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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 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.

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.

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.

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 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.

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.

The University of Maryland Space Systems Laboratory is developing the capability to simulate partial gravity levels for human operational activities through the use of ballast on body segments in the underwater environment. This capability will be important as NASA prepares to return to the Moon by the end of the next decade. The paper discusses various forms of partial gravity simulation used in the past, and derives a targeted set of applications for ballasted underwater simulations. Primary application of this technique is for static or quasistatic activities, such as collecting basic anthropometric data on reach envelopes or postural control, as well as accumulating an experience base on partial gravity habitat and vehicle design and operations.

In the present study, 8 experienced neutral buoyancy test divers were instructed to maintain quiet relaxed posture while ‘standing’ in instrumented space shuttle middeck (IVA) type foot restraints in the Space Systems Laboratory (SSL) Neutral Buoyancy Research Facility (NB) and onboard the NASA KC-135 reduced gravity aircraft (PF). Foot restraint reaction loads and subject joint angles were recorded during blind and sighted conditions. Visual cues played a significant role in subject anxiety onboard the KC; however, while subject joint angles and reaction loads differed between NB and PF conditions, no differences were found between sighted and blind conditions in either simulation environment for reaction loads or joint angles. This very surprising result indicates that there are not only anecdotal but concrete differences between reduced gravity and terrestrial posture mechanisms.

Since the earliest days of manned space flight, robotics and human activities have tended to view each other as the competition. Although the International Space Station lists robotic servicing as an alternative to extravehicular activity (EVA) operations, there has been little consideration of significant cooperation between humans and telerobots in the same work site. This paper proposes the establishment of a list of potential interaction levels between humans and robots in the extravehicular work site: Robotic assistant Robotic associate Robotic surrogate Robotic specialist Human/robotic symbiosis The first three categories deal with increasing levels of robotic capability to perform EVA tasks, particularly with EVA interfaces. “Specialist” activities refer to specific task assignments that are singularly associated with humans or robots, such as an Astronaut Support Vehicle or a Telerobotic Rescue System for EVA.

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 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.

The Terrapin Undergraduate Rover for Terrestrial Lunar Exploration (TURTLE) system was developed as part of a senior design course at the University of Maryland; it has since become a test bed for habitability and life support studies. The design requirements for the project dictated a 2,500 kg pressurized lunar rover to sustain two crew members for eight days with a range of 100 km. Part of the design effort included a full-scale mock-up populated with volumetric representations of interior elements. This research proposes a solution to the life support requirements for spacecraft as well as design requirements for other habitat elements. An analysis of relevant technologies and their application to small rovers is presented. Habitability issues (with respect to interior layout of life support hardware) are also considered. Testing was done with the full-scale TURTLE mockup to determine suitable configuration of life support equipment.

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.

Past approaches to space suit glove evaluation have primarily been subjective. This report details efforts at the University of Maryland Space Systems Laboratory to use standardized dexterity tests and advanced biomechanics instrumentation to provide objective measures of glove performance. Ten subjects participated in the study. Tests were conducted barehanded, and wearing pressurized and unpressurized space suit gloves. Data on performance time, range of motion, dexterity, strength, fatigue, and comfort were collected. Range of motion data was measured using an experimental data glove that instrumented the movement of the joints of the right hand. The results indicated that performance time wearing pressurized gloves is not adequately estimated by performance wearing unpressurized gloves. Also, joint angle results indicated a decrease in the range of motion from the bare handed condition, but no significant difference between the gloved-hand conditions.

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.

Neutral buoyancy (NB) and parabolic flight (PF) are the only available human-scale three-dimensional spaceflight simulation environments. As such, both environments are used extensively for both research and mission operations purposes despite a lack of quantitative (or even qualitative) characterization of the fidelity of either environment to the spacelfight 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; and tilted 90° Front, Back, Right, and Left. PF limitations prohibited 90° testing; consequently the PF test protocol included only Upright and 45° orientations.

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.