What makes a bomb ‘smart’?
A built-in guidance system. Conventional bombs are guided only by gravity and guesswork; pilots or bombardiers make visual sightings of their targets, calculate where the plane’s forward motion and winds will carry the bomb, and hope for the best. Since the 1960s, the Pentagon has been perfecting bombs with several types of built-in sensors that enable them to know exactly where they are on the way down, and to adjust tail fins to fine-tune their course. These smart bombs—dropped from as high as 50,000 feet—usually hit within a few dozen feet of the bull’s-eye.
How are the bombs guided?
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The first truly “smart” bombs, developed during the Vietnam War, were guided by lasers. A spotter in the bomber or a companion aircraft located the target below and pointed a laser beam at it. Once the bomb was released, an on-board sensor in its nose homed in on the laser light reflected off the target. The sensor kept the bomb on course by sending electrical impulses to move the bomb’s tail fins, which work like the rudder on a ship or the flaps on an airplane’s wings. Laser-guided bombs are extremely precise, and are still a major part of today’s arsenal. But they have two flaws: They cost about $60,000 each, and don’t work well when it’s cloudy. That’s why, in the past decade, the Pentagon has developed a new generation of smart bombs guided by global positioning satellites.
What is GPS?
It’s a system for pinpointing the exact latitude and longitude of any spot on the planet, utilizing 24 satellites in orbit around Earth. The GPS system can take signals from ships, automobiles, and even hikers, and send back their precise location. Recently, the Pentagon realized GPS would also work for bombs, and began installing a snap-on kit in its workhorse “dumb” bombs, such as the 2,000-pound Mk.84 BLU-109 and the 1,000-pound Mk.83. The guidance system—complete with adjustable tail fins—is called the Joint Direct Attack Munition, or JDAM (pronounced jay-dam). On the way down, a simple, off-the-shelf computer chip in the kit communicates with GPS satellites, adjusting the fins and guiding the bomb to a specific spot on the ground. A second type of JDAM uses gyroscopes to determine how much a bomb has drifted off its preprogrammed course.
Are they expensive?
Not compared to the most sophisticated munitions. Cruise missiles, the smart bomb’s self-propelled cousins, cost a million dollars each. A JDAM kit costs a mere $21,000. That’s why military analysts expect that the U.S. will rely heavily on retrofitted JDAM bombs in a second Iraq war. About 80 percent of all bombs dropped, analysts say, will be of the guided variety.
Who picks the targets?
Before the fighting begins, the Pentagon uses spy satellites, pilotless Predator airplanes, and Special Forces troops on the ground to spot and locate military targets, power plants, and enemy troops. Planners then draw up a list of important targets, with their precise GPS coordinates. Overhead, the bomber crew simply punches the target’s position into the bomb’s onboard computer, releases the bomb, and moves on to the next target.
How effective is this system?
It’s what has made U.S. air power so overwhelming. Precision munitions accounted for just 9 percent of the bombs the U.S. dropped in the Gulf War, but caused 75 percent of the damage inflicted on key targets. The high-tech weapons played a greater role in NATO’s 1999 bombing campaign in Serbia, and accounted for 60 percent of the munitions dropped on Afghanistan to rout the Taliban regime and al Qaida. In Afghanistan, U.S. fighters flying far beyond the range of anti-aircraft fire, and shielded from the ground by dense cloud cover, were able to use GPS coordinates to hit individual tanks and small clusters of soldiers. These astonishingly precise air strikes, seeming to come from nowhere, totally demoralized the Taliban fighters.
Are bombs getting smarter?
Like most forms of technology, this one is galloping ahead. Since the Gulf War, improvements in guidance systems and GPS technology have reduced the margin of error from 100 feet to about 20 feet. If war comes in Iraq, military analyst Daniel Goure said in The New Yorker, the U.S. attack will begin with a hail of smart bombs dropped from B-2 stealth jets and massive B-52 bombers. Other key targets will be destroyed by cruise missiles launched from submarines and ships at a safe distance. “It will be like the first night of the Gulf War,” Goure said, “but now we can do five times the damage with one-quarter of the planes.”
Are smart bombs foolproof?
No. A precision bomb or cruise missile is only as accurate as the information programmed into it. In the Serbia campaign, an American B-2 bomber flying over Belgrade hit a building 35,000 feet below with three GPS-guided bombs. The mark was supposed to be a military supply office, but someone punched in the coordinates for the Chinese Embassy. Three people were killed, causing a prolonged strain in American-Sino relations. “You can precisely hit exactly the wrong thing,” said Sarah Sewall of the Carr Center for Human Rights Policy at Harvard University. “They aren’t really smart bombs,” one U.S. officer said. “They’re just very, very obedient.”
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