NASA cancels Wednesday night shuttle launch

NASA said it was postponing Wednesday night's planned launch of the space shuttle Discovery because of a fuel leak.

NASA said it was postponing Wednesday night's planned launch of the space shuttle Discovery because of a fuel leak.

Shuttle managers put off the launch until Monday but said the problem might be fixed in time to permit an attempt on Sunday.

Discovery was scheduled to lift off at 9:20 p.m. ET on Wednesday to deliver the fourth and final set of solar panels to the International Space Station.

NASA said the launch was scrubbed due to a hydrogen leak in a liquid hydrogen vent line between the shuttle and its external fuel tank.

Discovery is also scheduled to deliver a replacement part for the station's new water recycling system and a new crew member, Japanese astronaut Koichi Wakata.

Wakata will replace U.S. astronaut Sandra Magnus as a member of the station's three-person crew, joining American astronaut Michael Finke and Russian cosmonaut Yury Lonchakov.

The latest delay means Discovery's two-week flight must be shortened and some spacewalks cut out of the mission.

With the installation of the solar panels, NASA hopes to give the station enough power to support the expansion of the station's crew from three to six members in May. The crew expansion will also signal a shift in the focus of the crew away from building the station and more toward conducting science experiments.

Canadian astronaut Robert Thirsk is scheduled to arrive at the station in May after travelling aboard a Soyuz rocket and will be one of the six astronauts that form the first six-person crew. Canadian astronaut Julie Payette is also scheduled to visit the station this year in a future shuttle mission.

NASA has planned seven more shuttle missions to the station before the shuttle fleet is retired in 2010.