The Hubble iconic telescope stops working, but should work normally

JACKSONVILLE, Fla. NASA is working on the resumption of the Hubble Space Telescope's scientific operations after the satellite entered safe mode on Friday, October 5, shortly after 18:00. Hubble's instruments are still fully operational and are expected to produce excellent scientific data for years to come.

Hubble went into safe mode after one of three actively used gyroscopes (gyroscopes) to point and immobilize the failed telescope. Safe Mode places the telescope in a stable configuration until ground control can correct the problem and return the mission to normal operation.

Built with multiple redundancies, Hubble installed six new gyroscopes during maintenance mission 4 in 2009. Hubble typically uses three gyroscopes at a time for maximum efficiency, but can continue to make scientific observations with one.

The failed gyroscope had end-of-life behavior for about a year and its failure was not surprising; two other gyroscopes of the same type had already failed. The other three gyroscopes available are technically improved and should therefore last much longer.

Two of these improved gyroscopes are currently operating. When turning on the third improved gyroscope that had been put in reserve, the analysis of the spacecraft telemetry showed that it was not working 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 conducting analysis and testing to determine the options available to restore the gyroscope and improve its operational performance.

Scientific operations with Hubble were suspended while NASA was investigating the anomaly. An anomaly review committee, including experts from the Hubble team and industry, familiar with the design and performance of this type of gyroscope, is being formed to investigate this problem. and to develop a recovery plan. If the results of this investigation make it possible to recover the defective gyroscope, Hubble resumes the scientific operations in its standard configuration with three gyroscopes.

If the result indicates that the gyroscope is not usable, Hubble will resume scientific operations in a previously defined "reduced gyro" mode that uses a single gyroscope. Although the reduced gyro mode offers reduced sky coverage at a given time, its impact on all of the science is relatively limited.