1. LAT TVAC Test Delta-PDR1 GLAST LAT Project25 May 2005 LAT Environmental Test Planning and Design Delta-Preliminary Design Review 25 May 2005 LAT T-Vac Test Final version: 10 June 2005 LAT Environmental Test Planning and Design Delta-Preliminary Design Review 25 May 2005 LAT T-Vac Test Final version: 10 June 2005 Jack Goodman

2. LAT TVAC Test Delta-PDR2 GLAST LAT Project25 May 2005 Thermal-Vacuum Test Sequence Prep Lat for TVAC Load LAT into Chamber Connect Instrumentation Open Door Checkout Chamber Pump Down Hot Op T-Balance Hot Op Thermal Control Hot Op Peak Power Hot Performance Cold Survival T-Balance Cold Performance Cold Op T-Balance Cold Op Thermal Control Thermal Cycling (4) Bake Out Return to Ambient P&T Pre-Bake

3. LAT TVAC Test Delta-PDR3 GLAST LAT Project25 May 2005 Temperature Requirements for Simulated Sink Hardware Operating/Performance –Hot at 40°C –Cold at 0°C Thermal Balance –Hot balance at 30°C –Cold balance at 0°C –Cold survival at -2°C Test Cycle –Four TVAC Cycles, 8 Transients Hot soak at 40°C Cold soak at 0°C Test: EGSE Failure/Safe Hold (not relevant to orbit) –+25°C Bake out –+45°C

4. LAT TVAC Test Delta-PDR4 GLAST LAT Project25 May 2005 LAT Surfaces Requiring Thermal Conditioning ACD thermal conditioning –ACD temperature controlled by thermal sink plates electrically heated with radiation cooling to TVAC Chamber cold shroud Radiator and X-LAT Plate MLI Blankets (Spacecraft Bus simulator) thermal conditioning –Spacecraft bus temperature controlled by thermal sink plates electrically heated and cryogenically cooled Radiator thermal conditioning – 3 options –Thermal Control Unit sink plate system Radiator temperature controlled by thermal sink plates heated and cooled with Thermal Control Units –NRL thermal conditioning system Radiator temperature controlled by thermal sink plates electrically heated and cryogenically cooled –Cal Rod cage system Radiator temperature controlled by balance of IR heating from Cal Rods and radiation cooling to TVAC chamber cold shroud

5. LAT TVAC Test Delta-PDR5 GLAST LAT Project25 May 2005 ACD Thermal Conditioning ACD thermal conditioning –ACD Temperature varies: -60°C to +60°C –Thermal sink plate requirements Dimensions1.8 m x 1.3 m (approx) Temperature-89 °C to +60 °C Temperature Uniformity+/- 5 °C Emissivity ~0.5 (Anodized Al or paint) Power Absorption<20W from ACD (TBD) Cyclenone Quantity5 –Heating of thermal sink plates is provided by resistive heaters Film/strip heaters—built into the plates Power supplies—outside chamber with feedback control off of TC’s on plates –Cooling of thermal sink plates is passive radiation cooling to the TVAC chamber cold shroud TVAC Chamber Cold Shroud Temperature = -150 °C –Thermal control 5 independent heater circuits controlled by chamber CDACS system with feedback on TC temps –Power requirements (includes 20% margin) ACD +X sink plate: 985 W ACD +Y sink plate: 625 W ACD -X sink plate: 625 W ACD -Y sink plate: 625 W ACD +Z sink plate: 911 W

6. LAT TVAC Test Delta-PDR6 GLAST LAT Project25 May 2005 Spacecraft Bus Thermal Conditioning Spacecraft Bus thermal conditioning –SC Bus temperature varies: -40°C to +25°C –Thermal sink plate requirements Dimensions1.6 m x 1.8 m (approx) Temperature-40 °C to +25 °C Temperature Uniformity+/- 5 °C Emissivity >0.85 (Anodized Al or paint) Power Absorption<25W (TBD) Cyclenone Quantity3 –Heating of thermal sink plates is provided by resistive heaters Film/Strip heaters—built into plates Power supplies—outside chamber with feedback control off of TC’s on plates –Cooling of thermal sink plates is primarily LN2/GN2 with some radiation loss Active cooling supplied by LN2 solenoid valves –Thermal control 3 independent heater circuits controlled by chamber CDACS system with feedback on TC temps –Power requirements (includes 20% margin) SC Y-side sink plates: 2 @ TBD W SC top-deck sink plate: TBD W

7. LAT TVAC Test Delta-PDR7 GLAST LAT Project25 May 2005 Radiator Thermal Conditioning – Option 1 Option 1 - Thermal Control Unit (TCU) sink plate system –Radiator Temperature -13°C to +2°C (Hot Case orbit average) –Thermal Sink Plate Requirements Dimensions1.65 m x 1.85 m (approx) Temperature-126 °C to +4 °C (Hot transient); -95 °C to -64 °C (Cold transient) Temperature Uniformity +/-2.5 °C (balance); +/-5 °C transient Emissivity >0.85 (Anodized Al or paint) Power Absorption0 W to 800 W max per Plate (includes margin) Cycle92 minutes sinusoidal Quantity2 –Heating and cooling of thermal sink plates is provided by 1 TCU per Radiator –Thermal control 1 control zone per Radiator, controlled by TCU –Power requirements TBD, rough estimate by 6/15/05

8. LAT TVAC Test Delta-PDR8 GLAST LAT Project25 May 2005 Radiator Thermal Conditioning – Option 2 Option 2 – NRL Thermal Conditioning System –Radiator Temperature -13°C, +2°C (Hot Case orbit average) –Thermal Sink Plate Requirements Dimensions1.65 m x 1.85 m (approx) Temperature-126 °C to +4 °C (Hot transient); -95 °C to -64 °C (Cold transient) Desired Temperature Uniformity +/- 2.5 °C (balance); +/- 5 °C transient Actual Temperature UniformityTBD; rough estimate available by 6/1/05 Emissivity >0.85 (Anodized Al or paint) Power Absorption0 W to 800 W max per Plate (includes margin) Cycle92 minutes sinusoidal Quantity2 Heater Power5 amps per circuit (max) –Heating of thermal sink plates is provided by resistive heaters built into panels –Cooling is provided by active cooling supplied by LN2 solenoid valves –Thermal control 1 heater/cooling circuit per Rad controlled by chamber CDACS system with feedback on TC temps –Power Requirements # of circuits and power per circuit TBD, rough estimate available by 6/15/05

9. LAT TVAC Test Delta-PDR9 GLAST LAT Project25 May 2005 Radiator Thermal Conditioning – Option 3 Option 3 - CAL Rod Cage System –Radiator Temperature -13°C, +2°C (Hot Case orbit average) –Thermal Sink Cage Requirements Dimensions 1.6 m x 1.8 m (approx) Temperature Uniformity +/- 2.5 °C (balance); +/- 5 °C transient Emissivity>0.38 (sandblasted stainless steel) Power AbsorptionN/A Cycle92 minutes sinusoidal Quantity2 –Heating and cooling Radiator temperature control is by balance of radiation loss to TVAC chamber cold shroud (-150 °C) and IR Heating from CAL Rod cage IR power from Cal-Rod resistive heating elements TVAC Chamber Cold Shroud Temperature = -150 °C –Thermal Control 3 independent Cal-Rod circuits per Radiator controlled by chamber CDACS system with feedback from radiometers mounted in front of Radiators –Power Requirements (includes 50% margin) 2400 W/cage –Radiator top: ~400 W –Radiator middle: ~ 1600 W –VCHP reservoirs: ~400 W

10. LAT TVAC Test Delta-PDR10 GLAST LAT Project25 May 2005 Trade Study - Radiator Thermal Conditioning A trade study of the three Radiator thermal control options was done to establish the optimal solution The results of this show that the Cal-Rod cage system is the preferred implementation Baseline: Cal-Rod cage

11. LAT TVAC Test Delta-PDR11 GLAST LAT Project25 May 2005 Option 3 Cal-Rod/Baffle Sensitivity Study Cal-Rod spacing = 5.6” Cal-Rod Box Offset = 1.0” Cal-Rod Box Height = 12” Panel Dimensions = ~1.5 x 1.5 m (for the study) Polished Al Frame Basis of study and boundary conditions: –Chamber shroud temperature = -150C –Panel internal heat gen = 300W –Panel temp uniformity goal: 5 C –Size system to maintain Rad temp at 0 C, 20 C, and 40 C –Stainless steel Cal Rods, 0.25” OD Results: Cal-rods need 5.6” max spacing 7” set-back from Rad surface Results of Thermal Analysis

12. LAT TVAC Test Delta-PDR12 GLAST LAT Project25 May 2005 Option 3 Cal-Rod Panel Temperature Distribution

13. LAT TVAC Test Delta-PDR13 GLAST LAT Project25 May 2005 Option 3 Cal-Rod Cage Heater Circuit Requirements Transient and steady-state thermal analyses of LAT system shows that the hot-case transient test case is the defining case for the heater system –At one extreme of the transient, all 600 W of LAT power is radiated off of one Radiator –The Cal-Rod cage on the opposite side of the LAT draws the most power at that time Max power needed: 1600 W/Radiator Heater cage requirements and boundary conditions –Power: 1600 W * 1.5 margin = 2400 W/Rad –Temp uniformity: 5 degC over surface of Radiator –Max process power: 300 W (with Cal-Rods operating at full-power) –Minimum of 3 control zones –Cold shroud minimum temp: -150 C –Low-profile/low-mass design to increase cool-down and warm-up rates Calrod Dissipation

14. LAT TVAC Test Delta-PDR14 GLAST LAT Project25 May 2005 Option 3 Cal-Rod Cage Heater Circuit Implementation Power requirements (includes 50% margin) –2400 W/cage Radiator top: ~400 W Radiator middle: ~ 1600 W VCHP reservoirs: ~400 W Cal-Rods –Heated length of 60 inches –O.D of 0.25 inches –Emissivity >0.38 (sandblasted stainless steel) –Resistance of at least 89 ohms –Max operating temperature: 750°C –Min non-operating temperature: -150°C Use standard NRL power supplies –1000 W max and 5 A max or 240 V max –Cal-Rod cage will likely be powered by 4 supplies: one for top, one for reservoirs, and two ganged together for middle zone Cal-Rod Heater

15. LAT TVAC Test Delta-PDR15 GLAST LAT Project25 May 2005 Summary of Heater Requirements