Hysteresis rods in the passive magnetic stabilization system for university micro and nanosatellites
- Paper number
IAC-08.C1.8.11
- Author
Ms. Maria Libera Battagliere, Scuola di Ingegneria Aerospaziale, Italy
- Coauthor
Prof. Fabio Santoni, Italy
- Coauthor
Prof. Michael Yu. Ovchinnikov, Keldysh Institute of Applied Mathematics, RAS, Russia
- Coauthor
Prof. Filippo Graziani, University of Rome "La Sapienza", Italy
- Year
2008
- Abstract
A passive magnetic attitude stabilization system is simple, easy to realize, cheap and does not require software development and energy consumption. Due to these features the passive magnetic attitude stabilization system is the most common attitude stabilization system implemented on board of small satellites. This system is based on a permanent magnet, which has to provide a restoring torque to align an oriented axis of the satellite with the Earth’s magnetic field direction, and a dissipation system of the energy of angular motion, which can consist on a set of magnetic hysteresis rods. For damping a magnetically soft material is required, with high initial relative magnetic permeability and low coercitive force (less than intensity of the Earth’s magnetic field). Typically the damper has the shape of a rod with high ratio length to diameter, because the magnetic properties of the damper are very sensitive to this parameter (maximum efficiency is obtained for very elongated rods). Nevertheless, the rod length is limited by the satellite geometry, so preliminary sizing of hysteresis rods can be made on the basis of geometrical considerations and basic design criteria. Despite the simplicity of this attitude stabilization system, predicting of performances in orbit and of the obtainable accuracy is not so easy: the main problem is represented by necessity of an accurate modelling of the hysteresis rod magnetization and by the evaluation of the magnetic parameters of the rods. As a matter of fact, the efficiency of the rods depends not only by their volume and by elongation, but also by the material used, by the scheme of their arrangement on board of the satellite and by heat treatment. It means that in the framework of manufacturing of the rods it is necessary to observe strictly all phases of the technological process. Numerical simulations of the dynamics of the satellite are also required in order to establish damping effects of hysteresis rods and to evaluate the number of hysteresis rods necessary to stabilize the satellite in orbit. The paper deals with sizing, choice of the material, manufacturing process and arrangement of a set of hysteresis on board of small satellites are considered and depicted. Basic criteria to obtain a real optimization of manufacturing process and of the arrangement on board of the spacecraft are also resumed. As an example the dynamics of the EduSAT microsatellite is investigated, using numerical methods. EduSAT (Educational Satellite) is a small satellite (31,5 cm x 31,5 cm x 25 cm), currently under design and realization, of the Astrodynamics Group of the “Sapienza” University of Roma (GAUSS) at the School of Aerospace Engineering of Roma. The launch of EduSAT microsatellite is planned on December 2009. This educational space program is devoted not only to university students and PhD students, but is specially dedicated to the students from high school. In the frame of this dissemination program of the space culture, younger students learn the principles of celestial mechanics, use didactical software, design and build a satellite mock-up. EduSAT project is supported by Italian Space Agency with the main goal to sustain the scientific education of the students and to promote the development and the realization of small and low-cost scientific and technological missions.
- Abstract document
- Manuscript document
IAC-08.C1.8.11.pdf (🔒 authorized access only).
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