STS-133 commander Steve Lindsey, right, straps himself into a Shuttle Training Aircraft at Kennedy Space Center's Shuttle Landing Facility in Cape Canaveral, Fla., Monday, Feb. 21, 2011. The space shuttle Discovery and her crew of six astronauts is scheduled to lift off Thursday afternoon on an 11-day mission to the international space station. (AP Photo/Chris O'Meara)
(AP) -- Discovery's astronauts are back at Kennedy Space Center for a launch attempt.
Good weather is forecast. Now all NASA needs this week is a smooth countdown all the way to zero.
NASA's countdown clocks will start ticking Monday afternoon. Liftoff is scheduled for 4:50 p.m. Thursday.
Discovery should have taken off on its final voyage in November. But fuel tank cracks kept the shuttle grounded for four months. The shuttle had to be returned to its hangar for the unprecedented repair work.
After returning from the International Space Station, Discovery will be retired and sent to a museum. Its final destination is expected to be the Smithsonian Institution.
Only three shuttle missions remain.
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