RadioAstron (also called Spektr -R ) is a space telescope for interferometric radio observations. The launch took place on 18 July 2011.

With RadioAstron a radio telescope with a 10 m diameter reflector was brought round trip time and the greatest Erdentfernung of about 350,000 km along an eccentric orbit with 9.5 days. In collaboration with ground-based telescopes are by the method of VLBI ( radio interferometry ) highest resolution observations in four areas 1.35 to 92 cm wavelength be possible. In the region around 1.35 cm wavelength (frequencies 18-25 GHz) as a resolution of 7 micro- arcseconds to be achieved.

Radio Astron is an international project under the auspices of the Moscow Cosmic Astro Centre at the Lebedev Institute of Physics of the Russian Academy of Sciences. More than 20 countries are involved.