Millikelvin temperature control system for the ExoplanetSat Imager

Abstract

ExoplanetSat is the prototype of a CubeSat-based space telescope for the discovery of transiting exoplanets around the nearest and brightest Sun-like stars. It is capable of monitoring a single target star from low Earth orbit, going through an orbit day-night cycle. In order to limit the noise induced by variable temperature, the temperature of the imaging device needs to be controlled within a steady level over the approximately 30 minutes of orbit night when the telescope is actively observing. In this thesis I present the design of a cold-biased system that controls the temperature of the irnager through passive cooling and active heating. The temperature is controlled by the system being heated to a slightly higher temperature than it's environment. The active control over the heater maintains the system at the target temperature within the 30 millikelvin range, with the best performance of 5 millikelvin control. The temperature control system can be used at various phases of ExoplanetSat development, including laboratory simulation of the temperature control of the ExoplanetSat imager during orbit night, characterizing the temperature response of any potential imager, and part of the design can be applied to the flight model of the prototype of ExoplanetSat for irnager temperature control.