Comet 67P/Churyumov-Gerasimenko rotation changes derived from sublimation induced torques

Abstract

(Context) The change of the rotation period and the orientation of the rotation axis of comet 67P/Churyumov-Gerasimenko (67P/C-G) is deducible from images taken by the scientific imaging instruments on-board the Rosetta mission with high precision. Non gravitational forces are a natural explanation for these data. (Aims) We describe observed changes for the orientation of the rotation axis and the rotation period of 67P/C-G. For these changes we give an explanation based on a sublimation model with a best-fit for the surface active fraction (model P). Torque effects of periodically changing gas emissions on the surface are considered. (Methods) We solve the equation of state for the angular momentum in the inertial and the body-fixed frames and provide an analytic theory of the rotation changes in terms of Fourier coefficients, generally applicable to periodically forced rigid body dynamics. (Results) The torque induced changes of the rotation state constrain the physical properties of the surface, the sublimation rate and the local active fraction of the surface. (Conclusions) We determine a distribution of the local surface active fraction in agreement with the rotation properties, period and orientation, of 67P/C-G. The torque movement confirms that the sublimation increases faster than the insolation towards perihelion. The derived relatively uniform activity pattern is discussed in terms of related surface features.

arXiv comment11 pages

References in corpus (6)

• Seasonal Mass Transfer on the Nucleus of Comet 67P/Chuyumov-Gerasimenko
• Cometary masses derived from non-gravitational forces
• Seasonal changes of the volatile density in the coma and on the surface of comet 67P/Churyumov-Gerasimenko
• Constraining models of activity on comet 67P/Churyumov-Gerasimenko with Rosetta trajectory, rotation, and water production measurements
• On the origin of inner coma structures observed by Rosetta during a diurnal rotation of comet 67P/Churyumov-Gerasimenko
• Further investigation of changes in cometary rotation

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• Varying water activity and momentum transfer on comet 67P/Churyumov-Gerasimenko from its non-gravitational forces and torques
• The ice composition close to the surface of comet 67P/Churyumov-Gerasimenko
• Preparing for the 2061 return of Halley's comet -- A rendezvous mission with an innovative imaging system
• Rotation dynamics and torque efficiency of cometary nuclei
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