Satellite Thermal Analysis Practice Questions Q1 A satellite in Low Earth Orbit has a square panel of area lm facing the sun. a) How much direct solar energy does it absorb per second? b) What is the equilibrium temperature of the panel? How much IR energy does it emit each second? Perform these calculations for a plate with surface: Polished aluminium Optical solar reflector [A1: a) 270 J; b) 467.1 K; c) 270J OSR-a) 108 J; b) 185.7K; c) 108 ] Q2 A spherical satellite has radius 1 m mass 100 kg and is made of unpolished aluminium (c = 900 J/kg K). An amplifier inside the spacecraft generates 200 W of heat. The spacecraft has an orbit period of 5792 s and its eclipse duration is 2126 s. Find: a) The equilibrium temperature in sunlight. b) The equilibrium temperature in eclipse. [ans: a) 290 K; b)183 KS] Q3 A rectangular enclosure has a base of 2 x 4 m and a height of 6m. Find: a) The view factor from the base to the top b) The view factor from the base to the 2 x 6 m side. The view factor from the base to the 4 x 6 m side. [ans: a) -0.06; b)-0.16; c)-0.3] A cube-shaped spacecraft 0.3 m per side, has solar panels on four sides. The panels have reflectivity=0.05, absorptivity=0.95, and emissivity=0.85. The top and bottom panels, facing nadir and zenith, are covered in MLI assumed to be a perfect insulator. The spacecraft bus uses 11.5 W of power, and the payload uses a peak of 20 W. Assume solar input is S=1358 W/m. Find the SC equilibrium temperatures at hottest and coldest scenarios: a) With full sunlight on one panel during payload operation b) During eclipse with no payload operation ( a) 303.7 Kb) 160.5 K] A 1U cubesat (10 cm per side) is in LEO with one panel facing earth, and one panel facing the sun. Assume the cubesat is covered in solar cells (a=0.80, =0.90). Find the equilibrium temperature of the cubesat in full sunlight (S=1350 W/m), assuming the albedo contribution is 20% of solar flux. [ 255.1 K] Q5