Space telescope to create radio 'eye' larger than Earth

At 10 metres, RadioAstron's antenna is small compared to Earth's largest radio telescopes, which span 100 metres or more. But when its signals are combined with those of telescopes on the ground – a technique called interferometry – the resulting observations are as sharp as those produced by a single telescope with a dish as wide as the maximum distance between the component antennas.

This strategy has been used for decades to create radio telescopes the size of the Earth, and in 1997 the Japanese Space Agency launched the first space telescope dedicated to radio interferometry, HALCA.

With an orbit that will extend more than 10 times as far from Earth as HALCA, out to some 350,000 kilometres, RadioAstron promises to capture detail that is more than 10 times as fine. At its best, RadioAstron will be able to resolve points separated by an angle of just 7 microarcseconds, about 10,000 times the resolution of the Hubble Space Telescope.  link