Inelastic Dissipation in Wobbling Asteroids and Comets

Asteroids and comets dissipate energy when they rotate about any axis different from the axis of the maximal moment of inertia. We show that the most efficient internal relaxation happens at twice the frequency of the body’s precession. Therefore earlier estimates that ignore the double frequency input underestimate the internal relaxation in asteroids and comets. We suggest that the Earth’s seismological data may poorly represent the acoustic properties of asteroids and comets as internal relaxation increases in the presence of moisture. At the same time, owing to the non-linearity of inelastic relaxation, small angle nutations can persist for very long time spans, but our ability to detect such precessions is limited by the resolution of the radar-generated images. Wobbling may provide valuable information on the composition and structure of asteroids and on their recent history of external impacts.