Live coverage: Delta 4 countdown and launch journal

Heading to space next week to replace a 12-year-old satellite in the Global Positioning System navigation network, a modernized spacecraft was placed atop its Atlas 5 launcher Wednesday.

The United Launch Alliance Atlas 5 rocket with the NROL-52 spacecraft aboard moved to the launch pad this morning for liftoff Saturday to serve the national interest. Liftoff is scheduled for 3:31 a.m. EDT (0731 GMT).

NASA expects to spend some $5 billion underwriting development of commercial spacecraft built by Boeing and SpaceX to carry astronauts to and from the space station, ending reliance on the Russians for crew flights and lowering the average cost per seat to around $58 million.