First Lt. Nate Larson, 321st Missile Squadron ICBM combat crew commander, and 2nd Lt. Mark Halling, 321st MS ICBM deputy combat crew commander, take a quiz in the 90th Operations Group March 25 to prepare for the 90th Missile Wing's upcoming Nuclear Surety Inspection. The quiz covers information the missileers should know to pass the NSI (U.S. Air Force photo by 2nd Lt. Christen Downing)