Found this on the web:
Israel to Build Airship to Track Missiles
March 4, 2004 :: Washington Times :: News
Precise monitoring and tracking of incoming ballistic missiles is an important element to defend against them. In recent months, the US has begun research on a High Altitude Airship, a necxt-generation blimp, to do just this. Now Israel has followed suit, and begun to develop its own such device. Theirs would be 200 yards long and 60 yards wide, would remain at 70,000 feet above the surface for years, and would be capable of tracking missiles up to 600 miles away.
Airship to keep eye on Mideast
By Abraham Rabinovich
THE WASHINGTON TIMES
JERUSALEM Ś Israel has begun development of a 200-yard-long airship that would remain stationed at almost 70,000 feet above Earth for years and permit tracking of aircraft and missile firings as far as 600 miles away, a distance covering most of the Arab world.
"It will be an airship the size of a football field, nothing like it in the world," engineer Avi Baum told the Ha'aretz newspaper. Mr. Baum is head of research for the Malam branch of Israel Aircraft Industries.
In addition to its military purposes, the airship, which is yet to be named, would permit a wide range of civilian uses. Mr. Baum said it could relay TV and radio signals, provide broadband Internet, monitor ground and air traffic and aid in weather forecasting. It also could serve as a communications transponder linking ground stations with planes and satellites.
The unmanned airship, which would be 60 yards wide, could stay aloft for up to three years and could shift its position at the order of its ground station. It could be brought down to Earth at will for refitting and be sent back into the atmosphere.
The craft would be divided into two compartments, one containing air and one containing helium. On the ground, the helium would be compressed, making it heavier than air. For liftoff, the helium would be released gradually to fill the air pocket.
A steering mechanism based on a rear propeller controlled by an electric motor would keep the craft in geostationary position. Solar panels would provide a continual supply of energy. Current specifications envision a craft made of flexible, lightweight polymers that would weigh 10 tons and be capable of carrying payloads of 1.9 tons.
"We thought of developing something less expensive than satellites," Mr. Baum said. The proposed craft would be positioned between the altitudes of planes and space satellites.
The cost of the project is estimated at $100 million to $150 million, and the company is seeking an international partner. Lockheed Martin is reportedly at work on a similar concept and is exploring a joint project with Malam. Defense Ministry officials said a prototype could be operational in four years. Although Malam is not the first to think about such airships, it is believed to be the first to have resolved the problem of keeping the craft in geostationary position, serving as an airborne watchtower.