Mixed flow ionospheric aerodynamics

The increasingly congested near earth environment requires accurate or-bital modelling to prevent collision events that threaten access to spaceinfrastructure. Ionospheric aerodynamics are the largest non-conservativesource of orbital perturbations. Work done by Capon et al provideda prediction method for drag forces on charged bodies in low earth orbitbased on applying approximations of single species flows to representa-tive plasma simulations. Recent work on mixed species plasma sheaths[2][3] motivates investigation of this assumption.

Mixed species plasma flows over charged bodies with representative LEOconditions were simulated, focusing on orbital motion limited O+ dom-inated flows, and sheath limited H+ dominated flows. The significanceof small concentrations of different ion species was analysed in terms ofaerodynamic effects on the body. Introduction of small concentrations ofH+ into a flow dominated by O+ molecules showed significant disrup-tions to the wake structure, coupled with an increase in drag coefficientfor a satellite in that flow. Introducing heavier O+ molecules into a sheathdominated H+ flow found little disruption to the wake structure.

A multi-species drag model was proposed, building on work in. Thismodel was found to qualitatively describe changes in wake structure, butconsistently over predicted drag coefficients. This finding suggests thatthe influence of mixed species flows on ionospheric aerodynamics involvessignificant contributions from inter-species interactions not described ad-equately by considering the separate species as either separate flows, orone flow with adjusted parameters.