Astronauts store jammed solar wing (Reuters)
19.12.2006 04:02 Space - Source: Yahoo space
Progress was achingly slow, with spacewalkers Robert Curbeam and Christer Fuglesang taking about five hours to gently poke at the partly retracted panel with insulated tools and shake the storage box to free the stuck sections.
The spacewalk took over 6-1/2 hours in total. Curbeam took part in all four spacewalks, the first time any astronaut did so many on a single shuttle mission.
Astronauts aboard the station sent commands to reel in the panel, section by section. The 110-foot long span needed to be folded up so it could be relocated to another part of the orbital outpost.
Ground control teams monitored and sent advice on every aspect the operation, which ended up being the most difficult task of a mission NASA considered its biggest challenge since station assembly began nine years ago.
At least 13 more missions are needed to complete the half-built $100 billion outpost before the shuttle fleet is retired in 2010.
As the last few inches of the panel finally folded up, flight controllers broke into applause at Mission Control. A piece of loose wire that did not make it into the box was eventually coaxed in, a NASA spokesman said.
FOURTH SPACEWALK
The spacewalk was the fourth since shuttle Discovery arrived at the station last Monday.
The U.S. space agency was prepared for problems, but managers expected they would come with the rewiring of the station's power grid. That task, which spanned two spacewalks last week, proved to be glitch-free.
The rewiring cleared the way for modules built by Europe and Japan to be attached to the station beginning next year.
The solar wing panel retraction was another story. Since Wednesday, engineers on the ground and astronauts aboard the station tried dozens of times to remotely command the panel to fold up along pleats, similar to raising a Venetian window blind. After folding up about half-way, enough to let the station's new solar panels rotate, NASA ran into a jam.
NASA managers approved the unplanned fourth outing to finish the job. The main problem involved grommets on the panel that repeatedly snared on guide wires intended to drive the folded sections into the storage box.
The additional spacewalk sparked a vigorous debate among NASA managers. Some wanted to leave the work for the station astronauts or the next shuttle crew to handle.
Others approved the extra spacewalk but wanted to skip a final inspection of the shuttle's heat shield in order to preserve an extra day in space in case poor weather or equipment problems postpone landing.
The inspection, which will hunt for damage from any micrometeoroid strikes, is among the safety upgrades made after the 2003 Columbia accident.
In the end, NASA made the unprecedented decision to give up one of its contingency days for landing, keep the inspection and add the spacewalk.
Touchdown is now targeted for 3:56 p.m. EST on Friday, a day later than planned. NASA will mobilize backup landing sites in California and New Mexico, in addition to the prime site in Florida.
(Additional reporting by Ed Stoddard in Dallas)
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