Heating and Modeling Effects in Tethered Aerocapture Missions

Abstract

The influence of thermomechanical and tether flexibility effects on tethered aerocapture missions is examined. The focus of these missions is capturing a system, consisting of an orbiter and tether-connected probe, from a hyperbolic to an elliptical orbit via aerodynamic braking. Two temperature-dependent dynamic models of the tether are included: a two-dimensional, straight, massive, extensible tether model derived via Lagrange's equations and a three-dimensional lumped mass model derived via Kane's equations. The dynamics of the aerocapture maneuver are shown to be affected by tether extensibility due to the change in system rotational inertia. If not properly accounted for, this can result in non-capture. The effect of thermal variations on the dynamics of the aerocapture maneuver is shown to be influenced strongly by the thermal properties of the tether material. As a consequence, these thermal variations can decrease the viability of certain proposed tethered aerocapture missions and should be accounted for during design.