Optical Orientation of Satellite Magnetometers

Magnetic measurements in space need accurate information about the orientation of the magnetic axes of the magnetometer with respect to the mechanical axes of the satellite. Necessary information for this can be obtained with the optical orientation method of the Nurmijärvi calibration system.

A theodolite will be installed at the distance of 60 meters from the coil system and along the magnetic South axis of the coils. The tested magnetometer in the centre of the coil system has a mirror fixed to its sensor determining two mechanical axes of the sensor. A light beam from the theodolite outdoors is reflected from the mirror and back to the theodolite. With this system two mechanical axes of the sensor can be measured with ±3 minutes accuracy. The third axis is levelled with a spirit level. After the orientation the automatic calibration gives the angles between the magnetic and the mechanical axes of the magnetometer.