Space Optical Interferometry for Astrometry

It is shown that the prospects for the development of astrometric measurements of submillisecond level augur well for use in space-based optical interferometry. The main problems of astrometry and astrophysics are discussed, with particular reference to those that can be solved with an accuracy of single position measurements of about 10-20 microseconds of arc. The concept of the ZODIAC space-based optical interferometer-arcmeter is presented, and the description of its optical diagram, of the system of metrological control of all its optical elements and of the process of measurements of the length of an arc between stars is given. The ZODIAC instrument can be implemented and installed both on a specialized small satellite and on the orbital Astation. The main characteristics of the instrument, designed to measure about ten thousand objects down to 18(m) with a single measurement accuracy of 20 (mo)as for 3 years of operation in orbit, are presented.