Even at the time when artificial satellites were still merely theoretical concepts; the widely used principle of eddy-current braking had suggested that the spin-motion of such freely-orbiting bodies would be perturbed and dampened by the various magnetic fields of the earth, of other bodies of the solar system, and of the galactic system. The necessity for predicting, explaining, and analyzing the rotational motions of metallic space vehicles led to the following rigorous derivation of equations of motion for the special cases of rigid axi-symmetrical distributions of matter rotating in magnetic fields. Later, when such satellites were actually launched and their rotation had been observed, the expected perturbations and spin-decay clearly appeared. Most precise numerical confirmation of the formulas was possible for the first two Vanguard satellites. The surprisingly large damping couple acting on Vanguard II due to the inclusion of parts having high magnetic permeability (since the couple varies as the square of such permeability) has suggested the planning and control of such reactions with the exterior magnetic fields for the purpose of stabilizing and steering space vehicles.


Cylindrical Shell Space Vehicle Transverse Axis JULIAN Date Elemental Ring 
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Copyright information

© Springer-Verlag Wien 1961

Authors and Affiliations

  • Raymond H. WilsonJr.
    • 1
  1. 1.NASA Coddard Space Flight CenterUSA

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