Introduction: The space techniques GPS, VLBI and SLR contribute in different ways to the determination of geodetic parameters, e.g station coordinates, earth orientation parameters and tropospheric parameters, and so to the realisation of global reference frames. The intensive VLBI campaign CONT02, initiated by the International VLBI Service for Geodesy and Astronomy (IVS) from 16.-31. October 2002, provides an ideal basis for combination studies. Due to a lot of common parameters for GPS and VLBI both techniques should benefit from a combination. Recently we included also SLR into these investigations.