Space Legos: A Concept for In-Space Assembly of Large Structures with a Stationary Robot

Citation

Dassanayake, Sahangi (2025) Space Legos: A Concept for In-Space Assembly of Large Structures with a Stationary Robot. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0pn5-3w42. https://resolver.caltech.edu/CaltechTHESIS:11072024-033128289

Abstract

Human nature is inherently driven by the desire to build; advancing from primitive shelters to skyscrapers, and extending this relentless pursuit of progress to space through technological innovations. As space missions require larger and more complex structures, traditional deployable systems face challenges due to constraints on launch mass, volume, and complex deployment mechanisms. In-space assembly (ISA) offers a promising solution for constructing large structures, such as telescopes and satellites, directly in space.

This thesis introduces a novel ISA concept with a centralized `truss builder' for autonomous assembly of polygonal-ring structures, using simple, repetitive operations and focusing on scalable mesh reflectors for communication and imaging. Utilizing the standard AstroMesh architecture, a rapid generalized design method is developed. Through the analysis of reflector geometry, optimized cable prestress, structural design, and a high-fidelity finite element model, analytical scaling laws are derived for mass, stowed envelope, and natural frequency based on aperture diameter. A semi-analytical homogenization model is introduced to efficiently predict fundamental natural frequencies. Stowed volume is a key limitation for large deployable reflectors, approaching current and future launch capacity limits, while the proposed ISA reflectors face no such constraints for apertures up to 200 meters.

A two-dimensional finite element model simulates the assembly kinematics of large ring-like structures with the proposed ISA concept, enhancing understanding of the process and evaluating key design aspects of a stationary robot assembling scalable ring-like trusses. The model provides insights for optimizing autonomous assembly systems and underscores the need for advanced numerical simulations to ensure smooth assembly and stability during ISA, especially as structures scale.

Lab-scale prototype testing validates the ISA concept, with results aligning qualitatively with simulations. Both experiments and simulations reveal a range of viable solutions, demonstrating flexibility for future mission designs. This research offers crucial insights into the design and scaling of mesh reflectors, setting the stage for comparing ISA with traditional deployable systems. The proposed ISA concept presents a practical solution for building high-precision, large-scale structures in space, advancing the field of space construction and supporting future extended space missions.