The AMSTE system uses software that tracks the target and predicts where it will be in the next minute or so. Thats the location AMSTE sends to the JDAM, via the aircraft that dropped it. A JDAM, dropped at 20,000 feet, ten kilometers from the target, takes about five minutes to reach the ground. The bombers fire control software lets the pilot know when the aircraft is close enough to the moving target for the bomb to reach the target no matter which direction it goes. AMSTE is basically a system of software programs that link different aircraft (the one spotting the target and the one dropping the bomb), and insure that the JDAM keeps getting accurate target updates until the last minute (or seconds, actually).
In the next few years, all the services will be getting radios that can communicate with each other, using digital data. This would make it possible for a navy P-3 maritime search aircraft to pass location data, for a ship below, to an air force bomber, that could then drop a JDAM to hit the moving ship. But the big breakthrough is being able to regularly hit moving targets with bombs, day or night and in any weather.
The U.S. Air Force is conducting naval tests of its AMSTE (Affordable Moving Surface Target Engagement) system. This is an attempt to use airborne radar to continuously track a moving surface target, then drop a JDAM that can have its target location continuously updated by radio, so that the JDAM will be able to hit and destroy the moving target. After three years of effort, the air force got this to work against a ground target last year. The JDAM went off within three meters of the moving truck it was aiming at. A 2,000 pound bomb was more than enough to take out a truck at that distance. Even a 500 pound JDAM would have worked. This month, tests are being conducted against moving ships. The air force is using its E-8 JSTARS aircraft, which carries a powerful radar that tracks moving objects on the surface (land or water). These tests are also meant to show the air force will be capable of quickly going after ships engaged in terrorist activities. The air force can get bomber and recon aircraft to any point on the planet within 24 hours, which is quicker than the navy can get a ship to some out of the way places. Compared to a truck that might be ten meters long and 1.5 meters wide, and traveling at 100 kilometers an hour, a small merchant ship would measure 150 meters long and 20 wide, and be traveling at 30-40 kilometers an hour.