Modeling and testing of a mechanical counterpressure BioSuit system

Abstract

The President's Vision for Space Exploration calls for a returned human presence on the Moon, followed by human missions to Mars. The astronauts on these missions will require a more robust and flexible spacesuit than currently exists to conduct exploration and science operations as well as maintain a base on planetary surfaces. The BioSuit system is a modular spacesuit concept based on the theory of mechanical counterpressure (MCP). Considerable experimental work has been conducted in the field of MCP, but there has been no analysis of the hypothetical best level of uniformity of pressure production for this type of spacesuit design. Therefore, computer modeling has been undertaken to verify the feasibility of such a design, which is based on not only providing the required pressure on the skin, but also limiting the variation of pressure production around a cross-section of the body. Given the data sets available, which exclusively consist of legs under normal atmospheric pressure, not mechanical counterpressure, the modeling work indicates that a MCP-based design can meet these requirements.

(cont.) This thesis advances the BioSuit design by laying out the system level requirements, and also by setting requirements for the fabric and closure mechanism in order to design a working prototype. As part of this design process, the team has further developed the elastic bindings concept, which previously was designed to produce pressure only on the calf. Now the team has extended the design to protect the entire leg in an underpressurized environment. Based on blood pressure, skin temperature, heart rate, and qualitative comfort ratings, the bands have proven successful at protecting the leg (with the exception of some minor edema on the knee) at the desired underpressure (-225 mm Hg) over a full hour. A simple knee brace which filled the concavities of the knee was also tested, and proved successful in preventing edema in one trial. While the design is not yet capable of operational testing due to limitations in mobility, it is a valuable stepping point towards developing a full BioSuit system.