Recent Developments in Space VLBI Geodesy Demonstration Experiment (GEDEX)

The unique radio astronomical technique of Space Very Long Baseline Interferometry (SVLBI) is an extension of the ground-based VLBI into the space. It has some important potential applications in geodesy and geodynamics, including the definition, practical realization, and interconnection of different reference frames, determining the geocentric positions of VLBI stations, estimation of the gravity field of the Earth, and satellite orbit determination using the delay and delay rate observables. With the launching of the first SVLBI satellite of the VLBI Space Observatory Programme (VSOP) of Japan, in February 1997, this technique has become a reality. An international team of scientists, working under the auspices of the FOMI Satellite Geodetic Observatory, Hungary, has designed the GEDEX, for the purpose of exploring the feasibility of the geodetic applications of SVLBI.