The Doppler Experiment for Search, Tracking, and Rescue (DEXSTR) is a 3U CubeSat being developed by the Missouri University of Science and Technology (Missouri S&T) and NASA's Goddard Space Flight Center. The low Earth orbit mission uses the Doppler shift of a ground-based beacon signal to geolocate the beacon. This technology has applications in the lunar domain, providing positioning support of assets on the surface of the Moon. The performance of the payload is highly dependent on maintaining its chip-scale atomic clock (CSAC) at a consistent temperature, as the CSAC is needed to accurately determine the Doppler shift. This poses a challenge for DEXSTR and other CubeSats due to their high power densities and limited thermal control capabilities. This study presents a preliminary thermal analysis of DEXSTR as the team progresses toward increasing the model fidelity of the payload and CSAC. Mission constraints and payload requirements are used to create hot and cold cases that account for currently undetermined mission elements such as DEXSTR's specific orbit. A thermal model is built in Thermal Desktop, utilizing the symbolic capabilities of the software to easily adjust model parameters as the mission concept is more fully detailed. This model is used to assess the spacecraft's ability to meet critical thermal requirements, namely the rate of temperature change of the payload and the operating temperature limits of DEXSTR's electronics. From this analysis, initial plans for DEXSTR's thermal control system are outlined. Finally, this study looks ahead to the lunar thermal environment and the unique challenges it will pose to the use of Doppler-shift location technology in cislunar space.
Gentry et al. (Sun,) studied this question.