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Pioneer 6, 7, 8, and 9

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Pioneer 6, 7, 8, and 9 were space probes in the Pioneer 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 as Pioneer A, B, C, and D. The fifth (Pioneer E) was lost in a launch accident, and therefore did not receive a numerical designation.

Pioneer 6, 7, 8, and 9
Artist's conception of the Pioneer 6–9 spacecraft.
Mission typeInterplanetary space
OperatorNASA
COSPAR ID
  • Pioneer 6: 1965-105A
  • Pioneer 7: 1966-075A
  • Pioneer 8: 1967-123A
  • Pioneer 9: 1968-100A
SATCAT no.
  • Pioneer 6: 1841
  • Pioneer 7: 2398
  • Pioneer 8: 3066
  • Pioneer 9: 3533
Mission duration
  • Pioneer 6: 34 years, 11 months and 22 days
  • Pioneer 7: 28 years, 7 months and 14 days
  • Pioneer 8: 28 years, 8 months and 9 days
  • Pioneer 9: 14 years, 6 months and 11 days
Spacecraft properties
ManufacturerTRW
Launch mass
  • Pioneer 6: 62.14 kg
  • Pioneer 7: 62.75 kg
  • Pioneer 8 and 9: 65.36 kg
Power79 W
Start of mission
Launch date
  • Pioneer 6: 16 December 1965, 07:31:21 (1965-12-16UTC07:31:21Z) UTC[1]
  • Pioneer 7: 17 August 1966, 15:20:17 (1966-08-17UTC15:20:17Z) UTC[2]
  • Pioneer 8: 13 December 1967, 14:08 (1967-12-13UTC14:08Z) UTC [3]
  • Pioneer 9: 8 November 1968, 09:46:29 (1968-11-08UTC09:46:29Z) UTC[4]
  • Pioneer E: 27 August 1969, 21:59:00 (1969-08-27UTC21:59Z) UTC
Rocket
Launch site
End of mission
Last contact
  • Pioneer 6: 8 December 2000
  • Pioneer 7: 31 March 1995
  • Pioneer 8: 22 August 1996
  • Pioneer 9: 19 May 1983
Orbital parameters
Reference systemHeliocentric
Perihelion altitudebetween 0.75 to 1 AU
Aphelion altitudebetween 0.99 to 1.2 AU

Purpose

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Pioneers 6, 7, 8, and 9 were created to make the first detailed, comprehensive measurements of the solar wind, solar magnetic field and cosmic rays. They were designed to measure large scale magnetic phenomena and particles and fields in interplanetary 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 on solar storms which affect communications and power on Earth.[5]

The experiments studied the positive ions (cations) and electrons in the solar wind, the interplanetary electron density (radio propagation experiment), solar and galactic cosmic rays, and the Interplanetary Magnetic Field.[5]

The spacecraft were important collectors of heliophysics and space 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 potent solar storms ever recorded, and the most hazardous to human spaceflight during the Space Age.[6]

Vehicle description

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Launch of Pioneer 6 on a Delta-E rocket
 
Pioneer 8 being prepared for launch
 
Launch of Pioneer 8 on a Delta-E1 rocket

Each craft was identical. They were spin-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) 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 60 RPM, and the spin axis was perpendicular to the ecliptic plane and pointed toward the south ecliptic pole.[5]

Instruments differed somewhat between spacecraft, with some being used in all four missions:

Instrument Pionner
6 7 8 9
Solar Wind Plasma Faraday Cup ✔ ✔
Cosmic-Ray Telescope ✔ ✔
Electrostatic Analyzer ✔ ✔ ✔
Superior Conjunction Faraday Rotation ✔ ✔
Spectral Broadening ✔
Relativity Investigation ✔
Uniaxial Fluxgate Magnetometer ✔
Cosmic-Ray Anisotropy ✔ ✔ ✔ ✔
Celestial Mechanics ✔ ✔ ✔ ✔
Two-Frequency Beacon Receiver ✔ ✔ ✔ ✔
Single-Axis Magnetometer ✔ ✔
Cosmic Dust Detector ✔ ✔
Cosmic Ray Gradient Detector ✔ ✔
Plasma Wave Detector ✔
Triaxial Magnetometer ✔
Solar Plasma Detector ✔
Electric Field Detector ✔

Communications

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By ground command, one of five bit 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 the radio 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]

Timeline and current status

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As stated by JPL, "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 described Pioneer 6 as "extant" as of 26 March 2007,[8] there has been no contact since December 8, 2000. At this time Pioneer 6 had operated for 12,758 days, making it the oldest operating space probe until it was surpassed by Voyager 2 on August 13, 2012.[9] It is also believed that contact is still possible with Pioneer 7 and 8;[citation needed] only Pioneer 9 is definitely not working.

Pioneer 6

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  • December 16, 1965 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 Traveling-wave tube (TWT) failed sometime 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 the University of Chicago, were turned on and working.
  • December 8, 2000 Successful telemetry contact for about two hours.

Pioneer 7

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  • August 17, 1966 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.[10]
  • March 31, 1995 Tracked successfully. The spacecraft and one of the science instruments were still functioning.

Pioneer 8

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  • December 13, 1967: Launched at 14:08:00 UTC from Cape Canaveral into solar orbit with a mean distance of 1.1 AU from the Sun.[11]
  • 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

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  • November 8, 1968: Launched at 09:46:00 UTC from Cape Canaveral into solar orbit with a mean distance of 0.8 AU.
  • 1983: Final contact.
  • 1987: Contact was attempted, but failed.[4]

Pioneer E

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  • August 27, 1969: Launched at 21:59:00 UTC from Cape Canaveral. The launch vehicle was destroyed by range safety after hydraulics in the first stage failed.[7]

See also

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  • 17776, a speculative fiction work featuring a sentient Pioneer 9

References

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  1. ^ "Pioneer 6 - NASA Science". science.nasa.gov. NASA. Retrieved December 1, 2022.
  2. ^ "Pioneer 7 - NASA Science". science.nasa.gov. NASA. Retrieved December 1, 2022.
  3. ^ "Pioneer 8 - NASA Science". science.nasa.gov. NASA. Retrieved December 1, 2022.
  4. ^ a b "Pioneer 9 - NASA Science". science.nasa.gov. NASA. Retrieved March 6, 2019.
  5. ^ a b c d e f "Pioneer 6". nssdc.gsfc.nasa.gov. NASA. Archived from the original on August 4, 2021. Retrieved September 9, 2018.   This article incorporates text from this source, which is in the public domain.
  6. ^ D. J. Knipp; B. J. Fraser; M. A. Shea; D. F. Smart (2018). "On the Little‐Known Consequences of the 4 August 1972 Ultra-Fast Coronal Mass Ejecta: Facts, Commentary and Call to Action". Space Weather. 16 (11): 1635–1643. Bibcode:2018SpWea..16.1635K. doi:10.1029/2018SW002024.
  7. ^ a b "Pioneer 6, 7, 8, 9, E - Quicklook". Jet Propulsion Laboratory. Archived from the original on July 21, 2010.
  8. ^ "The Pioneer Missions". nasa.gov. NASA. Archived from the original on August 15, 2011. Retrieved August 27, 2009.
  9. ^ "Voyager at 35 - Break on Through to the Other Side". nasa.gov. NASA. Archived from the original on March 8, 2015. Retrieved May 5, 2015.
  10. ^ J. D. Mihalov; H. R. Collard; D. S. Intriligator; A. Barnes (1987). "Observation by Pioneer 7 of He+ in the distant coma of Halley's Comet". Icarus. 71 (1): 192–197. Bibcode:1987Icar...71..192M. doi:10.1016/0019-1035(87)90172-2.
  11. ^ "Pioneer 8". nssdc.gsfc.nasa.gov. NASA. Archived from the original on June 29, 2019. Retrieved February 27, 2022.
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