AT least one panel on a solar antenna on the International Space Station was damaged overnight as it was repositioned by astronauts, images carried live on NASA television showed.
The edge of one of the 31 panels on the solar antenna tore just as the operation to redeploy the device – directed by mission control back on Earth – was almost complete, images carried live on NASA television showed.
"If you look at camera 24 right now you can see quite a bit of deformation in that whole area," an astronaut told mission control in Houston, Texas.
"Not just the panels that were torn, but several panels seem to be both backwards and kinked in different places," she said.
The solar antenna, which has wings measuring 76 meters when unfurled, was repositioned after astronauts earlier successfully installed a massive truss that is used to rotate the energy-generating solar arrays.
The US space agency started taking a series of photos of the solar panels to assess the scale of the damage and what repairs might be necessary. There was apparently no damage to the exterior cables between the panels.
The status of the solar antenna, one of three on the orbiting space station, has taken on added importance after problems emerged with a rotary joint for another solar antenna recently installed on the ISS.
The space station will need added electrical power for a European lab to be delivered in December and a Japanese lab due to be installed in 2008.
The mishap with the antenna occurred after a successful spacewalk in which shuttle astronauts Scott Parazynski and Doug Wheelock finished the installation of the P6 truss with the help of robotic arms operated by astronauts aboard the shuttle and ISS, culminating a three-day effort.
Lasting seven hours and eight minutes, it was the third of five scheduled space walks for the ambitious Discovery mission.
The giant truss, a large 16-ton metal beam, was needed to deploy the solar antenna and had been stored on the top of the space station for seven years.
NASA confirmed overnight it would extend the Discovery‘s mission by one day to allow for a closer inspection of the flawed rotary joint that turns solar arrays aboard the space station.
In a fourth space walk set for Friday, astronauts will examine the rotary joint after having found small metal shavings and unusual wear in the joint in an earlier space walk on Monday.
The inspection will require a space walk of more than six hours as the Discovery remains docked at the ISS. As a result, the shuttle is scheduled to return to Earth on November 7 instead of November 6.
International Space Station director Mike Suffredini said the problem was not insurmountable and would not affect plans for a shuttle mission in December to deliver Europe‘s Columbus laboratory.
The rotary joint helps spin a set of the power-generating solar panels that were installed four months ago.
During his space walk on Monday, astronaut Daniel Tani picked up metal shaving samples in the joint with adhesive tape so that engineers on Earth could analyse them.
The ISS, a giant manned laboratory orbiting 390km above Earth, is designed to be a potential jumping-off point for further exploration of the solar system.
The $US100 billion space station, supported by 16 countries, is considered key to US ambitions to send a manned mission to Mars and is due to be completed within three years.
The current mission is making space exploration history as shuttle Commander Pam Melroy, 46, and Whitson, 47, are the first women to hold the reins of the two spacecraft at the same time.
The shuttle is to be retired in 2010 to make way for Constellation, a new space exploration project that aims to put humans back on the moon by 2020.