Abstract
<jats:p>Scaling life support systems from a small crew of four to a large crew of 150 presents substantial engineering and operational challenges in maintaining a stable enclosed atmosphere. At small scales, atmospheric control can rely on relatively simple subsystems for carbon dioxide removal, oxygen replenishment, humidity regulation, and trace contaminant management. However, nonlinear scaling effects emerge as crew size increases. The metabolic loads of 150 individuals drive exponential increases in CO₂ production, O₂ demand, and water vapor generation, requiring greater throughput capacity, redundancy, and fine-tuned feedback control. Larger crews also amplify issues of spatial distribution. With more compartments, airflow mixing and uniformity of gas concentrations become more difficult, leading to localized hotspots of CO₂ accumulation or oxygen depletion. System reliability becomes critical: the failure of a single scrubber or electrolyzer in a 4-person system may be tolerable, but in a 150-person system such a failure could cascade into mission-threatening atmospheric imbalance. In addition, scaling demands a significant increase in the size and complexity of life support hardware. CO₂ scrubbers, O₂ generation systems, condensate recovery units, and trace contaminant filters that are compact and lightweight for a 4-person crew must be dramatically expanded or multiplied to meet the metabolic load of 150. This growth is not purely linear: equipment must be housed, interconnected, and maintained, imposing major constraints on volume allocation, structural integration, and crew accessibility. The physical footprint of atmosphere control systems competes directly with habitat space, storage, and other mission-critical infrastructure. As a result, modular, distributed, and space-efficient designs become essential to avoid disproportionate mass, power, and volume penalties associated with simple scaling. In summary, transitioning from 4 to 150 occupants transforms atmospheric control from a linear engineering problem into a multifaceted systems-integration challenge, requiring robust scalability, distributed control, and redundancy to ensure a safe, habitable environment.</jats:p>