Smart Bomb, informal term referring to a bomb equipped with devices to guide it precisely to a selected target. Smart bombs are officially known as precision guided munitions. They differ from free-falling general-purpose bombs, which are sometimes called dumb bombs. The term smart bomb is sometimes used to refer to guided air-launched or ground-launched cruise missiles, such as the Tomahawk, although these are technically self-propelled missiles and not bombs (see Guided Missiles). Smart bombs permit accurate destruction of military targets with a small number of weapons, rather than through mass or carpet bombings using numerous general-purpose bombs. Smart bombs were used in the 1991 Persian Gulf War, the war against the Taliban and al-Qaeda in Afghanistan in 2001, and the 2003 invasion of Iraq by United States and British forces.
Most smart bombs are simply general-purpose bombs that have been fitted with a guidance device in the nose and a small control module in the tail. One of the latest versions of these bombs is known as a Joint Direct Attack Munition (JDAM). A JDAM is basically a guidance kit containing an Inertial Navigation System/Global Positioning System (INS/GPS) that has been attached to a general-purpose bomb. A JDAM is sometimes called a satellite-guided precision weapon because radio signals from an array of satellites forming part of the Global Positioning System help steer the bomb to its target. Targeting data containing the longitude and latitude coordinates of the target are downloaded to the weapon from the host aircraft.
The 454-kg (1,000-lb) GBU-31 and the 908-kg (2,000-lb) GBU-32 are typical INS/GPS-guided smart bombs used by the United States Air Force and the United States Navy. The GBU-15 is an early type of smart bomb. It is a standard 908-kg bomb fitted with either an electro-optical or an infrared target system. In an electro-optical system, the pilot or weapons officer sees a television image from a camera in the bomb. Once the target is located, the pilot or weapons officer can guide the bomb manually by remote control, or lock the image in, and the bomb will automatically guide itself toward the image. In an infrared system, the bomb detects heat radiated by the target in the infrared spectrum. Infrared systems are useful at night or when visibility is poor.
Laser guidance is used on the 908-kg GBU-24 bomb, known as the Paveway III. A pilot or a soldier on the ground first aims a laser beam at the target. Once the bomb is released, it flies toward the beam, heading straight to the target. The GBU-28, a heavier version of the GBU-24, also uses a laser system, but has the unique ability to penetrate deep into the earth upon impact. It is used to destroy protected or hardened targets like underground bunkers and command centers. The GBU-28 is being replaced by the BLU-109 and the BLU-110, hard-target bombs outfitted with JDAM kits.
Smart bombs originated in Germany during World War II (1939-1945), and were used with limited success. The Fritz X was a radio-controlled glide bomb controlled from the bomber that dropped it. As the bomb fell, the bombardier would use a transmitter to move the fins on the bomb and steer it toward its target. The radio device was primitive and had limited range, but two such bombs sank the Italian battleship Roma in September 1943 as it sailed to surrender to the British.
The United States tested smart bombs in the Korean War (1950-1953) and used them successfully in combat during the Vietnam War (1959-1975). In 1972 U.S. fighter jets successfully attacked two heavily defended North Vietnamese bridges using smart bombs. The bridges, which had resisted conventional bombing attacks throughout the war, were destroyed with just a few laser-guided bombs. Smart bombs were used on a large scale during the Persian Gulf War in 1991, as the United States and its allies attacked Iraqi targets. Smart bombs were used on a large scale again during the 2003 U.S.-British invasion of Iraq.
Microsoft ® Encarta ® 2006. © 1993-2005 Microsoft Corporation. All rights reserved.