Spacewalkers cope with Hubble troubles

Image: astronaut
Spacewalker Mike Good sticks a pistol grip tool into Hubble's innards, as seen by crewmate Mike Massimino's helmet-cam from inside the space telescope.NASA TV
/ Source: The Associated Press

Spacewalking astronauts had to put a refurbished pair of gyroscopes into the Hubble Space Telescope after a brand-new set refused to go in Friday, but scientists were satisfied nonetheless and confident the observatory would point precisely to ever more distant objects in the cosmos.

Replacing the gyroscopes was the top priority of the repair mission, and the struggle had NASA on edge for two hours.

Thanks to the spacewalkers’ effort, Hubble ended up with four brand new gyroscopes and two refurbished ones that were original 19-year-old telescope parts, said to be almost as good as the new ones. The telescope also got fresh batteries.

Later, Mission Control told the cheering astronauts that the gyroscopes and new batteries all worked properly.

It was the second spacewalk in two days for the Atlantis astronauts, who once again were bedeviled by problems. On Thursday, another two-man team installed a powerful new camera and a computer data unit, after struggling with a stubborn bolt. NASA had hoped for an easier, less stressful spacewalk, but instead had to endure more drama.

As on Thursday, the astronauts got their work done, but it was harder and took longer than expected. Friday’s spacewalk was one of the longest ever, lasting nearly eight hours, and Mission Control told the weary crew members that they could sleep in and start Saturday’s spacewalk a little late.

Hubble chief scientist David Leckrone said he had a pet theory on “why things have been a little turbulent for the crew for two days in a row.”

“After seven years of not having people around, Hubble has lost its accommodation to people,” Leckrone said at a late Friday news conference. “It’s gone wild again. So we have to tame it. That will happen, I’m sure.”

The first two spacewalks have gone “a long way” toward extending Hubble’s life, Leckrone said. And Hubble’s new main camera installed on Thursday passed its functional test.

Saturday’s spacewalk is expected to be one of the most challenging ever attempted, because it involves repairing a science instrument in orbit, which has never been done before. But Leckrone joked that the operation will probably go smoothly, because nothing so far has gone quite as expected.

The gyro that wouldn't fit
On Friday, Michael Massimino, who was working from inside Hubble, and his partner, Michael Good, had no problem removing all six of Hubble’s 10-year-old gyroscopes. But one set of new gyroscopes wouldn’t fit properly, despite repeated tries.

Eventually, Mission Control told the men to get a spare box of gyroscopes from the shuttle and put that one in. This spare set originally was launched aboard Hubble in 1990 and returned in 1999.

The astronauts successfully installed the refurbished set. By then, however, five hours of the spacewalk had passed and they had yet to start on the other major chore of the day, the battery swap.

The gyroscopes were the No. 1 task. Three of the old gyroscopes no longer worked, and two others had been acting up. The other had seen a lot of use.

“My friend Leonidas has a couple of words for you guys that are appropriate right now,” shuttle commander Scott Altman told the spacewalkers, jokingly referring to the ancient Spartan king. “Remember this day, men, for it will be yours for all time.”

“We’ve got a little more work to do, but thanks,” replied Massimino.

Leonidas is said to have died in battle in 480 B.C., alongside a force of 300 men who held off the Persian army. The saga inspired the graphic novel "300" as well as a movie by the same name.

Nearly perfect grade
Hubble’s deputy senior project scientist, Mal Niedner, said he was not concerned the astronauts had to resort to refurbished gyroscopes. They lack the latest anticorrosive wiring, but it’s “the difference between an A and an A-plus.” The unused new gyroscopes will be analyzed once they’re returned to Earth.

In all, five spacewalks are planned so that the observatory — beloved by astronomers and many others for its breathtaking views of the universe — will be at its apex while living out its remaining years. Scientists expect the upgraded Hubble to look back even further in time, to within 500 million to 600 million years of creation.

Good was so tired near the end of Friday’s spacewalk that he asked, “Can I come in?”

Good drove in the bolts for the gyroscope boxes as Massimino, a returning Hubble mechanic who is over 6 feet tall, worked inside the telescope, into which he had wedged himself head first. “Trained my whole life for this,” he said.

Massimino had a brief scare when his communication system fouled up at the start of the spacewalk. For a minute or two, no one could hear him.

That wasn’t the only unnerving thing about this mission.

Space is particularly littered in Hubble's 350-mile-high (560-kilometer-high) orbit, and Atlantis and its crew face a greater risk of being slammed by a piece of junk. As a precaution, NASA has a rescue shuttle on standby, ready to launch in just three days if necessary.

Batteries replaced
Even though the spacewalk was running behind, the astronauts pressed on and replaced half of Hubble's batteries.

The hefty, nickel hydrogen batteries that came out were built before the telescope was launched in 1990. They come three to a pack, about the size of a big TV set with a mass of nearly 500 pounds. One of Hubble's two packs was replaced on Friday.

On Saturday, spacewalkers are scheduled to install a new instrument called the Cosmic Origins Spectrograph and try fixing the electronics for the Advanced Camera for Surveys. On Sunday, they'll take a crack at fixing the Space Telescope Imaging Spectrograph. Monday's final spacewalk will focus on replacing the rest of Hubble's batteries and its fine guidance sensors.

NASA hopes to get another five to 10 years of use out of Hubble once the Atlantis astronauts plug in all the new equipment. Atlantis' mission cost NASA more than $1 billion, one-tenth of what has been spent on Hubble over the decades.

This report was supplemented by

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