T-5 minutes and counting . . . Space shuttle Discovery and its crew of six astronauts are closing in on liftoff at 4:50 p.m. EST. There are no technical issues in work and the weather at NASA’s Kennedy Space Center in Florida is green. The ground launch sequencer has taken over control of this last phase of the countdown. The arm holding the "beanie cap" over the top of the tank will rotate away from the shuttle shortly. The shuttle’s three main engines will be ignited six seconds before launch. It will take Discovery 8 1/2 minutes to reach a speed of 17,500 mph and achieve orbit.