Monday , September 26 2022

The image of the first Hubble after returning to work. The telescope is fully operational again with three work gyros



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Hubble Space Telescope is a hero in the astronomical world. And when he suffered an inappropriate gyroscope on October 5, he needed a heroic effort from the Hubble team to make it work again. Now we have Hubble's first picture after his return to service.

Hubble's photo after his problems will not be the last, thanks to all his gyroscopes and to all those dedicated to the space telescope. Hubble had or had six gyros. The telescope is designed to operate with three gyros, the other three serving as backup. This was thinking ahead, because all the gyroscopes eventually fail.

Two have failed before – one in March 2014 and the other in April 2018 – leaving it four. But on the evening of the 5th, failure left him with only three operational gyros, without any support. When the giro failed, Hubble went into safe mode. He stopped doing science and turned the solar panels toward the Sun and waited for instructions.

"This was an incredible saga based on Hubble's heroic efforts," Hubble researcher Jennifer Wiseman told NASA Goddard.

The gyroscope failed at the beginning of a three-day weekend, and text messages came to Hubble members telling them what had happened. Since 2011, the Hubble Control Center has been automated, so when the team members gathered there, they were like the old days.

A Hubble Diagram. The six gyros are part of the telescopic position control system, which also includes reaction wheels and fine guidance sensors. All of these components work together to maintain the Hubble function. Picture: NASA.
A Hubble Diagram. The six gyros are part of the telescopic position control system, which also includes reaction wheels and fine guidance sensors. All of these components work together to maintain the Hubble function. Picture: NASA.

More than a dozen members gathered in the command room at the Goddard Space Flight flight center. They tried to revive their gyroscope, but they did not. They then activated a spare gyroscope, but they reported very high rotation rates of 450 degrees per hour. This with Hubble transforming less than one degree per hour.

Dave Haskins is Hubble's operations manager at Goddard, and, according to him, this has never happened. "This is something I have never seen before on any other gyroscopes – prices are so high," Haskins said.

The failure was Hubble's last backup. Hubble can work with a single gyro but its abilities are very low. This one-gyro mode has been previously designed and tested, but the Hubble team did not want to use it until it was their only final option. Mode with a gyroscope would work, but would limit Hubble's efficiency and how much the telescope could see at a time of the year. If that were the case, then everyone in the astronomical community knew the end was almost for the venerable Hubble.

Team members wondered what to do next, and for the first time in a few years, there were people in the control room constantly monitoring Hubble's health.

"This shows the versatility of the team." – Dave Haskins, the Hubble Hub Manager.

"The team has teamed together with staff non-stop, something we have not done for years," Haskins said. Team members intervened to exchange – some of the Hubble engineers, others who helped to perform tests and checks on the Hubble terrestrial systems, and others who had Hubble's control room control staff but had not been for a long time . "Years have passed since they were in the console to do this kind of shift work," Haskins said. "For me it was no problem. It shows the versatility of the team."

This is not the first time Hubble has had problems with its pointing system. In this picture, astronauts replace one of Hubble's reaction wheels in March 2002. Image Credit: NASA.
This is not the first time Hubble has had problems with its pointing system. In this picture, astronauts replace one of Hubble's reaction wheels in March 2002. Image Credit: NASA.

Hubble manager Pat Crouse was busy this weekend, recruiting a team of experts to analyze the unusual gyroscopic behavior and to see what could be done. The group met for the first time Tuesday, October 9, and helped to understand Hubble's recovery. After weeks of thinking through the problem-solving solution, Crouse's group and Hubble team suspected that something physically could obstruct the gyroscope. But whatever the problem was, it should have solved it from the ground. There would be no mission to repair the Hubble.

"At first, I had no idea if we could solve this problem or not," said Mike Myslinski, deputy director of the Hubble mission.

The team decided they would try to dislodge obstruction, if one were to exist. They have repeatedly changed the gyroscopes in different operational ways. They have rotated the telescope itself in large quantities. Finally, the high rate of rotation from the offensive giro began to drop, eventually returning to almost normal.

The team was encouraged by this result, but they were still cautious. If any gyroscope reported extremely high rotation rates, Hubble would return to safe mode again, disrupting any science it did. The team uploaded a new Hubble software to protect it again. They also placed the space telescope through some practice maneuvers to simulate real science observations. Hubble performed well and the team gave a sigh of relief.

"At first, I had no idea if we could solve this problem or not," Hubble's Hubble Mission Manager, Mike Myslinski, said about gyroscopic rates.

Another team was working hard in the background, preparing for an event that has hitherto been avoided. They were preparing for Hubble to operate only on a gyroscope, and another was kept in reserve as a reserve. This situation has been avoided this time, but it will eventually happen. "We know we will have to go to a gyroscope one day and we want to be as prepared as possible for this," Myslinski explained. "I have always said that once we have reached three gyros, we will do as much as possible a single gyroscope science. That day came.

For now, however, Hubble walks like nothing has happened. His first scientific picture of the whole business is a field of galaxies in the constellation Pegasus. The image contains star-forming galaxies up to 11 billion light-years away. No problem for Hubble.

The image of the first Hubble after returning to service is a field of galaxies in the constellation Pegasus. Image Credit: NASA, ESA and A. Shapley (UCLA)
The image of the first Hubble after returning to service is a field of galaxies in the constellation Pegasus. Image Credit: NASA, ESA and A. Shapley (UCLA)

"This was an incredible saga based on Hubble's heroic efforts," said Jennifer Wiseman, Hubble's principal investigator at NASA Goddard. "Thanks to this work, the Hubble Space Telescope is back to the full capacity of science that will bring benefits to the astronomical community and the public for years to come."

Over many years of operation, Hubble has become a family member of scientists and others. We know that one day his mission will end and that will be. It will be a sad day. But for now, Hubble still does science and captures some of the most amazing images of the universe we live in.

Enjoy it while we have it!

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