SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The matching method of lidar data analysis is explained, and the results from two flights studying the stratospheric aerosol using lidar techniques are summarized and interpreted. Support is lent to the matching method of lidar data analysis by the results, but it is not yet apparent that the analysis technique leads to acceptable results on all nights in all seasons.
Explore the source record for details and available documents.
Seven different human-centered alternatives for distributing traffic management responsibility between air and ground in the terminal area were simulated and evaluated at NASA-Ames Research Center in the man-machine integration branch. The alternatives differed in three divisions of decision-making responsibility ranging from completely ground-centered to completely air-centered and in the amount of information presented to the pilots via traffic situation displays (TSD). Objective, verbal and subjective measures of system performance, workloads, preferences, etc., were obtained. Based on the task and corresponding measures, the ground-centered (vectoring) alternative was the least favorable. Best overall performance was achieved and preferred with a moderate division of responsibility in which controllers issued sequence order only and pilots used a TSD with 30 sec path predictors on their own aircraft. Speculations on the use of the results in context of a ground-centralized system failure and for future ATC systems are presented.
Explore the source record for details and available documents.
The lunar rock and soil specimens studied include samples of the orange and gray soil strata from adjancent sites on the South rim of Shorty Crater, two vesicular mare basalts, and a mare basalt of the dense aphanitic type. The magnetic characteristics of the soils are discussed along with a hysteresis behavior analysis of Apollo 17 rocks. The remanent properties are examined, giving attention to viscous remanence, NRM stability, saturation isothermal remanence, and heating experiments.
Nineteen cast nickel-base alloys, five cast cobalt-base alloys, and two wrought nickel-base alloys are included in study. Five nickel-base alloys have directionally-solidified polycrystalline grain structure. Three diffusion coatings and vapor-deposited overlay coating are also included in investigation.
The maximum solar energy (16 Solar Constants) irradiating experiment orifice E6 intermittently during the mission of space probe HELIOS has been reproduced in a High Intensity Component Test Facility. A detailed comparison is given between test results and flight data evaluation.
The spatial distribution of lunar smooth plains is not consistent with experimental simulations of melt rock emplacement during cratering in layered materials. Nor is it consistent with the location of melt rocks (suevite) near the Ries basin. Lunar smooth plains surrounding Imbrium are most extensive in areas where pre-existing craters are most degraded. This observation suggests that plains form by impact of basin and local primary crater ejecta, together with deposition of debris excavated by the resultant secondary cratering events. Craters within the belt of smooth plains surrounding the Caloris basin on Mercury are most degraded nearest the basin; this suggests that Mercurian smooth plains must, at least in part, be emplaced in a manner similar to plains surrounding the Imbrium basin. Mercurian uplands have a primary crater population deficient in small crater diameters (less than approximately 30 km). Lunar uplands far from major basins also have a crater population deficient in small crater sizes. Martian cratered terrain exhibits a similar crater deficiency, which was previously interpreted as due to obliteration of small craters (less than approximately 30 km) by some surface process. A crater size distribution deficient in small sizes (less than approximately 30 km) on the Mercurian, lunar, and Martian uplands has implications for the origin of debris bombarding the inner solar system during the period recorded by these surfaces. It is proposed that during late heavy bombardment, the inner solar system was inundated with bodies that broke up under tidal fission as they approached the planets. Such a mechanism would lend to production of a crater population deficient in small crater sizes, and it would also explain the large degree of spatial clustering of primary craters on Mercury, the moon, and Mars.
The hardware selections available for fabrication of a nuclear electric propulsion stage for planetary exploration were explored. The investigation was centered around a heat-pipe-cooled, fast-spectrum nuclear reactor for an out-of-core power conversion system with sufficient detail for comparison with the in-core system studies completed previously. A survey of competing power conversion systems still indicated that the modular reliability of thermionic converters makes them the desirable choice to provide the 240-kWe end-of-life power for at least 20,000 full power hours. The electrical energy will be used to operate a number of mercury ion bombardment thrusters with a specific impulse in the range of about 4,000-5,000 seconds.
As future LTA vehicles will be doomed right from the start if they do not fill a real need, some differences in transport philosophy between design engineers on the one hand and freight forwarders on the other are discussed. Watching rising costs of energy necessary to transport our cargo from A to B, and realizing that this price of energy is always included in the product's selling price at B, the apparent correlation between installed specific tractive force per unit of cargo weight and pure freighting cost are contemplated. Very speedy and progressive Airship designs are mistrusted, because the key to any low cost transport tool is to design it for its given task only, without any unnecessary sophistication.
There are eight large bodies in the solar system about which definite statements regarding the existence or nonexistence of a magnetic field of internal origin can now be made. Of these bodies (Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, and the Earth's Moon), only Venus and the Moon have negligible surface magnetic fields. By negligible is meant that the magnetic fields are so weak that they do not sensibly perturb the local solar wind. The other bodies provide an interesting zoo of magnetic field configurations and attendant charged particle behavior. Six of these bodies have magnetic fields, and two do not. Furthermore, of those which have magnetic fields, it appears that only that of Mars is ineffective in accelerating charged particles.
Abstracts of papers regarding the Martian Channels, variable surface and atmospheric features on Mars, the surfaces and origins of the Martian Satellites, and the surface of Venus are presented.
Acquisition of a modern terrain model board display system for 'out-the-window' scene presentation has allowed for the repetition of an evaluation study of combined visual/motion cues for CTOL flare and touchdown control that was originally carried out on a 1965 vintage landing display system. The motion drive system used in both studies was a nonlinear coordinated adaptive washout based on the method of continuous steepest descent optimization. Comparisons of the results of the studies present flare and touchdown data, as well as dynamic response data, from the two visual landing systems. The new visual system also allowed for the repetition, under visual conditions, of a subjective comparison of a linear and a nonlinear motion washout method done previously under instrument conditions.
Various configurations combining solar-Rankine and fuel-Brayton cycles were analyzed in order to find the arrangement which has the highest thermal efficiency and the smallest fuel share. A numerical example is given to evaluate both the thermodynamic performance and the economic feasibility of each configuration. The solar-assisted regenerative Rankine cycle was found to be leading the candidates from both points of energy utilization and fuel conservation.
Examination of the presently known historical scientific literature related to the problem of reactive flight indicates that considerable attention had already been given to the idea of reactive propulsion in the nineteenth century; about thirty designs for reaction flying vehicles were proposed during this period. However, the authors of a majority of the designs limited themselves only to a presentation of a diagram of the engine or an account of the principle of its operation, giving neither plans for its structural development nor precise calculations of the amount of energy required for accomplishing reaction flight. None of these authors considered the reaction flying vehicle as an object of variable mass, their choice of energy sources was extremely random, and the theory of the flight of reaction flying vehicles remained completely undeveloped. Early rocket designs of Nezhdanovsky, Ganswindt, Goddard, Tsiolkovsky, and others are examined and the evolution of liquid-propellant rocket engines, solid-propellant rocket engines, and jet aircraft engines is reviewed.
Two hypotheses attempting to account for the anomalously low intrinsic density of Venus in terms of chemical fractionation processes are entertained. Both assume similar relative abundances of major elements (Fe, Si, Mg, Al, Ca) in Venus and earth. One model assigns a larger proportion of the total Fe present in Venus to the planetary mantle, implying a core/mantle ratio lower than that of earth, and more extensive oxidation. The alternate hypothesis projects a Venus more reduced than the earth, with a mantle devoid of oxidized Fe; the difference in intrinsic densities is then attributed to the earth accreting at a lower temperature consonant with its greater distance from the sun. Large amounts of sulfur are presumed accreted on the earth but not on Venus, in the second model. Available chemical evidence tends to favor the first model.
The coronal lines Si VIII (1446 A), Fe X (1463 A), Fe XI (1467 A), and Fe XII (1242 A and 1349 A) were observed above the limb over a quiet region, a coronal hole, and two active regions. The lines emitted at temperatures greater than 1 million K; i.e., the iron lines, are not observed in the coronal-hole spectra, so the indication is that in the coronal hole most of the plasma is at a temperature of less than 1 million K. The emission measures and column densities of the lines are derived from available atomic cross-section data, and the results are discussed. The nonthermal velocities in the coronal hole and quiet region are about 20 km/s. The velocities in the active regions are substantially less.
The use of sounding rockets for calibrating solar cells offers two principal advantages: (1) there is no effect due to the terrestrial atmosphere, and (2) the cells are recoverable immediately after the calibration. On March 30, 1976, 29 n/p silicon and four p/n gallium arsenide solar cells were calibrated in space and successfully recovered from a NASA-Astrobee F rocket that reached a peak altitude of 230 km. Approximately 75 IV characteristic curves were generated for 32 of the cells to an accuracy of plus or minus 0.2 ma and plus or minus 0.2 mV.