Dynamics Explorer

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Dynamics Explorer 1
NamesExplorer 62
DE-A
Dynamics Explorer-A
Mission typeSpace physics
OperatorNASA
COSPAR ID1981-070A
SATCAT no.12624
Spacecraft properties
SpacecraftExplorer LXII
Launch mass424 kg (935 lb)
Dimensions137 cm (54 in) in diameter and 115 cm (45 in) high
Power86 watts
Start of mission
Launch date3 August 1981, 09:56 UTC
RocketThor-Delta 3913
(Thor 642 / Delta 155)
Launch siteVandenberg, SLC-2W
ContractorDouglas Aircraft Company
Entered service3 August 1981
End of mission
Deactivated28 February 1991
Last contact28 February 1991
Orbital parameters
Reference systemGeocentric orbit
RegimeHighly elliptical orbit
Perigee567.60 km (352.69 mi)
Apogee23,289.00 km (14,471.11 mi)
Inclination89.90°
Period409.00 minutes
Instruments
Energetic Ion Composition Spectrometer (EICS)
High Altitude Plasma Instrument (HAPI)
Magnetic Field Observations Triaxial Fluxgate Magnetometer (MAG-A)
Plasma Wave Instrument (PWI)
Retarding Ion Mass Spectrometer (RIMS)
Spin-scan Auroral Imager (SAI)
Explorer program
← Explorer 61 (Magsat)
Explorer 63 (Dynamics Explorer 2) →
 


Dynamics Explorer 2
NamesExplorer 63
Dynamics Explorer-B
Mission typeSpace physics
OperatorNASA
COSPAR ID1981-070B
SATCAT no.12625
Spacecraft properties
SpacecraftExplorer LXIII
Launch mass420 kg (930 lb)
Dimensions137 cm (54 in) in diameter and 115 cm (45 in) high
Power115 watts
Start of mission
Launch date3 August 1981, 09:56 UTC
RocketThor-Delta 3913
(Thor 642 / Delta 155)
Launch siteVandenberg, SLC-2W
ContractorDouglas Aircraft Company
Entered service3 August 1981
End of mission
Decay date19 February 1983
Orbital parameters
Reference systemGeocentric orbit[1]
RegimeLow Earth orbit
Perigee309 km (192 mi)
Apogee1,012 km (629 mi)
Inclination89.99°
Period98.00 minutes
Instruments
Fabry–Pérot interferometer (FPI)
Ion Drift Meter
Langmuir probe
Low-altitude Plasma Instrument
Magnetometer
Neutral Atmosphere Composition Spectrometer
Retarding Potential Analyzer
Vector Electric Field Instrument
Wind and Temperature Spectrometer (WATS)
Explorer program
← Explorer 62 (Dynamics Explorer 1)
Explorer 64 (Solar Mesophere Explorer) →
 

Dynamics Explorer (DE-1 and DE-2 or Explorer 62 and Explorer 63) was a NASA mission, launched on 3 August 1981, and terminated on 28 February 1991.[2] It consisted of two unmanned 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[edit]

An aurora as seen by one of the Dynamics Explorers

The Dynamics Explorer (DE) 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[edit]

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]

Dynamics Explorer 1 Instrumentation[edit]

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.

Regions traversed[edit]

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

Dynamics Explorer 2 Instrumentation[edit]

The Dynamics Explorer 2 carried the following instruments for data collection:

  • Fabry–Pérot interferometer (FPI), which measured the meridional component of the neutral winds.[4] (The meridional wind component is the component in the direction of lines of longitude - i.e. North–South.)
  • Ion Drift Meter
  • Langmuir probe
  • Low-altitude Plasma Instrument
  • Magnetometer
  • Neutral Atmosphere Composition Spectrometer
  • Retarding Potential Analyzer, which measured the ion flux along the velocity vector of the spacecraft. This data was then used to determine the ion temperature and drift velocity in the spacecraft's area.[5]
  • Vector Electric Field Instrument
  • Wind and Temperature Spectrometer (WATS), which measured the zonal and vertical components of the neutral winds, as well as the kinetic temperature.[4] (The zonal wind component is the component in the direction of lines of latitude - i.e. East–West.) The WATS instrument on DE-2 is one of the few satellite instruments which has measured thermosphere vertical wind speeds, with the Neutral Atmosphere Temperature Experiment (NATE).[6] on Atmospheric Explorer C (AE-C) being one other.

Mission results[edit]

As a result of a malfunction in the Thor-Delta 3913 launch vehicle in which its main engine shut off slightly early, DE-2 was placed into a slightly lower orbit than was anticipated. This was not a serious problem, however, and the spacecraft had lasted its expected lifespan when it re-entered the Earth's atmosphere on 19 February 1983.

Atmospheric entry[edit]

DE-1, being in a higher orbit, continued to collect data until 28 February 1991, when the mission was officially terminated.

See also[edit]


Other articles of the topic Spaceflight : Northern Virginia Astronomy Club, List of largest stars, TMRO, Falcon 9 booster B1019, GASPACS, Mars Moon eXploration (MMX) rover, Ariane flight VA253
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  • Explorer program

References[edit]

  1. "Explorer 62 (DE-1) 1981-070A". NASA. 28 October 2021. Retrieved 22 November 2021. This article incorporates text from this source, which is in the public domain.
  2. DE (Dynamics Explorer)
  3. 3.0 3.1 3.2 3.3 "Explorer 62 (DE-1) 1981-070A". NASA. 28 October 2021. Retrieved 22 November 2021. This article incorporates text from this source, which is in the public domain.
  4. 4.0 4.1 Spencer, N. W., Wharton, L. E., Carignan, G. R. and Maurer, J. C. (1982), Thermosphere zonal winds, vertical motions and temperature as measured from Dynamics Explorer. Geophys. Res. Lett., 9: 953–956. doi:10.1029/GL009i009p00953.
  5. Dynamics Explorer 2 Archived 2007-03-15 at the Wayback Machine
  6. Spencer, N. W., Theis, R. F., Wharton, L. E. and Carignan, G. R. (1976), Local vertical motions and kinetic temperature from AE-C as evidence for aurora-induced gravity waves. Geophys. Res. Lett., 3: 313–316. doi:10.1029/GL003i006p00313.

External links[edit]


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