Neil Nawrocki, South Dakota School of Mines and Technology student, drills out a rivet hole on an aircraft panel during a cold spray repair demonstration in a SDMST laboratory in Rapid City, S.D., Jan. 31, 2013. Cold spray is a revolutionary maintenance process that involves spraying aircraft skin panels with powdered metal, using a carrier gas to accelerate the particles through a supersonic nozzle causing the particles to bond with the surface without damaging the panel. (U.S. Air Force photo by Airman Ashley J. Thum/Released)