This
story was updated at 8:41 p.m. EDT.
HOUSTON -
Two embattled astronauts fought through a stuck bolt and dead battery on Sunday
to fix a key instrument in the Hubble Space Telescope in a frustratingly long
spacewalk.
Atlantis
astronauts Michael Massimino and Michael Good were already expecting a
challenging day to repair a long-broken spectrograph on the 19-year-old
Hubble. The instrument was never designed to be fixed in orbit.
Ultimately,
the astronauts completed their repair work on Hubble's ailing Space Telescope
Imaging Spectrograph (STIS), which failed in 2004. But it was a long, tough
haul that prevented the spacewalkers from finishing all their tasks.
"Congratulations,
you brought STIS back to life," Atlantis astronaut John Grunsfeld told the
spacewalkers.
The
spectrograph, which can double as a camera, passed an initial power-up test,
but shut down soon after due to a temperature glitch, NASA officials said. Hubble
program manager Preston Burch said engineers at the telescope's mission
operations center at the Goddard Space Flight Center in Greenbelt, Md., would reattempt
a more in-depth functional test once the spectrograph warmed up later this
evening.
The
spacewalk began at 9:45 a.m. EDT (1345 GMT) and lasted just over eight hours,
making it the sixth longest in history. It was the fourth of five back-to-back
spacewalks by Atlantis astronauts extend Hubble's mission life through 2014.
Astronauts
vs. Hubble
Sunday's
string of bad luck for Massimino and Good began early in their spacewalk. A
stuck bolt, one of four securing a handrail to the exterior of their target
spectrograph, simply refused to budge. It was such a simple failure, NASA never
expected or simulated it, mission managers said.
The
handrail had to be removed so Massimino could attach a special plate on the
spectrograph that would catch the 111
tiny screws securing a cover in place. But the bolt appeared stripped and
his power screwdriver kept slipping.
An extra
tool bit didn't help. So Mission Control told Massimino to just rip it off by bending
the handrail until the bolt popped free. The astronauts taped up pieces of the
handrail and the bolt to make sure nothing shot out like a projectile.
"This is
just like tying branches together in Boy Scouts," Good said.
After two
hours of work, Massimino got the rail free. But it took some muscle and he
asked for a break. Mission Control concurred.
"I don't
know how to describe what just happened, but after what just happened I think
we all need a minute to straighten things out," he said.
Then a power
tool's battery failed sending them scrambling for a spare, which took more
time.
"Oh, for
Pete's sake," said an exasperated Massimino.
Fixing
Hubble's spectrograph
With the
handrail clear and the power tool charged up, Massimino and Good pressed ahead
with their repair.
Hubble's
broken Space Telescope Imaging Spectrograph is a versatile instrument that
breaks light into component wavelengths to detect supermassive
black holes and the chemical makeup of the atmosphere around distant alien
planets. It was installed in 1997, but failed five years ago.
Because the
spectrograph can also double as an imaging camera, the instrument was one of Hubble's
more unique features.
"The
science capabilities that we've been given today are fabulous," said Jennifer
Wiseman, chief of exoplanet research and stellar astrophysics at Goddard. "Now
we're going to start contemplating what kinds of things we can do with them."
After
removing the 111 tiny screws and six other fasteners - which were all captured
in a special enclosure - they replaced a power supply circuit board and then
buttoned the spectrograph up with a new cover that only required two latches
and a single bolt to secure. The hand-intensive work cut a small tear in the
outermost layer of the palm on Massimino's left spacesuit glove, but he was
never in any danger, mission managers said.
The apparently
successful repair was the second intricate fix in as many days for the Atlantis
crew. On Saturday, the astronauts revived Hubble's
main camera, which shutdown in 2007. They also added a powerful wide-field
camera, new gyroscopes and batteries, and a brand new spectrograph designed to
study the structure of the universe.
But
Massimino and Good ran out of time Sunday and had to skip a task to add extra
insulation to Hubble. That chore might be added to the mission's fifth
spacewalk - the last ever for Hubble - is slated for Monday.
Grunsfeld
and astronaut Andrew Feustel will perform that final spacewalk and be the last
people ever to touch the space telescope. Atlantis is flying NASA's fifth and
final mission Hubble in order to extend its life through 2014.
After the
exhausting spacewalk, Massimino and Good returned back to Atlantis' airlock to
conclude their orbital work. The spacewalk was the second and last scheduled
for both astronauts for the rest o the mission.
"It's a
real privilege to see what we've seen and to work on this magnificent machine,"
Massimino said. "I couldn't be any more grateful for the
opportunity."
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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