How to stabilize a satellite using the principle of conservation of angular momentum

Abstract

There are currently more than 9000 active satellites orbiting the Earth (2024 ESA Space Environment Report www.esa.int/Space_Safety/Space_Debris/ESA_Space_Environment_Report_2024). Most of them are used for communications: radio, telephony, televisión and internet. Some of them help ships steer a safer course at sea. Others give us warnings about hurricanes and storms, and do the same for forest fires and icebergs. Some more have military applications. Many observation satellites take photographs of the Earth and then send them to a ground station for processing and dissemination. To take photographs it is first necessary to stabilize the satellite, avoiding oscillations or spins. The aim of this article is to show how to stabilize a satellite using the principle of conservation of angular momentum. Only basic knowledge of classical mechanics is necessary to understand how to achieve it. The applied method is especially relevant for the stabilization of small satellites, which are often used by colleges, universities and even some high schools for many different purposes. Pursuing this goal, we will use the motor with a coupled wheel from an old DVD drive, an angular rate sensor and a microcontroller. The experimental results are shown at the end of the article. Additionally there is a video that shows how stabilization takes place.