Static and Dynamic Torque Generation Analysis of a Cable-Actuated Solar Sail

TL;DR

This work tackles propellantless momentum management for large solar sails by introducing CABLESSail, a cable-actuated boom-bending concept that induces SRP torques through controlled boom deflections. It develops a modular, reduced-order multi-body dynamic model with a membrane-shape SRP representation and compares CABLESSail to an active mass translator (AMT) while assessing performance under sail-membrane uncertainty via Monte Carlo simulations. Key findings show that open-loop cable tensioning can achieve attitude changes at or beyond AMT performance, with pitch and yaw torques reliably generated under membrane-shape uncertainty and roll torques achievable under certain boom actuation, though requiring feedback control to mitigate vibrations. The approach demonstrates a scalable, fuel-free momentum-management mechanism for large solar sails, potentially reducing reliance on reaction wheels and propellant while highlighting the need for robust sensing and control of boom deflections.

Abstract

This paper presents a static and dynamic torque analysis of the CABLESSail concept, which involves cables routed along the length of the flexible booms that hold the solar sail membrane in such a manner that tensioning the cables results in a bending deformation of the booms. This provides a mechanism where actuation of the cables can be used to create an imbalance in solar radiation pressure (SRP) on the sail and thus, impart SRP torques that can be used for momentum management of the solar sail. Simulation results are included that demonstrate how large SRP torques can be induced by tensioning the solar sail's cables, which can be used for momentum management. Comparisons to the existing active mass translator technology are included, along with simulations demonstrating the ability to reliably generate control torques in the presence of an uncertain sail membrane shape. An appendix contains a detailed derivation of the cable-actuated solar sail dynamic model used in this work.

Figures (19)

• Figure 1: An overview of the CABLESSail concept. Tensioning cables running through spreader plates along the booms deform the booms and sail shape.
• Figure 2: Torque generation about the pitch/yaw axes of CABLESSail by bending of the booms. The photon incidence angle on each half of the sail is changed and an imbalance in SRP generates the yaw torque.
• Figure 3: (a) Sun incidence angle, $\alpha$, and clock angle, $\delta$, conventions shown with flat sail membranes and straight booms. (b) Solar sail Assembly #2 with flat sail membranes, deformed booms, and body frame $\mathcal{F}_b$ attached.
• Figure 4: Top-down view of the triangular solar sail membrane mesh with booms along the $x$ and $y$ directions corresponding to $\underrightarrow{b}^1$ and $\underrightarrow{b}^2$ directions accordingly.
• Figure 5: SRP torque generated by all six combinations of membranes and boom tip deflections across all clock angles at an SIA of $17^\circ$ and resolved in the body fixed frame, $\mathcal{F}_b$.