PLEASE NOTE: since recording this one of the other headcanons has become canonized.
Our Intro and Exit Music is Mars from The Planets by Gustav Holst 1914-1916 (Public Domain). Performed by the United States Air Force Heritage of America Band Recorded 1998. This file is a work of a U.S. Air Force Airman or employee, taken or made as part of that person’s official duties. As a work of the U.S. federal government, the image or file is in the public domain. http://www.heritageofamericaband.af.mil/recordings/frontiers.asp