Dynamics Explorer was a NASA mission, launched on 3 August 1981, involving two spacecraft to study the interaction between the hot, thin, convecting plasma of Earth's magnetosphere and the cooler, denser plasmas and gases co-rotating in the ionosphere and upper atmosphere. DE 1 and DE 2 were launched together and placed in polar coplanar orbits to allow simultaneous measurements at high and low altitudes in the same field-line region.

The spacecraft approximated a short polygon 137 centimeters in diameter and 115 centimeters high. The antennas in the x-y plane measured 200 meters tip-to-tip, and on the z-axis 9 meters tip-to-tip. Two 6-m booms were provided for remote measurements. Science operations continued over a nine-year period until terminated on 22 October 1990. The spacecraft were also known as Explorer 62 and 63.