This paper explores the interaction of weak gravitational fields with slender elastic materials in space and estimates their sensitivities for the detection of gravitational waves with frequencies between 10–4 and 1 Hz. The dynamic behaviour of such slender structures is ideally suited to analysis by the simple theory of Cosserat rods. Such a description offers a clean conceptual separation of the vibrations induced by bending, shear, twist and extension and the response to gravitational tidal accelerations can be reliably estimated in terms of the constitutive properties of the structure. The sensitivity estimates are based on a truncation of the theory in the presence of thermally induced homogeneous Gaussian stochastic forces.