Blimps are experiencing a bit of a renaissance. Recently Montabello, Calif.-based Aeros said it was working on a rigid airship that could fly like a plane and float like a balloon. And now Raytheon has just finished testing a military aerostat of that, starting next year, will be a first line of defense for Washington, D.C.

It's called JLENS, for Joint Land Attack Cruise Missile Defense Elevated Netted Sensor, and it's a pair of radar-equipped helium blimps tethered to the ground that give personnel the ability to see further away than with ground-based radar. The two blimps work together with one using radar to "see" an enemy target and the other guiding a missile to destroy it.

Massive Airship Off to a Flying Start

Unlike a true airship, an aerostat doesn't have it's own power source or drive system. The concept goes back to World War I and World War II, when tethered balloons were used to defend against dive-bombers. Modern versions focus on surveillance.

Raytheon's aerostat is 75 yards long and hovers at about 10,000 feet. This gives it a 360-degree view over the horizon that is not blocked by trees, hills or houses. At that height, any aircraft, drone, cruise or short-range ballistic missile can be detected up to 320 miles away. That range allows JLENS to alert military personnel minutes before an attack. Ground-based radar systems may only provide a few seconds.

If tethered from a ship at sea, the JLENS would also provide early warning of an enemy ship or a cluster of small boats. "We all remember the stories of small boats in the Middle East," said JLENS program manager Doug Burgess. In the Persian Gulf, Iranian speedboats would approach American ships, and some analysts thought the boats might represent a prelude to an attack.

Should JLENS need to launch a missile as a counterattack, it can work with both the Aegis and Patriot missile systems, Burgess said. Having the capability of working with both means that the onboard software and hardware will be able to work with all branches of the armed services.

It's also able to stay in place for weeks at a time. "We did a six-week test," Burgess said. "The JLENS system was put aloft at altitude and maintained for an extended period. We fleshed out reliability of the system."

Man Flies Across Sea to Cape Town Using Balloons

That's another edge over traditional methods, such as drones or patrol aircraft, which can only stay in the air for a short period and would require several aircraft to get the same coverage as JLENS. Furthermore, the power sources for the aerostat are all on the ground, so there's no worry about battery life.

The lasts tests were conducted in June, in Utah. The JLENS system, one of two that were built, is being packed up and sent to the Aberdeen Proving Ground in Maryland. The other is at the White Sands Testing Facility in New Mexico. And then if everything goes well, the system will be launched over Washington, D.C. next year.

JLENS isn't the only military aerostat system in place. There's another one called "Blimp in a Box" built by World Surveillance Group. But that serves a very different function, said Dan Erdberg, director of business development. Blimp in a box isn't designed to go nearly as high -- it can get to 2,000 feet at the most -- and the balloons involved are a lot smaller. Instead of targeting missiles they're mainly geared to surveillance on the ground.