The Proteus is a unique aircraft designed as a high-altitude, long-duration telecommunications relay platform, with potential for use on atmospheric sampling and Earth monitoring science missions as well. It was designed by Burt Rutan, president of Scaled Composites, and built during 1997-98 at the firm's development facility in Mojave, CA. Normally flown by two pilots in a pressurized cabin, the Proteus also has potential to perform its missions semi-autonomously. The aircraft is designed to cruise at altitudes from 50,000 to more than 63,000 feet for up to 18 hours. Proteus' small cabin is pressurized to allow the flight crew a shirt-sleeve environment equivalent to an altitude of 14,500 feet when the aircraft is at 55,000 feet, or 15,500 feet at a 60,000-foot altitude.