Compact Deployment Control Mechanism for the Deployable Backbone Structure of a 500-m²-Class Solar Sail

Abstract

Spacecraft, intended for solar sailing mission rely on deployable systems to achieve large area to mass ratios once in space, while still being small enough for common launcher envelopes, in stowed configuration. Many deployable systems feature booms that are flattened and consequently, collectively coiled onto one hub. DLR and NASA have joined forces to realize a deployment system, using NASA booms in combination with a deployment mechanism, developed by DLR. This paper’s focus is lying on the mechanism part. The deployment mechanism is based on an existing, smaller scaled version, which has already undergone several functional tests at DLR. Besides the challenges of the up-scaling of a mechanism, featuring booms with a larger cross section to begin with, this paper also focusses on the development of a new, constant-torque brake. Braking systems have always been part of the deployment mechanisms, to prevent the booms from self-deployment through stowed elastic energy. To make these brakes as lightweight as possible, while maintaining torque and reliability, is a challenge on its own.