New Guided Bomb Strikes Afghanistan

The U.S.-led airstrikes against targets in Afghanistan involve a new type of guided bomb that relies on satellites for nearly pinpoint accuracy, U.S. officials said.

The bombs are called Joint Direct Attack Munition, or JDAM, and like laser-guided bombs used in the Persian Gulf War and subsequent conflicts, JDAMs can be steered toward targets. Conventional, or so-called dumb bombs, simply drop to the ground.

JDAMs, though, are more accurate than previous precision munitions, using the Global Positioning System — a series of orbiting satellites — to help pinpoint locations anywhere on Earth.

The $18,000 JDAM contains a tiny GPS receiver and can be programmed with the exact coordinates — longitude, latitude, and altitude — of a desired target.

Once released from the aircraft, a JDAM receives data from the GPS satellites to locate where the bomb is relative to the target coordinates. Small control fins on the tail of the bomb adjust to guide it as it falls.

Less Fuss, More Accurate

According to Tim Brown, a senior analyst with in Alexandria, Va., GPS-guided munitions are much safer and more accurate than laser-guided bombs — they're accurate to within a few feet, and can be dropped from much higher.

Laser-guided bombs require bomber crews to fly low enough to identify the target and illuminate it with a laser before dropping the bomb. If the laser encounters common battlefield conditions such as haze or smoke, "the bomb might lose signal on final approach and still miss [the target]," Brown said.

JDAMs don't require the bomber crew to locate the target. "Soon as you drop the bomb, there's no more involvement on the part of the flight crew," said Brown.

And since pilots don't need to see the target at all, they can fly their planes at higher, safer altitudes.

What's more, since JDAMs are guided by invisible satellite signals, they can be used in any type of weather.

Not Spoof-Proof

While JDAMs may be easier to use, Brown does note that the bombs can still miss their targets — mainly through inaccurate coordinate programming by the pilots. "We've seen that before with precision bombs missing their targets," said Brown, who noted that errant cruise missile that struck the Chinese Embassy in Belgrade, Yugoslavia in 1999 was blamed on faulty map data.

What's more, since JDAMs rely on signals from far away satellites, enemies could develop a jammer that would spoof the GPS signals and cause the bomb to go awry, he said. But he thinks that would require a massive effort by govenrments with a fair amount of tech savvy — something he doubts the Taliban government or terrorist forces have.

The Pentagon hasn't said which targets in Afghanistan may have been targeted by JDAMs — or how accurate JDAM attacks have been.

Brown doubts that there is any reason to believe JDAMs would be grossly inaccurate in the current conflict. "It's premature to say that they are successful," he said. "[But] there's no reason not to think they aren't working as advertised."