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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Advanced extravehicular activity systems requirements definition study

A study to define the requirements for advanced extravehicular activities (AEVA) was conducted. The purpose of the study was to develop an understanding of the EVA technology requirements and to map a pathway from existing or developing technologies to an AEVA system capable of supporting long-duration missions on the lunar surface. The parameters of an AEVA system which must sustain the crewmembers and permit productive work for long periods in the lunar environment were examined. A design reference mission (DRM) was formulated and used as a tool to develop and analyze the EVA systems technology aspects. Many operational and infrastructure design issues which have a significant influence on the EVA system are identified.

Source record↗
NASA NTRS1988

Testing expert systems

Software quality is of primary concern in all large-scale expert system development efforts. Building appropriate validation and test tools for ensuring software reliability of expert systems is therefore required. The Expert Systems Validation Associate (EVA) is a validation system under development at the Lockheed Artificial Intelligence Center. EVA provides a wide range of validation and test tools to check correctness, consistency, and completeness of an expert system. Testing a major function of EVA. It means executing an expert system with test cases with the intent of finding errors. In this paper, we describe many different types of testing such as function-based testing, structure-based testing, and data-based testing. We describe how appropriate test cases may be selected in order to perform good and thorough testing of an expert system.

Chang, C. L.↗
NASA NTRS1988

Measurement of metabolic responses to an orbital-extravehicular work-simulation exercise

This paper describes a new system designed to simulate orbital EVA work and measure metabolic responses to these space-work exercises. The system incorporates an experimental protocol, a controlled-atmosphere chamber, an EVA-work exercise device, the instrumentation, and a data acquisition system. Engineering issues associated with the design of the proposed system are discussed. This EVA-work simulating system can be used with various types of upper-body work, including task boards, rope pulling, and arm ergometry. Design diagrams and diagrams of various types of work simulation are included.

Lantz, Renee↗
NASA NTRS1988

Space truss construction studies

The ACCESS Shuttle Flight Experiment, designed to evaluate EVA for on-orbit assembly of erectable truss structure, is reviewed and principal results are summarized. In addition, two on-going ground test programs that address EVA assembly of full scale Space Station truss structure using a mobile transporter are described. A typical truss joint design that enables EVA assembly while satisfying structural requirements is also presented. Preliminary results indicate that assembly rates in excess of one strut/min are achievable.

Heard, Walter L.↗
NASA NTRS1989

Eyes open versus eyes closed - Effect on human rotational responses

The effect of eyelid closure on the response to rotational vestibular stimulation was assessed by evaluating 16 normal human subjects with both earth vertical axis (EVA) and earth horizontal axis (EHA) yaw rotations with either eyes closed (EC) or eyes open in the dark (EOD). Results indicated that for EVA rotation, the subjects' responses were of larger magnitude and less variable with EOD than with EC. However, for EHA rotation, responses were of larger magnitude and equally variable with EC as compared to EOD. Data also indicated that the quality of the EHA response with EC was altered because eyelid closure influenced the amount of periodic gaze. It is concluded that eyelid closure has an effect upon both canalocular and otolithocular reflexes and it is suggested that both EVA and EHA rotational testing be performed with EOD rather than with EC.

Wall, Conrad, III↗
NASA NTRS1990

Development of a regenerable metal oxide CO removal system

A regenerable metal oxide carbon dioxide (CO2) removal system was developed to replace the current means of a nonreusable chemical, lithium hydroxide, for removing the metabolic CO2 of an astronaut in a space suit. Testing indicates that a viable low-volume metal oxide concept can be used in the portable life support system for CO2 removal during Space Station extravehicular activity (EVA). A canister of nearly the same volume as that used for the Space Shuttle, containing 0.10 cu ft of silver-oxide-based pellets, was tested; test data analysis indicates that 0.18 cu ft of the metal oxide will result in an 8-hour EVA capability. The testing suggests that the metal oxide technology offers a low-volume approach for a reusable CO2 removal concept applicable for at least 40 EVA missions. The development and testing of the breadboard regeneration package is also described.

Cusick, Robert J.↗
NASA NTRS1990

The design and development of the Hubble space telescope neutral buoyancy trainer

The design and fabrication of Hubble Space Telescope (HST) Extra Vehicular Activity (EVA) training hardware for zero-gravity simulations in the Marshall Space Flight Center Neutral Buoyancy Simulator (NBS) are discussed. The HST NBS hardware was also used to support flight hardware development and development of EVA crew servicing procedures. The design and fabrication of simulator training and development hardware, the associated test support from utility divers, test conductors, and test subjects have all been with the common goal of enabling HST program management to use NBS EVA data to make design and program decisions.

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NASA NTRS1991

Ground controlled robotic assembly operations for Space Station Freedom

A number of dextrous robotic systems and associated positioning and transportation devices are available on Space Station Freedom (SSF) to perform assembly tasks that would otherwise need to be performed by extravehicular activity (EVA) crewmembers. The currently planned operating mode for these robotic systems during the assembly phase is teleoperation by intravehicular activity (IVA) crewmembers. While this operating mode is less hazardous and expensive than manned EVA operations, and has insignificant control loop time delays, the amount of IVA time available to support telerobotic operations is much less than the anticipated requirements. Some alternative is needed to allow the robotic systems to perform useful tasks without exhausting the available IVA resources; ground control is one such alternative. The issues associated with ground control of SSF robotic systems to alleviate onboard crew time availability constraints are investigated. Key technical issues include the effect of communication time delays, the need for safe, reliable execution of remote operations, and required modifications to the SSF ground and flight system architecture. Time delay compensation techniques such as predictive displays and world model-based force reflection are addressed and collision detection and avoidance strategies to ensure the safety of the on-orbit crew, Orbiter, and SSF are described. Although more time consuming and difficult than IVA controlled teleoperations or manned EVA, ground controlled telerobotic operations offer significant benefits during the SSF assembly phase, and should be considered in assembly planning activities.

Parrish, Joseph C.↗
NASA NTRS1991

Pre-integrated structures for Space Station Freedom

An in-space construction (erectable) approach to assembling Freedom is planned but the increasing complexity of the station design along with a decrease in shuttle capability over the past several years has led to an assembly sequence that requires more resources (EVA, lift, volume) than the shuttle can provide given a fixed number of flights. One way to address these issues is to adopt a pre-integrated approach to assembling Freedom. A pre-integrated approach combines station primary structure and distributed systems into discrete sections that are assembled and checked out on the ground. The section is then launched as a single structural entity on the shuttle and attached to the orbiting station is then launched as a single structural entity on the shuttle and attached to the orbiting station with a minimum of EVA. The feasibility of a pre-integrated approach to assembling Freedon is discussed. The structural configuration, packaging, and shuttle integration of discrete pre-integrated elements for Freedom assembly are discussed. It is shown that the pre-integrated approach to assembly reduces EVA and increases shuttle margin with respect to mass, volume, and center of gravity limits when compared to the baseline Freedom assembly sequence.

Cruz, Jonathan N.↗
NASA NTRS1990

EVA/ORU model architecture using RAMCOST

A parametrically driven simulation model is presented in order to provide a detailed insight into the effects of various input parameters in the life testing of a modular space suit. The RAMCOST model employed is a user-oriented simulation model for studying the life-cycle costs of designs under conditions of uncertainty. The results obtained from the EVA simulated model are used to assess various mission life testing parameters such as the number of joint motions per EVA cycle time, part availability, and number of inspection requirements. RAMCOST first simulates EVA completion for NASA application using a probabilistic like PERT network. With the mission time heuristically determined, RAMCOST then models different orbital replacement unit policies with special application to the astronaut's space suit functional designs.

Ntuen, Celestine A.↗
NASA NTRS1990

Long term life support for space exploration

A general strategy for the development of life-support systems is discussed in terms of present and future requirements for NASA exploration missions. A general life-support strategy is delineated for both intravehicular activity (IVA) and extravehicular activity (EVA) for lunar and Mars transfer vehicles, Mars habitats, and pressurized rovers. The baseline capability presented corresponds to the systems needs for the Space Station Freedom permanently manned capability and the Shuttle Extended Duration Orbiter. Design guidelines and system design goals are given for IVA life support with an emphasis on closed-loop systems, and the design prerogatives for EVA include a minimum time to transition between IVA and EVA, and minimum resitriction for human activity.

Rummel, John D.↗
NASA NTRS1992

Engineering design constraints of the lunar surface environment

Living and working on the lunar surface will be difficult. Design of habitats, machines, tools, and operational scenarios in order to allow maximum flexibility in human activity will require paying attention to certain constraints imposed by conditions at the surface and the characteristics of lunar material. Primary design drivers for habitat, crew health and safety, and crew equipment are: ionizing radiation, the meteoroid flux, and the thermal environment. Secondary constraints for engineering derive from: the physical and chemical properties of lunar surface materials, rock distributions and regolith thicknesses, topography, electromagnetic properties, and seismicity. Protection from ionizing radiation is essential for crew health and safety. The total dose acquired by a crew member will be the sum of the dose acquired during EVA time (when shielding will be least) plus the dose acquired during time spent in the habitat (when shielding will be maximum). Minimizing the dose acquired in the habitat extends the time allowable for EVA's before a dose limit is reached. Habitat shielding is enabling, and higher precision in predicting secondary fluxes produced in shielding material would be desirable. Means for minimizing dose during a solar flare event while on extended EVA will be essential. Early warning of the onset of flare activity (at least a half-hour is feasible) will dictate the time available to take mitigating steps. Warning capability affects design of rovers (or rover tools) and site layout. Uncertainty in solar flare timing is a design constraint that points to the need for quickly accessible or constructible safe havens.

Morrison, D. A.↗
NASA NTRS1992

Metabolic responses to simulated extravehicular activity

Automatic control of the liquid cooling garment (LCG) worn by astronauts during extravehicular activity (EVA) would more efficiently regulate astronaut thermal comfort and improve astronaut productivity. An experiment was conducted in which subjects performed exercise profiles on a unique, supine upper body ergometer to elicit physiological and thermal responses similar to those achieved during zero-g EVAs. Results were analyzed to quantify metabolic rate, various body temperatures, and other heat balance parameters. Such data may lead to development of a microprocessor-based system to automatically maintain astronaut heat balance during extended EVAs.

Williamson, Rebecca C.↗
NASA NTRS1993

Loads produced by a suited subject performing tool tasks without the use of foot restraints

With an increase in the frequency of extravehicular activities (EVA's) aboard the Space Shuttle, NASA is interested in determining the capabilities of suited astronauts while performing manual tasks during an EVA, in particular the situations in which portable foot restraints are not used to stabilize the astronauts. Efforts were made to document the forces that are transmitted to spacecraft while pushing and pulling an object as well as while operating a standard wrench and an automatic power tool. The six subjects studied aboard the KC-135 reduced gravity aircraft were asked to exert a maximum torque and to maintain a constant level of torque with a wrench, to push and pull an EVA handrail, and to operate a Hubble Space Telescope (HST) power tool. The results give an estimate of the forces and moments that an operator will transmit to the handrail as well as to the supporting structure. In general, it was more effective to use the tool inwardly toward the body rather than away from the body. There were no differences in terms of strength capabilities between right and left hands. The power tool was difficult to use. It is suggested that ergonomic redesigning of the power tool may increase the efficiency of power tool use.

Rajulu, Sudhakar L.↗
NASA NTRS1994

Task network models in the prediction of workload imposed by extravehicular activities during the Hubble Space Telescope servicing mission

In a joint effort with Brooks AFB, Texas, the Flight Crew Support Division at JSC has begun a computer simulation and performance modeling program directed at establishing the predictive validity of software tools for modeling human performance during spaceflight. This paper addresses the utility of task network modeling for predicting the workload that astronauts are likely to encounter in extravehicular activities (EVA) during the Hubble Space Telescope (HST) repair mission. The intent of the study was to determine whether two EVA crewmembers and one intravehicular activity (IVA) crewmember could reasonably be expected to complete HST Wide Field/Planetary Camera (WFPC) replacement in the allotted time. Ultimately, examination of the points during HST servicing that may result in excessive workload will lead to recommendations to the HST Flight Systems and Servicing Project concerning (1) expectation of degraded performance, (2) the need to change task allocation across crewmembers, (3) the need to expand the timeline, and (4) the need to increase the number of EVA's.

Diaz, Manuel F.↗
NASA NTRS1994

An overview of Space Shuttle anthropometry and biomechanics research with emphasis on STS/Mir recumbent seat system design

The Anthropometry and Biomechanics Laboratory (ABL) at JSC conducts multi-disciplinary research focusing on maximizing astronaut intravehicular (IVA) and extravehicular (EVA) capabilities to provide the most effective work conditions for manned space flight and exploration missions. Biomechanics involves the measurement and modeling of the strength characteristics of the human body. Current research for the Space Shuttle Program includes the measurement of torque wrench capability during weightlessness, optimization of foot restraint, and hand hold placement, measurements of the strength and dexterity of the pressure gloved hand to improve glove design, quantification of the ability to move and manipulate heavy masses (6672 N or 1500 lb) in weightlessness, and verification of the capability of EVA crewmembers to perform Hubble Space Telescope repair tasks. Anthropometry is the measurement and modeling of the dimensions of the human body. Current research for the Space Shuttle Program includes the measurement of 14 anthropometric parameters of every astronaut candidate, identification of EVA finger entrapment hazards by measuring the dimensions of the gloved hand, definition of flight deck reach envelopes during launch and landing accelerations, and measurement of anthropometric design parameters for the recumbent seat system required for the Shuttle/Mir mission (STS-71, Spacelab M) scheduled for Jun. 1995.

Klute, Glenn K.↗
NASA NTRS1994

The SCRAM tool-kit

This paper proposes a new series of on-orbit capabilities to support the near-term Hubble Space Telescope, Extended Duration Orbiter, Long Duration Orbiter, Space Station Freedom, other orbital platforms, and even the future manned Lunar/Mars missions. These proposed capabilities form a toolkit termed Space Construction, Repair, and Maintenance (SCRAM). SCRAM addresses both intra-Vehicular Activity (IVA) and Extra-Vehicular Activity (EVA) needs. SCRAM provides a variety of tools which enable welding, brazing, cutting, coating, heating, and cleaning, as well as corresponding nondestructive examination. Near-term IVA-SCRAM applications include repair and modification to fluid lines, structure, and laboratory equipment inside a shirt-sleeve environment (i.e. inside Spacelab or Space Station). Near-term EVA-SCRAM applications include construction of fluid lines and structural members, repair of punctures by orbital debris, refurbishment of surfaces eroded by contaminants. The SCRAM tool-kit also promises future EVA applications involving mass production tasks automated by robotics and artificial intelligence, for construction of large truss, aerobrake, and nuclear reactor shadow shields structures. The leading candidate tool processes for SCRAM, currently undergoing research and development, include Electron Beam, Gas Tungsten Arc, Plasma Arc, and Laser Beam. A series of strategic space flight experiments would make SCRAM available to help conquer the space frontier.

Tamir, David↗
NASA NTRS1993

A unique exercise facility for simulating orbital extravehicular activity

A unique exercise facility has been developed and used to simulate orbital extravehicular activity (EVA). The device incorporates an arm ergometer into a mechanism which places the subject in the zero-g neutral body posture. The intent of this configuration is to elicit muscular, cardiovascular, respiratory, and thermoregulatory responses similar to those observed during orbital EVA. Experiments done with this facility will help characterize the astronaut's dynamic heat balance during EVA and will eventually lead to the development of an automated thermal control system which would more effectively maintain thermal comfort.

Williamson, Rebecca C.↗