Design of an Attitude Determination and Control Subsystem for a Femtosatellite

Abstract

The world of satellites is evolving very rapidly on the past few years, with satellites going from huge machines with complex and expensive systems, to rapidly getting smaller and smaller. Our satellite, a PocketQube, is a satellite that can fit in one’s hand, being it a cube with sides of 5x5 cm. This type of cubes are the cheapest way of exploring parts of the Earth’s orbit, as well as obtaining information that conventional and much bigger satellites would not even bother to get. This is the case of our satellite, which is aimed to obtain information of Earth’s lower Thermosphere. As it is well known, in these upper parts of the Earth’s atmosphere, the presence of air is almost non-existent and any perturbation to the satellite, or any environmental torque, can cause the satellite to spin without control and not be able to perform its tasks correctly. In the point of view of Attitude Control, this is a serious problem as many satellites require a precise pointing to its objective to perform their job well, and whereas this is almost no problem in bigger satellites as they normally carry complex systems to ensure that attitude, what happens to a satellite that weights less than 100 grams? This thesis aims to find reliable ways to ensure Attitude Control on smaller satellites, and hopefully the conclusions obtained in this thesis can help many other femto-satellites(¡100g) that might have the same problems. As stated, the aim of this project focuses on Attitude Control and Determination Systems, and all the simulations performed will be kept as simple as possible, as our objective is not to deal with complex orbital dynamics, Electro-Magnetic Compatibility (EMC) problems or other complex situations.