NASA's Swift Observatory may have suffered an attitude control failure

NASA's Neil Gehrels Swift Observatory has run into difficulties after 17 years of largely smooth service. The orbiting explorer has entered safe mode after detecting a "possible failure" in one of the six reaction wheels used to change attitude. While it's not clear exactly what (if anything) went wrong, NASA has halted direction-based scientific observations until it can either give the all-clear or continue operations with five wheels.