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THEMIS MISSION PRE-SHIP REVIEW Thermal Christopher Smith University of California - Berkeley

THEMIS MISSION PRE-SHIP REVIEW Thermal Christopher Smith University of California - Berkeley. Thermal Hardware Status Update. Thermal Hardware Status Update. Thermal Modeling Status. Second Model Correlation Complete All boxes within 5 degrees of test temperatures

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THEMIS MISSION PRE-SHIP REVIEW Thermal Christopher Smith University of California - Berkeley

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  1. THEMIS MISSION • PRE-SHIP REVIEW • Thermal • Christopher Smith • University of California - Berkeley

  2. Thermal Hardware Status Update

  3. Thermal Hardware Status Update

  4. Thermal Modeling Status • Second Model Correlation Complete • All boxes within 5 degrees of test temperatures • Thermostat set points verified … except: • IDPU and BAU Primary and Secondary • IRU Primary and Secondary was verified on P5 only • Heater duty cycles less than 70% • Flight Predicts for launch case are complete • The remainder are currently running

  5. PFRs and RFAs • Five PFRs closed since PER • PFR-186: Thermal Blanket Velcro Adhesion Failure • PFR-205: Fuel Line Zone #1 Secondary Thermostat to Low • PFR-215: F3 XPNDR Secondary Setpoints the Same as Primary • PFR-225: F3 MSSS Primary and Secondary service switched • PFR-226: P1 Thermistors BTMPRCSLN1 and BTMPRCSSVC swapped • RFAs • P3_PSR_4: Periodic Emissivity Measurements, closed • P1_PSR_2: Transponder Radiator Resizing, submitted • P1_PSR_3: Test Versus Flight Radiator Heat Flow Comparison, closed • P1_PSR_4: Comparison of Pre-test Flight Predicts to Correlated Model, submitted

  6. Test Facilities • Testing took place in JPL chamber #7 • 74”x134” • Simultaneously accommodated two Themis probes for testing with chamber divider shroud • Gaseous or liquid nitrogen controlled shrouds • GN2: –130 to +125 deg C • LN2: -175 deg C • Two TQCMs • Nitrogen Vent-back is rate limited • 30 power Supplies • 168 Type T thermocouple feedthroughs • 250 Channel DAQ system • 1000 L/sec Leybold and 2000 L/sec Balser Turbo pumps • Tank cleanliness certified prior to T-V test

  7. TVAC Flow for P2

  8. TVAC Flow for P1, P3, P4, and P5

  9. Thermal Vac Configuration P2Hot Balance #1

  10. Thermal Vac Configuration P1,P3-5Cold Balance #3

  11. TVAC #2 Setup

  12. TVAC #2 Setup

  13. TVAC #2 Setup

  14. Test Heaters • 12 test heaters provided for each thermal box • 1 heater for the Antenna Hat Coupler • 1 Heater for the Separation Ring • 1 heater for controlling the beam warm up

  15. Instrumentation • 168 T-type thermocouples used on P2 • 80 T-type thermocouples used on P1, P3-5 • 64x2 used on the spacecraft • 16x2 used for heaters and environment • Transponder fully instrumented • Added thermocouples to the RCS system on P3

  16. P2 TVAC Results After 1st Correlation

  17. TVAC Hot Balance Results Before 2nd Correlation

  18. TVAC Cold Balance Results Before 2nd Correlation

  19. Combined Probe Correlation Changes

  20. Combined RCS Correlation Changes

  21. Other Changes • Increased transponder radiator size by 30% to match hardware modifications • Heater power applied as a function of bus voltage • Added heat leak from sun sensor to thermal box corner panel • Ran two separate cold balance cases to account for different top plate temperatures in actual test • Moved several Thermostat node locations to better reflect as installation photographs • Added Thermostat masses on RCS Fuel Lines Heater Zones (12 grams per TSTAT) • Removed Line 1 heater service from service valve TSTAT node

  22. TVAC Hot Balance Results After 2nd Correlation

  23. TVAC Cold Balance Results After 2nd Correlation

  24. Test Heater Power Summary

  25. Anomalies During Test • TVAC 1 • PFR-205, Closed: Fuel Line Zone #1 Secondary Thermostat to Low • Heat leak to bottom deck caused TSTAT to appear to be tripping at a low temperature when it was functioning normally. However this exposed a real cold spot in the RCS fuel line 1. Fly As Is. Only presents a problem in long eclipses when the primary heater service has also failed. • TVAC 2 and 3 • PFR-215, Closed: F3 Transponder Secondary Setpoints the Same as Primary • Fly As Is • PFR-225, Closed: F3 MSSS Primary and Secondary service switched • Fly As Is • PFR-226, Closed: P1 Thermistors BTMPRCSLN1 and BTMPRCSSVC swapped • Database Updated to swap mnemonics

  26. THERMAL • BACKUP SLIDES

  27. Thermal Testing History • Thermal Testing History

  28. Individual Instrument TVAC (2 Cycles) Probe Level TVAC (4 Cycles, 3 Balance Points) Thermal Cycle Accumulation Instrument Suite TVAC (6 Cycles) Individual Probe Component TVAC (8 Cycles)

  29. Thermal Vac Testing History Instruments

  30. Thermal Vac Testing History Instruments

  31. Thermal Vac Testing History Suite and IDPU

  32. Thermal Vac Testing History Mag Booms

  33. Thermal Vac Testing History SPB

  34. Thermal Vac Testing History AXB

  35. Thermal Vac Testing History Probe Components

  36. Post TVAC 1 • Correlation Changes and Data

  37. P2 TVAC Results Before Correlation • Comparison of the test data with test predicts show most components are within 5°C of test predicts for Hot and Cold Balance Cases • The Survival Balance Case (Cold 2) results indicate that the model is conservative on the cold side which means that flight heater powers will be less than predicted.

  38. Correlated Interface Conductances

  39. Correlated Blanket e*

  40. Correlated Thermostat Set Points

  41. Other Changes • Added Thermostat masses on RCS Fuel Lines Heater Zones (12 grams per TSTAT) • RCS Max Heater Power multiplied by 1.375 (Accounts for 33V Bus instead of 24V) • Adjusted RCS Latch Valve, P-Ducer and Solenoid Valve MCp values to account for single node model (FAC 0.2). • Adjusted Sun Sensor outer face emissivity from 0.2 to 0.8 (accounts for black anodized Baffles)

  42. P2 TVAC Results After Correlation

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