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The University of Maryland Space Systems Laboratory has developed a system that replicates some limited aspects of pressure suits to facilitate neutral buoyancy research into EVA bioinstrumentation, advanced EVA training, and EVA/robotic interactions. After a two year upgrade from its MX-1 predecessor, the MX-2 space suit analogue is currently undergoing a variety of system integration tests in preparation for initial operational testing, leading to routine use for EVA simulation and as a testbed for advanced space suit technology. The MX-2 is built around a hard upper torso with integrated hemispherical helmet and rear-entry hatch. Three-layer soft-goods are used for the arms and lower torso, while an open loop air system regulates suit pressure to 3 psid. Wrist disconnects allow the use of standard EMU or Orlan gloves, or experimental gloves such as the mechanical counterpressure gloves and power-assisted gloves developed previously by the SSL.

Real time knowledge of the metabolic workload of an astronaut during an Extra-Vehicular Activity (EVA) can be instrumental for space suit research, design, and operation. Three indirect calorimetry approaches were developed to determine the metabolic workload of a subject in an open-loop space suit analogue. A study was conducted to compare the data obtained from three sensors: oxygen, carbon dioxide, and heart rate. Subjects performed treadmill exercise in an enclosed helmet assembly, which simulated the contained environment of a space suit while retaining arm and leg mobility. These results were validated against a standard system used by exercise physiologists. The carbon dioxide sensor method was shown to be the most reliable and a calibrated version of it will be integrated into the MX-2 neutral buoyancy space suit analogue.

Extensive prior research at the University of Maryland Space Systems Laboratory has identified significant operational advantages to high levels of integration between EVA crew and dexterous robotics. Crew performance on recent Hubble Space Telescope repair missions was broken down into task primitives, and evaluated for the impact of dexterous robotics in direct support of extravehicular activity. Results demonstrate that direct EVA-robotic cooperation can increase human performance in satellite servicing tasks by factors ranging from at least 60% (for highly complex and dexterous servicing tasks) to as much as 400% for more simple activities with greater levels of planned orbital replacement unit (ORU) interchange. This paper details experimental and analytical investigations of differing approaches to adding dexterous robotic capabilities to the EVA work site, via increasingly direct integration of robotics into the space suit system itself.

Space suit design has been limited to evolutionary steps since the first pressure suit was developed in 1934. While this development process has improved the fit to the wearer, it is still common to measure the performance of a pressure suit by identifying what fraction of shirtsleeve capability it allows. Given sufficient government and commercial support, space could in the future be an expanding realm of commercial and exploration activities, including return to the moon and human Mars exploration, with requirements for extravehicular activity orders of magnitude beyond the maximum envisioned for the International Space Station era. In such an environment, the need for breakthrough technology is to make the space suit into an augmentation of the human wearer, rather than an impediment.

A fully operational space suit analogue for use in a neutral buoyancy environment has been developed and tested by the University of Maryland’s Space Systems Laboratory. Repeated manned operations in the Neutral Buoyancy Research Facility have shown the MX-2 suit analogue to be a realistic simulation of operational EVA pressure suits. The suit is routinely used for EVA simulation, providing reasonable joint restrictions, work envelopes, and visual and audio environments comparable to those of current EVA suits. Improved gloves and boots, communications carrier assembly, in-suit drink bag and harness system have furthered the semblance to EVA. Advanced resizing and ballasting systems have enabled subjects ranging in height from 5′8″ to 6′3″ and within a range of 120 lbs to obtain experience in the suit. Furthermore, integral suit instrumentation facilitates monitoring and collection of critical data on both the suit and the subject.