The Cluster sensor couples a lightweight design (300g) with good low-noise performance.  The sensor and accompanying electronics were designed and built by Goddard Space Flight Center.

Key Features

• measures magnetic field in sensor x, y and z directions separately, data then transposed to other coordinate systems
• improved linearity through operation in null field mode, where current feedback nulls out the field measured in the sense coil
• 3 ring cores used - one per axis

Mass optimisation through:

• common sense/feedback coils

Minimisation of thermal effects

• sensor and pigtail wrapped in insulating MLI
• Delrin stand offs to thermally isolate the sensor from boom
• low power heater inside sensor to maintain sensor temperature during eclipse
• sensor temperature monitored by non-magnetic thermistor

Key Performance measures

• noise density < 10pT/√Hz over the temperature range from -35ºC to 25ºC
• digital resolution 7.5pT in most sensitive range (-64nT to +64nT)
• scale factor drift < 40 ppm/ºC
• sensor operating range: -80ºC to 70ºC
  sensor survival range: -130ºC to 90ºC
• electronics operating range: -20ºC to 50ºC
  electronics survival range: -30ºC to 60ºC