The international space station comes another piece closer to completion Saturday.
Two spacewalking astronauts plan to install a major addition onto the orbiting lab's frame.
They'll guide crews inside the space station in maneuvering the two-ton, 11-million dollar segment into place with a crane-like robot arm.
The spacewalk is scheduled to last more than six hours.
NASA, in the meantime, is looking into a troubling gouge discovered on the belly of shuttle Endeavour yesterday during a camera inspection before it docked.
The crew will be inspecting the affected area in detail tomorrow using the shuttle's robot arm.
Lasers on the end of an extension beam will gauge the exact size
and depth of the gash, believed to have been caused by a chunk of
ice during liftoff.
That inspection will help determine if a repair job is necessary.