Development and construction of the optical system for the airborne observatory SOFIA

The stratospheric observatory SOFIA will provide astronomers routine access to celestial objects at wavelength bands which are not observable from the ground due to atmospheric absorption. SOFIA comprises a 2.5 m entrance pupil diameter telescope, including all required control systems, installed in a Boeing 747SP aircraft to form an observatory which is operated at altitudes above 12.5 km. Since January 1997 the telescope system is being developed by an industrial team for the German and US space agencies DLR and NASA. Operating a high precision instrument within the extreme environment of the stratosphere as well as stringent restrictions on the telescope mass demand technical solutions that represent the cutting edge of the state of the art optical instrument design.