The Kepler telescope has suffered the loss of two reaction wheels. This means that it cannot use the wheels to control orientation about all three axes.
One option is to use thrusters and reaction wheels at the same time as actuators. Princeton Satellite Systems Core GN&C Bundle does just that.
Aero/Astro vehicle control products.
We’ve simulated the system for the Kepler spacecraft
You can see a movie of a reorientation here: