NASA's principal rocket propulsion testing center, employing approximately 3,500 people. Stennis Space Center occupies nearly 14,000 acres and is surrounded by a 125,828-acre acoustical buffer zone. It boasts a seven and one-half-mile, man-made Panama Canal-type lock system used to transport liquid propellants to the center as well as a water transportation route to the Gulf of Mexico and to Kennedy Space Center in Florida. Stennis Space Center's test complex consists of two massive concrete and steel vertical rocket propulsion test stands and a smaller concrete and steel three-position horizontal test stand. The vertical stands are utilized to test Space Shuttle Main Engines. These testing facilities are supported by a 66-million-gallon water storage reservoir, electrical power generating plant, gaseous storage vessels and cryogenic propellant facilities. Stennis is also a major oceanographic and meteorological research center for the US Navy.