This story was updated at 10:00 p.m.
EDT.
HOUSTON - Two spacewalking
astronauts opened up a camera inside the Hubble Space Telescope Saturday to
make unprecedented repairs Saturday after successfully adding a brand new
instrument to boost the observatory's view on the universe.
Astronauts John Grunsfeld and
Andrew Feustel ventured outside the shuttle Atlantis for more than six
hours to give the 19-year-old Hubble a powerful new spectrograph and revive the
observatory's broken
main camera.
It was the third of five consecutive
spacewalks for the Atlantis astronauts to overhaul
Hubble for the fifth and final time to extend its lifetime through at least
2014. NASA expected Saturday's work to be the crew's toughest job yet. After
all, the broken imager - Hubble's Advanced Camera for Surveys - was never
designed to be fixed in space.
But the physical repair job went off
without a hitch and was free of the glitches that plagued the two earlier
spacewalks.
"It was smooth sailing for the team
today," Atlantis commander Scott Altman radioed Mission Control.
"Lots of people happy down here, as
well," Mission Control called back.
After an initial power check of the
camera, engineers at Hubble's mission operations center at NASA's Goddard Space
Flight Center in Greenbelt, Md., performed a more in-depth test of its three
science-collecting modes - which include a solar blind, wide-field and high-resolution
imaging channel - to check their health.
"You never want to take these things
for granted," Hubble program manager Preston Burch told reporters after the
initial spacewalk repair, adding that it promised a more capable Hubble
telescope. "We're enjoying the moment and savoring it."
Late Saturday, they completed a
check of the camera's wide-field mode - a channel that was physically repaire in the spacewalk - but encountered a power glitch
while checking its high-resolution imaging channel. Engineers hoped to revive
the high-resolution mode indirectly by rerouting power through the repaired
wide-field channel since there was not time to physically fix it during
Hubble's service call.
Most of the
survey camera's observations are made with the wide-field channel, so the impact to
science, should the high-resolution mode stay offline, would be minimal, NASA
officials said. Engineers continue to study the glitch, they added.
Unprecedented repair
Hubble's Advanced Camera for Surveys
was once the telescope's most-used instrument, but it suffered a power system
failure in 2007 that left it nearly incapable of science. Engineers were only
able to revive the ultraviolet-scanning solar blind channel.
Using custom-made
tools, Grunsfeld
removed two access covers and 32 screws from the camera's wide-field channel in
order to reach four delicate computer cards inside. It was delicate work that
the astronaut tackled bulky spacesuit glove-clad hands.
"Yay!" cheered
Grunsfeld,
an astrophysicist-turned-astronaut, as the first screw came out. "Somehow, I don't think brain
surgeons go 'yahoo' when they pull something out."
Working swiftly through the challenging
repair, Grunsfeld
plucked out the camera's four ailing computer cards and replaced them with an
electronics box containing new ones. He and Feustel then hot-wired the box into
Hubble's electrical grid by patching it into an external power box.
Engineers successfully powered up
the camera in a so-called "aliveness test." Hubble scientists had high hopes
for the repair but said repeatedly that it offered no guarantees and more tests
were planned overnight. It was those tests that encountered the high-resolution
channel power glitch.
"We have demonstrated the very first
internal repair of an instrument in space today," said a jubilant Dave Leckrone,
Hubble's senior project scientist, after the spacewalk. "This is an instrument
that was dead, and it's now been demonstrated that it's alive."
Hubble's new cosmic eye
Before the repair, the astronauts
also accomplished their initial spacewalk goal - installing the $88 million Cosmic
Origins Spectrograph (COS) in Hubble. The phone booth-sized instrument will
take light from distant quasars and scan its individual wavelengths to study
the structure of the universe and chemical makeup of galaxies, stars and
planets.
"COS was designed to be a
go-for-broke, go as far as possible as fast as possible instrument," Leckrone
said.
They plugged the new spectrograph
into a slot that was occupied by a device known as COSTAR, which contained
Hubble's vital corrective optics that were once used to clear its blurry
vision.
When Hubble launched in 1990, it had
a flawed mirror that left it near-sighted. Astronauts installed COSTAR,
essentially glasses
for Hubble, three years later to fix it, but the device is no longer needed
since newer instruments already compensate for the flawed mirror.
"This is really pretty historic,
holding the COSTAR," Grunsfeld said as they packed it
away for the return to Earth.
The spacewalk began at 9:35 a.m. EDT
(1335 GMT) and marked the seventh for Grunsfeld, who is making his
third trip to Hubble. It was the second for Feustel and the 21st ever for
Hubble as it orbits 350 miles (563 km) above Earth.
In addition to Saturday's work,
Atlantis astronauts have a new wide-field camera, gyroscopes and batteries to
Hubble, and fixed a vital computer data unit that beams images to Earth.
Another tough repair awaits a different spacewalking team on Sunday.
The shuttle's 11-day mission is
NASA's final service call to Hubble before the agency retires its three-orbiter
fleet next year.
SPACE.com is providing continuous
coverage of NASA's last mission to the Hubble Space Telescope with senior
editor Tariq Malik in Houston and reporter Clara Moskowitz in New York. Click here for mission
updates, live spacewalk coverage and SPACE.com's live NASA TV video
feed.
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