Design and Flight Performance of the Combined Thermal Control System of the BOLIDE Experiment in Balloon Mission PMC Turbo/2018

Abstract

The Polar Mesospheric Cloud Turbulence experiment (PMC Turbo) is intended to observe and quantify the dynamics of small-scale gravity waves and instabilities in the upper mesosphere. The instruments aboard a stratospheric balloon include seven high-resolution cameras and a Rayleigh lidar (BOLIDE). BOLIDE provided profiles of atmospheric temperature up to 85 km altitude throughout the flight and consists of a laser, the electronic/optical equipment housed in a sealed electronics box, and a stand-alone telescope. Flight duration was ~5.9-days from Esrange/Sweden to northern Canada in July 2018 at altitude 38±2 km. Experiment BOLIDE uses two types of thermal control systems (TCS), an active one for the equipment in the electronic box and a passive system for the telescope. The most demanding component of BOLIDE is the laser, which generates 150 W of heat and operates at temperature level +10…+26 oC. Active combined TCS included the liquid cooling of the laser installed on a cold plate and forced gas convection inside the sealed cabinet for cooling of units distributed on three levels. The heat from the laser and circulating gas is removed by circulating liquid via heat exchanging surfaces and is transferred to the radiator. The closed liquid loop consists of a tank, vain pump, connecting lines, heat exchangers, cold plate, temperature-regulating electronics and a 1.6 sq.m one-sided radiator with a total capacity of rejecting 450 W into space. The proposed TCS design allows modification of the inner layout of components in the electronics box, adding/removal/replacement of the units, isolation from external thermal disturbances, and protecting the instrument in a clean gas atmosphere. An overview of the TCS for the BOLIDE experiment, the approaches used in the thermal mathematical model as well as details of the elaborated solutions and flight data are presented in this paper.