NASA astronauts were preparing on Thursday for a tricky space walk to fix a ripped solar wing on the International Space Station, a crucial task which has become the focus of the shuttle Discovery's mission.
NASA planners informed the crew early on Thursday that the space walk would now take place on Saturday instead of Friday to allow more time to prepare for the procedure, which will involve an astronaut dangling at the end of an extension boom.
The job will fall to veteran spacewalker Scott Parazynski, who will try to install a makeshift bracket to take the load off hinges that broke while the 110-foot (33-metre) solar power panel was being extended on Tuesday. "It's probably a little bit of a disappointment," Mission Control in Houston said after informing the Discovery and space station crews of the delay.
The astronauts are keen to resolve the problem which has put other tasks on hold. These include another space walk - also not originally planned - to inspect a joint contaminated by metal scrapings that rotates another pair of solar arrays to track the sun for power. That has now been left for future shuttle crews. The point of Discovery's mission was to deliver a vestibule with docking ports for Europe's Columbus laboratory and Japan's three-part Kibo complex.
But NASA needs to stabilise the broken power wing before any more modules can be added to the growing outpost. The panel is attached to an 18-ton truss that was moved to the far end of the station's frame. It tore as it neared the end of its 110-foot extension.
Parazynski will be deployed at the end of a 50-foot (15-metre) extension boom to the station's robotic arm to try to put him within arm's reach of the tattered wing.
If the repair is successful, NASA plans to clear the shuttle for undocking on Monday and landing at the Kennedy Space Center in Florida on Wednesday. The crews of the station and shuttle were to speak later on Thursday with former US President George H. W. Bush, who was due to visit the Johnson Space Center in Houston.