Spacecraft spin stabilization using a transverse wheel for any inertia ratio

Hughes Space and Communications Company recently launched the first of a se ries of satellites featuring a patented control strategy capable of stabili zing spin about a given spacecraft axis, regardless of spin-to-transverse i nertia ratio. The control system, which functions during the ascent phase o f the mission, makes use of on-station control hardware, a gyro and a trans verse reaction wheel, to stabilize spin. This is believed to be the first i nstance of stabilization of spin with arbitrary inertia ratio using a singl e transverse wheel. For stability reasons, these satellites are the first H ughes satellites to spin negatively in transfer orbit. It is paradoxical th at, for some inertia ratios, negative spin can be stabilized when positive spin cannot. Note that, in such cases, even the negative spin, though stabl e, may be technically uncontrollable at one point in the mission. The histo ry of active spin control is discussed, and some global principles for spin stabilization using a single wheel are established. Theory, design, and fl ight experience of the Hughes active spin controller are presented and cont rasted to prior solutions. Finally, ground simulations and Right telemetry are presented and compared.