A United Launch Alliance Delta 4 rocket carrying an upgraded Global Positioning System navigation satellite is poised for launch from the Cape Canaveral Air Force Station this evening. Liftoff from complex 37 is targeted for 8:40 p.m. EST (GMT-5), the opening of a 19-minute launch window. Forecasters are predicting an 80 percent chance of good weather.
The goal of the mission is to place the GPS 2F-5 navigation beacon into a 12,500-mile-high orbit tilted 55 degrees to the equator. The new GPS satellite will replace an aging member of the 24-satellite constellation, beaming ultra-accurate timing and position signals to military and civilian receivers around the world.
If all goes well, the GPS 2F-5 satellite will be released from the Delta 4's second stage three hours and 33 minutes after launch.