Orbit . ... The orbit of the RadioAstron provides four types of study: . rough images of radio sources with ultra-high angular resolution, using all baselines up to the radius of the apogee, that is much larger than Earth diameter; . ... high quality imaging of radio sources, with moderate resolution, by observing either with small projected base lines Earth-spacecraft, i.e. close to the orbital plane, or near the perigee. ... high accuracy orbit determination. ... Space Radio Telescope . ...