Hot- and Cold-Case Orbits for Robust Thermal Control

Realizing cheaper, more flexible alternatives to traditional satellites requires robust design approaches. Robust satellite subsystems are designed to meet a broad range of mission requirements; consequently, they drastically reduce nonrecurring engineering costs and greatly diminish design, development, assembly, integration, and test schedules. Robust thermal control subsystems must be capable of handling a broad range of thermal environments, thus reducing design and development costs but can be susceptible to overdesign. Therefore, improved design methodologiesareneededtomaintaintheiradvantageswhileminimizingexcessivedesign.Asa firststep,designhotandcold-case orbits shouldbe examined. Theprimarygoal of the study described in thispaper wasto identify single hot- and cold-case design orbits that work well in the design of robust thermal control subsystems over a wide range of satellite surface properties and likely operating environments. A general approach was developed to identify worst-case orbits that employ a combination of statistical and historical data such that statistically insignificant orbits are disregarded. Using this method, individual hot- and cold-case design orbits were found at beta angle/ inclinationcombinationsof72 deg =52 degand0 deg =28 deg,respectively.Theuseofthesedesignorbitsworkswell for a wide range of different satellite surface properties.