Development of a mechanical counter pressure Bio-Suit System for planetary exploration

Abstract

Extra-vehicular activity (EVA) is critical for human spaceflight and particularly for human planetary exploration. The MIT Man Vehicle Laboratory is developing a Bio-Suit EVA System, based on mechanical counterpressure (MCP), that has the potential to maximize and even augment the EVA capabilities of future planetary explorers. This thesis describes the design and implementation of novel MCP concepts for the Bio-Suit System. Two concepts known as the detached bands and elastic bindings were initially developed and tested in ambient conditions on a human leg. The elastic bindings proved superior to the detached bands and demonstrated greater mobility, comfort and ease of donning than previous MCP garments. After refining the bindings design to improve the uniformity of its pressure distribution, five subjects donned bindings on one calf and exposed the suited calf to -30kPa (-225mmHg, -0.3atm) for up to an hour - a greater magnitude and longer duration of underpressure than previous MCP garment tests - to demonstrate the effectiveness of the bindings as a pressure garment. Changes in heart rate, skin temperature and blood pressure were recorded during these experiments.

(cont.) The bindings prevented the increase in blood pressure that occurs when the unprotected calf is exposed to underpressure, further demonstrating their efficacy as a pressure layer. The elastic bindings concept in its current form is not a final design for an operational EVA system. However, it exhibits many of the attributes necessary for use in such a system and is thus extremely valuable for studying the engineering, physiological and practical issues associated with utilizing mechanical counterpressure as a cornerstone of the Bio-Suit.