Inspired by the possibilities of their earlier manned solar-powered aircraft, AV first began developing a solar-powered HALE UAV in 1981 to provide a continuous high altitude platform. After making 9 successful test flights, the 99 ft wingspan Pathfinder was mothballed for a decade because of technology limits in the propulsion system at that time.
The Pathfinder aircraft was then adopted by NASA’s Environmental Research Aircraft and Sensor Technology (ERAST) program in 1994, to assist in the development of research platforms for the Stratosphere. Pathfinder flew to 50,567 feet at Edwards September 12, 1995, its first trip to the stratosphere. From there, it was improved and taken to the Pacific Missile Range Facility (PMRF), Kauai, Hawaii for test flights in 1997, where it flew to 71,504 feet on July 7, before performing a series of science missions over the Hawaiian Islands.