Up to date Oct. 23 4:30 p.m. Japanese with Chandra rising from protected mode.
KNOXVILLE, Tenn. — Engineers have made progress correcting a defective gyro on the Hubble Area Telescope, making NASA optimistic the area telescope can resume regular operations within the close to future.
Hubble has been in protected mode for the reason that failure of the third of its six gyroscopes Oct. 5. Whereas the telescope can function usually with simply three gyros, a type of three was not functioning correctly, reporting rotation charges far larger that precise ranges. NASA mentioned on the time that the issue prevented the gyro from precisely monitoring small actions of the observatory in what’s often called “low mode.”
In a presentation on the Oct. 22 assembly of NASA’s Astrophysics Advisory Council, Paul Hertz, director of NASA’s astrophysics division, mentioned engineers had made progress in correcting what are often called “excessive bias charges” with the defective gyro, designated gyro 3.
Engineers, he mentioned, have been “altering among the controls on gyro 3 and have succeeded in decreasing the anomalous excessive bias charges to charges which can be within the usable vary.” Further exams are underway to see if the charges stay in that acceptable vary.
“If all that had been to bear out, then we might be capable of return Hubble to science mode utilizing all three gyros,” he mentioned. He didn’t give a timeframe for resuming regular operations, however mentioned that he anticipated these engineering exams to proceed by means of this week.
In a NASA assertion issued later Oct. 22, the company offered extra particulars about the issue and makes an attempt to repair it. After some efforts, together with turning the gyro off and instantly again on, failed, controllers executed a sequence of spacecraft maneuvers Oct. 18 to attempt to clear any potential blockage throughout the gyro.
“Following the Oct. 18 maneuvers, the workforce seen a major discount within the excessive charges,” NASA acknowledged. “On Oct. 19, the operations workforce 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 is ready to function on solely a single gyro, a plan Hertz mentioned was developed during the last a number of years in anticipation of gyro failures. Hubble would shift into one-gyro mode as soon as it has two working gyros left, utilizing one after which the opposite to maximise Hubble’s lifetime.
Hertz acknowledged there are drawbacks to utilizing Hubble in a one-gyro mode. “A smaller fraction of the sky is on the market,” he mentioned, in addition to limits on simultaneous or time-constrained operations. “We will do Hubble-quality science, in a smaller fraction of the sky, after we go to one-gyro mode.”
One other NASA area telescope, the Chandra X-Ray Observatory, additionally suffered an issue with a gyro Oct. 10 that triggered a protected mode. Hertz mentioned he expects Chandra to renew regular operations a while this week after the completion of engineering exams calibrating the spacecraft’s different gyros.
NASA introduced Oct. 23 that Chandra has resumed science observations. The gyro that skilled issues, NASA mentioned, had not failed however was positioned into reserve. “Information instantly earlier than the protected mode transition point out that the glitch resolved inside roughly 3 seconds,” Chandra venture officers mentioned in an announcement.
In contrast to Hubble, Chandra has had a lot better luck with its gyros, with no issues since its launch in 1999. “It had by no means misplaced a gyro in 19 years,” Hertz mentioned. The spacecraft launched with 4 gyros and may function on simply two.
Regardless of the coincidental timing, Hertz mentioned there was no proof the issues of the Hubble and Chandra gyros are associated in any method. “They’re utterly completely different gyros,” he mentioned.