The Rotation of Hyperion
Abstract
For almost the entire range of dimensions of Hyperion allowed by uncertainties in the observations, the satellite cannot librate stably about a rotation rate which is synchronous with its orbital mean motion. Rather, the large gravitational torques on the asymmetric satellite coupled with the large eccentricity forced by the orbital resonance with Titan cause Hyperion to tumble in a random manner. Large changes in orientation of body axes relative to inertial space and in the instantaneous spin rate occur on timescales of the order of the orbit period. Numerical evaluation of the exponential divergence of nearby trajectories in the phase space of the motion verifies that the tumbling is truly chaotic. This newly defined state of chaotic rotation for Hyperion is likely to be the only example of confined, continuously observable chaotic motion in the Solar System.
 Publication:

Philosophical Transactions of the Royal Society of London Series A
 Pub Date:
 November 1984
 DOI:
 10.1098/rsta.1984.0090
 Bibcode:
 1984RSPTA.313..147P
 Keywords:

 Celestial Mechanics;
 Hyperion;
 Planetary Rotation;
 Spin Dynamics;
 Axes Of Rotation;
 Libration;
 Orbital Resonances (Celestial Mechanics);
 Astronomy;
 CELESTIAL MECHANICS;
 HYPERION;
 PLANETARY ROTATION;
 SPIN DYNAMICS;
 AXES OF ROTATION;
 LIBRATION;
 ORBITAL RESONANCES (CELESTIAL MECHANICS)