Explorer 31: Difference between revisions
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=== Electron Temperature === |
=== Electron Temperature === |
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The purpose of the electron temperature probe was to measure the energy distribution of ionospheric electrons. From these measurements electron temperature and density could be derived. The sensor was a disk, 2 |
The purpose of the electron temperature probe was to measure the energy distribution of ionospheric electrons. From these measurements electron temperature and density could be derived. The sensor was a disk, {{cvt|2|cm}} in diameter, mounted flush with the satellite surface. The probe current-voltage characteristics were investigated by means of the same modulation technique that was used in the spherical ion-mass spectrometer.<ref name="Experiment3">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1965-098B-03|title=Experiment: Electron Temperature|publisher=NASA|date=28 October 2021|access-date=9 November 2021}} {{PD-notice}}</ref> |
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=== Energetic Electron Current Monitor === |
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The purpose of this experiment was to measure the electron energy spectrum in the suprathermal energy range of 0.2 to 2000 [[Electronvolt|eV]]. Two three-grid retarding potential analyzers were used, one providing analog data in the 0.2 to 200 eV range and the other providing digital data in the 0.2 to 2000 eV range. The two analyzers had separate power supplies and associated electronics. The instrumentation for the digital measurement included an electron multiplier and a digital pulse counting system. Because of moisture contamination of the detector in the launch tower prior to launch, the gain of the electron multiplier was so degraded that no geophysical measurements could be obtained. The instrumentation for the analog measurement included a range-changing electrometer. The analog data were plots of the measured current-voltage function. The analog experiment yielded excellent data for 4 months, after which the experiment deteriorated because of radiation damage to its circuitry.<ref name="Experiment7">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1965-098B-07|title=Experiment: Energetic Electron Current Monitor|publisher=NASA|date=28 October 2021|access-date=9 November 2021}} {{PD-notice}}</ref> |
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Revision as of 21:48, 9 November 2021
Names | DME-A Direct Measurement Explorer-A |
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Mission type | Earth science |
Operator | NASA |
COSPAR ID | 1965-098B |
SATCAT no. | 01806 |
Spacecraft properties | |
Spacecraft | Explorer XXXI |
Launch mass | 98.9 kg (218 lb) |
Start of mission | |
Launch date | 29 November 1965, 04:48:47 GMT [1] |
Rocket | Thor SLV-2 Agena B (Thor 453 / Agena 6102 (TA5)) |
Launch site | Vandenberg, SLC-2E |
Contractor | Douglas Aircraft Company / Lockheed Corporation |
Entered service | 29 November 1965 |
End of mission | |
Decay date | 21 February 1967 |
Orbital parameters | |
Reference system | Geocentric orbit [2] |
Regime | Low Earth orbit |
Perigee altitude | 505 km (314 mi) |
Apogee altitude | 2,978 km (1,850 mi) |
Inclination | 79.80° |
Period | 121.40 minutes |
Instruments | |
Cylindrical Electrostatic Probes Electron Temperature Energetic Electron Current Monitor Ion Mass Spectrometer Magnetic Ion-Mass Spectrometer Thermal Electron Probe Thermal Ion Probe | |
Explorer program |
Explorer 31, also called DME-A, was a NASA satellite launched as part of the Explorer program. Explorer 31 was launched on 29 November 1965 from Vandenberg Air Force Base, California, with a Thor-Agena launch vehicle. Explorer 31 was released along with the Canadian satellite Alouette 2.[3]
Explorer 31 was a small ionospheric observatory instrumented to make direct measurements of selected ionospheric parameters at the spacecraft. Since the spacecraft had no tape recorder, data could be observed at the spacecraft only when the spacecraft was in sight of the telemetry station and when commanded on. Experiments were operated either simultaneously or sequentially, as desired. The satellite was spin-stabilized with the spin axis perpendicular to the orbit plane. The spin rate and spin axis were controlled by an onboard magnetic torquing system. The attitude and spin rate information were observed by a sun sensor and a three-axis magnetometer.[3]
Satellite performance was satisfactory except for a partial power failure in May 1966, which reduced data acquisition time to about half the nominal amount. Some difficulties were encountered in obtaining attitude information that was necessary for the reduction of the experiment observations. On July 1, 1969, the satellite data observations were terminated with five of the seven experiments operating. Responsibility for standby monitoring of the satellite was given to the ESSA telemetry station at Boulder, Colorado, on July 8, 1969. During this standby operation, experiment data were collected only once on 1 October 1969, for 9 minutes from the electrostatic probe for use in studying a red arc event. On January 15, 1971, no response was received from a variety of satellite commands, and the satellite was abandoned.[3]
Instruments
- Cylindrical Electrostatic Probes
- Electron Temperature
- Energetic Electron Current Monitor
- Ion Mass Spectrometer
- Magnetic Ion-Mass Spectrometer
- Thermal Electron Probe
- Thermal Ion Probe
Experiments
Cylindrical Electrostatic Probes
The cylindrical electrostatic probes were used to measure electron temperature and density in the ionosphere. Each sensor was basically a Langmuir probe consisting of a collector electrode extending from the central axis of a cylindrical guard ring. The guard rings extended 23 cm (9.1 in) from the spacecraft and the collector electrode extended 46 cm (18 in). The two sensors were mounted on opposite sides of the spacecraft, and were perpendicular to the spin axis and in the orbit plane.[4]
Electron Temperature
The purpose of the electron temperature probe was to measure the energy distribution of ionospheric electrons. From these measurements electron temperature and density could be derived. The sensor was a disk, 2 cm (0.79 in) in diameter, mounted flush with the satellite surface. The probe current-voltage characteristics were investigated by means of the same modulation technique that was used in the spherical ion-mass spectrometer.[5]
Energetic Electron Current Monitor
The purpose of this experiment was to measure the electron energy spectrum in the suprathermal energy range of 0.2 to 2000 eV. Two three-grid retarding potential analyzers were used, one providing analog data in the 0.2 to 200 eV range and the other providing digital data in the 0.2 to 2000 eV range. The two analyzers had separate power supplies and associated electronics. The instrumentation for the digital measurement included an electron multiplier and a digital pulse counting system. Because of moisture contamination of the detector in the launch tower prior to launch, the gain of the electron multiplier was so degraded that no geophysical measurements could be obtained. The instrumentation for the analog measurement included a range-changing electrometer. The analog data were plots of the measured current-voltage function. The analog experiment yielded excellent data for 4 months, after which the experiment deteriorated because of radiation damage to its circuitry.[6]
See also
References
- ^ "Launch Log". Jonathan's Space Report. 21 July 2021. Retrieved 9 November 2021.
- ^ "Trajectory: Explorer 31 (DME-A) 1965-098B". NASA. 28 October 2021. Retrieved 9 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ a b c "Display: Explorer 31 (DME-A) 1965-098B". NASA. 28 October 2021. Retrieved 9 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Cylindrical Electrostatic Probes". NASA. 28 October 2021. Retrieved 9 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Electron Temperature". NASA. 28 October 2021. Retrieved 9 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Energetic Electron Current Monitor". NASA. 28 October 2021. Retrieved 9 November 2021. This article incorporates text from this source, which is in the public domain.