Dynamics Explorer 1
| Names | Explorer 62 DE-A Dynamics Explorer-A |
|---|---|
| Mission type | Space physics |
| Operator | NASA |
| COSPAR ID | 1981-070A |
| SATCAT no. | 12624 |
| Mission duration | 1 year (planned) |
| Spacecraft properties | |
| Spacecraft | Explorer LXII |
| Launch mass | 424 kg (935 lb) |
| Dimensions | 137 cm (54 in) in diameter and 115 cm (45 in) high |
| Power | 86 watts |
| Start of mission | |
| Launch date | 3 August 1981, 09:56 UTC |
| Rocket | Thor-Delta 3913 (Thor 642 / Delta 155) |
| Launch site | Vandenberg, SLC-2W |
| Contractor | Douglas Aircraft Company |
| Entered service | 3 August 1981 |
| End of mission | |
| Deactivated | 28 February 1991 |
| Last contact | 28 February 1991 |
| Orbital parameters | |
| Reference system | Geocentric orbit [1] |
| Regime | Highly elliptical orbit |
| Perigee altitude | 567.60 km (352.69 mi) |
| Apogee altitude | 23,289.00 km (14,471.11 mi) |
| Inclination | 89.90° |
| Period | 409.00 minutes |
| Instruments | |
| Auroral Physics Theory Controlled and Naturally Occurring Wave Particle Interactions Theory Energetic Ion Composition Spectrometer (EICS) High Altitude Plasma Instrument (HAPI) | |
Explorer program | |
Dynamics Explorer 1 (DE-1 or Explorer 62) was a NASA mission, launched on 3 August 1981, and terminated on 28 February 1991.[2] It consisted of two satellites, DE-1 and DE-2, whose purpose was to investigate the interactions between plasmas in the magnetosphere and those in the ionosphere. The two satellites were launched together into polar coplanar orbits, which allowed them to simultaneously observe the upper and lower parts of the atmosphere.[3]
Mission
The Dynamics Explorer mission's general objective is to investigate the strong interactive processes coupling the hot, tenuous, convecting plasmas of the magnetosphere and the cooler, denser plasmas and gases corotating in the Earth's ionosphere, upper atmosphere, and plasmasphere. Two satellites, DE-1 and DE-2, were launched together and were placed in polar coplanar orbits, permitting simultaneous measurements at high and low altitudes in the same field-line region. The DE-1 spacecraft (high-altitude mission) uses an elliptical orbit selected to allow: (1) measurements extending from the hot magnetospheric plasma through the plasmasphere to the cool ionosphere; (2) global auroral imaging, wave measurements in the heart of the magnetosphere, and crossing of auroral field lines at several Earth radii; and (3) measurements for significant periods along a magnetic field flux tube.[3]
Spacecraft
The spacecraft approximated a short polygon {{cvt|137|cm} in diameter and 115 cm (45 in) high. The antennas in the X-Y plane measured 200 cm (79 in) tip-to-tip, and on the Z-axis are 9 m (30 ft) tip-to-tip. Two 6 m (20 ft) booms are provided for remote measurements. Power is supplied by a solar cell array, mounted on the side and end panels. The spacecraft is spin-stabilized, with the spin axis normal to the orbital plane, and the spin rate at 10 ± 0.1 rpm. A pulse-code modulation (PCM) telemetry data system is used that operates in real time or in a tape recorder mode. Data have been acquired on a science-problem-oriented basis, with closely coordinated operations of the various instruments, both satellites, and supportive experiments. Data acquired from the instruments are temporarily stored on tape recorders before transmission at an 8:1 playback-to-record ratio. Additional operational flexibility allows a playback-to-record ratio of 4:1. The primary data rate is 16,384 bits per second. Since commands are stored in a command memory unit, spacecraft operations are not real time, except for the transmission of the wideband analog data from the Plasma Wave Instrument (1981-070A-02). On 22 October 1990, the science operations were terminated. On 28 February 1991, Dynamics Explorer 1 operations were offically terminated.[3]
Instrumentation
Dynamics Explorer 1 carried the following instruments:[3]
- Energetic Ion Composition Spectrometer (EICS)
- High Altitude Plasma Instrument (HAPI)
- Magnetic Field Observations Triaxial Fluxgate Magnetometer (MAG-A)
- Plasma Wave Instrument (PWI), which measured auroral kilometric radiation, auroral hiss, Z-mode radiation, and narrow band electromagnetic emissions
- Retarding Ion Mass Spectrometer (RIMS)
- Spin-scan Auroral Imager (SAI)
In addition, there were two Earth-based investigations: Auroral Physics Theory, and, Controlled and Naturally Occurring Wave Particle Interactions Theory. The later involved broadcasting very-low-frequency/low-frequency (0.5–200-kHz) signals from a transmitter located at Siple Station, Antarctica, which were received by the PWI instrument on Dynamics Explorer 1.
Experiments
Auroral Physics Theory
The primary goal of this investigation was to use the results from other experiments, particularly 1981-070A-03, to test theoretical models and to develop new ones, with emphasis on research areas related to auroral arcs, field-aligned currents, plasma wave turbulence associated with anomalous resistance, generation of auroral electron beams, production of kilometric and VLF hiss radiation. In addition, correlation studies were organized by selecting events that were interesting to the various investigators, and data reduction procedures were suggested to facilitate comparison and interpretation of the data.[4]
Controlled and Naturally Occurring Wave Particle Interactions Theory
This investigation used a ground-based very-low-frequency/low-frequency (VLF/LF) (0.5-200 kHz) transmitter located at Siple Station, Antarctica, at an L value of about 4, and the broad-band magnetic field detector from experiment 1981-070A-02. The primary objective of the investigation was to determine the relationship between VLF/LF waves and energetic electrons in the magnetosphere, with emphasis on wave growth, stimulated emissions, and wave-induced perturbations of the energetic electrons. Other objectives were: (1) to determine how wave propagation from both ground and magnetospheric sources was affected by field-aligned plasma structures such as the plasmapause and ducts of enhanced ionization, (2) to use the wave data to describe the structure of the plasmapause and the distribution of ionization along field-aligned ducts, and (3) to study the effects of Earth power-line radiation and other VLF wave activity. The spacecraft instrumentation for this experiment consisted of the Linear Wave Receiver (LWR) provided by the Plasma Wave Instrument (1981-070A-02). The LWR provided a waveform output with a 30-dB linear amplitude response for bands of 1.5-3.0, 3.11 ± 7.5%, 3-6, or 10-16 kHz for a selected magnetic or electric sensor. This receiver was used to measure growth rates for waves stimulated by the Siple station VLF transmitter or by natural wave phenomena.[5]
Energetic Ion Composition Spectrometer (EICS)
The Energetic Ion Composition Spectrometer (EICS) had high sensitivity and high resolution, and covered the energy range from 0 to 17 keV per unit charge and the mass range from less than 1 to greater than 150 u/Q. This investigation provided data used in investigating the strong coupling mechanism between the magnetosphere and the ionosphere that results in large fluxes of energetic O+ ions being accelerated from the ionosphere and injected into the magnetosphere during magnetic storms. The properties of the minor ionic species such as He+ and He++ relative to the major constituents of the energetic magnetosphere plasma were also studied in order to evaluate the relative importance of the different sources of the plasma and of various energization, transport, and loss processes that may be mass-or charge-dependent. One of the primary objectives was to measure the energy and pitch angle distributions of the principal mass constituents (O+ and H+) of the upward flowing ions from the auroral acceleration region. An important area for study was the cusp region. The instrument was similar to one flown on the ISEE-1 satellite, and consisted of a curved-plate electrostatic energy analyzer, followed by a combined cylindrical electrostatic-magnetic mass analyzer. Open electron multipliers were used with pulse-amplitude discrimination as the mass analyzer detectors in order to improve the mass separation characteristics of the spectrometer. The energy resolution, (delta E)/E (internal), was 5%. The mass resolution M/(delta M) was less than or equal to 10 on the focus line. Time resolution was 32 samples per second.[6]
High Altitude Plasma Instrument (HAPI)
The High Altitude Plasma Instrument (HAPI) consisted of an array of five electrostatic analyzers capable of making measurements of the phase-space distributions of electrons and positive ions in the energy/charge range from 5 eV to 32 keV as a function of pitch angle. This investigation provided data contributing to the studies of (1) the composition and energy of Birkeland current charge carriers, (2) the dynamic configuration of high-latitude magnetic flux tubes, (3) auroral particle source regions and acceleration mechanisms, (4) the role of E parallel to B and E perpendicular to B in the magnetosphere-ionosphere system, (5) the sources and the effects of polar cap particle fluxes, (6) the transport of plasma within and through the magnetospheric clefts, (7) wave-particle interactions, and (8) hot-cold plasma interactions. This instrument consisted of five identical detector heads, each having an electrostatic analyzer (of the ISIS-2 type) and two sensors (one electron channel and one ion channel). The detector heads were mounted on the main body. One of the detector heads was mounted in the spin plane, two were offset by ± 12°, and two were offset by ± 45°. One detector swept within a few degree of the field line during each rotation of the spacecraft, except when the magnetic field was greatly deformed from its meridian plane. The basic mode of operation provided a 32-point energy spectrum from each sensor, but the voltages on the electrostatic analyzers were programmable to allow for operation over limited portions of the energy spectrum, or at higher time resolution with reduced energy resolution. The energy resolution was 32%. The angular resolution was 2.5° Full width at half maximum (FWHM) (in the plane of detection) by 10° (polar angle). The sampling rate was 64 per second, and the total acceptance angle was 5° by 20°. Due to a failure in the high voltage power supply for the detectors, the instrument ceased operation on 1 December 1981.[7]
Launch
Explorer 62 was launched on 3 August 1981, at 09:56 UTC from Vandeberg Air Force Base,
Mission results
As a result of a malfunction in the Thor-Delta 3913 launch vehicle in which its main engine shut off slightly early. Dynamics Explorer 1, being in a higher orbit, continued to collect data until 28 February 1991, when the mission was officially terminated.[8]
See also
References
- ^ "Trajectory: Explorer 62 (DE-1) 1981-070A". NASA. 28 October 2021. Retrieved 23 November 2021.
This article incorporates text from this source, which is in the public domain.
- ^ DE (Dynamics Explorer)
- ^ a b c d "Display: Explorer 62 (DE-1) 1981-070A". NASA. 28 October 2021. Retrieved 23 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Auroral Physics Theory". NASA. 28 October 2021. Retrieved 23 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Controlled and Naturally Occurring Wave Particle Interactions Theory". NASA. 28 October 2021. Retrieved 23 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Energetic Ion Composition Spectrometer (EICS)". NASA. 28 October 2021. Retrieved 23 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: High Altitude Plasma Instrument (HAPI)". NASA. 28 October 2021. Retrieved 23 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ DE (Dynamics Explorer)
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