Washington - The space shuttle Discovery blasted off in a midnight launch on a mission taking it to the International Space Station (ISS). Discovery lifted off the launching pad at Cape Canaveral, Florida at 11:59 pm Friday (0359 GMT Saturday), exactly on schedule, after days of postponements due to a questionable valve on the shuttle's external fuel tank and poor weather.
Weather forced a delay of a planned takeoff on Tuesday and then problems with the valve scrubbed a scheduled liftoff Wednesday. NASA then sought to fire up Discovery early Friday, but elected to postpone it again to review data in connection to the valve.
NASA officials said Friday afternoon the problem with the valve was resolved and began fuelling up, turning the primary concern to the weather off the Florida coast.
The current planned 13-day mission is designed to transport new equipment and experiments to the space station. Astronaut Nicole Stott is expected to relieve Timothy Kopra aboard the ISS, and three spacewalks are planned for the mission.
Discovery's crew for the mission includes six Americans and Swede Christer Fuglesang, flying for the European Space Agency.
The shuttle also carries a 5-million-dollar treadmill named for television comedian Stephen Colbert, who egged on his viewers to vote for him in a NASA's naming contest.
Fuel-valve problems have dogged recent shuttle launches as the ageing craft and launch apparatus enters the final phase of the decades-old shuttle programme.
By late next year, NASA hopes to have completed the build-out of the orbiting ISS so it can retire the shuttles. In their place, a new spacecraft is being designed that will be available in 2015 at the earliest.
Delayed takeoffs are common with space shuttle missions. The last shuttle to blast off, Endeavour, only did so in July after five scrubbed missions due to technical problems and bad weather.
