11. Before hibernation, two of the spacecraft's four reaction wheels began exhibiting " noise ". 12. For this reason, reaction wheels are often used to aim spacecraft carrying cameras or telescopes. 13. Reaction wheels resist changes in orientation due to torque.14. The orbit was sun-synchronous, and the attitude of the spacecraft could be controlled through reaction wheels . 15. In 2004, during the mission of the " Hayabusa " spacecraft, an X-axis reaction wheel failed. 16. The ROSAT reaction wheels lasted over 8 years. 17. Ground controllers grew concerned when one of the reaction wheels turned sluggishly in response to their commands. 18. Attitude is adjusted through three reaction wheels . 19. However, it also has a set of actual spinning reaction wheels to turn the telescope without using propellant. 20. On July 14, 2012, one of the four reaction wheels used for fine pointing of the spacecraft failed.
