NASA CHIEF: Trump's space force will guard U.S. from above. There's a lot of opinion being passed around that the 'Space Force' should be part of - or modeled after - the Air Force, but I disagree. It should be modeled after, but not be part of, the Navy/Marine Corps. Star Trek notwithstanding, the Navy/Marine Corps is the only U.S. military force with a history dating back to the founding of this Nation with a history of patrolling and enforcing U.S. law on the frontiers beyond our borders.