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

2. 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

3. 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

4. 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

5. 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

6. Thermal Requirements

7. 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

8. 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

9. 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

10. 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*:
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

11. 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

12. 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

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

14. Focal Plane Assembly – Temperature Profile
72 minute
eclipse period

15. 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

16. Instrument Housekeeping Sensors and Heaters (1 of 2)

17. Instrument Housekeeping Sensors and Heaters (2 of 2)

18. Spacecraft Monitored Sensors and Survival Heaters

19. Thermal Design and Analysis Status
Driving Thermal Requirements Defined
Thermal Peer Review held October 15, 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