Measurement of Free Molecule Heating in the Very Low Earth Orbit using Satellite Temperature Sensor

Abstract

The Super Low Altitude Test Satellite: TSUBAME (SLATS) was launched on December 23, 2017, operated in the Very Low Earth Orbit (VLEO), and completed its operation in October 2019. A bumper of SLATS which was covered with multi-layer insulation (MLI), was attached to the proceeding direction of this satellite. A temperature sensor was attached to the thermal control film, which was the outermost layer of the MLI. In this paper, free molecular heating by the upper atmosphere is reported with the temperature sensor data of SLATS at an altitude of less than 220km. The temperature on the bumper was affected by the sunlight, the earth's albedo, and the earth's infrared rays. The effect was evaluated using thermal analysis, and the temperature rise due to free molecular heating was extracted. As a result, they obtained a relationship between temperature rise, atmospheric density and free molecular heating at altitudes below 220km, where there are almost no actual measurements.