Libration Damping System in the Attitude Stabilization of University Microsatellites

In the last twenty years a large impulse in the production of micro and nanosatellites has been recorded all over the world. A number of space university programs started in different countries with the aim to provide students with hands-on training in the field of space technologies. In this field the Gruppo di Astrodinamica dell’Università degli Studi di Roma “La Sapienza” (GAUSS), has been working for more than 15 years with the UNISAT program. Currently, three new educational projects are under development: Unisat-5, EduSAT and UNICubeSAT. Both UNISAT-5 and EduSAT satellites use passive attitude stabilization systems, which permit to keep costs low and to get adequate system reliability. In the paper an overview of EduSAT and UNISAT-5 attitude stabilization systems and an analysis of the main issues related to these topics are given. Moreover the paper deals with the design and sizing of a libration damping system in the attitude stabilization of EduSAT, stabilized by a passive magnetic system, and UNISAT-5, stabilized by a gravity gradient boom. Finally, results of numerical simulations are sketched. Keywords: Satellite, attitude stabilization, gravitational stabilization, magnetic stabilization, magnetic damping, hysteresis rods