October 22, 2018 – NASA took nice strides final week to press into service a Hubble House Telescope backup gyroscope (gyro) that was incorrectly returning extraordinarily excessive rotation charges. The backup gyro was turned on after the spacecraft entered protected mode as a consequence of a failed gyro on Friday, October 5. The rotation charges produced by the backup gyro have since decreased and at the moment are inside an anticipated vary. Further assessments can be carried out to make sure Hubble can return to science operations with this gyro.
A gyro is a tool that measures the pace at which the spacecraft is popping, and is required to assist Hubble flip and lock on to new targets.
A wheel contained in the gyro spins at a continuing charge of 19,200 revolutions per minute. This wheel is mounted in a sealed cylinder, referred to as a float, which is suspended in a thick fluid. Electrical energy is carried to the motor by skinny wires, roughly the dimensions of a human hair, which might be immersed within the fluid. Electronics throughout the gyro detect very small actions of the axis of the wheel and talk this data to Hubble’s central pc. These gyros have two modes — excessive and low. Excessive mode is a rough mode used to measure massive rotation charges when the spacecraft turns throughout the sky from one goal to the subsequent. Low mode is a precision mode used to measure finer rotations when the spacecraft locks onto a goal and desires to remain very nonetheless.
In an try to appropriate the erroneously excessive charges produced by the backup gyro, the Hubble operations group executed a operating restart of the gyro on October 16. This process turned the gyro off for one second, after which restarted it earlier than the wheel spun down. The intention was to clear any faults that will have occurred throughout startup on October 6, after the gyro had been off for greater than 7.5 years. Nevertheless, the ensuing information confirmed no enchancment within the gyro’s efficiency.
On October 18, the Hubble operations group commanded a sequence of spacecraft maneuvers, or turns, in reverse instructions to aim to clear any blockage that will have triggered the float to be off-center and produce the exceedingly excessive charges. Throughout every maneuver, the gyro was switched from excessive mode to low mode to dislodge any blockage that will have accrued across the float.
Following the October 18 maneuvers, the group seen a big discount within the excessive charges, permitting charges to be measured in low mode for temporary intervals of time. On October 19, the operations group commanded Hubble to carry out extra maneuvers and gyro mode switches, which seem to have cleared the problem. Gyro charges now look regular in each excessive and low mode.
Hubble then executed extra maneuvers to make it possible for the gyro remained secure inside operational limits because the spacecraft moved. The group noticed no issues and continued to watch the gyro via the weekend to make sure that it remained secure.
The Hubble operations group plans to execute a sequence of assessments to judge the efficiency of the gyro underneath situations just like these encountered throughout routine science observations, together with shifting to targets, locking on to a goal, and performing precision pointing. After these engineering assessments have been accomplished, Hubble is anticipated to quickly return to regular science operations.
Hubble is managed and operated at NASA’s Goddard House Flight Middle in Greenbelt, Maryland.