Shuttle Discovery's countdown begins

CBS News

KENNEDY SPACE CENTER, FL--Engineers restarted the repaired shuttle Discovery's countdown Monday, setting the stage for launch Thursday on a space station resupply mission that's been grounded since November because of cracks in the ship's external tank.

The countdown began at 3 p.m. EST (GMT-5) and if all goes well, Discovery will blast off on its 39th and final flight at 4:50:24 p.m. Thursday, roughly the moment Earth's rotation carries the launch pad into the plane of the International Space Station's orbit.

"The people who work on this team have loved Discovery for many, many years," said NASA Test Director Jeffrey Spaulding. "And so it's a bittersweet thing for them to say goodbye to her. ... I think everybody's proud of what they've done and they're really happy to see her go off on this last mission."

Spaulding said there were no major technical problems going into the countdown and weather officer Kathy Winters said forecasters expect an 80 percent chance of acceptable conditions Thursday. Higher-than-allowable winds are expected at NASA's backup emergency landing sites in California and New Mexico, but with good weather expected in Florida and at two emergency runways in Europe, there are no constraints to launch.

The forecast deteriorates somewhat after Thursday, however, dropping to 70 percent "go" on Friday and 60 percent Saturday. After that, NASA managers will have to work around two upcoming unmanned launches that use the same Air Force tracking systems as the shuttle. Discovery's launch window closes March 6 to avoid conflicts with an upcoming Russian Soyuz mission.

A countdown overview is posted on the Flight Data File page.