University of California, Berkeley Thermal Design Christopher Smith RBSP Thermal Engineer Space Sciences Lab University of California, Berkeley

Outline Requirements APL – UCB Interface Thermal Model Description IDPU Board Level Thermal Analysis Thermal Model Case Set Inputs Current Predicts Current Testing Overview

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) 27 degrees composite, normal operation (EFW-202) 33 degrees, Safe mode (SCRD 3.10.4.4) (Was 47) 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 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) -25 to +65 for top deck interface, new since PDR Instruments to survive without damage with -30 to +60 spacecraft boundary conditions. (EFW-79, EFW-80) -30 to +70 for top deck interface, new since PDR 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

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.

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. 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.

Thermal Model Overview Instruments and Boundary Spacecraft IDPU AXBs SPBs

Thermal Model Overview AXB -Stowed Sphere / Preamp in Caging Mechanism (Clear Alodine, GeBK Blanket) Sphere / Preamp (DAG 213) Rod to Stacer Hinge (DAG 213) Mounting Tube (M55J) Stacer (Elgiloy)

Thermal Model Overview AXB -Deployed Stacer (Elgiloy) Sphere (DAG 213) DAD (AntiSun: Clear Alodine) (Sun: Clear Alodine / GeBk Tape mix) Sphere Caging Mechanism (AntiSun: Clear Alodine) (Sun: GeBk Blanket / Clear Alodine mix)

Thermal Model Overview SPB Deployed Elements SPB Sphere SPB Preamp Thick Wire Thin Wire

Thermal Model Overview SPB & IDPU SPB - Deployed IDPU (Mostly Black Kapton XC Tape, Some Gold Alodine) (Black Kapton XC Tape) (Clear Alodine) SPB - Stowed (Black Kapton Blanket, Shown in Green)

DCB Component Dissipations

DFB Component Dissipations

LVPS Component Dissipations

LVPS Board Distribution

Optical Materials Most properties tested, used, and correlated for the THEMIS mission Properties approved by the GSFC coatings committee July 07, 2008.

Thermophysical Properties Hot Cases Use Low e* Anti-Sunward and High e* Sunward Cold Cases Use High e* Anti-Sunward and Low e* Sunward

Interfaces IDPU SPB AXB Conductively mounted to spacecraft side panel. 9 #10 Bolts = 0.75 W/C each. Radiative coupling to spacecraft interior, Black Kapton XCTape SPB 4 #10 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 at each end = 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. Caging mechanisms conductively mounted to top deck, 4 #8 Bolts = 0.75 W/C each.

Power, Heaters Current power used in model IDPU, SPB and AXB do not have any survival heaters

General Case Sets APL Case Set Parameters UCB Case Set Parameters

Limit Categories Science Operation Limit Operation – Out of Spec Limits placed on an operating instrument Specifies the range of temperatures the instrument will provide calibrated / useful science data Operation – Out of Spec 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

Current Thermal Limits

Predicts, Deployed Case Sets

Margins, Deployed Case Sets Positive Margins for all deployed cases

APL and UCB Predict Comparison, Table Each case set compared at a specific time and a representative node All case sets agree to within 1.5 degrees

APL and UCB Predict Comparison, Plot

ETU Thermal Vac Testing Completed