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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.

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.

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.

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.

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.

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.

The Ranger Telerobotic Flight Experiment is a highly complex teleoperated spacecraft, requiring direct human control of 36 major degrees of freedom. The University of Maryland Space Systems Laboratory and the NASA Ames Research Center are cooperating on the development of a virtual reality control station to streamline human interfaces with the Ranger spacecraft. This describes the design and integration of the Ranger Command Chair, a system incorporating fully immersive helmet-mounted stereo displays with head tracking, hand tracking for direct positional control, and supplemental controls and displays to allow a single operator to functionally control the entire vehicle. This system is currently undergoing tests with the Ranger Neutral Buoyancy Vehicle, a functionally identical vehicle used for systems development and flight operations simulations.

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.

Future space missions will involve humans and robots cooperatively performing operational tasks in various team combinations. Part of the required preparation for such missions includes understanding the issues involved in task allocation between disparate agents, and efficiently ordering tasks within the mission constraints. The scheduling tool developed in this research distributes pre-allocated task primitives between a cooperative human crew and dexterous robotic team. It combines real-world precedent constraints with algorithms from scheduling theory to reorder and tighten each crew member's individual schedule. The schedules minimize astronaut involvement time by stacking astronaut-performed tasks together in the schedule. This also minimizes astronaut workload in the completion of each task. Hubble Space Telescope Servicing Mission 3A was used as an example to test the allocation and scheduling tool.

The Maryland Advanced Research/Simulation (MARS) Suit is designed to be a low-cost test bed for extravehicular activity (EVA) research, providing an environment for the development and application of biomedical sensors and advanced EVA technologies. It is also designed to be used in gaining more experience with human-telerobotic interactions in an integrated EVA worksite. This paper details the first generation MARS Suit (MX-1) design, describes the low-cost development process, and presents results from ongoing suit testing, as well as plans for future work.