Adm. William Houston, director, Naval Nuclear Propulsion Program (left), presents a challenge coin to Electronics Technician (nuclear) Petty Officer 2nd Class Riley Spilker, Fishers, during a visit of the Nimitz-class aircraft carrier USS John C. Stennis (CVN 74) in Newport News, Va., on Oct. 3. 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.