This fall, two high-flying, blimp-like craft may take flight over the northeast corner of Maryland, carrying a radar system capable of detecting trains, boats, cars, and — the Pentagon hopes — cruise missiles. The Washington Post reports that in October, the Aberdeen Proving Ground military base plans to start a three-year test of how surveillance aerostats (essentially large, tethered balloons) could improve missile defense systems on the Eastern Seaboard. The two craft would float up to 10,000 feet above the ground for 30 days at a time, and their attached radar system is supposed to be able to detect airborne objects from up to 340 miles away — which means it could reach as far as Boston — and vehicles on the surface from up to 140 miles away, closer to the distance between the base and New York City. The system has previously been tested in Utah, where small planes simulated the flight of missiles, and similar tests will be carried out in Maryland.