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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Ground truth observations for TRMM

Plans to obtain ground truth data for the validation of the Tropical Rainfall Measuring Mission (TRMM) are examined. The experimental rainfall measuring techniques considered for the program are discussed, including optical and Doppler rain gages, satellite beacon attenuation, underwater hydrophones, profilers, microwave attenuation, multiple frequency/polarization radar, and scanning and airborne Doppler radar. The TRMM validation program is considered, noting observations to compare averaged TRMM rainfall data with similar ground truth data and to compare the rainfall and height distribution data from TRMM with instantaneous ground truth data.

Thiele, Otto W.↗
NASA NTRS1989

Neutral buoyancy methodology for studying satellite servicing EVA crewmember interfaces

Current economic constraints indicate the need for incorporating the satellite servicing philosophy of commonality within the design of spacecraft subsytems. This philosophy is essential for conserving resources including hardware/software development and implementation costs, on-orbit and ground-based manpower, crew training/testing time, and documentation. In addition, spacecraft subsystem commonality may be coupled with standardization of operation procedures, and test and verification techniques for spacecraft design. Several spacecraft have adopted this practice, including Hubble Space Telescope, Space Station Freedom, and the Explorer Platform. As these and other programs continue and if effective crew interfaces and procedures are clearly and consistently defined, crew retraining for similar spacecraft subsystems will lessen, and procurement efforts will diminish. A relatively high fidelity zero-gravity simulation using water immersion is available to establish crew interfaces economically. The flexibility and utility of this space simulation medium for planning and assisting on-orbit operations was exemplified by astronaut evaluations of potential EVA electrical connectors. The testing was conducted at a NASA underwater neutral buoyancy training facility.

Barnby, Mary E.↗
NASA NTRS1991

Anthropomorphic Robot Hand And Teaching Glove

Robotic forearm-and-hand assembly manipulates objects by performing wrist and hand motions with nearly human grasping ability and dexterity. Imitates hand motions of human operator who controls robot in real time by programming via exoskeletal "teaching glove". Telemanipulator systems based on this robotic-hand concept useful where humanlike dexterity required. Underwater, high-radiation, vacuum, hot, cold, toxic, or inhospitable environments potential application sites. Particularly suited to assisting astronauts on space station in safely executing unexpected tasks requiring greater dexterity than standard gripper.

Engler, Charles D., Jr.↗
NASA NTRS1991

Testbed For Telerobotic Servicing

Telerobot testbed used to evaluate technologies for remote servicing, including assembly, maintenance, and repair. Enables study of advantages and disadvantages of modes and problems encountered in implementing them. Best technologies for implementing modes chosen. Provides delays simulating transmission delays between control stations on ground and orbiting spacecraft. Includes five major equipment subsystems, each consisting of such commercially available equipment as video cameras, computers, and robot arms. Used on Space Station and on Space Shuttle and satellites in orbit. Also used in hazardous and underwater environments on Earth.

Matijevic, Jacob R.↗
NASA NTRS1991

Bidirectional Drive-And-Brake Mechanism

Vehicle that crawls along monorail combines features of both bicycle and railroad handcar. Bidirectional drive-and-brake mechanism includes selectable-pawl-and-ratchet overrunning clutch (drive mechanism) and mating stationary and rotating conical surfaces pressing against each other (brake mechanism). Operates similarly to bicycle drive-and-brake mechanism except limits rotation of sprocket in both directions and brakes at both limits. Conceived for use by astronaut traveling along structure in outer space, concept also applied on Earth to make very small railraod handcars or crawling vehicles for use on large structures, in pipelines under construction, or underwater.

Swan, Scott A.↗
NASA NTRS1991

Polarimetric radar for assessing subsurface characteristics

The potential of using the NASA airborne polarimetric radar system to assess the subsurface characteristics of the Rogers lake bed and the Atchadafaya Basin study sites is described. Preliminary analysis of acquired data indicated that VV polarization is capable of muddy water penetration and that the radar system could be used to assess underwater sediment distribution. Statistical analysis of the data will provide insight on the depth of muddy water penetration.

Wu, Shih-Tseng↗
NASA NTRS1991

High energy efficiency and high power density proton exchange membrane fuel cells: Electrode kinetics and mass transport

The development of proton exchange membrane (PEM) fuel cell power plants with high energy efficiencies and high power densities is gaining momentum because of the vital need of such high levels of performance for extraterrestrial (space, underwater) and terrestrial (power source for electric vehicles) applications. Since 1987, considerable progress has been made in achieving energy efficiencies of about 60 percent at a current density of 200 mA/sq cm and high power densities (greater than 1 W/sq cm) in PEM fuel cells with high (4 mg/sq cm) or low (0.4 mg/sq cm) platinum loadings in electrodes. The following areas are discussed: (1) methods to obtain these high levels of performance with low Pt loading electrodes - by proton conductor impregnation into electrodes, localization of Pt near front surface; (2) a novel microelectrode technique which yields electrode kinetic parameters for oxygen reduction and mass transport parameters; (3) demonstration of lack of water transport from anode to cathode; (4) modeling analysis of PEM fuel cell for comparison with experimental results and predicting further improvements in performance; and (5) recommendations of needed research and development for achieving the above goals.

Supramaniam Srinivasan↗
NASA NTRS1991

Maintaining Hubble Space Telescope performance through in-orbit servicing

The HST system design is described as well as the in-orbit servicing program. In order to verify the feasibility and the design of the HST servicing features, a design verification program, which included 1-g tests and 0-g underwater simulations, was carried out. The major elements of the space support equipment, including the flight support system, the orbital replacement unit carrier, and the solar array carrier, are addressed in detail.

Cuviello, Michael J.↗
NASA NTRS1991

Design and fabrication of an aerobrake mock-up

The paper reports on the design and fabrication of a Mars aerobrake mockup that has been used in a series of underwater neutral buoyancy tests designed to address this on-orbit assembly issue. Particular attention is given to the aerobrake shell, truss components, and fastener issues. It is noted that soft docking alignment fasteners, fasteners between petals, and fasteners to connect the petal-to-petal truss members are all needed for this mockup.

Lee, Gordon K. F.↗
NASA NTRS1990

Terrain interaction with the quarter scale beam walker

Frame walkers are a class of mobile robots that are robust and capable mobility platforms. Variations of the frame walker robot are in commercial use today. Komatsu Ltd. of Japan developed the Remotely Controlled Underwater Surveyor (ReCUS) and Normed Shipyards of France developed the Marine Robot (RM3). Both applications of the frame walker concept satisfied robotic mobility requirements that could not be met by a wheeled or tracked design. One vehicle design concept that falls within this class of mobile robots is the walking beam. A one-quarter scale prototype of the walking beam was built by Martin Marietta to evaluate the potential merits of utilizing the vehicle as a planetary rover. The initial phase of prototype rover testing was structured to evaluate the mobility performance aspects of the vehicle. Performance parameters such as vehicle power, speed, and attitude control were evaluated as a function of the environment in which the prototype vehicle was tested. Subsequent testing phases will address the integrated performance of the vehicle and a local navigation system.

Chun, Wendell H.↗
NASA NTRS1992

Moving And Working On Space Structures

Clawlike device attaches boots to rails. Memorandum presents, in sketches and brief text, concept for boot-toe clip helping astronaut move about outside on structures being built at Space Station. Clip also helps astronaut maintain stable position at worksite. Concept adaptable to underwater work on such structures as offshore oil rigs.

Mclaughlin, Pat B.↗
NASA NTRS1992

Fixed Or Controlled-Movement Foot Restraint

Foot restraint gives user three options: holds user's feet in fixed position, allows them to slide sideways, or allows them to pivot independently about axis through ball of foot, as user chooses. Selects degree of restraint to suit task at hand. Movements to enter and leave foot restraint simple and direct. Simply forces each cleat lightly into space between rails until spring force of movable rail secures it. Body movements for sliding and rotation equally straightforward. Designed for use in absence of gravitation, restraint useful on Earth, underwater or in some hazardous locations where movements restricted.

Reilly, Gloria B.↗
NASA NTRS1990

27th JANNAF Combustion Subcommittee Meeting

This volume, the third of four, is a collection of 49 papers which were presented at the conference. Specific subjects discussed include advanced propellants, ramjets, liquid and solid rocket performance, and underwater propulsion.

Gannaway, Mary T.↗
NASA NTRS1991

A method of evaluating efficiency during space-suited work in a neutral buoyancy environment

The purpose was to investigate efficiency as related to the work transmission and the metabolic cost of various extravehicular activity (EVA) tasks during simulated microgravity (whole body water immersion) using three space suits. Two new prototype space station suits, AX-5 and MKIII, are pressurized at 57.2 kPa and were tested concurrently with the operationally used 29.6 kPa shuttle suit. Four male astronauts were asked to perform a fatigue trial on four upper extremity exercises during which metabolic rate and work output were measured and efficiency was calculated in each suit. The activities were selected to simulate actual EVA tasks. The test article was an underwater dynamometry system to which the astronauts were secured by foot restraints. All metabolic data was acquired, calculated, and stored using a computerized indirect calorimetry system connected to the suit ventilation/gas supply control console. During the efficiency testing, steady state metabolic rate could be evaluated as well as work transmitted to the dynamometer. Mechanical efficiency could then be calculated for each astronaut in each suit performing each movement.

Greenisen, Michael C.↗
NASA NTRS1991

Dynamic inter-limb resistance exercise device for long-duration space flight

Essential for fitness on Earth, resistive exercise is even more important for astronauts, who must maintain muscle and bone strength in the absence of gravity. To meet this need, designers and scientists at NASA Ames Research Center, Life Science Division, have worked to develop more effective exercise devices for long-duration exposure to microgravity. One of these concepts is the Inter-Limb Resistance Device which allows the subject to exercise one limb directly against another, strengthening muscle groups in the arms, legs, and back. It features a modular harness with an inelastic cable and instrumented pulley. Forces similar to other high resistance exercise equipment are generated. Sensors in the pulley measure force and velocity for performance feedback display and data acquisition. This free-floating apparatus avoids vibration of sensitive experiments on board spacecraft. Compact with low mass, this hardware is also well suited for a 'safe haven' from radiation on board Space Station Freedom, and may prove useful in confined environments on Earth, such as Antarctic stations, submarines, and other underwater habitats. Potential spin-offs of this technology include products for personal strengthening and cardiovascular conditioning, rehabilitation of hospital patients, fitness exercise for the disabled, and retraining after sports injuries.

Schwandt, Douglas F.↗
NASA NTRS1991

Neutral Buoyancy Portable Life Support System performance study

The Neutral Buoyancy Portable Life Support System (NBPSS) has been designed to support astronaut underwater training activities associated with EVA operations. The performance of competing NBPSS configurations has been analyzed on the basis of a modified 'Metabolic Man' program. NBPSS success is dependent on the development of novel cryogen supply tank and liquid-cooling garment vaporizer. Attention is given to mass and thermal balances and the evaluation results for the vent-loop ejector and heat-exchanger designs.

Chang, Chi-Min↗
NASA NTRS1992

Mars aerobrake assembly simulation

On-orbit assembly operation simulations in neutral buoyancy conditions are presently undertaken by a partial/full-scale Mars mission aerobrake mockup, whose design, conducted in the framework of an engineering senior students' design project, involved several levels of constraints for critical physical and operational features. Allowances had to be made for the auxiliary constraints introduced by underwater testing, as well as the subsegmenting required for overland shipment to the neutral-buoyancy testing facility. This mockup aerobrake's fidelity is determined by the numerous, competing design objectives.

Filatovs, G. J.↗