Orbiting stellar interferometer

The Orbiting Stellar Interferometer (OSI) is a concept for a first-generation space interferometer with astrometric and imaging capabilities and its responsive to the recommendations of the Astronomy and Astrophysics Survey Committee for an astrometric interferometry mission. OSI is a triple Michelson interferometer with articulating siderostats and optical delay lines. The design uses a 7 m maximum baseline and aperture diameters of 33 cm; the targeted astrometric performance is a wide-field accuracy of 5 (mu) as for 20-mag objects. The instrument would also be capable of synthesis imaging with a resolution of 10 mas. Laser metrology is used to relax structural requirements thereby reducing cost. The currently envisaged flight system fits into an Atlas II shroud, for insertion into a 900 km sun- synchronous orbit.