Thermal investigation of spacecraft optical electronic observation system without protective cover in low earth orbit

The present work was dedicated to the development and introduction of the effect of no payload cover on image quality during spacecraft(SC) operation. Payload is mounted as a monoblock on a framework (constituting the SC body) along +Z axis on the side of upper end panel. The analysis is done for payload configuration with permanently open protective cover. Thermal simulation and payload elements temperature analysis is performed using software Thermal Desktop/Sinda Fluent. The goal of analysis is to determine temperature variation of payload elements (primary mirror, carbon plastic cylinder, light protective tube) in stand-by mode and in session mode under effect of external heat fluxes with electric heaters (EH) automatic operation when maintaining average temperature of the primary mirror at 20°C and given EH arrangement. Required EH power with different EH switching on/off configurations in order to is estimated to maintain the primary mirror temperature at 20°C taking into account allowed number of operation cycles (switching on-off) of switching keys of 90000 over the whole SC lifetime. The analysis is performed with SC moving in Low Earth Orbit (LEO).At that two extreme SC orientation modes with respect to external heat fluxes effect are considered (maximum external heat fluxes, and minimum external heat fluxes).