Canonical rotation variables and non-Hamiltonian forces: solar radiation pressure effects on asteroid rotation

Abstract

The differential equations for canonical rotation variables are formulated as functions of the torque components on the principal axes of a rigid body. The resulting structure of the equations is. then used to prove that solar photons absorbed by a body orbiting the Sun are not able to change the body's rotation state, if the absorption is uniform across its surface. Otherwise, a tendency induced by the absorbed photons could be to drive the spin axis into the body's orbit plane while the rotation period is increased, consistent with observations of Eros. The ability of this radiation pressure to change the rotational excitation could be as important as that due to inelastic energy dissipation for subkilometre asteroids.