One measuring device is placed on the body of the craft. The identical second of the pair is placed the necessary distance away from the body by unfolding a 1 m long boom (carbon composite tube). Two redundant pyrotechnical cutters cut one loop of thin rope to free the power of metal springs. The driven knee lever rotates the boom perpendicularly outwards and latches it in place. Only the use of a pair of sensors together with the rotation of the sonde allows the spacecraft to resolve the small natural magnetic field beneath the disturbing fields of the probe itself. The measurements to identify the fields produced by the craft took place on the route from Earth to Venus. The lack of magnetic cleanness was due to the reuse of the "Mars Express" spacecraft bus which did not carry a magnetometer. By combining the data from two-point simultaneous measurements and using software to identify and remove interference generated by "Venus Express" itself, it was possible to obtain results of a quality comparable to those produced by a magnetically clean craft.