STAFF Sergeant Barton Bosarge, USAF, as mascot Iron Mike, leads the Knights of the 21st Space Wing, Peterson Air Force Base, Colorado, in a rally cheer as the Knights arrive at Vandenberg Air Force Base, California. GUARDIAN CHALLENGE, the world's premier space and missile competition, is a four-day event hosted annually at Vandenberg AFB, CA "to recognize the best and demonstrate the commands warfighting skills. GUARDIAN CHALLENGE creates competition-tough crews; improves readiness and combat capabilities through preparation, innovation and sharing; enhances esprit de corps and strengthens teamwork across all mission areas in the command."