This story was updated at 1:38 a.m. EDT.
NASA is scrambling to rework plans
for the last of three spacewalks by astronauts at the International Space
Station after a string of bad luck Saturday ended up in lost time and
incomplete tasks, mission managers said.
Topping the list was an incorrectly
placed restraint pin that Discovery shuttle astronauts Steven Swanson and
Joseph Acaba apparently installed in the wrong position during
a Saturday spacewalk, blocking their later attempts to swing out a cargo carrier
outside the space station.
The astronauts were able to
accomplish most of their planned
maintenance chores in what was otherwise a successful spacewalk, but the stuck pin left the cargo
carrier in limbo - half deployed and half stowed. Swanson secured it in place
with a few tethers and engineers are studying how long the temporary fix should
stay in place. The tethers are rated for about three months, mission managers
said.
Glenda Laws-Brown, NASA's lead
spacewalking officer, said Acaba may have inadvertently left the pin in a
position 180 degrees opposite where it was supposed to be, which would have
been easy to do in the weightless
environment of space. Even when immersed in the giant pool that is NASA's
spacewalk training facility, there is still gravity to pull objects up and
down, she said.
"That is most likely what happened,"
Laws-Brown said, stressing that the pin could have been fine had it been
installed just a few inches to either side of its final position. "Even with
it being installed in the opposite location, he just drew a card of bad luck ...
so, some days you're lucky, and some days you're less lucky."
Laws-Brown and her spacewalk
planning team is now reviewing plans for the third spacewalk of Discovery's
mission on Monday to determine which tools and techniques would be best to free
the stuck cargo carrier once and for all, should mission managers decide it's a
priority. The mistake, she said, will likely not be one spacewalkers make
again.
"The good news is they're well
trained and will be able to recover," she said.
Spacesuit glitches
There were a few other unlucky
moments during Saturday's spacewalk.
Swanson found a bad battery in his
spacesuit while donning
the NASA-issue garment, then found a slight leak in his spacesuit during a leak
check before the excursion. Astronauts had to pause in their preparations to
reattach a glove to make sure the seal was secure.
Just before starting the 6 1/2-hour
excursion, Swanson reported a glitch with his spacesuit's electronic display,
which he also overcame after rebooting his spacesuit by shutting down and
restarting some systems, including his fans and communications system.
"It was not [his] day when it came
to having a clean suit to go outside," Laws-Brown said.
All of the glitches with Swanson's
spacesuit were minor and not a concern for Monday's planned spacewalk,
Laws-Brown said.
"That suit is good to go," she
added.
Late Saturday, mission managers gave
Discovery's heat shield a clean bill of health after studying data and images
from a pair of inspections by shuttle and station astronauts. Mission Control radioed the good news up to the shuttle's crew.
"Thanks, we really appreciate you
passing that along," shuttle skipper Lee Archambault radioed back. "Please
thank all the people who did a lot of work to help make that decision."
Heat shield checks are
standard practice for NASA shuttle flights since the tragic 2003 loss of the Columbia orbiter and its crew due to wing heat shield damage. A final heat
shield inspection to look for new dings from orbital debris will be conducted
once Discovery leaves the space station.
Discovery's STS-119 astronauts have
passed the midpoint of their planned
13-day mission to the International Space Station. The astronauts delivered
a new member of the orbiting lab's crew, the final pair of gleaming solar
arrays and a vital spare part for the station's urine recycling system.
The space shuttle is due to undock
from the station on Wednesday and land on March 28.
SPACE.com is providing continuous
coverage of STS-119 with reporter Clara Moskowitz and senior editor Tariq Malik
in New York. Click here
for mission updates and SPACE.com's live NASA TV video feed.
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