Integrated Sensor is Structure

The Integrated Sensor is Structure (ISIS) was a program managed by the United States Air Force (USAF) Research Laboratory to research the feasibility of using an unmanned airship as a high-altitude aerial reconnaissance and surveillance platform.

[2] As proposed, the 450-foot (140 m)-long surveillance airship could be launched from the US and stationed for up to 10 years at an altitude of 65,000 feet (20,000 m), observing the movement of vehicles, aircraft, and people below.

The airship would be filled with helium and powered, at least in part, by solar-powered hydrogen fuel cells.

[4] In April 2009, DARPA awarded a $399.9 million contract to Lockheed Martin as the systems integrator and Raytheon as the radar developer for phase three of the project: the construction of a one-third scale model, which would remain in the air for up to a year.

The contract initially awarded $100 million to the two companies, with the rest to follow in phases, with a completion date of March 2013.