The Polar Satellite is a satellite launched by NASA on February 24 1996 aboard a Boeing Delta II rocket from Vandenberg Air Force Base in California, to observe the polar magnetosphere. Polar is in a highly elliptical, 86 deg inclination orbit with a period of about 17.5 hours. It gathers multi-wavelength imaging of the aurora, and measures the entry of plasma into the polar magentosphere and the geomagnetic tail, the flow of plasma to and from the ionosphere, and the deposition of particle energy in the ionosphere and upper atmosphere.
