The proposed innovation is a membrane bioreactor system to produce a biopolymer from methane gas. This new methane fermentation process will expand and advance current gas delivery techniques to create affordable fermentation methods on Earth and beyond. Mango Materials is currently working to scale up and commercialize the production of polyhydroxyalkanoate (PHA) from methane, but its scaled-up fermentation systems are typically tall and narrow to take advantage of hydrostatic pressure for the transfer of methane into solution. The proposed work represents a unique approach that could enable the production of biopolymer on Earth and also non-Earth environments, thus creating a closed-loop system for producing biopolymer products on-demand in outer space. The proposed design is a novel, membrane-based bioreactor that will enable bacterial growth and biopolymer production to occur in microgravity environments on moist membranes that are sandwiched between layers of the gaseous feedstocks methane and oxygen. This system will allow for efficient energy use, minimal square footage, and effective mass transfer from the gaseous to the liquid phase without being dependent on hydrostatic pressure. Mango Materials will partner with Colorado School of Mines where there is extensive experience with membrane bioreactors, to design and construct this system.