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HOUSTON - Astronauts aboard the International Space Station ran into a jam trying to fold up one of the station's solar wing panels today, a key step in the mission to rewire the outpost's electrical system.
The station and space shuttle crews spent more than five tedious hours retracting and then re-extending the balky wing, hoping to smooth out misalignments that repeatedly caused the array to jam.
The 33-metre panel needs to be moved out of the way so new arrays installed on the station in September can rotate to track the sun for power.
The delicate golden panels, which are studded with solar cells, were supposed to fold up like a Venetian blind into a storage box at the base of the array. They did -- at first -- but then the bottom-most panels started buckling out of position.
The problem repeated dozens of times, but the panel was folded up enough so the new arrays had room to spin.
Engineers had been concerned the wing might not fold as designed since it has been spread out in the harsh space environment for twice as long as planned.
The panel is one of two that have been providing power to the US part of the space station since 2000.
Nasa wanted to rewire the station in 2003, but the destruction of the space shuttle Columbia halted all shuttle flights.
Station assembly resumed in September, with a new deadline to complete the outpost before the shuttle fleet is retired in 2010. Nasa needs at least another 13 missions to finish building the complex.
The Discovery crew, which arrived at the station on Monday for a weeklong stay, needs to rewire the station's electrical system to tap power produced by the new solar panels. The rewiring will pave the way for laboratories built by Europe and Japan to be attached to the space station beginning next year.
While NASA assessed options for fixing the problem with the panel, spacewalkers Robert Curbeam and Christer Fuglesang prepared to make their second spacewalk of the mission on Thursday.
The men are scheduled to begin rewiring the station, but could be dispatched to work on the jammed solar wing.
Curbeam and Fuglesang completed the first of three planned spacewalks on Tuesday, successfully installing a new metal piece to the station's backbone.
As the spacewalk was wrapping up, Nasa got word of a powerful solar flare that discharged higher levels of X-ray radiation and charged particles toward Earth.
Flight controllers told the commanders of the shuttle and the station to have their crews sleep in protected parts of their spacecraft.
The radioactive environment is not expected to affect plans for spacewalks on Thursday and Saturday, though Nasa will continue to monitor the space weather, Johnson Space Centre spokesman Bill Jeffs said.
- REUTERS
