Known as Scaled Composites Model 281,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 Proteus. Proteus has an extremely efficient design, and can orbit a point at over 19,800 m for more than 18 hours. source: nasa
The Proteus features an unconventional tandem-wing, twin-boom configuration with two rear-mounted turbofan engines providing power. The aircraft features modular construction that allows payloads to be carried in a variety of locations.source: nasa
Proteus is an “optionally piloted” aircraft ordinarily flown by two pilots in a pressurized cabin. However, it also has the capability to perform its missions semi-autonomously or flown remotely from the ground.