Sublimation Cooling Technology for CubeSat Thermal Control

Small, inexpensive satellites called CubeSats are commonly used for conducting academic and commercial space research. Typically, there is no thermal control system to dissipate heat from the CubeSat avionics, which can limit onboard computing and payload power. Sublimators are a small-volume, passive thermal control technology with a proven 60-year flight history which may allow CubeSats to fly more powerful computers and conduct more complex experiments. Sublimators utilize water, a consumable; their size and passive nature is especially useful for CubeSat missions with volume constraints and short durations. Even with flight history, there are aspects of the heat and mass transfer processes in sublimation cooling which are not fully understood. Both historical and current modeling efforts make assumptions which require further exploration. This paper proposes CubeSat sublimation cooling technology, reviews past and current sublimator applications, and discusses the knowledge gaps and shortcomings of past sublimator uses and models. A UC Davis sublimator model is introduced with an initial analysis which addresses the assumptions often found in literature. Further, the overall thermal control system for a CubeSat with a sublimator is described, along with an initial sublimator sizing procedure and example.