Live in orbit: Airlock depressurization under way

The rock-and-roll crews of shuttle Discovery and the International Space Station are running ahead of schedule once again as preparations for a spacewalk at the outpost continue in low Earth orbit.

With the Byrd's "Turn, Turn, Turn" blaring through the communications systems of the linked spacecraft, mission specialists Scott Parazynski and Douglas Wheelock are suited up in the U.S. Quest airlock, which is being depressurized in advance of the planned seven-hour excursion.

The music actually is part of a communications systems check between the astronauts in the airlock and crewmates inside the station. The idea is to make sure crane operators and astronauts directing the excursion from inside the station can hear spacewalkers outside the outpost when the critical stages of truss mounting work are taking place.

At this rate, the spacewalk almost certainly will begin before the advertised start time of 5:28 a.m. EDT. The astronauts are about an hour ahead of schedule.

The object of their work day -- the P6 truss -- already is hanging on the end of the station's 57-foot robot arm, and crane operators Stephanie Wilson and Dan Tani are preparing to mount it on the outboard end of the port side of the outpost's central truss.

Parazynski is the lead spacewalker, answering to the radio call sign "EV-1." He is wearing a spacesuit with solid red stripes on its pant legs. Wheelock is "EV-2" and is wearing an all-white suit.

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