Evolution of Spacesuit Pressure Systems: From Gas Pressurization to Mechanical Counter-Pressure Concepts

The renewed interest in long-duration human exploration missions to the Moon and Mars has highlighted the need for spacesuits capable of ensuring both physiological protection and operational performance. Operational extravehicular activity (EVA) spacesuits rely primarily on gas pressurization, which can impose mobility constraints, increase metabolic cost and contribute to fatigue and musculoskeletal injury risk. Mechanical counter-pressure (MCP) systems have therefore been investigated since the pioneering work of Annis and Webb in the 1970s. By applying compression directly to the body through close-fitting textiles, MCP garments may reduce some mobility-related constraints associated with conventional gas-pressurized suits. This review examines the physiological requirements governing spacesuit pressurization, the limitations of conventional EVA suits and the evolution of MCP technologies from early partial-pressure garments to BioSuit™ concepts. Hybrid architectures and active materials are also discussed as strategies for improving pressure control and garment performance. Attention is devoted to the available evidence, distinguishing between conceptual studies, numerical analyses, component-level demonstrations and human-subject validation. Although MCP systems show promising potential, their development remains constrained by pressure non-uniformity, garment fit, donning and doffing complexity, activation requirements, durability and limited validation under operationally representative conditions. Current evidence therefore supports MCP as a promising but not yet fully mature alternative, while hybrid architectures may represent a more realistic intermediate approach for future EVA systems.