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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.

With NASA's resources dedicated to the six-fold increase in extravehicular operations required for the construction of International Space Station, there are few or no opportunities to conduct neutral buoyancy research which requires the use of pressure suits. For this reason, the University of Maryland Space Systems Laboratory has developed a system which replicates some limited aspects of pressure suits to facilitate neutral buoyancy research into EVA bioinstrumentation and EVA/robotic interactions. The MX-2 suit analogue is built around a hard upper torso with integrated hemispherical helmet and rear-entry hatch. Three-layer soft goods (pressure bladder, restraint layer, and thermal/micrometeoroid garment with integral ballast system) are used for the arms and lower torso.

Decomposition of high-grade hydrogen peroxide (H2O2) generates water vapor, oxygen, and heat. By converting heat to electrical energy with a Stirling engine, a spacesuit portable life support system can be maintained exclusively with H2O2; however, incorporation of additional cooling water may reduce the overall system mass. System components comprising the hydrogen peroxide portable life support system (HyPerPLSS) are discussed and analyzed. Component considerations and thermodynamic relations indicate an optimal hydrogen peroxide concentration of 95%. Life support requirements for eight hours of extravehicular activity are satisfied with 10.9 kg of liquid H2O2.

The research discussed in this paper demonstrates further advancements in the concept of a Morphing Upper Torso, which incorporates robotic elements within the pressure suit design to enable a resizable, highly mobile and easy to donn/doff spacesuit. A full scale experimental model has been made, which accompanies several analytical models. The Jacobian matrix for the robotic system, which multiplies the total twist vector of the system to yield the vector of actuator velocities, is derived. This dynamic analysis enables quantification of the dynamic actuator requirements, given demanded trajectories of the rings. A motion capture pilot study was done to develop a methodology to obtain measurements of suit movement and hence the ring trajectories. Subjects performed various tasks that a suited astronaut may perform on a planetary surface, while wearing a torso mockup within the motion capture system.

Neutral buoyancy (NB) and parabolic flight (PF) are the only presently available human-scale three-dimensional spaceflight simulation environments, and as such, both NB and PF are used extensively to simulate spaceflight conditions for both research and mission operations purposes. However, there is little or no quantitative (or even qualitative) material in the literature to characterize the fidelity of either environment to its analog. The present study was undertaken as part of a larger research effort to begin to build such characterizations. Eight healthy adults (4 men and 4 women) were asked to adopt relaxed postures while “standing” in space shuttle middeck standard-type foot restraints, in NB and during the 0g periods of PF. Subjects were tested in NB in 9 orientations, 3 trials each: Upright; tilted 45° Front, 45° Back, 45° Right, 45° Left; tilted 90° Front, 90° Back, 90° Right, and 90° Left.

The Space Systems Lab has evaluated several different types of generic hand controllers to see which performs the best when used by a suited subject. This paper outlines the types of hand controllers selected for this experiment and the results of the performance testing. The evaluation was conducted by subjects wearing spacesuit gloves in a partial pressure glovebox at a pressure differential of 4.3 pounds/square inch. Performance for each hand controller was measured by the completion of several one degree-of-freedom (DOF) tasks presented to the subject on a computer screen. Performance metrics for this experiment included the error associated with attempting to follow an ideal trajectory and a subjective Cooper-Harper questionnaire given after each session was complete. The same information was also collected for unpressurized suit gloves and for the bare hand.

The hybrid elastic design is based upon an American Society for Engineering Education (ASEE) glove designed by at the Space Systems Laboratory (SSL) in 1985. This design uses an elastic restraint layer instead of convolute joints to achieve greater dexterity and mobility during EVA (extravehicular activity). Two pilot studies and a main study were conducted using the hybrid elastic glove and a 4000-series EMU (extravehicular activity unit) glove. Data on dexterity performance, joint range of motion, grip strength and perceived exertion was assessed for the EMU and hybrid elastic gloves with correlations to a barehanded condition. During this study, 30 test subjects performed multiple test sessions using a hybrid elastic glove and a 4000-series shuttle glove in a 4.3psid pressure environment. Test results to date indicate that the hybrid elastic glove performance is approximately similar to the performance of the 4000-series glove.

With a renewed focus on manned exploration, NASA is beginning to prepare for the challenges that lie ahead. Future manned missions will require a symbiosis of human and robotic infrastructure. As a step towards understanding the roles of humans and robots in future planetary exploration, NASA headquarters funded ILC Dover and the University of Maryland to perform research in the area of human and robotic interfaces. The research focused on development and testing of communication components, robotic command and control interfaces, electronic displays, EVA navigation software and hardware, and EVA lighting. The funded research was a 12-month effort culminating in a field test with NASA personnel.

The MX-2 neutral buoyancy space suit analogue has been designed and developed at the University of Maryland to facilitate analysis of space suit components and assessment of the benefits of advanced space suit technologies, The MX-2 replicates the salient features of microgravity pressure suits, including the induced joint torques, visual, auditory and thermal environments, and microgravity through the use of neutral buoyancy simulation. In this paper, design upgrades and recent operations of the suit are outlined, including many experiments and tests of advanced space suit technologies, This paper focuses on the work done using the MX-2 to implement and investigate various advanced controls and displays within the suit, to enhance crewmember situational awareness and effectiveness, and enable human-robotic interaction.

There has recently been an increasing focus on humans working cooperatively with robotic systems in space exploration and operations. Considerable work has been performed on distributed architectures to enable such interaction. The research described here looks at the human-robot interaction from the EVA astronaut's perspective, describing a first generation human-machine interface implemented and tested on an existing experimental spacesuit analog, the MX-2. The ultimate goal is to enable EVA astronauts to operate more independently of remote operators and work effectively with autonomous and teleoperated robots. The current system integrates speech interaction and visual interfaces as a first step towards this goal.

The fit of a spacesuit has been identified as a crucial factor that will determine its usability. Therefore, because one-size-fits-all spacesuits seldom fit any wearer well, and because individually tailored spacesuits are costly, the University of Maryland has conducted research into a resizable Extravehicular Activity (EVA) suit. This resizing is accomplished through a series of cable-driven parallel manipulators, which are used to adjust the distance between plates and rings built into a soft space suit. These actuators, as well as enabling passive suit resizing, could be used to actively assist the astronaut's motion, decreasing the torques that must be applied for movement in a pressurized suit. This paper details the development and testing of an arm prototype, which is used to better understand the dynamics of a more complex torso-limb system.

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.

The next generation of pressure suits must enable large-scale planetary Extra-Vehicular Activities (EVA). Astronauts exploring the moon and Mars will be required to walk many kilometers, carry large loads, perform intricate experiments, and extract geological samples. Advanced pressure suit architectures must be developed to allow astronauts to perform these and other tasks simply and effectively. The research developed here demonstrates integration of robotics technology into pressure suit design. The concept of a robotically augmented pressure suit for planetary exploration has been developed through the use of analytical and experimental investigations. Two unique torso configurations are examined, including a Soft/Hard Upper Torso with individually adjustable bearings, as well as advances in Morphing Upper Torso research, in which an all-soft torso is analyzed as a system of interconnected parallel manipulators.

This paper summarizes the activities of the University of Maryland Space Systems Laboratory in performing a design study for a minimum functionality lunar habitat element for NASA's Exploration Systems Mission Directorate. By creating and deploying a survey to personnel experienced in Earth analogues, primarily shipboard and Antarctic habitats, a list of critical habitat functions was established, along with their relative importance and their impact on systems design/implementation. Based on a review of relevant past literature and the survey results, four habitat concepts were developed, focused on interior space layout and preliminary systems sizing. Those concepts were then evaluated for habitability through virtual reality (VR) techniques and merged into a single design. Trade studies were conducted on habitat systems, and the final design was synthesized based on all of the results.

The University of Maryland Space Systems Laboratory and ILC Dover LP have developed a novel concept: a soft pressure garment that can be dynamically reconfigured to tailor its shape properties to the wearer and the desired task set. This underlying concept has been applied to the upper torso of a rear entry suit, in which the helmet ring, waist ring and two shoulder rings make up a system of four interconnected parallel manipulators with tensile links. This configuration allows the dynamic control of both the position and orientation of each of the four rings, enabling modification of critical sizing dimensions such as the inter-scye distance, as well as task-specific orientations such as helmet, scye and waist bearing angles. Half-scale and full-scale experimental models as well as an analytical inverse kinematics model were used to examine the interconnectedness of the plates, the role of external forces generated by pressurized fabric, and the controllability of the system.

This paper describes a unique concept for donning and doffing a spacesuit from a pressurized rover or habitat, which merges three independent concepts: suitports, neck-entry EVA suits, and the Morphing Upper Torso. The union of these concepts creates a novel and exciting suit and suitport system architecture, with many potential benefits over traditional suitport systems. To develop this concept, a neck-entry Morphing Upper Torso experimental model has been designed and fabricated, and systems level design studies have been performed, including visualization with the aid of CAD models of the neck-entry suitport on a small pressurized rover and a lunar habitat. As well, a donning test-station has been developed and used for experiments in 1-G, simulated microgravity and simulated partial gravity.

Performance of new space suit designs is typically tested quantitatively in laboratory tests, at both the component and integrated systems levels. As the suit moves into neutral buoyancy testing, it is evaluated qualitatively by experienced subjects, and used to perform tasks with known times in earlier generation suits. This paper details the equipment design and test methodology for extended space suit performance metrics which might be achieved by appropriate instrumentation during operational testing. This paper presents a candidate taxonomy of testing categories applicable to EVA systems, such as reach, mobility, workload, and so forth. In each category, useful technologies are identified which will enable the necessary measurements to be made. In the subsequent section, each of these technologies are examined for feasibility, including examples of existing technologies where available.

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.

Employing a cooperative human and robotic team has the potential to greatly reduce human workload during space missions and create more efficient operational teams. The Hubble Space Telescope Servicing Mission 3A tasks were assessed and modeled with three different human and robot team pairings to elucidate the difference to team performance. Tasks were allocated to the standard two-human EVA crew and a robotic agent for each of the cases. The schedules reduce the human crew's involvement time in each EVA day's activities by rearranging subtasks to minimize the human crew's wait time. This work examines three agent participation scenarios and their effect on the expected efficiency of the cooperative team during mission activities.