Two U.S. astronauts have completed another spacewalk expanding the international space station. Their work Saturday combined the skills of plumbers, electricians, mechanics, and television technicians.
Visiting U.S. space shuttle Atlantis crewmen David Wolf and Piers Sellers went on a second excursion outside the station in three days to continue connecting a newly-installed section of the outpost's growing backbone to the first.
The backbone is an aluminum girder that will eventually span more than 100 meters to support cooling, power, and data relay equipment for future research laboratories.
On the latest outing, the two astronauts installed an external television camera on the existing U.S. laboratory, connected coolant tubes between the two girder sections, and released brakes on a small rail flatcar that will roll along the girder during future construction activities.
One more spacewalk is scheduled for Monday to continue the truss work before Atlantis departs the station on Wednesday.