R.D. Reeves, E. Esen
International Space Station U.S. National Laboratory,
Keywords: space, manufacturing, microgravity, optical fiber, biomaterials, additive manufacturing
Summary:Scientists and engineers subconsciously accept that the force of gravity is a constant in the manufacturing process and often work to design around it. In some cases, gravity is essential to production, for example, in separation processes. Distillation in the gas industry or the alcohol industry requires gravity to drive the buoyancy-driven phase separation. However, in other manufacturing processes, gravity is a fact of nature and an engineering constraint which complicates the process. Recently, researchers and companies are beginning to look beyond traditional manufacturing and realize the untapped potential for in-space manufacturing in the microgravity environment onboard the International Space Station (ISS). The ISS U.S. National Laboratory serves as a unique research platform and provides the potential for advanced manufacturing of materials not possible on Earth. The persistent microgravity environment mitigates gravitational phenomena such as buoyancy-driven convection and density-driven segregation and sedimentation. In addition, the microgravity environment eliminates the need for structural supports or scaffolding during the manufacturing process. This removes additional engineering constraints, can reduce processing steps, and simplifies the final product. We will highlight several examples of companies developing in-space manufacturing processes and working to transition from the research and development phase to production. For example, three separate companies are pursuing in-space manufacturing of optical ZBLAN fibers on the ISS. When drawn in terrestrial manufacturing, these fluoride-based optical fibers exhibit defects and crystal formation. However, these defects are nearly absent when manufactured in microgravity, which leads to substantial improvement in signal loss and optical properties compared with ground-based samples. If the process can be demonstrated to scale in low Earth orbit (LEO), it is expected to significantly impact the telecommunications and fiber laser industries, with additional impacts in the medical, defense, and diagnostic sectors. We will discuss the microgravity experiments and preliminary economics of manufacturing ZBLAN fibers in LEO. In addition, we will discuss additive and biomaterial manufacturing progress on the ISS, including various facilities for additive manufacturing of polymers and bioprinting of tissues. Microgravity presents great opportunity for improved design of 3D-printed human tissues. Unlike terrestrial tissue printing, where tissues collapse under their own weight, microgravity allows tissues to be printed and cultured to strengthen over time so they are self-supporting when returned to Earth. Overall, the potential for in-space manufacturing is high, both for in-situ resource utilization for space exploration and for manufacturing of products to benefit life on Earth. The ISS is a unique platform for research and manufacturing that allows for the production of materials that cannot be produced anywhere on Earth. The potential platforms for in-space manufacturing are expected to increase with more commercial presence in space and more launch capabilities from the private sector. NASA has also recently announced new commercialization initiatives for the ISS to accelerate a commercial economy in LEO. Altogether, the industrialization of space is in progress, and in-space manufacturing in LEO is just beginning.