NASA has confirmed it is working to resume science operations on the Hubble Space Telescope after an ongoing gyroscope issue put it in safe mode.

According to NASA, the instruments are stable and telescope is in good health, but a faulty reading from one of its gyros caused it to automatically enter safe mode, suspending science operations once again, on November 23rd.

Directions to resume operations must come from the ground.

Among the paused instruments onboard are an advanced camera for surveys, a cosmic origins spectograph, a space telescope imaging spectrograph, wide field camera, fine guidance sensor and near infrared camera and multi-object spectrometer.

The November 23rd incident was the third time in a week such incident had occurred. The misbehaving gyro caused the space telescope to enter safe mode on November 19th and November 21st. Both incidents were recoverable.

However, its now apparent that gyro is going to need some fixing. NASA revealed it is running tests to understand the issue and come up with a solution.

Hubble can operate with one gyro rather than its normal six, or current three operational ones, but having three working gyros is more efficient than one.

The gyros are needed to point the telescope. They measure the speed Hubble is turning as it shifts between targets and help the spacecraft aim. Each gyro contains a wheel, which is mounted in a sealed cylinder that is floating in a thick fluid, that spins at 19,200 rotations per minute on gas bearings. Electronics inside the gyro detect small movements from the wheel's axis.

Hubble has so far had a good 33-year run. It was last serviced in 2009, when it had its six gyros installed in a 12-day space shuttle mission. At that time, it also received new batteries, a science computer, a refurbished fine guidance sensor, new insulation on three electronic bays and a device added to its base to facilitate its de-orbit when it is finally put out to pasture.

NASA said it "anticipates" Hubble will continue throughout this decade and possibly into the next. The space telescope is currently migrating from its intended orbit thanks to atmospheric drag. It is expected to drop to 500 kilometers above Earth by 2025 after being placed at 569 km in 1990. At the rate it is falling and failing any fixes, it could reenter Earth's atmosphere in the mid-30s. ®

https://www.theregister.com//2023/11/30/hubble_science_instruments_down_for/