the main economic activity on the island is centred on the military bases at wideawake airfield, and the bbc world service's atlantic relay station. the ministry of defence estate and facilities are managed by the infrastructure support provider interserve defence. serco runs the airport services and sodexo provides catering and domestic facilities. a former feature of ascension was a 70,000-tonne tanker permanently moored offshore that was operated by maersk as a bulk fuel facility. in december 2002, this was replaced by an on-shore petroleum supply depot under military management, with fuel still being delivered by a chartered tanker, "maersk rapier", which operates on an mod resupply contract for both ascension and the falkland islands every two months. fuel for the island is transferred via a floating hose, which is connected to the on-shore depot at the island's pier head and to the ship at anchor.