spase://SMWG/Observatory/DynamicsExplorer1

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.
     
      The spacecraft approximated a short polygon 137 cm
      in diameter and 115 cm high. The antennas in the X-Y plane
      measured 200-m tip-to-tip, and on the Z-axis are 9 meters tip-
      to-tip. Two six-meter 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 ten plus or minus 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 (81-070A-02).
     
      On October 22, 1990 science operations were terminated. On
      February 28, 1991 Dynamics Explorer 1 operations were
      offically terminated.
     
      Additional details may be found in R. A.
      Hoffman et al., Space Sci. Instrum., v. 5, n. 4, p. 349, 1981.