the Batch 2 taking over duties as the Falkland Islands patrol ship. Ocean survey ships is a dedicated Antarctic patrol ship that fulfils the nation's mandate to provide support to the British Antarctic Survey (BAS). is an ocean survey vessel and at 13,500 tonnes is one of the largest ships in the Navy. The other is the multi-role ship HMS Enterprise, which came into service in 2003. As of 2018, the newly commissioned also undertakes survey duties at sea. The Royal Navy also plans to commission a new Multi-Role Ocean Surveillance Ship in 2024, in part to protect undersea cables and gas pipelines. Royal Fleet Auxiliary The Royal Fleet Auxiliary (RFA) provides support to the Royal Navy at sea in several capacities. For fleet replenishment, it deploys one Fleet Solid Support Ship and six fleet tankers (two of which are maintained in reserve). The RFA also has one aviation training and casualty reception vessel, which is planned for conversion into a Littoral Strike Ship. Three amphibious transport docks are also incorporated within its fleet. These are known as the landing ships, of which four were introduced in 2006–2007, but one was sold to the Royal Australian Navy in 2011. In November 2006, the First Sea Lord Admiral Sir Jonathon Band described the Royal Fleet Auxiliary vessels as "a major uplift in the Royal Navy's war fighting capability". In January 2023, a commercial vessel was also acquired to act as a Multi-Role Ocean Surveillance (MROS) Ship for the protection of critical seabed infrastructure and other tasks. An additional vessel was acquired in 2023 to act as a mothership for autonomous minehunting systems. Other ships On 29 July 2022, the Royal Navy christened a new experimental ship, XV Patrick Blackett, which it aims to use as a testbed for autonomous systems. Whilst the ship flies the Blue Ensign, it is crewed by Royal Navy personnel and will participate in Royal Navy and NATO exercises. Submarine Service The Submarine Service is the submarine based element of the Royal Navy. It is sometimes referred to as the "Silent Service", as the submarines are generally required to operate undetected. Founded in 1901, the service made history in 1982 when, during the Falklands War, became the first nuclear-powered submarine to sink a surface ship, . Today, all of the Royal Navy's submarines are nuclear-powered. Ballistic missile submarines (SSBN) The Royal Navy operates four ballistic missile submarines