and ranging of surfaced vessels; airborne and satellite Electronic countermeasures and acoustic countermeasures such as noise and bubble makers Passive acoustic countermeasures such as concealment and design of sound-absorbing materials to coat reflecting underwater surfaces Magnetic anomaly detection (MAD) Active and (more commonly) passive infra-red detection of surfaced parts and water anomalies. In modern times forward looking infrared (FLIR) detectors have been used to track the large plumes of heat that fast nuclear-powered submarines leave while rising to the surface. FLIR devices are also used to see periscopes or snorkels at night whenever a submariner might be incautious enough to probe the surface. Weapons B57 nuclear bomb Naval Mines Torpedoes (acoustic, wake homing, Wire-guided) Depth charges Rockets Mk 101 Lulu nuclear depth charge Anti-submarine missiles Anti-submarine mortar Anti-submarine net Nuclear depth bomb Ramming WE.177 Platforms Satellites have been used to image the sea surface using optical and radar techniques. Fixed-wing aircraft, such as the P-3 Orion & Tu-142 provide both a sensor and weapons platform similar to some helicopters like the Sikorsky SH-60 Seahawk, with sonobuoys and/or dipping sonars as well as aerial torpedoes. In other cases the helicopter has been used solely for sensing and rocket delivered torpedoes used as the weapon. Surface ships continue to be an important ASW platform because of their endurance, now having towed array sonars. Submarines are the main ASW platform because of their ability to change depth and their quietness, which aids detection. In early 2010 DARPA began funding the ACTUV programme to develop a semi-autonomous oceangoing unmanned naval vessel. Today some nations have seabed listening devices capable of tracking submarines. It is possible to detect man-made marine noises across the southern Indian Ocean from South Africa to New Zealand. Some of the SOSUS arrays have been turned over to civilian use and are now used for marine research. India introduced supersonic missiles to deliver torpedo at long ranges called SMART or Supersonic missile assisted torpedo system. This new technology helps to deliver the torpedo 1000 kms away and gives flexibility in terms of the launch platform. Identifying friendly vs hostile submarines See also Anti-submarine weapon Naval tactics Naval tactics in the Age of Steam References Notes Citations Bibliography Further reading Abbbatiello, John, ASW in World War I, 2005. Compton-Hall, Richard, Submarine Boats, the beginnings of underwater warfare, Windward, 1983. Franklin, George, Britain's ASW Capability, 2003. Llewellyn-Jones, Malcolm, The RN and ASW (1917–49),