The shuttle will take off from Kennedy Space Center in Cape Canaveral, Fla., for its final voyage. Later this year, the space shuttles Atlantis and Endeavour will also make their final trips.
Discovery's final launch was originally supposed to take place in November but was delayed because of mechanical problems.
Watch the takeoff live at 4:50 p.m. Eastern time below. If you want your space fix before the launch, tune in now to watch NASA TV interviews with experts and commentary.
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