Examples of Dual-Spin Satellites

A large number of dual-spin satellites were built by Hughes Space and Communications Company, which was bought by Boeing in 2000.  A complete manifest of Boeing satellites is given here.

The GOES D-H weather satellites launched between 1980 and 1987 had a despun antenna section.

The Boeing 376 series of satellites also used a dual-spin configuration.  A few examples are the Anik C communications satellites.  These were launched on the shuttle:

Anik C-3, 1982, STS-5: mission details and video

Anik C-2, 1983, STS-7: mission details and video

Anik C-1, 1985, STS-51D: mission details and video

Another good example of several satellite deployments was on STS-51G: mission details and video.

Note that the videos of deployment from the shuttle show the satellites in stowed configuration in a spin-stabilized mode for the Payload Assist Module.  They don't actually show the dual-spin operation.

Three-Axis Stabilization

Honeywell Aerospace's line of reaction wheels and CMGs.

Astrium's CMG.

Attitude Acquisition by Barba & Aubrun

Barba & Aubrun ("Satellite Attitude Acquisition by Momentum Transfer", AIAA Journal, 1976) describe the initial attitude acquisition out of a spin-stabilized configuration by applying a constant torque to a reaction wheel.  This animation shows the behavior of the momentum sphere (for the entire system, which is constant) and the energy ellipse (for just the spacecraft body, which is not constant) for the maneuver.  The animation uses the same inertias, initial conditions, and torque values as Fig. 3 of Barba & Aubrun.  The maneuver brings the spacecraft nearly to rest from a spin-stabilized configuration, and the angular momentum of the wheel is increased.  This explains the reduction in size and offset of the energy ellipsoid through the maneuver.

From the equations of motion (Eqs. (8) in Barba & Aubrun), the reaction-wheel motor applies a positive torque to the wheel and a torque in the negative b2 direction to the spacecraft body.  As seen in Fig. 3, the b2 component of angular velocity is positive throughout the maneuver.  Therefore, this torque does negative work on the spacecraft body, again explaining the reduction in size of the energy ellipsoid.

The b2 component of angular velocity, however, has been brought to zero at the end of the maneuver.  If the motor torque was continued, the b2 component of angular velocity would become negative.  The motor would start doing positive work on the spacecraft.  The energy ellipsoid would continue shifting, but also start growing in size.  The left edge would stay "stuck" inside the momentum sphere.

(In the animation, the label of the h2 axis is cut off.  Also, you may have to save the file to your hard drive to play it, due to the codec it uses.)