Abstract
One of the main challenges to support life in space is the development of sustainable, circular processes that reduce the high cost of resupply missions. Space biomanufacturing is an emerging paradigm that aims to reduce the need for resources, enabling on-demand manufacture of products. The cost of installing biomanufacturing systems in space depends on the cost of transporting the system components, which is directly proportional to their mass/weight. From this perspective, the system mass is a critical factor that dictates process design, and this has important implications in how we can approach such design. For instance, mass constraints require circular use of resources and tight process integration (to minimize resupply) and restricts the type of resources and equipment needed. In this work, we evaluate the lactic acid bioproduction design using Escherichia coli, Saccharomyces cerevisiae, and Pichia pastoris. We use the Equivalent System Mass (ESM) metric as a key design measure. ESM allows the quantification of different physical properties of the system in a common mass basis. Our analysis reveals that 97.7 kg/year of lactic acid can be produced using Saccharomyces cerevisiae in a 10 L stainless steel fermenter. Furthermore, considering that stainless steel is the design material and quantifying the mass of 1 g/cm2 of shielding material, the total system mass was 19 kg. This modeling framework also identified the critical system elements responsible for the highest system mass and launch cost. Overall, our analysis reveals how focusing on system mass can bring new design perspectives that can aid the design of traditional manufacturing systems.