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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Bayesian recursive image estimation.

A procedure for recursively estimating images that are characterized statistically by the mean and correlation functions associated with the random process representing the brightness level is proposed for the case where the images are corrupted by additive noise. First, a dynamic model is developed with a response characteristic which matches that of the scanner output (the input of the estimator is the output of a horizontal line scanner) in a statistical sense. Such models have the form of an ordinary differential or difference equation with white noise input. An insignificant approximation is introduced by using a constant-coefficient model. The appropriate model is a vector valued difference equation with the solution representing a vector Markov process. The next step is to obtain the minimum mean square estimate of the image by using a Kalman filter. Since the image estimation is an interpolation problem, two successive runs over the observation are performed in opposite directions and the resultant estimates are averaged. Examples are included for illustration.

Nahi, N. E.↗
NASA NTRS1971

The Apollo Lunar Roving Vehicle.

After listing the basic requirements such as operational demands and lunar environmental conditions, characteristic design data of the roving vehicle are given with special attention to the four wheel drive and its control system, the steering system, and the navigational instrumentation. The overall system is optimized in view of total mass, range, mobility, load carrying capability, safety, highest reliability through redundancy, and last but not least, cost and development time. Optimization of the drive and power system has first been evaluated by mathematical models and computational simulation of the vehicle hardware, the wheel/soil interaction, and the lunar terrain profile. The next step to refine optimization and evaluation of the drive, steering, and power system including man/machine interaction has been carried out by the use of a six-degree-of-freedom simulator subjecting the astronauts in their space suits to simulated vehicle motions while driving over a simulated terrain, observable on a cathode ray tube display.

Haeussermann, W.↗
NASA NTRS1973

Research and applications modules /RAM/ - A family of payload carriers.

RAM is a family of payload carriers, pressurized, unpressurized and pressurizable, that operate in conjunction with the Space Shuttle and associated space systems to provide modular facilities to conduct manned or man-tended research in low earth orbit. RAM family elements are discussed as the next step in evolution from the Sortie Laboratory required to provide a significant increase in experimental capability, flexibility, and economy necessary to meet the needs of an expanding program of research and applications activities. Examples of RAM missions and operations as sortie mission laboratories and observatories, and free-flying man-tended observatories are illustrated.

Withee, W. W.↗
NASA NTRS1975

Advanced computer technology - An aspect of the Terminal Configured Vehicle program

NASA is conducting a Terminal Configured Vehicle program to provide improvements in the air transportation system such as increased system capacity and productivity, increased all-weather reliability, and reduced noise. A typical jet transport has been equipped with highly flexible digital display and automatic control equipment to study operational techniques for conventional takeoff and landing aircraft. The present airborne computer capability of this aircraft employs a multiple computer simple redundancy concept. The next step is to proceed from this concept to a reconfigurable computer system which can degrade gracefully in the event of a failure, adjust critical computations to remaining capacity, and reorder itself, in the case of transients, to the highest order of redundancy and reliability.

Berkstresser, B. K.↗
NASA NTRS1976

Preentry communications study. Outer planets atmospheric entry probe

A pre-entry communications study is presented for a relay link between a Jupiter entry probe and a spacecraft in hyperbolic orbit. Two generic communications links of interest are described: a pre-entry link to a spun spacecraft antenna, and a pre-entry link to a despun spacecraft antenna. The propagation environment of Jupiter is defined. Although this is one of the least well known features of Jupiter, enough information exists to reasonably establish bounds on the performance of a communications link. Within these bounds, optimal carrier frequencies are defined. The next step is to identify optimal relative geometries between the probe and the spacecraft. Optimal trajectories are established for both spun and despun spacecraft antennas. Given the optimal carrier frequencies, and the optimal trajectories, the data carrying capacities of the pre-entry links are defined. The impact of incorporating pre-entry communications into a basic post entry probe is then assessed. This assessment covers the disciplines of thermal control, power source, mass properties and design layout. A conceptual design is developed of an electronically despun antenna for use on a Pioneer class of spacecraft.

Hinrichs, C. A.↗
NASA NTRS1978

Critical fault patterns determination in fault-tolerant computer systems

The method proposed tries to enumerate all the critical fault-patterns (successive occurrences of failures) without analyzing every single possible fault. The conditions for the system to be operating in a given mode can be expressed in terms of the static states. Thus, one can find all the system states that correspond to a given critical mode of operation. The next step consists in analyzing the fault-detection mechanisms, the diagnosis algorithm and the process of switch control. From them, one can find all the possible system configurations that can result from a failure occurrence. Thus, one can list all the characteristics, with respect to detection, diagnosis, and switch control, that failures must have to constitute critical fault-patterns. Such an enumeration of the critical fault-patterns can be directly used to evaluate the overall system tolerance to failures. Present research is focused on how to efficiently make use of these system-level characteristics to enumerate all the failures that verify these characteristics.

Mccluskey, E. J.↗
NASA NTRS1978

Free as a bird - A point of view

A number of ways are discussed in which ingenious people can further increase their enjoyment of experimenting in air (balloons, man-powered flight, etc.). For the lowest cost forms of flight, private sponsorship has been modestly successful. Much more could be done if people would not take themselves so seriously and always demand that advanced technology should serve some nationalistic or economic goals. For the society, the next step forward will perhaps originate if it is demonstrated to the government, manufacturers, and customers that private flying has become too costly due to those factors which limit the acquisition and introduction of new knowledge.

Burke, J. D.↗
NASA NTRS1979

Properties and performance of fine-filament bronze-process Nb3Sn conductors

Fine-filament bronze-process Nb3Sn superconductors were fabricated to fulfill stringent requirements on critical current under tension in a one-inch bend diameter, current density, stability, and conductor losses. A large fraction of niobium filaments was incorporated in a bronze matrix, and a cable containing 4453 2-micron diameter filaments in each of six strands provided a current density of 85,000 A/sq cm at 10 to the -11th ohm-cm, 10 T, and 4.2 K. The next step was to incorporate copper stabilizer in a conductor with 20,538 filaments. These conductors, fabricated so that bend strains of about 1% would be experienced by the filaments in the one-inch bend, stably carried currents in the 200-500 A range. A quench current of 540 A in a 5-cm bend corresponds to 158,000 A/sq cm in the bronze and filament area, believed to be the highest critical current density reported for multifilamentary Nb3Sn.

Walker, M. S.↗
NASA NTRS1979

Computer aided control of a mechanical arm

A method for computer-aided remote control of a six-degree-of-freedom manipulator arm involved in the on-orbit servicing of a spacecraft is presented. The control configuration features a supervisory type of control in which each of the segments of a module exchange trajectory is controlled automatically under human supervision, with manual commands to proceed to the next step and in the event of a failure or undesirable outcome. The implementation of the supervisory system is discussed in terms of necessary onboard and ground- or Orbiter-based hardware and software, and a one-g demonstration system built to allow further investigation of system operation is described. Possible applications of the system include the construction of satellite solar power systems, environmental testing and the control of heliostat solar power stations.

Derocher, W. L., Jr.↗
NASA NTRS1979

The interaction between giant gaseous protoplanets and the primitive solar nebula

The manner in which a giant gaseous protoplanet becomes embedded in the primitive solar nebula determines surface boundary conditions which must be used in studying the evolution of such objects. On the one hand, if the system resembles a contact binary system, then the envelope of the protoplanet should approach the entropy of the surrounding nebula. On the other hand angular momentum transfer by resonance and tidal effects between the nebula and the protoplanet may cause the nebula to exhibit a zone of avoidance near the protoplanet, thus inhibiting exchange of material. This problem has been studied with a computer program developed by D. N. C. Lin which simulates disk hydrodynamics by particle motions with dissipation. These studies suggest that for expected values of the protoplanet/protosun mass ratios, significant inhibition of mass exchange is likely, so that it is a reasonable next step to undertake protoplanet evolution studies with the imposition of minimum protoplanet surface temperatures.

Cameron, A. G. W.↗
NASA NTRS1982

Walking-Beam Solar-Cell Conveyor

Microprocessor-controlled walking-beam conveyor moves cells between work stations in automated assembly line. Conveyor has arm at each work station. In unison arms pick up all solar cells and advance them one station; then beam retracks to be in position for next step. Microprocessor sets beam stroke, speed, and position.

Feder, H.↗
NASA NTRS1981

Galileo - Mission to Jupiter

The Galileo mission to Jupiter in the latter half of this decade is NASA's next step in the exploration of Jupiter. The primary science objectives are to study the satellites, the magnetosphere, and Jupiter's atmosphere. In general, there are four characteristics of the Galileo mission which provide the capability to address questions not answered by Voyager: (1) long-term observations - at least 11 orbits of Jupiter in nearly two years - will allow temporal studies of Io vulcanism as well as of interactions between the satellites and magnetosphere; (2) very close satellite flybys - at a distance less than 1000 km at each Galilean satellite - will allow in-depth studies of these satellites at distances 20 to 100 times closer than Voyager achieved; (3) an atmospheric entry probe will measure composition, structure, temperature, energy balance, cloud layer locations and structure, and particle size distribution in Jupiter's atmosphere; and (4) the Orbiter's advanced instrumentation will allow higher resolution and more detailed studies of the satellites, atmosphere, and magnetosphere

Casani, J. R.↗
NASA NTRS1982

Geographic science team

The rational for using remote sensing in land use/land cover, geomorphology, and cartography applications is stated as well as potential uses in each of these areas. The next step to be perfected is indicated. Spatial and spectral resolution requirements for photointerpretations and/or multispectral pattern recognition of geomorphic elements and of cultural surface cover are listed. Requirements for photographic/analog or digital photogrammetry from spaceborne multispectral linear array sensors are included. A prioritized summary of data gaps in the geographic sciences is included.

Bryant, N.↗
NASA NTRS1983

An alternate concept for expanding man's presence in space

A logical next step after shuttle is a manned orbital service system (MOSS) consisting of a two-man crew module mated with a propulsion module. The resulting spacecraft would remain in low Earth orbit for months or years at a time conducting civil or military satellite servicing, experimental, or applications missions while being periodically supplied and refueled by Shuttle flights from the ground. The system would accumulate experience invaluable to the design of future large and more expensive spacecraft. Key features of the vehicle are versatility and mobility. With Centaur-type propulsion and a large payload, the MOSS could leave an initial orbit of 370 km (200 nmi) altitude and inclinations up to 56 deg, make a plane change of up to + or - 14 deg, reach altitudes to 5500 km (2970 nmi), and then return the payload to the original orbit altitude and inclination. Obviously, the size of the performance envelope varies with the payload and propulsion-unit selected. The MOSS can reach orbits and perform tasks not possible with Shuttle alone or with the much larger space stations currently being proposed.

Hook, W. R.↗
NASA NTRS1984

Producing gallium arsenide crystals in space

The production of high quality crystals in space is a promising near-term application of microgravity processing. Gallium arsenide is the selected material for initial commercial production because of its inherent superior electronic properties, wide range of market applications, and broad base of on-going device development effort. Plausible product prices can absorb the high cost of space transportation for the initial flights provided by the Space Transportation System. The next step for bulk crystal growth, beyond the STS, is planned to come later with the use of free flyers or a space station, where real benefits are foreseen. The use of these vehicles, together with refinement and increasing automation of space-based crystal growth factories, will bring down costs and will support growing demands for high quality GaAs and other specialty electronic and electro-optical crystals grown in space.

Randolph, R. L.↗
NASA NTRS1984

Level of effort

The generation of a planar model of the ground test experiment structure is examined. This was done by adapting an in-house modal analysis code (Gimbalflex) to allow placement of sensors and actuators at certain locations on the structure. The next step in the development of this model was to adapt if for use with the control pole placement algorithm. The uncontrollable rigid body mode was removed from the model. This uncontrollable mode was due to the pointing of the gimbal. Control system design for the planar model was also initiated. A digital controller was planned utilizing the Control Pole Placement technique. The existence of rate of state feedback was assumed. Once this controller and other control algorithms were developed, it became necessary to conduct speed tests. A study was then made of additional hardware/software necessary to meet the speed requirement.

Source record↗
NASA NTRS1985

Active control landing gear for ground loads alleviation

An active landing gear has been created by connecting the hydraulic piston in an oleo strut to a hydraulic supply. A controller modulates the pressure in the oleo to achieve the desired dynamic characteristics. Tests on ground rigs (documented by a film) have demonstrated the successful alleviation of induced structural ground loads and the next step will be a flight test using a fighter aircraft.

Mcgehee, J. R.↗