Space Shuttle Atlantis (Orbiter Vehicle Designation: OV-104) is one of the three currently operational orbiters in the Space Shuttle fleet of NASA, the space agency of the United States. (The other two are Discovery and Endeavour.) Atlantis is named after a two-masted sailing ship that was operated for the Woods Hole Oceanographic Institute from 1930 to 1966. Atlantis was the fourth operational shuttle built and was delivered to Kennedy Space Center in April 1985.