SCIAMACHY Calibration Review Meeting Thermal Control Aspects 11 September 2002

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SCIAMACHY Calibration Review MeetingThermal
Control Aspects11 September 2002

• Presentation
• Trevor Watts

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Sciamachy on Envisat
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SciamachyTEMPERATURE CONTROL

• Two Heater Systems
• Part 1 - Optical Module at -17.9 ºC
• Part 2 - Detector temperature range 140 K to 230 K

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SciamachyOPTICAL MODULE - 4

• Heat-Pipe Network in 3 Dimensions for Optical
  Module
• 5 Embedded heatpipes, bonded
• 4 Transport Heatpipes, bolted
• 1 Equalizing Cross Heatpipe, bolted
• Connection to Radiator at -20 ºC

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SciamachyHEATPIPE NETWORK
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SciamachyATC CONTROL SYSTEM

• Optical Module thermal requirements
• Temperature -17.9 /- 0.3 deg C
• Lifetime 4 year
• Optical Module thermal characteristics
• Massive Aluminium Structure packed in MLI
• OBM coupled via Heat-Pipe Network to dedicated
  radiator
• Heat enters through two Optical Baflles
• Three PI Controlled Heater Loops
• Radiator-A
• Nadir Baffle
• Limb Baffle

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SciamachyThermistors and ATC Heaters
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SciamachyPerformance ATC System
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Present situationOBM temp -17.85 /- 0.15 K
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SciamachyDuty Cycles ATC Heaters (pred.)
Orbital Variation
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Sciamachy ATC Duty Cycles (pred. meas.)
Orbital Variation
Measured
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SciamachyTEMPERATURE CONTROL

• Two Heater Systems
• Part 1 - Optical Module at -17.9 ºC
• Part 2 - Detector temperature range 140 K to 230 K

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SciamachyDETECTOR COOLING

• Passive Cooler
• Temperature 130 K
• 2 Cryogenic Heatpipes
• Distance to Passive Cooler 1 meter
• 3 Trim Heaters, 1 watt each, near Detectors
• 8 Detectors

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SciamachyCOOLER and THERMAL BUS
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SciamachyPASSIVE COOLER
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DetectorsSeasonal Prediction
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Predicted versus MeasuredC1, C2, C6
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Predicted versus MeasuredC3, C4, C5
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Predicted versus MeasuredC7, C8
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Present situationChanels 1 upto 6
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SciamachyChannel 8 after De-contamination
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Drift Channel 8
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Present situationChanels 7 8, drift lt 0.05
K/day
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SciamachyCONCLUSION

• The OBM Temperature is on the target -17.9 deg
  C.
• Orbital temperature variation OBM /- 0.15 K.
• Duty Cycle ATC Heaters 57 is lower than
  expected.
• Chosen Detector Temperature Levels
• Channels 1-6 within 1 or 2 K from T_cal_L
• Channel 7 1 K above target T_cal_L
• Channel 8 2 K above target T_cal_L
• Chosen Detector Temperature Levels
• Channels 1-6 within 1 or 2 K from T_cal_L
• Channel 7 1 K above target T_cal_L
• Channel 8 2 K above target T_cal_L