A brief summary of the general problem of orbit evolution due to frictional forces

We analyze frictionaly damped orbits in central potentials. When the potential is a monomial in the radius, the orbit shape and precession angle remain constant to leading order in the linear friction coefficient. This is not a consequence of any obvious symmetry, but for motion in the Kepler potential may be understood in terms of the generalization of Poisson structure to damped systems suggested recently by Tarasov[1]. In this generalized algebraic structure the orbit-averaged Runge-Lenz vector remains a constant in the linearly damped Kepler problem to leading order in the damping coefficient.