Troubled space walk a success

The space railcar is moving again after a stowed UHF antenna was opened.

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JOHNSON SPACE CENTER, Texas (CNN) -- Despite early problems with a stalled railcar, two NASA astronauts successfully completed a seven-hour space walk Saturday evening.

When astronauts John Herrington and Michael Lopez-Alegria started the space walk after 2 p.m. ET, their first task was to figure out what was keeping the railcar from moving. Within an hour, the glitch had been discovered and the space walk continued with only minor revisions to the schedule.

"Today has gone quite well. We've accomplished all of our objectives," said Mission Operations representative Bob Castle.

All of the planned tasks were completed along with two additional tasks.

The early problems were fixed within an hour of the start of the space walk. Herrington found a UHF antenna array entangled with the railcar, keeping the car hung up on its tracks about 10 feet from its destination between two workstations.

The railcar is designed to travel up and down the two main trusses that make up the backbone of the exterior structures, carrying spacewalkers, tools, construction items and the robotic arm. The trusses will eventually house power, data and temperature control lines for the space station's electronics.

Herrington and Lopez-Alegria opened a stowed UHF antenna that had blocked the railcar's path, and shortly after 5 p.m. ET, the railcar crept toward its proper position. Opening the antenna was one of the two "get ahead" tasks scheduled for the space walk. It became a critical task once Herrington discovered the antenna was blocking the railcar.

With the railcar working, Herrington and Lopez-Alegria focused on continuing to assemble the station. The astronauts completed work on a newly installed girder.

The space walk began nearly seven days into the mission and 248 statute miles above Earth.

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