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Iconic Planet-Hunting Kepler Telescope Wakes Up, Phones Home (space.com)
Kepler, which has discovered about 70 percent of the 3,800 known exoplanets to date, woke up from a four-week hibernation yesterday and has begun beaming data home, just as planned, NASA officials announced today. From a report: Kepler had been sleeping in an attempt to save thruster fuel, which is running very low. Mission team members wanted to make sure the spacecraft had enough propellant left to orient its antenna toward Earth for yesterday's data dump. Far-flung NASA spacecraft send information back to mission controllers via the agency's Deep Space Network (DSN), a system of radio dishes around the globe. The sun-orbiting Kepler's latest allotted DSN window opened yesterday, agency officials have said.
OY VEY! Kepler has reaction wheels that do exactly as you suggest, as have all similar spacecraft for many decades.
The problem with Kepler is that the reaction wheel bearings failed on multiple wheels, so they had to use the thrusters exclusively, which it did for a long time now, and now, finally, they are running out.
Despite that, it was designed for a 3 and a half year mission and it is still functioning after more than 9 years.
It's really hard to see this as any sort of failure.