Formation Pointing Dynamics of Tether-Connected Architecture for Space Interferometry

Abstract

The baseline pointing dynamics, i.e., the attitude of the instantaneous plane of rotation, of a linear tethered interferometer with single baseline orbiting in an Earth trailing, heliocentric orbit is analyzed. Two tether arms provide a passive control of the spacecraft formation by keeping two light collectors and one combiner aligned while spinning about the boresight of the interferometer. The interferometer optical path delay variation under gravity gradient perturbation and unbalanced solar radiation torque is investigated analytically for a fixed-length dumbbell model. Analytical results are compared with results from numerical simulations of a visco-elastic massive tether model in order to assess the effect of the tether dynamics on the pointing stability of the formation. The study highlights the fundamental role of spin stabilization in counteracting the effect of external perturbation on the interferometer Optical Path Delay (OPD).