Spacewalkers to finish space station rewiring job

Houston, Dec 16: Astronauts today prepared for a spacewalk to finish rewiring the International Space Station's power grid, while NASA, stymied in its efforts to free a jammed solar panel, considered turning to the spacewalkers for help.

Lead spacewalker Robert Curbeam will team with first-timer Sunita Williams to complete a power grid rewiring that Curbeam and Christer Fuglesang, Sweden's first astronaut, started on Thursday.

The rewiring, delayed after the 2003 Columbia disaster, will provide a power upgrade needed to support additional laboratories due to arrive next year.

NASA said the six-hour spacewalk could be extended by up to one hour to inspect, and possibly help resolve, the problem with the panel.

''We are currently visualizing this as an inspection task,'' Stephen Robinson at Mission Control told the astronauts on Thursday. ''Think of it as going up and taking a good close look and telling us what is really going on.'' The 33-metre panel retracted enough on Wednesday to allow new solar arrays to rotate and track the sun. But NASA needs the whole span folded up so it can be moved to a new position next year.

NASA had concerns the panel would not retract as planned because it had been exposed to the extreme temperatures of space for six years, twice as long as planned, after Columbia halted construction on the station until this year.

Kirk Shireman, deputy space station program manager, said the astronauts could be asked today to push on the storage box to try to free a guide wire they suspect is preventing the array from folding properly.

MAY POSTPONE REPAIRS NASA

may also decide later today to mount a fourth spacewalk to fix the stuck array, or to postpone repairs to another mission.

''We are perfectly willing to live without that task if we don't have time,'' Shireman said at a briefing late yesterday. ''We'll live to fight another day. The primary objective ... is to rewire the space station.'' Half of the space station will be powered down to protect the astronauts during the spacewalk while they unplug and move cables.

Mission controllers said they expect some tense moments while they wait to see if the new routing switches and cooling system work after the new connections are made.

The first spacewalk went flawlessly and ended an hour early, boosting hopes that Curbeam and Williams would have time for the added task of inspecting the panel.

The spacewalkers are expected to remove some debris shields from Discovery's payload bay and stow them on the outside of the space station to be installed on the Russian service module next year.

A fourth spacewalk on Monday would delay the shuttle's departure from the station by a day and likely would force the crew to skip a final inspection of Discovery's heat shield.

NASA has been meticulous about scouting for damage on the shuttle's protective heat shields since losing Columbia to a debris strike in 2003.

Discovery is scheduled to land at the Kennedy Space Center in Florida on December 21.

REUTERS

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