Keywords: Muscular strength, weightlessness, astronaut performance, torque
Abstract: Strength, the capability to produce an external force, is one of the most important determining characteristics of human performance. Knowledge of strength capabilities of a group of individuals can be applied to designing equipment and workplaces, planning procedures and tasks, and training individuals. In the space program, with the high risk and cost associated with spaceflight, information pertaining to human performance is important to ensure mission success and safety. Knowledge of individuals' strength capabilities in weightlessness is of interest to NASA, including workplace design, tool development, and mission planning. The weightless environment of space places the human body in a completely different context. Astronauts perform a variety of manual tasks while in orbit. Their ability to perform these tasks is partly determined by their strength capability as demanded by that particular task. An important step in task planning, development, and evaluation is to determine the ability of the humans performing it. This can be accomplished by using quantitative techniques to develop a database of human strength capabilities in weightlessness. If strength characteristics are known, equipment and tools can be built to optimize the operators' performance. There is a spectrum of ways of looking at strength, from basic research to applied engineering. This study examined strength in performing a simple task, specifically, using a tool to apply a torque to a fixture.
Keywords: Expert Systems, Programming Languages, Computer Techniques
Abstract: Expert systems are computer programs which emulate human expertise in well defined problem domains. The potential payoff from expert systems is high: valuable expertise can be captured and preserved, repetitive and/or mundane tasks requiring human expertise can be automated, and uniformity can be applied in decision making processes. The C Language Integrated Production System (CLIPS) is an expert system building tool, developed at the Johnson Space Center, which provides a complete environment for the development and delivery of rule and/or object based expert systems. CLIPS was specifically designed to provide a low cost option for developing and deploying expert system applications across a wide range of hardware platforms. The development of CLIPS has helped to improve the ability to deliver expert system technology throughout the public and private sectors for a wide range of applications and diverse computing environments. The Third Conference on CLIPS provided a forum for CLIPS users to present and discuss papers relating to CLIPS applications, uses, and extensions.
Keywords: Apollo, Apollo Lunar Experiment Module, reduced gravity, manned lunar surface vehicles, lunar dust, lunar roving vehicles, astronauts, tools
Abstract: This catalog reviews Apollo mission reports, preliminary science reports, technical crew debriefings, lunar surface operations plans, and various relevant lunar experiment documents, collecting engineering- and operation-specific information by experiment. It is organized by discrete experimental and equipment items emplaced or operated on the lunar surface or at zero gravity during the Apollo missions. It also attempts to summarize some of the general problems encountered on the surface and provides guidelines for the design of future lunar surface experiments with an eye toward operations. Many of the problems dealt with on the lunar surface originated from just a few novel conditions that manifested themselves in various nasty ways. Low gravity caused cables to stick up and get caught on feet, and also made it easy for instruments to tip over. Dust was a problem and caused abrasion, visibility, and thermal control difficulties. Operating in a pressure suit limited a person's activity, especially in the hands. I hope to capture with this document some of the lessons learned from the Apollo era to make the jobs of future astronauts, principle investigators, engineers, and operators of lunar experiments more productive.
Keywords: Hubble Space Telescope, orbital replacement units, extravehicular activity, spacewalks, International Space Station, zero-g environment, PABF, COSTAR, motion analysis
Abstract: The STS-61 mission was for servicing the Hubble Space Telescope (HST), which had been providing valuable information; but modifications were necessary to correct the degraded performance of several components. In addition to servicing orbital replacement units (ORUs), STS-61 crew members replaced the HST solar arrays and performed other maintenance. Without a correction to the optical flaw, usefulness of the HST in the visible light spectrum would have been less than optimal. Also, although NASA had considerable experience in on-orbit extravehicular activities (EVAs), it had never performed such a quantity of complex EVAs as was scheduled for this mission (5 days of EVA and high demands on the crew members and the ground team); it was to be an indication of NASA preparedness to build and maintain a space station. Quality training, therefore, had to be provided so that there were no significant surprises during the tasks of this mission. The purpose of this study was to validate the training techniques for STS-61 crew members in a simulated zero-g environment and to simulate and monitor the reaction of test subjects who were maneuvering the ORU. It was hoped that this study would provide information concerning whether the crew, while moving ORUs, could react to, and counteract comfortably, those forces imparted by the simple motions of mass and inertia. Four subjects participated in our study; tests were conducted on the PABF; mockups were built to simulate the mass characteristics of the COSTAR . Video cameras obtained video data for motion analysis. The main objective of this study was to determine the forces and moments applied and encountered by test subjects during the RMS run start/stop condition.
Keywords: space debris, space pollution
Keywords: Research Projects, Research and Development, NASA Programs, Technology Utilization, Space Technology Experiments
Abstract: Issued as a companion to Johnson Space Center's Research and Technology Annual Report, which reports JSC accomplishments under NASA Research and Technology Operating Plan (RTOP) funding, this report describes 47 additional projects that are funded through sources other than the RTOP. Emerging technologies in four major disciplines are summarized: space systems technology, medical and life sciences, mission operations, and computer systems. Although these projects focus on support of human spacecraft design, development, and safety, most have wide civil and commercial applications in areas such as advanced materials, superconductors, advanced semiconductors, digital imaging, high density data storage, high performance computers, optoelectronics, artificial intelligence, robotics and automation, sensors, biotechnology, medical devices and diagnosis, and human factors engineering.
Keywords: Research Projects, Research and Development, NASA Programs, Technology Utilization, Space Technology Experiments
Abstract: Johnson Space Center research and technology accomplishments during fiscal year 1993 are described and principal researchers and technologists are identified as contacts for further information. Each of the four sections gives a summary of overall progress in a major discipline, followed by detailed, illustrated descriptions of significant tasks. The four disciplines are Life Sciences, Human Support Technology, Solar System Sciences, and Space Systems Technology. The report is intended for technical and management audiences throughout NASA and the worldwide aerospace community. An index lists project titles, funding codes, and principal investigators.
Keywords: Research and Development, Technology Transfer, Discretionary Fund, NASA Programs, Space Technology Experiments
Abstract: As an independent research medium, the Johnson Space Center Director's Discretionary Fund often initiates investigations of significant value to NASA with eventual application to commercial uses. The projects provide technical support to the NASA mission and development opportunities for the science and engineering staff. Thirty-six projects were supported from the $1,779,000 in FY93 funds. Some notable projects that made outstanding progress and produced significant results: multilayer microspheres of medication were processed in microgravity; virtual environment techniques were used for visualization of repair tasks and training in the successful repair of the Hubble Space Telescope; a prototype axial flow pump for heart ventricle assist was demonstrated in a calf implant; the electronic still camera rapidly transmitted high resolution images from the Space Shuttle; water was obtained from a lunar soil sample and from lunar soil simulant, confirming a patented oxygen extraction process; a regenerative water recovery system was demonstrated; patent disclosures were made on a dried blood sampling method.
Keywords: lunar orbiter, lunar satellites, lunar spacecraft, lunar topography, lunar geology, geological surveys, geology, geodesy, geochemistry, lunar gravitational effects, mineralogy
Abstract: The Lunar Scout Program was one of a series of attempts by NASA to develop and fly an orbiting mission to the Moon to collect geochemical, geological, and gravity data. Predecessors included the Lunar Observer, the Lunar Geochemical Orbiter, and the Lunar Polar Orbiter - missions studied under the auspices of the Office of Space Science. The Lunar Scout Program, however, was an initiative of the Office of Exploration. It was begun in late 1991 and was transferred to the Office of Space Science after the Office of Exploration was disbanded in 1993. Most of the work was done by a small group of civil servants at the Johnson Space Center; other groups also responsible for mission planning included personnel from the Charles Stark Draper Laboratories, the Lawrence Livermore National Laboratory, Boeing, and Martin Marietta. The Lunar Scout Program failed to achieve New Start funding in FY93 and FY94 as a result of budget downturns, the de-emphasis of the Space Exploration Initiative, and the fact that lunar science did not rate as high a priority as other planned planetary missions, and was cancelled. The work done on the Lunar Scout Program and other lunar orbiter studies, however, represents assets that will be useful in developing new approaches to lunar orbit science.
Keywords: carbon-carbon composites, carbon fibers, reinforcing materials, ablation, abort trajectories, temperature effects, erosion, silicon carbides, silicon dioxides, oxidation
Abstract: Reusable, oxidation-protected reinforced carbon-carbon (RCC) has been successfully flown on all Shuttle Orbiter flights. Thermal testing of the silicon carbide-coated RCC to determine its oxidation characteristics has been performed in convective (plasma Arc-Jet) heating facilities. Surface sealant mass loss was characterized as a function of temperature and pressure. High-temperature testing was performed to develop coating recession correlations for predicting performance at the over-temperature flight conditions associated with abort trajectories. Methods for using these test data to establish multi-mission re-use (i.e., mission life) and single mission limits are presented.
Keywords: Kalman filters, algorithms, space rendezvous, state vectors
Abstract: A new derivation of an algorithm which fuses the outputs of two Kalman filters is presented. Unlike other works, this derivation clearly shows the combination of estimates to be optimal, minimizing the trace of the fused covariance matrix. The algorithm assumes that the filters use identical models, and are stable and operating optimally with respect to their own local measurements. Evidence is presented which indicates that the error ellipsoid derived from the covariance of the optimally fused estimate is contained within the intersections of the error ellipsoids of the two filters being fused. Modifications which reduce the algorithm's data transmission requirements are also presented, including a scalar gain approximation, a cross-covariance update formula which employs only the two contributing filters' autocovariances, and a form of the algorithm which can be used to reinitialize the two Kalman filters. A sufficient condition for using the optimally fused estimates to periodically reinitialize the Kalman filters in this fashion is presented and proved as a theorem. When these results are applied to an optimal spacecraft rendezvous problem, simulated performance results indicate that the use of optimally fused data leads to significantly improved robustness to initial target vehicle state errors. Two other applications of estimate fusion methods to spacecraft rendezvous are also described: state vector differencing, and redundancy management.
Keywords: motion, human performance, video data, image analysis, image processing, underwater photography
Abstract: Video-based motion analysis systems are widely employed to study human movement, using computers to capture, store, process, and analyze video data. This data can be collected in any environment where cameras can be located. One of the NASA facilities where human performance research is conducted is the Weightless Environment Training Facility (WETF), a pool of water which simulates zero-gravity with neutral buoyance. Underwater video collection in the WETF poses some unique problems. This project evaluates the error caused by the lens distortion of the WETF cameras. A grid of points of known dimensions was constructed and videotaped using a video vault underwater system. Recorded images were played back on a VCR and a personal computer grabbed and stored the images on disk. These images were then digitized to give calculated coordinates for the grid points. Errors were calculated as the distance from the known coordinates of the points to the calculated coordinates. It was demonstrated that errors from lens distortion could be as high as 8%. By avoiding the outermost regions of a wide-angle lens, the error can be kept smaller.
Keywords: space stations, workstations, human factors engineering, man machine systems, productivity, remote manipulator system, control systems, control boards
Abstract: Previous development testing for the Space Station Remote Manipulator System Workstation controls determined the need for hardware controls for the emergency stop, brakes on/off, and some camera functions. This report documents the results of an evaluation to further determine control implementation requirements, requested by the Canadian Space Agency (CSA) to close outstanding review item discrepancies. This test was conducted at the Johnson Space Center's Space Station Mockup and Trainer Facility in Houston, Texas, with nine NASA astronauts and one CSA astronaut as operators. This test evaluated camera iris and focus, back-up drive, latching end effector release, and autosequence controls, using several types of hardware and software implementations. Recommendations resulting from the testing included providing guarded hardware buttons to prevent accidental actuation; providing autosequence controls and back-up drive controls on a dedicated hardware control panel; and that "latch on/latch off", or on-screen software, controls not be considered. Generally, the operators preferred hardware controls although other control implementations were acceptable. The results of this evaluation will be used along with further testing to define specific requirements for the Workstation design.
Keywords: projectile cratering; impact damage; hypervelocity impact; Teflon; thermal protection
Abstract: Impact experiments in Teflon targets were conducted to reproduce craters and penetration holes in thermal protective blankets that were exposed to space on board the long duration exposure facility, to understand the relationships between projectile size and the resulting crater or penetration-hole diameter over a wide range of impact velocities. Powder propellant and light-gas guns were used to launch soda-lime glass spheres into pure Teflon targets at velocities ranging from 1 to 7 km/s. Target thickness (T) was varied over more than three orders of magnitude from infinite halfspace targets to very thin films. Cratering and penetration of massive Teflon targets is dominated by brittle failure and the development of extensive spall zones. Mass removal by spallation at the back side of Teflon targets may be so severe that the absolute penetration-hole diameter can become larger than that of a standard crater at relative target thicknesses of Dp/T = 0.6-0.9. The crater diameter in infinite halfspace Teflon targets increases with encounter velocity by a factor of V 0.44. In contrast, the penetration-hole size in very thin foils is essentially unaffected by impact velocity. Penetrations at target thicknesses intermediate to these extremes will scale with variable exponents of V. Our experimental matrix is sufficiently systematic and complete to make reasonable recommendations for the velocity scaling of Teflon craters and penetrations. We suggest that cratering behavior and associated equations apply to all impacts in which the shock-pulse duration of the projectile is shorter than that of the target.
Keywords: computer systems design, software engineering, program verification, computer programs, computer systems performance, design analysis, reliability analysis
Abstract: This handbook documents the three software analysis processes the Space Station Software Analysis team uses to assess Space Station software, including their backgrounds, theories, tools, and analysis procedures. Potential applications of these analysis results are also presented. The first section describes how software complexity analysis provides quantitative information on code, such as code structure and risk areas, throughout the software life cycle. Software complexity analysis allows an analyst to understand the software structure; identify critical software components; assess risk areas within a software system; identify testing deficiencies; and recommend program improvements. Performing this type of analysis during the early design phases of software development can positively affect the process, and may prevent later, much larger, difficulties. The second section describes how software reliability estimation and prediction analysis, or software reliability, provides a quantitative means to measure the probability of failure-free operation of a computer program, and describes the two tools used by JSC to determine failure rates and design tradeoffs between reliability, costs, performance, and schedule.
Keywords: booster rocket engines, space shuttle boosters, launch vehicles, solid propellant rocket engines, recoverable launch vehicles, booster recovery
Abstract: The concept of a flyback booster has been around since early in the Shuttle program. The original two-stage Shuttle concepts used a manned flyback booster. These boosters were eliminated from the program for funding and size reasons. The current Shuttle uses two redesigned solid rocket motors (RSRMs), which are recovered and refurbished after each flight; this is one of the major cost factors of the program. Replacement options have been studied over the past ten years. The conclusion reached by the most recent study is that the liquid flyback booster (LFBB) is the only competitive option from a life-cycle cost perspective. The purpose of this study was to assess the feasibility and practicality of LFBBs. The study provides an expansion of the recommendations made during the aforementioned study. The primary benefits are the potential for enhanced reusability and a reduction of recurring costs. The potential savings in vehicle turnaround could offset the up-front costs. Development of LFBBs requires a commitment to the Shuttle program for 20 to 30 years. LFBBs also offer enhanced safety and abort capabilities. Currently, any failure of an RSRM can be considered catastrophic, since there are no intact abort capabilities during the burn of the RSRMs. The performance goal of the LFBBs was to lift a fully loaded Orbiter under optimal conditions, so as not to be the limiting factor of the performance capability of the Shuttle. In addition, a final benefit is the availability of growth paths for applications other than Shuttle. Participants included JSC, KSC, and MSFC. If it is determined that a more detailed study is warranted, a new study would be initiated to obtain baseline requirements, which would lead the way for detailed vehicle designs and a reference concept with bottoms-up cost.
Keywords: human performance, human factors engineering, habitability, SpaceHab-1
Abstract: SpaceHab-1 (STS-57) was the first of six scheduled Commercial Middeck Augmentation Module (CMAM) missions seeking to offer entrepreneurial companies an opportunity to use the resource of microgravity. The SpaceHab module, which occupies about one-fourth of the payload bay, is approximately 2-3/4 m long and 4 m diameter. It provides a shirtsleeve environment and contains the storage space equivalent of 50 middeck lockers. A modified Spacelab tunnel links the SpaceHab module to the middeck. While in orbit, the Orbiter payload bay doors remain open. The crew for SpaceHab-1 was comprised of four males and two females, each of whom participated in some part of the human factors assessment (HFA) evaluation. The HFA was one of over twenty experiments manifested on this maiden flight of the SpaceHab module. HFA consisted of HFA-EPROC, HFA-LIGHT, HFA-SOUND, HFA-QUEST, and HFA-TRANS. The goal of HFA-EPROC was to assess the advantages and disadvantages of paper versus computer presentation for procedural tasks. The second of two evaluations investigated the modules' lighting and acoustic environment. HFA-TRANS sought to evaluate the design of the SpaceHab tunnel and to characterize translation through it. HFA-QUEST represented a consolidation of the in-flight questions generated by the HFA principal investigators involved in the acoustic, lighting and translation studies.
Keywords: virtual reality; artificial intelligence; robotics
Abstract: The Fourth International Symposium on Measurement and Control in Robotics (ISMCR '94) Topical Workshop on Virtual Reality was organized to respond to the growing interest and importance of the niche area of virtual reality in the field of telerobotics and supervised autonomous robotics. The Symposium, organized by IMEKO Technical Committee 17, sponsored by the AIAA/IEEE/ISA, and hosted by the Clear Lake Council of Technical Societies and the NASA Johnson Space Center attempts to bring together a comprehensive international overview of the rapidly moving advanced technology which comprises the field of virtual reality. This focused Symposium deals with each of the critical technology areas in an integrated fashion, such that advances, problems and issues which cut across technologies can be viewed and evaluated from an integrated, common perspective. Papers in the areas of rendering, tracking sensors, displays, sensory feedback, and applications are included in the six sequential sessions of the Symposium. It is felt that this Symposium provides an important and timely indepth look at the interaction of these technologies as they apply to the applications of virtual reality to robotics.
Keywords: Lunar Exploration, Manned Mars Missions, Instrument Packages, Payloads
Abstract: This catalog collects and describes science payloads considered for future robotic and human exploration missions to the Moon and Mars. The science disciplines included are geosciences, meteorology, space physics, astronomy and astrophysics, life sciences, in-situ resource utilization, and robotic science. Science payload data is helpful for mission scientists and engineers developing reference architectures and detailed descriptions of mission organizations. One early step in advanced planning is formulating the science questions for each mission and identifying the instrumentation required to address these questions. The next critical element is to establish and quantify the supporting infrastructure required to deliver, emplace, operate, and maintain the science experiments with human crews or robots. This requires a comprehensive collection of up-to-date science payload information--hence the birth of this catalog. Divided into lunar and Mars sections, the catalog describes the physical characteristics of science instruments in terms of mass, volume, power and data requirements, mode of deployment and operation, maintenance needs, and technological readiness. It includes descriptions of science payloads for specific missions that have been studied in the last two years: the Scout Program, the Artemis Program, the First Lunar Outpost, and the Mars Exploration Program.
Keywords: robotics, robots, computers, computer programming, artificial intelligence
Abstract: The AIAA/NASA Conference on Intelligent Robotics in Field, Factory, Service, and Space (CIRFFSS '94) was originally proposed because of the strong belief that America's problems of global economic competitiveness and job creation and preservation can partly be solved by the use of intelligent robotics, which are also required for human space exploration missions. It was also recognized that there are a far greater set of common problems and solution approaches in field, factory, service, and space applications to be leveraged for time and cost savings than the differences in details would lead one to believe. This insight made a continuing series of conferences to share the details of the common problems and solutions across these different fields not only a natural step, but a necessary one. Further, it was recognized that a strong focusing effort is needed to move from recent factory-based technology into robotic systems with sufficient intelligence, reliability, safety, flexibility, and human/machine interoperability to meet the rigorous demands of these fields, the scope of which is beyond the capability of any one area. The papers in these proceedings are evidence that users in each field, manufacturers and integrators, and technology developers are rapidly increasing their understanding of integrating robotic systems on Earth and in space to accomplish economically important tasks requiring mobility and manipulation. The 21 sessions of technical papers in 7 tracks plus 2 plenary sessions cover just the tip of this major progress, but reveal its presence nonetheless.
Keywords: Weightlessness, Biodynamics, Orthostatic tolerance, Space flight stress, Cardiovascular system, Exercise physiology, Osteoporosis, Deconditioning
Abstract: Exercise countermeasures have been a part of long-duration space flight for both the U.S. and Russian programs. In this regard, the Exercise Countermeasures Project (ECP) sponsored a workshop entitled, "Countering Space Adaptation with Exercise: Current Issues." The workshop proceedings represent an update to the problems associated with living and working in space and the possible impact exercise would have on helping reduce risk. The meeting provided a forum for NASA scientists, engineers, and technicians to discuss and debate contemporary issues in exercise science and medicine as they relate to manned space flight with outside investigators. These outside investigators are experts who have performed investigations relating to exercise and its effect on the deconditioning process before, during, and after space flight or its analog. This meeting also afforded an opportunity to introduce the current status of the ECP science investigations and inflight hardware and software development. In addition, techniques for physiological monitoring and the development of various microgravity countermeasures were discussed. This document is a collection of the papers presented, abstracts submitted, and Socratic debates held at the NASA Johnson space Center.
Keywords: microwave, biotechnology, intelligent systems, software analysis, automation, bioinstrumentation, software engineering, advanced avionics and robotics
Abstract: This document contains papers presented at the Dual-Use Space Technology Transfer Conference and Exhibition held at the Johnson Space Center February 1-3, 1994. Possible technology transfers covered during the conference were in the areas of information access; innovative microwave and optical applications; materials and structures; marketing and barriers; intelligent systems; human factors and habitation; communications and data systems; business process and technology transfer; software engineering; biotechnology and advanced bioinstrumentation; communications signal processing and analysis; new ways of doing business; medical care; applications derived from control center data systems; human performance evaluation; technology transfer methods; mathematics, modeling, and simulation; propulsion; software analysis and decision tools; systems/processes in human support technology; networks, control centers, and distributed systems; power; rapid development; perception and vision technologies; integrated vehicle health management; automation technologies; advanced avionics; and robotics technologies. More than 77 papers, 20 presentations, and 20 exhibits covering various disciplines were presented by experts from NASA, universities, and industry.
Keywords: mass, orbital assembly, space logistics, space erectable structures, orbital servicing, weight (mass), maintenance, scheduling
Abstract: To prepare for Space Station Alpha's on-orbit assembly, maintenance, and resupply, NASA requires information about the crew members' ability to move heavy masses on orbit. Ease of movement in microgravity and orbiter stay time constraints may change the Space Station equipment and outfitting design requirements. Therefore, the time and effort required to perform a particuar task and how and where the forces and torque should be applied become critical in evaluating the design effort. Thus, the three main objectives of this investigation were to: 1) quantify variables such as force and torque as they relate to heavy mass handling techniques; 2) predict the time required to perform heavy mass handling tasks; and 3) note any differences between males and females in their ability to manipulate a heavy mass.
Keywords: Electric Batteries, Primary Batteries, Safety Factors, Handbooks
Abstract: This handbook provides engineers and safety personnel with guidelines for the safe design or selection and use of primary batteries in spaceflight programs. Types of primary batteries described are silver oxide zinc alkaline, carbon-zinc, zinc-air alkaline, manganese dioxide-zinc alkaline, mercuric oxide-zinc alkaline, and lithium anode cells. Along with typical applications, the discussions of the individual battery types include electrochemistry, construction, capacities and configurations, and appropriate safety measures. A chapter on general battery safety covers hazard sources and controls applicable to all battery types. Guidelines are given for qualification and acceptance testing that should precede space applications. Permissible failure levels for NASA applications are discussed.
Keywords: human factors engineering, protective clothing, gloves, manual control, astronaut performance, extravehicular activity
Abstract: One of the reasons for reduction in performance when gloves are donned is the lack of tactile sensitivity. It was argued that grasping force for a weight to be grasped will be a function of the weight to be lifted and the hand conditions. It was further reasoned that the differences in grasping force for various hand conditions will be a correlate of the tactile sensitivity of the corresponding hand conditions. The objective of this experiment, therefore, was to determine the effects of glove type, pressure, and weight of load on the initial grasping force and stable grasping force. It was hypothesized that when a person grasps an object, he/she grasps very firmly initially and then releases the grasp slightly after realizing what force is needed to maintain a steady grasp. This would seem to be particularly true when a person is wearing a glove and has lost some tactile sensitivity and force feedback during the grasp. Therefore, the ratio of initial force and stable force and the stable force itself would represent the amount of tactile adjustment that is made when picking up an object, and this adjustment should vary with the use of gloves. A dynamometer was fabricated to measure the grasping force; the tests were performed inside a glove box. Four female and four male subjects participated in the study, which measured with four variables: load effect, gender effect, glove type, and pressure variance. The only significant effects on the peak and stable force were caused by gender and the weight of the load lifted. Neither gloves nor pressure altered these forces when compared to a bare-handed condition, as was suspected before the test. It is possible that gloves facilitate in holding due to coefficient of friction while they deter in peak grasp strength.
Keywords: restraints, optimization, human factors engineering
Abstract: The zero-gravity environment creates a need for a proper human body restraint system to maintain a comfortable posture with less fatigue and to maximize productivity. In addition, restraint systems must be able to meet the loading demands of maintenance and assembly tasks performed on orbit. The Shuttle's primary intravehicular astronaut restraint system is currently a foot loop design that attaches to flat surfaces on the Shuttle, allowing for varying mounting locations and easy egress and ingress. However, this design does not allow for elevation, pitch, or foot loop length adjustment. Several prototype foot restraint systems are being evaluated for use aboard the Space Station and the Space Shuttle. The JSC Anthropometry and Biomechanics Laboratory initiated this study to quantify the maximum axial forces and moments that would be induced on a foot loop type of restraint while operators performed a torque wrench task, also allowing for angling the restraint pitch angle to study yet another effect. Results indicate that the greatest forces into the torque wrench and into the foot restraint system occur while the operator performs an upward effort. This study did not see any significant difference in the operators' force due to pitch orientation. Thus, in a work environment in which hand holds are available, no significant influence of the pitch angle on forces imparted to the restraint system existed.
Keywords: Carbon dioxide production, water vapor production, regenerable carbon dioxide removal system (RCRS)
Abstract: The current environmental control device in the Shuttle uses lithium hydroxide (LiOH) filter canisters to remove carbon dioxide (CO2) from the cabin air, requiring several bulky filter canisters that can only be used once and must be changed frequently. To alleviate a stowage problem and decrease launch weight, the Crew and Thermal Systems Division (CTSD) at the NASA Johnson Space Center has been researching a system to be used on future Shuttle missions. This system uses two beds of solid amine material to absorb CO2 and water, later desorbing them to space vacuum. In this way the air scrubbing medium is regenerable and reusable. To identify the efficacy of this regenerable CO2 removal system (RCRS), CTSD began investigations in the Shuttle mockup. The purpose of this investigation was to support the CTSD program by determining mean levels of carbon dioxide and water vapor production in normal, healthy males and females age-matched with the astronaut corps. Subjects' responses were measured at rest and during exercise at intensity levels equivalent to normal Shuttle operation activities. The results were used to assess the adjustments made to RCRS and are reported as a reference for future investigations in Shuttle environmental control.
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