Astronauts Prep Station’s Railcar
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CAPE CANAVERAL, Fla. (AP) _ Space shuttle Atlantis’ astronauts completed their third spacewalk, rewiring part of the international space station and prepping its new railcar for a test run.
``Another great day in the construction business here,″ mission operations representative Milt Heflin said following Sunday’s spacewalk.
The 6 1/2-hour excursion by astronauts Steven Smith and Rex Walheim set the stage for Monday’s debut of the $190 million railcar that is mounted on the station’s newly attached girder.
NASA planned to use a remote control to move the empty railcar back and forth along the track that runs the length of the 44-foot girder. Its top speed is one inch per second, but engineers said they would stay well below that.
The railcar eventually will be used to transport the space station’s robot arm from one end of the outpost to the other.
During the spacewalk, Smith and Walheim released the clamp that had temporarily held the girder in place on the space station laboratory. Then they began the tricky connector work needed to extend the reach of the robot arm _ via the railroad.
By rerouting power, data and video cables, the spacewalkers paved the way for the 58-foot robot arm, designed to move like an inchworm, to step onto the railcar and be transported along the track. But first, a base for the arm must be installed on the car during the next shuttle flight in June.
The ambidextrous arm, which has a hand on each end, is needed to assemble space station Alpha as it continues to grow.
Over the next few years, eight more girders with more track will be attached to the segment delivered last week by Atlantis. The framework ultimately will extend 356 feet and support four sets of solar wings as well as radiators and science experiments.
The railcar _ with the robotic construction crane and cargo riding inside _ will be able to traverse the entire framework.
On Sunday, Smith and Walheim released launch-restraint bolts on the railcar in preparation for Monday’s trial run. They also admired the view 240 miles below.
``Beautiful place we live,″ Smith observed.
A fourth and final spacewalk is scheduled for Tuesday to wrap up the girder work. Atlantis will undock from the space station on Wednesday.
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