the reaction wheels have failed on a number previous missions, it appears to be down to solar storms inducing current in the spacecraft and arcing across the bearings causing pitting, and so increased friction.
I don't think they can know for sure, however the bearings have been designed with this in mind using ceramics. Also I just realised with the JSWT going around the L2 point it won't be cutting through the Earth's magnetic field, mind you it will be exposed to the direct solar wind.
I don't think they can know for sure, however the bearings have been designed with this in mind using ceramics. Also I just realised with the JSWT going around the L2 point it won't be cutting through the Earth's magnetic field, mind you it will be exposed to the direct solar wind.