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PLM external MLI configuration

Payload Module thermal control

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ESA / Applications / Observing the Earth / Meteorological missions / MetOp

Thermal control of the PLM is passive (i.e. radiators and MLI) and supplemented by heaters.

These are the main elements of the thermal control:

  • Multi-Layer-Insulation (MLI)
  • flexible Second Surface Mirror Radiators
  • thermal doublers to spread the heat of high dissipating units
  • black paint on inner side of PLM panels
  • hardware controlled heaters
  • software controlled heaters
  • monitoring thermistors

Hardware controlled heaters use thermostats and maintain minimum non-operating temperatures to allow immediate activation of the:

  • Payload Module Computer (PMC)
  • Thermal Control Unit (TCU)
  • Power Distribution Unit (PDU)
  • Power Control Unit (PCU)

Software controlled heaters are controlled by the PMC on the basis of thermistor readings and defined temperature limits. They are used for warm-up and for control of operational temperatures.

Most instruments have their own thermal control and are thermally de-coupled from the PLM structure. For the Advanced Very High Resolution Radiometer (AVHRR), High Resolution Infra-Red Sounder (HIRS) and the Search and Rescue Repeater (SARR) instruments, baseplate temperatures are controlled by the PLM.

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