Astronauts aim to fix camera in orbit for the first time ever
CAPE CANAVERAL, Fla. - Astronauts began what could be the most complex spacewalk of their mission to upgrade the Hubble Space Telescope on Saturday, with an agenda that includes installing a new instrument and fixing an old one.
The shuttle Atlantis' crew was given an extra hour to sleep because the previous day's spacewalks were so long and difficult.
But scientists have said Saturday's work could be some of the most intricate of the mission. For the first time ever, spacewalkers John Grunsfeld and Drew Feustel will be attempting to fix a scientific instrument while in orbit. Before, Hubble repair crews have just swapped one instrument for another.
The effort to revive the Advanced Camera for Surveys, which was crippled by a short circuit two years ago, involves new tools and dozens of pieces that could fly around and do damage to Hubble.
Grunsfeld and Feustel are also tasked with putting in the Cosmic Origins Spectrograph, an instrument that is designed to chart the web of material that serves as the largest-scale structure of the universe.
Saturday's outing was the third in a series of five spacewalks aimed at restoring and upgrading the 19-year-old Hubble's capabilities for a final time. On Thursday, Grunsfeld and Feustel installed a powerful new camera and a computer data unit, after struggling with a stubborn bolt. On Friday, a different team of spacewalkers put in new batteries and four brand-new gyroscopes. One additional set of gyros wouldn't fit in its mounting bracket, however, and the astronauts had to install a refurbished spare unit instead.
Because of the difficulties, Friday’s spacewalk was one of the longest in NASA history, lasting nearly eight hours. 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.”
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.
The difficulties that cropped up during the first two spacewalks were not the only things NASA had to worry about. 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.
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.
On Sunday, spacewalkers will take a crack at fixing the Space Telescope Imaging Spectrograph. Monday's final spacewalk will focus on finishing the replacement 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 includes material from The Associated Press and msnbc.com.
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