Hubble in Safe Mode as Gyro Issues are Diagnosed

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bystander
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Hubble in Safe Mode as Gyro Issues are Diagnosed

Post by bystander » Tue Oct 09, 2018 5:43 pm

Hubble in Safe Mode as Gyro Issues are Diagnosed
NASA | Goddard | Hubble | 2018 Oct 08

NASA is working to resume science operations of the Hubble Space Telescope after the spacecraft entered safe mode on Friday, October 5, shortly after 6:00 p.m. EDT. Hubble’s instruments still are fully operational and are expected to produce excellent science for years to come.

Hubble entered safe mode after one of the three gyroscopes (gyros) actively being used to point and steady the telescope failed. Safe mode puts the telescope into a stable configuration until ground control can correct the issue and return the mission to normal operation.

Built with multiple redundancies, Hubble had six new gyros installed during Servicing Mission-4 in 2009. Hubble usually uses three gyros at a time for maximum efficiency, but can continue to make scientific observations with just one.

The gyro that failed had been exhibiting end-of-life behavior for approximately a year, and its failure was not unexpected; two other gyros of the same type had already failed. The remaining three gyros available for use are technically enhanced and therefore expected to have significantly longer operational lives.

Two of those enhanced gyros are currently running. Upon powering on the third enhanced gyro that had been held in reserve, analysis of spacecraft telemetry indicated that it was not performing at the level required for operations. As a result, Hubble remains in safe mode. Staff at NASA’s Goddard Space Flight Center and the Space Telescope Science Institute are currently performing analyses and tests to determine what options are available to recover the gyro to operational performance.

Science operations with Hubble have been suspended while NASA investigates the anomaly. An Anomaly Review Board, including experts from the Hubble team and industry familiar with the design and performance of this type of gyro, is being formed to investigate this issue and develop the recovery plan. If the outcome of this investigation results in recovery of the malfunctioning gyro, Hubble will resume science operations in its standard three-gyro configuration.

If the outcome indicates that the gyro is not usable, Hubble will resume science operations in an already defined “reduced-gyro” mode that uses only one gyro. While reduced-gyro mode offers less sky coverage at any particular time, there is relatively limited impact on the overall scientific capabilities.
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Update on the Hubble Space Telescope Safe Mode

Post by bystander » Sat Oct 13, 2018 12:27 am

Update on the Hubble Space Telescope Safe Mode
NASA | GSFC | Hubble | 2018 Oct 12

NASA continues to work toward resuming science operations of the Hubble Space Telescope after the spacecraft entered safe mode due to a failed gyroscope (gyro) on Friday, Oct. 5.

Following the gyro failure, the Hubble operations team turned on a backup gyro on the spacecraft. However, that gyro did not perform as expected, reporting rotation rates that are orders of magnitude higher than they actually are. This past week, tests were conducted to assess the condition of that backup gyro. The tests showed that the gyro is properly tracking Hubble’s movement, but the rates reported are consistently higher than the true rates. This is similar to a speedometer on your car continuously showing that your speed is 100 miles per hour faster than it actually is; it properly shows when your car speeds up or slows down, and by how much, but the actual speed is inaccurate.

When the spacecraft turns across the sky from one target to the next, the gyro is put into a coarser (high) mode. In this high mode it may be possible to subtract out a consistent large offset to get an accurate reading. However, after the large turns are over, the spacecraft attempts to lock onto a target and stay very still. For this activity, the gyro goes into a precision (low) mode to measure very small movements. The extremely high rates currently being reported exceed the upper limit of the gyro in this low mode, preventing the gyro from reporting the spacecraft’s small movements.

An anomaly review board that consists of professionals experienced in the manufacturing of such gyros, Hubble operations personnel, flight software engineers and other experts was formed earlier this week to identify the cause of this behavior and determine what solutions can be implemented from the ground to correct or compensate for it. ...
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

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neufer
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Re: Update on the Hubble Space Telescope Safe Mode

Post by neufer » Sun Oct 14, 2018 5:29 pm

bystander wrote:
Sat Oct 13, 2018 12:27 am
Update on the Hubble Space Telescope Safe Mode
NASA | GSFC | Hubble | 2018 Oct 12
NASA continues to work toward resuming science operations of the Hubble Space Telescope after the spacecraft entered safe mode due to a failed gyroscope (gyro) on Friday, Oct. 5.

Following the gyro failure, the Hubble operations team turned on a backup gyro on the spacecraft. However, that gyro did not perform as expected, reporting rotation rates that are orders of magnitude higher than they actually are. This past week, tests were conducted to assess the condition of that backup gyro. The tests showed that the gyro is properly tracking Hubble’s movement, but the rates reported are consistently higher than the true rates. This is similar to a speedometer on your car continuously showing that your speed is 100 miles per hour faster than it actually is; it properly shows when your car speeds up or slows down, and by how much, but the actual speed is inaccurate. When the spacecraft turns across the sky from one target to the next, the gyro is put into a coarser (high) mode. In this high mode it may be possible to subtract out a consistent large offset to get an accurate reading. However, after the large turns are over, the spacecraft attempts to lock onto a target and stay very still. For this activity, the gyro goes into a precision (low) mode to measure very small movements. The extremely high rates currently being reported exceed the upper limit of the gyro in this low mode, preventing the gyro from reporting the spacecraft’s small movements.
https://en.wikipedia.org/wiki/Gyro_Gearloose wrote:


<<Gyro Gearloose is an anthropomorphic chicken created by Carl Barks for The Walt Disney Company. He is a friend of Donald Duck, Scrooge McDuck and anyone who is associated with them.

Gyro is Duckburg's most famous inventor, even though his inventions don't always work the way he wants them to. His outrageous productivity is presented as a factor in the quality of his inventions; because he always comes up with new ideas, the fact that his inventions often lack an important feature, will often cause trouble for Scrooge or Donald who have bought the invention. Gyro is often assisted by his Little Helper, who is a small anthropomorphic robot with a light bulb for a head. Besides Little Helper, he has also a "thinking cap", a hat shaped like a combination of a roof-top and a nest, with three black birds living in it. Wearing this thinking cap helps Gyro figure out particularly difficult problems, but it only works if the birds are currently nesting in the cap. Some stories have involved the birds leaving Gyro's thinking cap, resulting in the cap becoming ineffective. Some of Gyro's relatives include his father Fulton Gearloose, his grandfather Ratchet Gearloose, and Newton Gearloose, his nephew.>>
Art Neuendorffer