In-Space Manufacturing for Flexible Membranes: Process, Applications, and Vacuum Test Insights

An experimental setup is presented to demonstrate the in-space manufacturing of a support structure for flexible membranes as a proof-of-concept. Membranes, for example, used in flexible solar arrays, can be reinforced by a continuous extrusion of photopolymer. This process is intended to provide a more scalable and cost-effective solution compared to deployable structures. This paper presents a test setup and the results of functional tests under atmospheric and vacuum conditions. The flexible membrane is unrolled from a spool and pulled through a circular nozzle on one side of the flexible membrane. Through this nozzle, a photopolymer is extruded onto the membrane at the same feed rate. Directly after the nozzle outlet, UV-lights are located to cure the photopolymer in parallel to the deployment. After a short section, where rolls stabilize the membrane, and the resin has time to cure, the in-space manufactured structure is deployed into free space. With this setup, the manufacturing of structures with a total length of over 300 mm was demonstrated. However, the structures intended to be manufactured with that technology could support membranes with a length of several meters. For longer support structures, the cross-section and geometry of the nozzle, as well as the amount of material would need to be increased to enhance the bending stiffness. Functional tests in ambient conditions and vacuum showed a successful extrusion of photopolymeric structure on the membrane. However, bubble formation was observed for the structure extruded in vacuum which was not present in the structure manufactured under atmospheric conditions. Potential causes include inadequate resin degassing, air entrapment during filling, or outgassing from hardware components. Addressing these bubbles is crucial for in-space manufacturing technology as future applications require a predictable and reproducible manufacturing process to design structures optimized for their load cases. Previous fundamental experiments of the photopolymer extrusion have been demonstrated by ground-based experiments, in microgravity during zero-g flights, as well as in microgravity and vacuum conditions during a sounding rocket experiment. With the presented concept, a high bending stiffness can be achieved due to the continuous solidified structure. Furthermore, the technology offers an energy-efficient curing mechanism, a high packing efficiency, and a low number of moving elements. This makes it a competitive solution compared to other in-space manufacturing technologies. More importantly, it brings new approaches to conventional spacecraft designs to reduce costs and increase mission capabilities.