Thermal response of radiantly heated spinning spacecraft booms

Abstract

This article describes a study of the thermal response of radiantly heated spacecraft booms spinning about their principal axis. Thermally induced structural disturbances occur as the result of uneven solar heating and can reduce the pointing accuracy of a spin-stabilized spacecraft and in extreme cases affect the stability of the entire vehicle. The thermal response of radiantly heated spinning circular cross-sectional tubes is investigated using analytical, computational, and experimental approaches. An approximate analytical solution for the transient thermal response is presented. A finite element formulation is developed to evaluate the effects of natural convection, internal radiation, and temperature-dependent material properties on the thermal response. An experimental program undertaken to validate the analytical and computational models is described. The results of laboratory experiments conducted in the atmosphere are presented for a range of tube spin rates. Predictions from finite element analysis correlate well with experimental data and verify important aspects of spinning tube thermal behavior. Key aspects of the thermal behavior of radiantly heated spinning tubes are identified as 1) the independence of the tube average temperature of spin rate, 2) a decrease in the difference between maximum and minimum temperatures around the tube circumference with increasing spin rate, and 3) a shift in the steady-state temperature distribution in the direction of tube rotation.