Polar space craft.

The fluxgate sensors are ring core-types, each composed of a 'driver' coil and a 'feedback' coil surrounding a ring-shaped magnetically permeable core. The drive coil is used to periodically drive the the core into saturation, while the feedback coil zeros out any DC field in the core. When the presence of external 'DC' fields in the core are sensed by the appearance of second harmonics of the drive frequency, the current in the feedback coil is changed to keep the core field near zero. Three orthogonal sensors make each of the two fluxgate units. 'Flippers' can mechanically change a sensor in the spacecraft spin plane with the one along the spin axis in order to determine any zero-level offsets in the measured fields. The magnetometer is a fully redundant system with duplicate processors, analog-digital converters, spacecraft interface electronics, power conversion circuits and two independent basic magnetometers, one designed to measure fields up to 47,000 nT and one designed to measure fields up to 5500 nT. Each magnetometer has two outputs that are continuously available, a low range and a high range.

The MFE Characteristics are summarized below:
Sensors	Mass-Inboard 686 g Mass-Outboard 620 g Dimensions 9.5 cm diameter, 15.5 cm length Power 0.05 W (sensors)
Electronics	Mass 3.86 g Volume 18.3 X 24.1 X 15.2 cm3 Power-normal 4.3 W
Range	Inboard Magnetometer 46700 or 5860 nT (plus and minus) Outboard Magnetometer 5525 or 694 nT (plus and minus)