Astronauts store space station's jammed solar wing

CAPE CANAVERAL, Fla, Dec 19 (Reuters) Spacewalking astronauts coaxed a balky solar wing panel on the International Space Station into its storage box yesterday, capping a tedious but ultimately successful mission by the shuttle Discovery crew.

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.

Astronauts aboard the station sent commands to reel in the panel, section by section. The 110-foot (33-metre) 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 dollars 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.

''I've got one little bad piece of news,'' Curbeam said, as he spotted a piece of loose wire that didn't make it into the box.

Engineers were assessing the problem.

FOURTH SPACEWALK The spacewalk was the fourth since shuttle Discovery arrived at the station last Monday. The US 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.

Curbeam and station crew member Sunita Williams made some progress fixing the problem after they finished the station rewiring during Saturday's rpt Saturday's spacewalk.

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 spacewalkers also dealt with a bit of frayed wire and slack tension in the system needed to reel in the wing.

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 pm EST (local time) on Friday, a day later than planned. NASA will mobilise backup landing sites in California and New Mexico, in addition to the prime site in Florida.

REUTERS PKS BST0645