The Air Force's decision this week to award SpaceX its second national security space launch services mission -- a win over longtime provider United Launch Alliance -- came down to cost, a service official confirmed Wednesday. SpaceX on Tuesday nabbed a $96.5 million contract to fly a GPS III payload on an upgraded version of its Falcon 9 rocket. The company said in a statement it is "proud to have been selected." The Evolved Expendable Launch Vehicle mission is slated...