Category: Control Systems

Reaction wheels are used to point spacecraft where you want them to point. They don’t provide as much torque as Control Moment Gyroscopes (CMGs) and they require more power for the torque you get, but they’re smaller and lighter than CMGs. In fact, if CubeSat and small satellites have any kind of wheel, it’s a…

Reaction wheels are the most common approach for small spacecraft. Gyroscopes are the most common approach for medium to large spacecraft.

There are not many options because the market is not that large and they tend to require analysis and resources not compatible with “off the shelf” solutions.

A Control Moment Gyroscope is just a wheel attached to a motor. The whole thing can be flipped in different directions with different motors to make your spacecraft twist. The wheel is usually heavy and spins at a high speed that does not change.

This article looks at the properties of reaction wheels you can buy. You may find some of the equations and data useful as you consider how to design your own system.

For the most part, this is a “solved” problem. There are thousands of spacecraft and most all of them are using some combination of a handful of options.