[narby]

I saw that program. The difficulty would be with those instruments that depend on magnetic north to perform correctly (navigation systems, some satellites, etc).

I worked at JPL writing software, and performing spacecraft controller duties for the AMPTE project in the early 80's. It was "torqued" to point toward the sun by powering up magnetic coils to work against the earths magnetic field.

I never worked on another spacecraft, and I've never heard technical details on others, so I don't know how common this positioning system is.

[RadioAstronomer]

I never worked on another spacecraft, and I've never heard technical details on others, so I don't know how common this positioning system is.

Usually torque rods are used to unload momentum in a reaction wheel system (or gas jet) for attitude control. This is primarily used in low Earth orbiters as apposed to high altitude platforms such as geosync. Torque rods are quite common.