SCOTT AIR FORCE BASE, Ill. -- Every day, around the world, hundreds of military and military-contracted commercial aircraft travel the world delivering troops and cargo. These missions allow hundreds of thousands of military personnel, retirees, family members, and other Department of Defense-eligible travelers to fly at almost no cost, courtesy of the DOD Space-Available (Space-A) Travel Program. (U.S. Air Force illustration/Master Sgt. Scott T. Sturkol)