CAPE CANAVERAL, Fla. (AP) _ Astronauts climbed aboard space shuttle Discovery on Wednesday for NASA's fourth shot at launching the space-station construction mission.

``One more time,'' a launch controller assured commander Brian Duffy.

The flight _ the 100th in space shuttle history _ is almost a week late because of trouble with bolts, a valve, wind and a pin.

Workers had to hustle to remove the small metal pin that was left on an oxygen line running between Discovery and its external fuel tank. The pin resulted in an embarrassing and costly delay for NASA on Tuesday.

This time, the sky was overcast and a waterspout was spotted, but forecasters remained hopeful.

Discovery contains two new segments for the international space station. The crew's job is to attach the girderlike truss and docking port; four spacewalks will be needed to make all the connections.

The 11-day mission has been on hold for two years, as have subsequent assembly flights, because of Russia's difficulties in launching the space station's crew quarters. The module was finally placed in orbit in July and was outfitted by a visiting space shuttle crew in September.

The truss and docking port aboard Discovery must be installed on the space station before the first permanent crew can move in. NASA astronaut Bill Shepherd and his two-cosmonaut crew are scheduled to lift off from Kazakstan on Oct. 30.

This will be NASA's fifth visit to the space station. The first station pieces were launched in 1998.

Six Americans and one Japanese make up the crew. Air Force Lt. Col. Pamela Melroy is making her first space flight; she is only the third woman to serve as a shuttle pilot.

NASA's first shuttle flight was in 1981.

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