A coil system with 3 meter high coils is located at the Conrad Observatory and used for calibration of highly sensitive magnetic field measuring devices, which will later carry out important analyzes in space. Magnetometers for the JUICE mission of ESA were tested in this coil system, which was set up jointly by the ÖAW and GeoSphere. JUICE (JUpiter ICy moon Explorer) is the first mission of the European Space Agency ESA to the outer solar system. In particular, the three largest moons of Jupiter are examined: Callisto, Europa and Ganymede.