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. It is sometimes called Integrated Sensor is the Structure, as a fundamental innovation was the use of the airship structure as the sensing component of a state-of-the-art radar system.

In 2006, contracts were awarded to Raytheon for development of a large-area, light, Active electronically scanned array antenna which could be bonded to the structure of a blimp, Northrop Grumman for antenna development, and Lockheed Martin for development of the airship. As proposed, the 450 ft-long surveillance airship could be launched from the US and stationed for up to 10 years at an altitude of 65000 ft, observing the movement of vehicles, aircraft, and people below. At that altitude, the airship would be beyond the range of most surface-to-air and air-to-air missiles. The airship would be filled with helium and powered, at least in part, by solar-powered hydrogen fuel cells.

On March 12, 2009, the USAF announced that it had budgeted $400 million for work on ISIS .{{cite web| last = Barnes | first = Julian E. | date = March 13, 2009

As of 2012, the development of the airframe had been delayed to focus on "radar risk reduction". The United States Department of Defense ended the program in 2015. $471 million had been spent from 2007 through 2012.