What's the Latest Development?
If tests continue to go well, starting next year the city of Washington, DC will have one more line of defense against air attacks: The Joint Land Attack Cruise Missile Defense Elevated Netted Sensor (JLENS) consists of two helium blimps that use radar to see any incoming airborne enemies and to help guide any missiles launched to destroy them. Designed by Raytheon, JLENS -- which will be tethered to the ground, or possibly to a ship at sea -- will hover at 10,000 feet, a height that allows it to send alerts to personnel minutes, rather than seconds, in advance. Also, unlike drones, it can stay up there for weeks, because its power sources are also on the ground.
What's the Big Idea?
The concept of using blimps and other types of aerostats for defense purposes goes all the way back to World War I, and the Raytheon project is one of several that are attempting to use this technology in a more modern way. These include the World Surveillance Group's Blimp in a Box, which only goes up to 2,000 feet and, as the company's name implies, focuses on watching events down here rather than happenings in the air.