Detailed direct simulation Monte Carlo/Particle in Cell simulations involving the inter- action of a hydrazine chemical rocket plume with the rarefied ambient magnetosphere are presented for steady thruster firings in geostationary Earth orbit (GEO). The hydrazine chemical rocket plume is modeled as a neutral gas mixture with thruster exit conditions corresponding to a mass flow rate of 5:0 × 10-4 kg/s. The interaction of the steady plume with the rarefied magnetosphere is modeled using a combined direct simulation Monte Carlo/Particle in Cell methodology, allowing for a detailed assessment of non-equilibrium collisional and plasma-related phenomena relevant for these conditions. Charge exchange interactions between the plume chemical mixture and the ambient ions are modeled using detailed total and differential cross sections. The in uence of the Earth’s magnetic field on the development of the ion plume is also modeled assuming a field strength of B = 1:1×10-7 T. The magnetic field is found to have only a minor impact on the development of the resulting neutral and ion plumes. The relative motion of the magnetic field lines with re- spect to the spacecraft is assumed to be negligible for a satellite in geosynchronous orbit, so spacecraft ions formed through charge exchange become trapped in gyroscopic orbit about field lines that are stationary relative to the spacecraft. The incorporation of the plume mixture into the model captures the variation in plume dissipation times per species, with the longest dissipation time corresponding to the H2 plume of 33 seconds.