The Pentagon is taking a page from the history books, specifically the section about the 1937 Hindenburg disaster. The military announced yesterday that it will spend $400 million on an unmanned blimp with the capability to hover over enemy territory for 10 years. "It is absolutely revolutionary... It is constant surveillance, uninterrupted," said the Air Force's chief scientist of the aircraft, which will serve as both a satellite and a spy plane. The special blimp (hard to see at 65,000 feet in the air) is likely to be deployed over Afghanistan and Pakistan and could be sign of future military tactics.