Found this article recently regarding aerostats from Ratheon that are protecting east coast. Ravn is in partnership with Ratheon on this project as reported in earlier news stories for the area over last few months.
Washington Business Journal 1/23/14
Two Maryland-built aerostats are about to take flight above Army-owned land about 45 miles northeast of Washington, D.C., according to the Washington Post.
The aerostats are lighter-than-air craft tethered to the ground. The two giant, white blimps will hover around 10,000 feet with the mission of securing the U.S. homeland. Their radar will stretch from Raleigh, N.C., to Boston and west to Lake Erie. The aerostats will help detect cruise missiles or enemy aircraft so they could be intercepted before reaching the capital.
The aerostats will be able to detect airborne objects from up to 340 miles away and ground vehicles from up to 140 miles away.
In July, we reported that the Army had just completed six weeks of testing of the Raytheon Co.'s Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System, or JLENS for short. Those tests cleared the way for operational observation at Aberdeen Proving Ground and within a year, a pair of the systems hovering 10,000 feet above D.C. to detect incoming missiles.