Rose Navarro HMI Lead Thermal Engineer Rose.d.navarro@lmco.com HMI Thermal Design Rose Navarro HMI Lead Thermal Engineer Rose.d.navarro@lmco.com

Thermal – Agenda Thermal Design Overview Spacecraft Accommodation Requirements Baseline Thermal Design Description of HMI Optics Package Thermal Design On orbit temperature and heater power predictions Eclipse Period Precision Oven HMI Electronics Box S/C and Instrument Sensors Thermal Design Status Summary

Thermal Design Overview (1 of 2) HMI Optics Package Isolated OP structure has multiple heater zones to control package temperature and minimize gradients Isolated CCD assemblies (two) have their own dedicated radiators Isolated CEBs radiate dissipated load directly from box walls Independent front window heater minimizes gradients and offsets eclipse transient effects Spacecraft provides survival heater power HMI Filter Oven Mounted inside HMI Optics Package Isolated, independently-controlled filter oven maintains strict temperature control of Michelsons

Thermal Design Overview (2 of 2) HMI Electronics Box (HEB) Mounted inside spacecraft bus and thermally coupled to temperature-controlled spacecraft radiator Spacecraft provides survival heater power and LMSAL provides heaters and thermostats

Spacecraft Accommodation HEB mounted inside s/c bus to s/c radiating surface Spacecraft surface geometry provided by GSFC. Used to predict environment for locating and sizing HMI radiators. HMI OP mounted to +Z side of spacecraft optical bench

Thermal Requirements

Current Baseline of Thermal Design Based on trade studies that were presented in the Thermal Peer Review the current HMI Optics design is as follows Heaters and radiator designed for front window 5 Control zones for HMI Optics Package Door open 170°, clear anodized Door mechanism, FOSR

Exterior View of HMI Package Germanium Coated Black Kapton, MLI Door Mech FOSR, ITO Coated CCD Radiator NS43G CEB Radiator NS43G Lid Clear Anod FOSR, MLI ITO Coated Window Sunshade

Interior View of HMI Package Oven (heater) controlled to 30 ± 0.1°C Oven Controller, 0.35 Watts Tilt Mirror PZT, 0.2 Watts Limb Tracker Elec Box, 0.3 Watts Oven Controller Preamp Board, 0.2 Watts CCD Header Primary Lens

Thermal Model Detailed thermal math model of Optics Package ready to run on-orbit operational and survival predictions Number of nodes: 639 Contains heater logic, masses, interface connections, power dissipation, simplified oven, and optics MLI effective emittance e*: 0.01 - 0.03 BOL and EOL Optical Thermal Properties Defined hot and cold environments Operating Cold: Beta angle 0°, 72 minute eclipse, BOL. Solar Constant 1316 W/m2, Albedo 0.25 and Earth IR 208 W/m2 Operating Hot: Beta angle +52°, no eclipse, EOL. Solar Constant 1428 W/m2, Albedo 0.35 and Earth IR 269 W/m2 Survival Cold: Beta angle 0°, 72 minute eclipse, BOL. Solar Constant 1316 W/m2, Albedo 0.25 and Earth IR 208 W/m2. Door closed Incorporated S/C thermal model with detailed model. Reduced model of Optics Package exchanged with SDO Thermal Engineer Reduced model contains 282 nodes of which 180 are external nodes Contains heater logic, masses, interface connections, power dissipation, simplified oven Provided Interface linear conduction with S/C bench (total Resistance ~45 °C/W) Preliminary Analysis shows detailed and reduced model temperature and heater power predictions compare well. Exchanged model produced similar results

Operational Temperature and Heater Power Predictions Hot Case Raw Predictions are within 10°C margin of Mission Allowable Temperature (MAT) Maintain ~2°C Temperature Gradient at 1/3 aft portion of package Achieved ~1°C Radial Gradient of front window (non-eclipse) for Hot and Cold Cases

Survival Temperature and Heater Power Predictions Survival heaters required for CEBs Temperatures within Non-operating MAT range Exterior surface thermal properties provide protection from deep space or direct solar exposure during slews and ascent and early orbit attitudes

Eclipse Period – Front Window Recovery ~1 °C gradient Recovery, 60 min after eclipse 72 minute eclipse period

Focal Plane Assembly – Temperature Profile 72 minute eclipse period

HMI Electronics Box Thermal interface temperature,defined at the base plate, shall be controlled by S/C to within the Mission Allowable temperature Operating MAT 0 to +40°C and Non-Operating MAT –20 to +55°C Outside of HEB, black anodized 6 Housekeeping sensors and 1 S/C monitored sensors No operational heaters LMSAL will provide the heaters, thermistors and thermostats Power Electronic Board hard mounted to the base of the box, closest to radiator Daughter boards mounted to wall by wedge locks Major components are heat sunk and mounted on the edge of the boards Junction temperatures shall not be warmer than 100°C

Instrument Housekeeping Sensors and Heaters (1 of 2)

Instrument Housekeeping Sensors and Heaters (2 of 2)

Spacecraft Monitored Sensors and Survival Heaters

Thermal Design and Analysis Status Driving Thermal Requirements Defined Thermal Peer Review held October 15, 2003. No action items. Spacecraft Accommodation of Optics Package and HEB Determined Detailed Thermal Model Trade studies Front Window Analysis Nearly Complete Door Assembly Analysis Complete CCD and CEB Radiators Designed Trade Studies Performed to Evaluate Optics Package Heater Zones Number and Location of S/C and Instrument Sensors Defined Filter Oven Detailed Thermal Analysis Initiated Reduced Optics Package Thermal Math Model Provided to GSFC