SpaceX ends historic year with its final launch of 2018

SpaceX just ended 2018 with a bang.  Elon Musk's private spaceflight company performed its 21st launch of the year on Sunday, Dec. 23, lofting a GPS satellite to orbit for the U.S. Air Force.  SEE ALSO: NASA spacecraft finds signs of water on Bennu asteroid The company didn't bring its Falcon 9 rocket booster back in for a landing due to the Air Force's mission requirements. Instead, this brand new rocket was used the old fashioned way and discarded after it performed its duties admira