Hubble Space Telescope solar array: A thermally induced disturbance torque

The thermoelastic behavior of one solar array wing of the Hubble Space Telescope (HST) as it enters sunlight (or eclipse) was investigated by taking a simplified model of the blanket longitudinal elasticity and a Coulomb friction model within the drum bearings at one end and within the spreader bar compensator mechanism at the other end of the blanket. A temperature increase (or decrease) linear in time was assumed for the blankets. The interaction torque between one wing and the HST body was assessed to evaluate the impact of array thermoelastic motions on HST pointing. Dynamic simulations were performed for different combinations of friction coefficients within the drum and spreader bars. The equations of motion are derived from a Lagrangian analysis, where the blankets are represented by a continuum. The behavior of the moving parts of the array and the interaction torque are shown.