When forest fires broke out in a remote area of Massachusetts a couple of years ago, firefighters hampered by a lack of access roads to the blaze relied on helicopters to douse the flames. But the  helicopters were ill-equipped for the task: each small craft could carry only 100 gallons of water. In fact, to extinguish the blaze, firefighters spent several days scooping water from a pond, flying to affected areas, dumping water on the flames, and then returning for more pond water.

Mike deGyurky, a program manager at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., figures there must be a better way to handle such emergencies. His novel approach would entail deploying a giant blimp, perhaps a mile in length. With a capacity of 50,000 tons or more, such an airship could pour more than 10 million gallons of water on a forest fire. It could also be used to transport food and water (perhaps even a small iceberg) to drought-stricken regions, dump tons of dirt and sand on a nuclear reactor to smother an incipient meltdown, or even deploy a vast tarp to contain oil spills from leaky seafaring tankers.

The concept began as a "what-if" exercise spawned during one of JPL's lunchtime brainstorming sessions. De-Gyurky was also inspired by Theodore von Karman, JPL's cofounder who speculated about mile-long blimps after conducting research on lighter-than-air vessels in the 1930s.

"We're basically taking von Karman's idea and applying technologies that have become available in the intervening 60 years," deGyurky explains. "These include lightweight materials-synthetic fibers such as Kevlar, graphite epoxies, and the like-that are awesome in strength, and thin-film solar cells that would line the roof of the airship and provide most of the propulsive power."