Preparation for a Thermal Balance Test of the MIST student satellite

Sammanfattning: The MIST project was founded in 2014 at KTH and has been worked on by roughly 100 students since.Thermal engineering has been an important part of the project from start and a thermal model has beendeveloped to predict ight conditions. The thermal model created by previous students has to be correlatedby performing a thermal balance test. This test is going to take place in a thermal vacuum chamberat KTH Albanova during the period November 2019 to February 2020. This thesis describes the process ofpreparation for a Thermal Balance Test for MIST. Included in the preparation of the test are; developingthe test specications and denition of ground support equipment needed for the Thermal Balance Testin order to successfully correlate the thermal model.To perform the test some of the equipment has to be replaced with replacement components. The batteryand the solar panels are two expensive and crucial systems for the mission and has been chosen to bereplaced with mass dummies. These mass dummies are used in the thesis both to keep the correct thermalcapacity and approximate the conductive properties. The solar panel dummy plates can be drilled into, tomake sure the cables for thermocouples and heaters can get inside the satellite. Heaters will be mountedon the satellite, both to create gradients across the satellite to be able to measure them, and to useas safety heaters to prevent the temperature to get to low and damage components. The heaters will bemounted on the battery replacement board, the solar panel replacement plates and the bottom cover plate.The thermocouples to be used in the test are already installed in the vacuum chamber, which are of TypeT class 1 with a temperature accuracy of 0:5 C. The chamber has 50 thermocouples installed where24 are planned to be used to measure gradients across interfaces to be able to correlate them with thethermal model.In this thesis the thermal model is simulated in the new vacuum chamber environment to investigatewhat temperatures can be expected in the test and nd components and interfaces of interest to placethermocouples on. The test will start from ambient temperature of 20 C, then change the temperatureof the chamber to 0 C, with a temperature ramp of 1.5 C/min. The chamber will stay at 0 C until thetemperature of the satellite has stabilized within the chosen stability criteria of 0.5 C over two hours. Thisset point is chosen to take measurements for the hot case. When measurements are made, the chamberwill go to -50 C and stabilize at that temperature to take temperature measurements for the cold case.The temperature gradients measured in both the hot and cold case will be used to correlate the thermalmodel with the physical model.