Aerodynamics of Stardust Sample Return Capsule

Successful return of interstellar dust and cometary material by the Stardust Sample Return Capsule requires an accurate description of the Earth entry vehicle's aerodynamics. This description must span the hypersonic-rarefied, hypersonic-continuum, supersonic, transonic, and subsonic flow regimes. Data from numerous sources are compiled to accomplish this objective. These include direct simulation Monte Carlo analyses, thermochemical nonequilibrium CFD, transonic CFD, existing wind-tunnel data, and new wind-tunnel data. A static instability is revealed in the free-molecular and early transitional flow regimes due to aft location of the vehicle's center of gravity. The aerodynamics across the hypersonic regime are compared with the Newtonian flow approximation, and a correlation between the accuracy of the Newtonian flow assumption and the sonic line position is found. The primary effect of shape change due to ablation is shown to be a reduction in drag, and a subsonic dynamic instability that necessitated the addition of a stabilizing drogue parachute is found. (Author)