnetic field andcosmic rays. They were designed to measure large scale magnetic phenomena and particles and fields ininterplanetary space. Data from the vehicles have 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 onsolar storms which affect communications and power on Earth.[5]
The experiments studied the positiveions (cations) andelectrons in the solar wind, the interplanetary electron density (radio propagation experiment), solar and galactic cosmic rays, and theInterplanetary Magnetic Field.[5]
The spacecraft were important collectors ofheliophysics andspace weather data. In conjunction with other spacecraft these, for the first time, enabled spaceborne observations to be combined with terrestrial observations on the ground and from sounding balloons. In early August 1972 Pioneer 9 recorded significant observations of one of the most potentsolar storms ever recorded, and the most hazardous tohuman spaceflight during theSpace Age.[6]
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Each craft was identical. They werespin-stabilized 0.94 m (3 ft 1 in) diameter × 0.81 m (2 ft 8 in) tall cylinders with a 1.8 m (5 ft 11 in) longmagnetometer boom and solar panels mounted around the body.
The mainantenna was ahigh-gain directional antenna. The spacecraft were spin-stabilized at about 60 RPM, and the spinaxis wasperpendicular to theecliptic plane and pointed toward the southecliptic pole.[5]
Instruments differed somewhat between spacecraft, with some being used in all four missions:
| Instrument | Pioneer | |||
|---|---|---|---|---|
| 6 | 7 | 8 | 9 | |
| Solar Wind PlasmaFaraday Cup | ✔ | ✔ | ||
| Cosmic-Ray Telescope | ✔ | ✔ | ||
| Electrostatic Analyzer | ✔ | ✔ | ✔ | |
| Superior ConjunctionFaraday Rotation | ✔ | ✔ | ||
| Spectral Broadening | ✔ | |||
| Relativity Investigation | ✔ | |||
| UniaxialFluxgate Magnetometer | ✔ | |||
| Cosmic-RayAnisotropy | ✔ | ✔ | ✔ | ✔ |
| Celestial Mechanics | ✔ | ✔ | ✔ | ✔ |
| Two-FrequencyBeacon Receiver | ✔ | ✔ | ✔ | ✔ |
| Single-AxisMagnetometer | ✔ | ✔ | ||
| Cosmic Dust Detector | ✔ | ✔ | ||
| Cosmic Ray Gradient Detector | ✔ | ✔ | ||
| Plasma Wave Detector | ✔ | |||
| Triaxial Magnetometer | ✔ | |||
| Solar Plasma Detector | ✔ | |||
| Electric Field Detector | ✔ | |||
By ground command, one of fivebit rates, 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 theradio propagation experiment. The fourth data format contained mainly engineering data.[5]
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 was read out at whatever bit rate was appropriate to the satellite distance from Earth.[5]
As stated byJPL, "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."[7] Although the four 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.
Although NASA describedPioneer 6 as "extant" as of 26 March 2007[update],[8] there has been no contact since December 8, 2000. At this timePioneer 6 had operated for 12,758 days, making it the oldest operating space probe until it was surpassed byVoyager 2 on August 13, 2012.[9] It is also believed that contact is still possible withPioneer 7 and8;[citation needed] onlyPioneer 9 is definitely not working.
This article incorporates text from this source, which is in thepublic domain.| Early missions |  | |
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| Venus missions | ||
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