USS O?Bannon (DD 987) fires her MK-45 five inch gun mount during a live fire exercise. The destroyer is participating in testing and evaluation of the Integrated Maritime Portable Acoustic Scoring and Simulation (IMPASS) system. IMPASS is part of the Virtual at Sea Training (VAST) system used to test the accuracy of shipboard weapons systems as well as live fire skills. U.S. Navy Photo by Photographer?s Mate 1st Class Marthaellen L. Ball.