The honorable Dr. Mark Esper, Secretary of Defense, visits Schriever Air Force Base, Colorado, Aug. 20, 2020. Esper visited the National Space Defense Center as part of his visit for the NORAD/NORTHCOM and USSPACECOM changes of command. U.S. Space Command’s Joint Task Force - Space Defense executes it’s protect and defend mission through various operations centers, including the NSDC. (U.S. Air Force photo by Airman 1st Class Jonathan Whitely)