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