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Thermal Design

Thermal Design. Christopher Smith RBSP Thermal Engineer Space Sciences Lab University of California, Berkeley. Spacecraft Level Thermal Requirements. Orbit: 500-675 km x 30,050 - 31,250 km (EFW-7, EFW-8) Inclination: 10 degrees +/- 0.25 (EFW-6) 2 year design life, plus 60 days (EFW-1)

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Thermal Design

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  1. Thermal Design Christopher Smith RBSP Thermal Engineer Space Sciences Lab University of California, Berkeley EFW INST+SOC PDR

  2. Spacecraft Level Thermal Requirements • Orbit: 500-675 km x 30,050 - 31,250 km (EFW-7, EFW-8) • Inclination: 10 degrees +/- 0.25 (EFW-6) • 2 year design life, plus 60 days (EFW-1) • Spacecraft top deck pointed to sun within: 25 degrees N/S and E/W, normal operation (EFW-201) 15 to 27 degrees composite, normal operation (EFW-202) 47 degrees, Safe mode (SCRD 3.10.4.4) • S/C spin rate (about top deck): 4 to 6 RPM, normal and safe modes (EFW-9) 3 to 15 RPM, instrument commissioning (EFW-203) • S/C shall survive 112 minute eclipse (Derived EFW-6, EFW-7, EFW-8) EFW INST+SOC PDR

  3. EFW Thermal Requirements • Conductive external surfaces with 105 Ohms/Sq. (EFW-133) • Contamination: 100,000 class (EFW-132) • Instruments to operate within specification with -25 to +55 spacecraft boundary conditions. (EFW-76, EFW-77) • Instruments to survive without damage with -30 to +60 spacecraft boundary conditions. (EFW-79, EFW-80) • Comply with contamination control plan. APL document 7417-9007. (EFW-132) • Comply with Environmental Design and Test Requirements Document. APL document 7417-9019. (EFW-136) • Comply with RBSP_EFW_SYS_301_ETM, RBSP engineering test matrix EFW INST+SOC PDR

  4. Engineering Test Matrix • 7 total cycles per instrument, 5 at component level, 2 at suite level. • Pre-Amps cycled separately due to larger temperature swing. • No need for thermal balance as all instruments are conductively coupled to the spacecraft. EFW INST+SOC PDR

  5. APL Thermal Modeling Interface • Berkeley maintains a thermal desktop model of the EFW instrument and a boundary node definition of the spacecraft. • APL Maintains a TSS geometry and SINDA network model of the spacecraft. • APL integrates Berkeley geometry via Thermal Desktop TSS export. • Provides environmental heat flux data to instruments. • Berkeley currently does not use them at this stage of integration but generates their own. • APL integrates Berkeley SINDA network model into the SINDA spacecraft network model. • APL specifies spacecraft connection nodes. • APL runs integrated model and provides temperature predicts back to Berkeley. • Design cycles as necessary. • APL is responsible for producing high fidelity temperature predicts. EFW INST+SOC PDR

  6. Thermal Model OverviewInstruments and Boundary Spacecraft IDPU AXBs SPBs EFW INST+SOC PDR

  7. Thermal Model OverviewAXB -Stowed Sphere / Preamp (DAG 213) Rod to Stacer Hinge (DAG 213) Mounting Tube (M55J) Stacer (DAG 154) EFW INST+SOC PDR

  8. Thermal Model OverviewAXB -Deployed Sphere (DAG 213) Stacer (DAG154) DAD (AntiSun: Clear Alodine) (Sun: Clear Alodine / GeBk Tape mix) EFW INST+SOC PDR

  9. Thermal Model OverviewSPB & IDPU SPB - Deployed IDPU (Black Anodized) (GeBk Tape) (Clear Alodine) SPB - Stowed EFW INST+SOC PDR

  10. Optical Materials • Most properties tested, used, and correlated for the THEMIS mission • Properties submitted by APL and approved by the GSFC coatings committee July 07, 2008. EFW INST+SOC PDR

  11. Thermophysical Properties • No blankets currently required. • If blankets are needed at a later date the model will use e*=.05 and .01, Germanium Black Kapton outer layer. EFW INST+SOC PDR

  12. Interfaces IDPU • Conductively mounted to spacecraft side panel. • 6 #8 Bolts = 0.75 W/C each. • Radiative coupling to spacecraft interior, black anodized SPB • Conductively mounted to spacecraft side panel. • 4 #8 Bolts = 0.75 W/C each. • Deployed elements are completely isolated from the spacecraft by wire. • Low radiative coupling to spacecraft interior, Clear Alodined Aluminum AXB • Conductively mounted to the top and bottom spacecraft deck. • 6 #8 Bolts = 0.75 W/C each. • Radiative coupling somewhat isolated from major portions of the spacecraft since the mechanical units are stowed inside a carbon fiber tube which is also stored inside a spacecraft carbon fiber tube. • Deployed elements are isolated from spacecraft influence by stacer. • Antisun Pre-Amp Sphere temperature can be super sensitive to the conduction through the Stacer-Rod hinge. Depends on stacer shadow length. Worst at SAA 20. EFW INST+SOC PDR

  13. Power, Heaters • Current power used in model • IDPU has a survival heater, set points -30 to -20 • SPB and AXB do not have any survival heaters • AXB currently has a place holder for a deployment heater. Need mature integrated spacecraft model to determine if heater is needed. EFW INST+SOC PDR

  14. Current Thermal Limits • Limits are produced in cooperation with mechanical and systems engineers. • Thermal predicts can drive mechanical and electrical design. or • Mechanical and electrical design can drive the thermal design. EFW INST+SOC PDR

  15. Limit Categories • Science Operation Limit • Limits placed on an operating instrument • Specifies the range of temperatures the instrument will be calibrated to • Operation – Out of Spec • Limits placed on an operating instrument • May represent a wider range that is survivable but may be out of spec • Temperatures beyond Science Op Limit need not be calibrated to • Non-Operation • Limits placed on a non operating instrument • Pre-Deployment Limit • Limits placed on a mechanical system before it is actuated • Deployment Limit • Limits placed on a mechanical system at the time of actuation • Post-Deployment Limit • Limits placed on a mechanical system after it has executed its one-time deployment EFW INST+SOC PDR

  16. General Case Sets • All current case sets run at a solar aspect angle of 20 degrees • Will scan attitudes and beta angles in the future to find the hottest and coldest attitudes. • These attitudes will be fed back to APL for inclusion in their nominal runs EFW INST+SOC PDR

  17. Current results • Basic science attitudes are within limits • Future runs will explore off nominal attitudes and full spacecraft model EFW INST+SOC PDR

  18. Status • Instrument thermal models are complete. • Geometry has been shipped to APL and included in the spacecraft geometry. • UCB boundary spacecraft model complete. • Preliminary check of science attitudes shows temperatures within limits. • Currently working to integrate the instrument network model with the spacecraft network model. • Need to incorporate APL heat rates into UCB analysis. • Need to produce high fidelity predicts from APL EFW INST+SOC PDR

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