Thermal environment analysis for TianQin: II. Solar irradiance disparity across constellation

Abstract

Space-borne gravitational wave (GW) detectors aim to detect GWs in low and middle frequency ranges, as a complement to the terrestrial detectors like LIGO and VIRGO. As the detectors are extremely sensitive to temperature fluctuation, great efforts have been taken to perform thermal analyses on the satellite platforms. Our previous work analysed the external thermal environment of an individual satellite for the TianQin mission. This paper raises the issue of thermal disparity across the triangular constellation. Based on optimized orbits of the TianQin, the LISA, the eLISA/NGO, and the ASTROD-GW, we evaluate the solar irradiance differences between adjacent satellites and make comparisons of the results among the missions. We subsequently introduce a universal relation to describe how orbit type and arm lengths may affect the maximum disparity. For the geocentric orbits of TianQin, we further extend the discussion on the science observation windows.