Kepler Reaction Wheel Fails, May be Mission Ending
The vaunted Kepler Spacecraft, responsible for the discovery of hundreds of exoplanets, has experienced the failure of it’s final reaction wheel. The spacecraft has four reaction wheels and needs at least three to function properly. The reaction wheels are used to point the spacecraft without using thrusters. This is so that the fuel can be conserved as the reaction wheels use only electricity where as the thrusters use the finite fuel on board. Reaction wheel number 2 had failed a few years ago, leaving the minimum number of three available. Recently reaction wheel number 4 had shown signs of failure. There were current spikes indicating a problem with the wheel bearings. Controllers took some proactive measures, trying to redistribute some of the lubricant in the hopes of prolonging the life of this wheel. Unfortunately on May 14th the spacecraft had placed itself in thruster-Controlled Safe Mode, the second time this month. While recovering the spacecraft reaction wheel 4 remained at full torque while the spin rate dropped to zero. A clear indication that there has [...]
