MMS Optical Bench Assembly (OBA) Thermal Design Validation and Thermal Model Correlation

摘要

The Optical Bench Assembly (OBA) consists of dual star trackers mounted inside the MMS spacecraft. Each star tracker is comprised of a Camera Head Unit (CHU) that has a thermal requirement to operate at or below 3.5°C passively. Because the MMS spacecraft temperatures are relatively warm (20°C), the OBA must be conductively isolated and radiatively insulated to minimize heat leaks from the spacecraft into the CHUs. The OBA thermal design must also be able to reject the CHU heat dissipation into the composite baffle shades and ultimately to deep space through a designed cut-out in the spacecraft structure. This paper provides an overview of the MMS OBA passive thermal design challenges, and describes the thermal analysis, thermal balance tests, design updates and thermal model correlation performed to verify that the thermal design meets requirements. The MMS mission is currently in the flight build phase and is scheduled to launch in August of 2014.