Payload Module thermal control

PLM external MLI configuration

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.

Last update: 21 June 2006

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