Orbiting very long base interferometer (OVLBI) for radio and optical astronomy

Abstract Three missions are now under consideration related to OVLBI technology: Radioastron, Millimetron and VOT. Radioastron consists of a 10-m diameter antenna and receiving complex for cm and dm ranges. This space radio telescope will operate with global network of all largest ground radio telescopes and realize angular resolution up to 30 microsecond of arc. Millimetron is the same type mission with more precise 10-m antenna for mm and cm ranges and angular resolution up to a nanosecond of arc for OVLBI mode. Second type of operation is a single dish mode for short millimeter and submillimeter observations with very high sensitivity. VOT is a VLBI optical system on a geostationary orbit for the synthesis of images in ultraviolet, optical and near infrared ranges with angular resolution up to a microsecond of arc. The array of identical freely flying satellites — telescopes with laser synchronyzation and information down-link will synthesize such images.