Hubble went into safe mode May 24 due to an ongoing issue with one of its gyroscopes (gyros), which measure the telescope’s slew rates and are part of the system that determines and controls the direction the telescope is pointed. The gyro had been increasingly returning faulty readings over the past six months, suspending science operations multiple times. This led the Hubble team to transition from a three-gyro operating mode to observing with only one gyro, enabling more consistent science observations and keeping another operational gyro available for future use. The agency discussed this transition in detail during a media teleconference June 4.