U.S. Navy Adm. William Houston, director of the Naval Nuclear Propulsion Program, left, presents a challenge coin to Electronics Technician Petty Officer 2nd Class Riley Spilker of Fishers during an Oct. 3 visit of the Nimitz-class aircraft carrier USS John C. Stennis in Newport News, Virginia. John C. Stennis is in Newport News Shipbuilding conducting refueling and complex overhaul to prepare the ship for the second half of its 50-year service life. Challenge coins bear an organization’s insignia or emblem and are carried by an organization’s members. They often are collected by service members and law enforcement personnel. (U.S. Navy photo by Mass Communication Specialist 2nd Class Daniel Tillie)…