VSOP (VLBI Space Observatory Program) is an international radio astronomy project led by ISAS (Institute of Space and Astronautical Science) and the National Astronomical Observatory of Japan. It involves correlating measurements by the HALCA (Highly Advanced Laboratory for Communications and Astronomy) satellite with those of various ground-based telescopes to form a telescope effectively 32,000 kilometers across size (three times larger than Earth) which has a maximum resolving power at radio wavelengths of about 90 microarcseconds (roughly 100 times greater the resolving power of the Hubble Space Telescope).