Timbre Thermal Dwell Balance Estimation Tool¶
The timbre package enables one to calculate the required contiguous cold time to balance a specified hot observation, or alternatively the maximum contiguous hot time yielded by a given cold observation, for a given Xija thermal model.
The primary purpose of this package is to enable the Chandra SOT Mission Planning Team to estimate the required mix of observations that will yield a feasible schedule, without depending on past dwell profiles that may no longer be relevant for future schedules.
Introduction¶
As Chandra’s external thermal protective surfaces degrade over time, resulting in steadily increasing heat absorption from the sun, many components have begun to approach their health and safety thermal limits. As these components begin to approach their limits, predictive thermal models for these locations are built using the Xija thermal modeling framework, enabling SOT and FOT Mission Planning to plan observation schedules that maintain temperatures within specified limits. These limits are set based on original qualification testing, material-based capability, or other performance-based criteria, and are re-evaluated periodically to balance scheduling challenges with vehicle performance towards optimizing science goals.
Occasionally, new locations need to be added to this set of modeled components, resulting in new planning challenges and rendering past scheduling strategies incompatible with future scheduling requirements. The algorithm Timbre uses to determine dwell time is independent of past profiles, and is therefore more flexible than approaches that have used these past observing profiles to characterize future capability, which had worked very well earlier in the mission.
This documentation will first cover how to run Timbre to calculate the estimated dwell time to balance two known configurations (e.g. pitch, roll, fep_count, etc.) and a known initial dwell time. After covering very basic usage, further examples will show how to use this data to characterize dwell capability and how to use the interaction of all thermal models to generate composite maximum dwell estimates.