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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

Thermal Design

Christopher Smith

RBSP Thermal Engineer

Space Sciences Lab

University of California, Berkeley

EFW INST+SOC PDR

spacecraft level thermal requirements
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

efw thermal requirements
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

engineering test matrix
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

apl thermal modeling interface
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

thermal model overview axb stowed
Thermal Model OverviewAXB -Stowed

Sphere / Preamp

(DAG 213)

Rod to Stacer Hinge

(DAG 213)

Mounting Tube (M55J)

Stacer

(DAG 154)

EFW INST+SOC PDR

thermal model overview axb deployed
Thermal Model OverviewAXB -Deployed

Sphere

(DAG 213)

Stacer (DAG154)

DAD

(AntiSun: Clear Alodine)

(Sun: Clear Alodine / GeBk Tape mix)

EFW INST+SOC PDR

thermal model overview spb idpu
Thermal Model OverviewSPB & IDPU

SPB - Deployed

IDPU

(Black Anodized)

(GeBk Tape)

(Clear Alodine)

SPB - Stowed

EFW INST+SOC PDR

optical materials
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

thermophysical properties
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

interfaces
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

power heaters
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

current thermal limits
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

limit categories
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

general case sets
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

current results
Current results
  • Basic science attitudes are within limits
  • Future runs will explore off nominal attitudes and full spacecraft model

EFW INST+SOC PDR

status
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