REX

REX (Radiation Experiment) or ISES (Integrated Space Experiment System) is an Air Force Rome Laboratory ionospheric research satellite which will test the effects of the atmosphere on radio transmissions, and will employ GPS for on-board navigation and attitude control. The spacecraft was gravity gradient stabilized (approx. 5 degrees control) using a 6 m boom and 2.5 kg tip mass. Minor control was provided by three axis torque coils.