main

Following the success of the VLBI Space Observatory Programme (VSOP), a next generation space VLBI mission, currently called VSOP-2, is being planned. Very Long Baseline Interferometry (VLBI) is a technique used by radio-astronomers to achieve very high angular resolution imaging of celestial radio sources, by combining the signals from widely separated radio telescopes. Space VLBI extends this beyond the Earth by placing one telescope on a satellite. For VSOP-2, higher observing frequencies, cooled receivers, increased bandwidths and a larger telescope diameter will result in gains in resolution and sensitivity by factors of 10 over the VSOP mission. The possibility of including a rapid slewing capability for the spacecraft is also being pursued, so that observations using the phase-referencing technique will enable the sensitivity to be improved even further. The VSOP-2 satellite has been the 25th ISAS Scientific satellite and given the pre-launch name ASTRO-G (just as HALCA was MUSES-B before launch). But because of the technical problems of ASTRO-G, the project was decided to cancel in December, 2011, and the ASTRO-G project finished in May, 2012.