Video: Delta 4 lifts off

United Launch Alliance said Monday it did not submit a proposal in a competition to launch a U.S. Air Force GPS navigation satellite, apparently relinquishing the contract to rival SpaceX, the only other company certified to launch the mission.

United Launch Alliance crews at Cape Canaveral are finishing final preparations for an Atlas 5 rocket launch Saturday evening to dispatch three U.S. military satellites directly to an orbital perch more than 20,000 miles over the equator.

The mobile platform intended to carry NASA’s Space Launch System will trek to the mega-rocket’s launch pad at the Kennedy Space Center in Florida as soon as Thursday, before heading inside the spaceport’s huge Vehicle Assembly Building for the first time next month.