He earned a Master of Science degree in astronautical engineering in 1980 from the Air Force Institute of Technology.

Following his first assignment, Shelton reported to the US Air Force Institute of Technology at Wright-Patterson AFB, Ohio.

In July 1985, Shelton moved on to the Armed Forces Staff College in Norfolk, Virginia.

He moved on from Colorado Springs in August 1988 to Washington, D.C., to work for the Secretary of the Air Force in the office of Space Plans and Policy.

Promoted to lieutenant colonel on March 1, 1990, he took command of the 2d Space Operations Squadron at Falcon AFB in Colorado in August of the same year.

Following his second command tour, Shelton returned to school at the National War College at Fort Lesley J. McNair in Washington, D.C.

In September 1997 he assumed command of the 90th Space Wing at Francis E. Warren AFB in Wyoming.

[4] The president nominated Shelton for the appointment to lieutenant general with continued assignment as the 14 AF/CC and CDR JFCC SPACE (Ref: 8 November 2007 Senior Leader Announcement, AF/A1).