Dynamics Explorer 1

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
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
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. 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.

Mission

An aurora as seen by one of the Dynamics Explorers

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.

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.

Instrumentation

Dynamics Explorer 1 carried the following instruments:

• 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.

Launch

Explorer 62 was launched on 3 August 1981, at 09:56 UTC from Vandeberg Air Force Base,

Regions traversed

Ionosphere, magnetosphere, plasmapause, plasmasphere, and trapped particle belts.

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.

See also

• Explorer program

External links

• Dynamics Explorer image gallery