JPL-Operated Hubble Space Telescope is Back in Business After Backup Gyroscope is Activated

Published : Tuesday, October 30, 2018 | 5:19 AM

This photograph of NASA’s Hubble Space Telescope was taken on the fifth servicing mission to the observatory in 2009. Credits: NASA

NASA’s Hubble Space Telescope, whose original camera and a replacement camera were designed, constructed and managed by the Jet Propulsion Laboratory, returned to normal operations late Friday, October 26, after a three-week break when one of its gyroscopes failed to function.

NASA announced the space telescope completed its first science observations since the breakdown on Saturday, October 27, at 11:10 p.m. The observations were of the distant, star-forming galaxy DSF2237B-1-IR and were taken in infrared wavelengths with the Wide Field Camera 3 instrument.

NASA said the Hubble’s operations team at JPL has successfully recovered a backup gyroscope, or gyro, which they activated remotely on October 6 to replace the gyro that had failed the day before.

Unexpectedly, the backup was turning too fast, in excess of the actual and intended rotation rates, so the team had to test and re-test it, commanding Hubble to perform numerous maneuvers and switching the gyro between different operational modes – procedures that the team believes successfully cleared whatever was causing the excessively high rotation values.

After a number of additional maneuvers to test the gyro’s stability, the team switched the gyro one more time, and then restarted.

On Friday, the team began the process to restore the scientific instruments to standard operating status. Hubble successfully completed maneuvers to get on target for the first science observations, and the telescope collected its first science data since October 5. The space telescope is now back to normal operations mode – with three fully functional gyros, NASA said.

The Hubble’s original camera, the Wide Field/Planetary Camera (WPFC) was designed and constructed by JPL engineers and carried by the space telescope when it launched on April 24, 1990 aboard the space shuttle Discovery from the Kennedy Space Center in Florida.

When the first images from the WPFC – now referred to as WPFC 1 to differentiate it from the two other cameras that followed – came down from Hubble about a month after, it was only then that mission scientists discovered there was a flaw with the camera’s mirror, and the pictures it was taking were not as good as NASA promised.

NASA announced the problem to the world in June 1990, while engineers at JPL looked for a solution.

Former JPL Director Lew Allen, now deceased, chaired a board to investigate the problem, but even as the board was investigating, John Trauger, now a Senior Research Scientist at JPL, proposed to NASA to correct for Hubble’s “spherical aberration” by refiguring small mirrors within WFPC2, a spare camera that JPL had been developing since 1985 as they worked on WFPC1.

Ultimately, Allen’s investigating board found the specific cause of Hubble’s aberration, and Trauger and his team set out to rework the optics of the still-to-be-completed WFPC2.

On December 2, 1993, the space shuttle Atlantis took off from the Goddard Space Flight Center carrying WFPC2. In the days that followed, astronauts retrieved WPFC1 and deployed the new camera on Hubble.

Sixteen days later, the JPL team celebrated with intense joy when the first images from the new camera came down from Hubble – they were so sharp the team knew they had succeeded.

WFPC2 was eventually removed and replaced by Wide Field Camera 3 in May 2009 as part of the mission’s first spacewalk. WFPC2 is now displayed at the Smithsonian’s National Air and Space Museum.

Since the Hubble mission began in 1990, the space telescope has made more than 1.3 million observations and helped publish more than 15,000 scientific papers.

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