Enhanced Planetary Surface EVA Mobility For Space Colonization

Abstract

Extravehicular activity (EVA), especially those EVAs performed on other planetary bodies, will play an integral role in future space exploration missions. However, the high joint torques in current space suits limit astronaut flexibility and mobility. These joint torques arise predominately from the change in pressurized volume associated with joint motion. In an attempt to reduce this torque while working within the framework of the current Extravehicular Mobility Unit (EMU), a redesign of the restraint layer (the layer that restrains the pressure bladder) was created to minimize the pressurized volume. This was accomplished by utilizing the concept of lines of non-extension, which are lines along the body that do not stretch or contract with joint motion. Working with an industry partner, the David Clark Company Inc., an advanced mockup elbow joint (pressure bladder and restraint layer) was borrowed for baseline torque measurements. All tests were performed in a vacuum chamber at the MIT Man Vehicle Laboratory. Suit volume was filled in both baseline case and redesigned restraint layer case with a mannequin arm. Torques were measured from angles zero to 105 degrees. A comparison of torque measurements between the two restraint layers indicated that the new restraint layer did not lower elbow joint torque from the baseline; however, the torque was of similar magnitude to that of the baseline case. This finding, shown with a first iteration of a new restraint layer, shows that the lines of non-extension concept has merit and should be further pursued. A more indepth analysis of the concept is required to elucidate its merits in ultimately creating a more livable and workable environment for astronauts on EVAs.