THEMIS MISSION PRE-ENVIRONMENTAL REVIEW Thermal Christopher Smith Thermal Engineer

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

2. Thermal Hardware Status

3. Thermal Hardware Status

4. Thermal Hardware Status

5. Thermal Modeling Status • Model Correlation Substantially Complete • All boxes within 5 degrees of test temperatures • Thermostat set points verified • Except IDPU, Transponder and BAU Secondary which could not get cold enough • Except Fuel Line Zone #1 and Service Valve Secondary which would have required turning off RCS Zone #1 and Zone #2 • Heater duty cycles less than 70% • Predicts for TVAC #2 and #3 complete • Flight Predicts in process including correlated heater power predicts

6. RFAs, and PFRs • PFRs • PFR-186:Thermal Blanket Velcro Adhesion Failure remains open until fix is implemented on all probes • RFAs • Four recent thermal RFAs assigned at Swales PSRs are currently open • ??: VDG optical property monitoring • P1_PSR_2: Transponder Radiator Resizing • P1_PSR_3: Test Versus Flight Radiator Heat Flow Comparison • P1_PSR_4: Comparison of Pre-test Flight Predicts to Correlated Model.

7. 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)

8. Thermal Vac Testing History Instruments

9. Thermal Vac Testing History Instruments

10. Thermal Vac Testing History Suite and IDPU

11. Thermal Vac Testing History Mag Booms

12. Thermal Vac Testing History SPB

13. Thermal Vac Testing History AXB

14. Thermal Vac Testing History Probe Components

15. Test Facilities • Testing will take place in JPL chamber #7 • 74”x134” • Will simultaneously accommodate two Themis probes for F3-F4 and F1-F5 • 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 • 20 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

16. TVAC Flow for P2

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

18. Thermal Vac Configuration

19. Feed-through Allocation • Feed-through Plate #1 and #2 (Identical 15” Plate) • Probe Umbilical (TBF2821PS x3) • Thruster Enable Test Set (TBF2821PS) • Solenoid Valve Turn Around (TBF2821PS) • Virtual Sat/Bridge, MSS Stimulator Controller (TBF2821PS) • Feed-through Plate #2 (15” Plate) • Heater #1 (10 channels, JPL Provided) • Heater #2 (10 Channels, JPL Provided) • Thermocouple #1 (55 Channels, JPL Provided) • Thermocouple #2 (56 Channels, JPL Provided) • Thermocouple #3 (56 Channels, JPL Provided) • Miscellaneous 3.5” Feed-through Plates Assigned by JPL • TQCM system (x2) • EFI Boom Simulator (MS3126E22-55P) • Instrument SST Source Shutter (Free pins of TBD connector) • Probe RF Cable (TNC Connector)

20. Thermal Box - Probe Mounting • Probe On Thermal Vac Rail

21. Thermal Box – MLI Baffling • Baffling Taped In

22. P2 Lifted On To Rail

23. TVBOX #2 Test

24. TVBOX #2 Test

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

26. Instrumentation • 80 T-type thermocouples specified for each probe (168 used for F2 alone) • 64x2 used on the spacecraft • 16x2 used for heaters and environment • Transponder fully instrumented • Added thermocouples to the RCS system on P3

27. TVAC Procedures • THM-SYS-004, THEMIS Contamination Control Plan • THM-SYS-014, THEMIS ESD Control Plan • THM-MINT-PROC-010, THEMIS Probe Power On/Off Procedure • THM-MINT-PROC-013, THEMIS Probe LPT Procedure • THM-MINT-PROC-014, THEMIS Probe AT Procedure • THM-MINT-PROC-032, THEMIS Instrument LPT Procedure • THM-MINT-PROC-034, THEMIS Instrument AT Procedure • THM-MINT-PROC-048, THEMIS Probe TV Functional • THM-MINT-PROC-056, THEMIS Probe Rollover Procedure • THM-MINT-PROC-058, THEMIS Probe Lift in Rollover Fixture Proc • THM-MINT-PROC-059, THEMIS Thermal Vac Chamber Loading Proc • THM-MINT-PROC-140, THEMIS Probe Thermal Closeout Procedure • THM-MINT-PROC-102, THEMIS TV Functional Configuration Test • THM-MINT-PROC-047, THEMIS Probe Pair TV Test Procedure • In Progress

28. 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.

29. Correlated Interface Conductances

30. Correlated Blanket e*

31. Correlated Thermostat Set Points

32. 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)

33. P2 TVAC Results After Correlation

34. RFAs, and PFRs • RFA ??: VDG optical property monitoring • Description: Monitor the optical properties of the VDG Top Deck through environmental testing and up to launch. • Resolution: The following actions are being taken by THEMIS Project Office to satisfy the intent of Probe 3 PSR RFA #4. • THEMIS VDG witness coupons will be cut into sections of 2 x 2 inches square. • The square VDG coupons will be sent to GSFC for Alpha and E measurements. • The VDG coupons will be exposed to probe thermal vacuum test environment. • The VDG coupons will be measured for optical properties up to launch. • The VDG test results will be documented and summarized in a report.

35. RFA_P1_PSR_#2 • RFA P1_PSR_#2: Transponder Radiator Resizing • Description: Provide rational and supporting data to support the decision to increase the transponder radiator area by 30% rather than replacing the Cho-therm interface material that had been reused. Have the transponder to radiator bolts been re-torqued after the test? How do you know that poor interface conductance experienced for Probe 2 is only attributed to the Chotherm and not surface flatness which may or may not be consistent with other probes. • Resolution: In progress, Rommel Zara is working on this issue. • All probes now use fresh Chotherm, including P2 • All Chotherm interfaces experienced the same degradation from predicts, which suggests this is an issue with Chotherm and the composite deck. • Testing of remaining probes will help resolve this question • Two thermal balances will be done on the following probes to help nail down the variables. • Heater power cost will be analyzed but it is expected that the increase in heater power will be covered by the decrease in the RCS heater power.

36. RFA_P1_PSR_#3 RFA P1_PSR_#3: Test Versus Flight Radiator Heat Flow Comparison Description: Provide a comparison of the energy flows for all un-insulated surfaces (i.e. radiators) between the hot and cold test conditions and the associated flight condition. Also provide a comparison of the combined heat flow through MLI blankets for test and associated flight design cases Resolution: Lou requested this prior to the P2 testing but I was unable to get to this then. Icompletely agree and this is in the plan. Analysis has started and it will be completed before the 01 July due date.

37. RFA_P1_PSR_#4 RFA P1_PSR_#4: Comparison of Pre-Test Flight Predicts to Correlated Model Description: Provide a comparison of flight predictions using the correlated model with pre-test flight predictions. Identify temperature sensitive components whose temperatures were substantially changed. Revisit correlation changes made to the model that effect these components and assure yourself that the changes make physical sense. Include heater powers and provide a comparison of assumed component power dissipation versus available test measured values. Resolution: Completely agree and this was already in the plan, analysis has started and it will be completed by the 01 July due date.