Electrostatic radiator for satellite temperature control

An objective for advanced satellites and spacecraft is to continually reduce both their size and mass. This reduction can place severe constraints on the thermal control systems. In addition, mission requirements also may dictate the need to alter the spacecraft energy profile during the course of the mission. To facilitate these advances, significant research has been conducted to develop variable emittance coatings and devices to provide active spacecraft thermal control. Several of these technologies have matured to a level where space based testing is feasible and will be performed as part of the ST5 new millennium spacecraft mission. One of these technologies utilizes electrostatic hold-down of a high emissivity composite film to actively control spacecraft skin temperature. This electrostatic radiator (ESR) device functions as a thermal switch and changes the mode of heat transfer between the spacecraft skin and the radiator film from conduction to radiation. This device has demonstrated large changes in effective emissivity in laboratory cold thermal vacuum testing. In this paper, the theory of operation of the ESR and the construction of the device as configured for demonstration on the ST5 mission is presented. The role of the ST5 mission in the maturation process for VEC technologies is discussed. This paper also describes test results for the ESR through flight qualification testing for the ST5 mission. Finally, anticipated operational characteristics and mission reliability estimates are provided.