Return to Mercury: An Overview of the MESSENGER Spacecraft Thermal Environmental Predictions and Analysis Process
Holtzman, G. Allen
Begley, Shawn M.
Ercol, Carl J.
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At 01:00 UTC on 18 Mar 2011, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft became the first to achieve orbit around the planet Mercury. Designed and built by The Johns Hopkins University Applied Physics Laboratory in conjunction with the Carnegie Institution of Washington, MESSENGER was launched on 3 Aug 2004, and after studying the planet Mercury from orbit for more than four years, impacted the planet at 19:25 UTC on 30 Apr 2015. This paper provides an overview of the thermal support activities for the spacecraft and the process used to make temperature predictions for critical spacecraft components. The planned operational profile for the spacecraft position and attitude was run through the thermal analysis process to generate environmental and internal heating profiles for spacecraft components. The environmental heating calculations were performed with a custom algorithm that was run on a graphics processing unit for increased performance and that takes into account the thermal environment of Mercury, including spatial variation of the surface properties. Temperature predictions were generated from physical models of each spacecraft component, and the operational plan was modified if temperature limits were exceeded. Each Mercury year, flight temperatures were compared with the predictions, and adjustments to the process were made as necessary. Special thermal challenges, such as comet observations, instrument calibrations, or potential safe-hold demotions, were analyzed on an individual basis and sometimes involved several iterations of planning. The fidelity of the enhanced thermal analysis process optimized science return while mitigating thermal risks to the spacecraft and its instruments.