The space shuttle Atlantis and Europe's Columbus lab is poised for a Thursday lift-off to the International Space Station

NASA hopes to launch its fourth shuttle mission in six months tomorrow if things continue to go well, bringing with it a science lab to help round out the space station for 2010 completion. The lab is Europe's main contribution to the $100-billion, multinational program.

Japan's Kibo complex is scheduled to follow in 2008.

The team has one week in December to get Atlantis off the ground with Columbus.

If there are delays, the launch will have to be postponed January because of unfavorable sun angles for the docked shuttle and a concern that flying at the end of the year may be an issue. NASA wants to avoid the date switch to 2008 in the computer software while on a mission.

A multinational crew of seven astronauts led by Atlantis commander Steve Frick will go on three spacewalks to attach the new lab and its external experiment platforms to the station.

Atlantis is scheduled to fly its last mission, a servicing call to the Hubble Space Telescope, in August.

Japan International Space Station NASA