Quartermaster 1st Class Charles Thompson and civil service mariner Terrance O'Malley plot a course aboard the Military Sealift Command hospital ship USNS Mercy (T-AH 19) as it transits the Columbia River after completing Mercy Exercise 02-15. The quarterly exercise is designed to train and integrate medical and other core Navy personnel to operate the ship as a Medical Treatment Facility. Mercy is entering a scheduled maintenance period. (U.S. Navy photo by Chief Mass Communication Specialist Christopher E. Tucker/Released)