A multiscale central difference scheme applied to magnetohydrodynamic simulations of cometary atmospheres

The hyperbolic equations describing the interaction between a cometary atmosphere and the solar wind are solved through a central differencing scheme. This work will enable us to better predict conditions that robotic spacecraft will encounter on comet nucleus flyby or rendezvous missions. We are interested in studying the coma characteristics from large distances from the nucleus, where the solar wind just begins to be perturbed by the comet, to very near the nucleus. We employ a multifluid approach in which the equations governing the ions, neutrals, and electrons are coupled. We solve these equations by the use of a total variation diminishing Lax-Friedrichs solver combined with an adaptive mesh refinement technique. Magnetic fields and plasma pressure, velocity, and density profiles are calculated and compared with other models. We show that this approach is well suited to provide an accurate solution over a large computational domain, and we present results for a Halley-like comet.