The US Air Force Research Lab (AFRL) has awarded to contracts for the DARPA Integrated Sensor is Structure (ISIS) program to develop sensors for 500 foot long, autonomous High Altitude Airships (HAA) that stay aloft for years at a time. Lockheed Martin received $8.8 million to develop a power system for the stratospheric airship. Northrop Grumman got $15.5 million for power systems and the Active Electronically Scanned Array (AESA) sensor that will be bonded directly to the hull material of the airship. The ISIS platforms are intended to be able to track cruise missle up to 370 miles away and "enemy combatants" (people) up to 200 miles away. The robot airships would float in geostationary positions at 70,000 feet, safely above the jet stream and severe weather. Helium would provide lift, while a thin film of photovoltaic cells would charge fuel cells. Differential thrust would be provided by electric props. Lockheed Martin has previously been awarded $40 million in 2003 by NORAD, which wants 10 ships to cover the continental borders of the US and another $149 million earlier this year for development of a prototype. Some graphics of the proposed vehicle can be seen on the HAA page and in the Lockheed HAA brochure (PDF format).