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At least 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Nuclear electric propulsion mission engineering study development program and costs estimates, Phase 2 review

The results are presented of the second six-month performance period of the Nuclear Electric Propulsion Mission Engineering Study. A brief overview of the program, identifying the study objectives and approach, and a discussion of the program status and schedule are presented. The program results are reviewed and key conclusions to date are summarized. Planned effort for the remainder of the program is reviewed.

Source record↗
NASA NTRS1971

A survey of Kaufman thruster cathodes

A survey is presented of the various cathodes which were developed and used in the Kaufman ion thruster. The electron bombardment type ion source is briefly described. The general design, operating characteristics, and power requirements are shown for each type of cathode from the refractory metals used in 1960 to the plasma discharge hollow cathodes of today. A detailed discussion of the hollow cathode is given, including starting and cyclic operating characteristics as well as more fundamental design parameters. Tests to date show that the plasma hollow cathode is an efficient electron source with demonstrated durability over 10,000 hours.

Weigand, A. J.↗
NASA NTRS1972

Asynchronous sampling of speech with some vocoder experimental results

The method of asynchronously sampling speech is based upon the derivatives of the acoustical speech signal. The following results are apparent from experiments to date: (1) It is possible to represent speech by a string of pulses of uniform amplitude, where the only information contained in the string is the spacing of the pulses in time; (2) the string of pulses may be produced in a simple analog manner; (3) the first derivative of the original speech waveform is the most important for the encoding process; (4) the resulting pulse train can be utilized to control an acoustical signal production system to regenerate the intelligence of the original speech.

Babcock, M. L.↗
NASA NTRS1971

Remote sensing of vigor loss in conifers due to dwarf mistletoe

The initial operation of a multiband/multidate tower-tramway test site in northeastern Minnesota for the development of specifications for subsequent multiband aerial photography of more extensive study areas was completed. Multiband/multidate configurations suggested by the tower-tramway studies were and will be flown with local equipment over the Togo test site. This site was photographed by the NASA RB57F aircraft in August and September 1971. It appears that, of all the film/filter combinations attempted to date (including optical recombining of several spectral band images via photo enhancement techniques), Ektachrome infrared film with a Wratten 12 filter is the best for detecting dwarf mistletoe, and other tree diseases as well. Using this film/filter combination, infection centers are easily detectable even on the smallest photo scale (1:100,000) obtained on the Togo site.

Meyer, M. P.↗
NASA NTRS1972

Summary of 1971 land remote sensing investigations

Techniques to provide land use up-date information using remotely sensed data and automatic data processing technology are being developed. The approach utilizes multispectral scanners, the associated data analysis station, and the pattern recognition programs to identify and classify land surface characteristics, including wetlands, and to convert these data to demonstration type experiments in the various disciplines.

Mooneyhan, D. W.↗
NASA NTRS1972

Space configuration as an explanation for lithology-related cross-polarized radar image anomalies

Three rock types are described that produce dark cross-polarized images on Ka-band imagery: lava flows dating from Pleistocene and Holocene, some Tertiary volcanics, and certain massive sandstones. Their planar surfaces are large with respect to the wavelength of the Ka-band system, yet are small in comparison to the resolution. It is found that only outcrops with proper faceted surface orientations produce significant radar returns showing the dominance of specular reflectors. The omnidirectional attitude of the facets and their wide distribution on the outcrops explains the independence of look-direction that the flat-lying anomalous outcrops exhibit in production of darker cross-polarized images.

Mccauley, J. R.↗
NASA NTRS1972

Radar signature and systems studies at Kansas University

The radar signature and systems studies described have concentrated in two areas: octave bandwidths radar spectrometry using a truck-mounted system, and scatterometry using primarily the 13.3 GHz system on aircraft. In addition, the results of the experiments to date have been synthesized into a pair of representative designs for spacecraft radar systems: one for small spacecraft and one for large spacecraft.

Moore, R. K.↗
NASA NTRS1972

Corn blight review: Sampling model and ground data measurements program

The sampling plan involved the selection of the study area, determination of the flightline and segment sample design within the study area, and determination of a field sample design. Initial interview survey data consisting of crop species acreage and land use were collected. On all corn fields, additional information such as seed type, row direction, population, planting date, ect. were also collected. From this information, sample corn fields were selected to be observed through the growing season on a biweekly basis by county extension personnel.

Allen, R. D.↗
NASA NTRS1971

Monitoring the evolving land use patterns using remote sensing

The urbanization of Walnut Valley from 1953-71 prompted land use change from intensive von Thunen market-oriented patterns to extensive, disinvested, production-factor-minimized patterns. Shortrun, interim land use planning, has allowed agriculture to persist but only in the form of barley farming and grazing. Aerial photography used synoptically recorded six periods of land use change that bracketed dates before and after the freeway was announced and built. Interpretations of these changes help recognize potential conversions to urban uses which allow guidelines to be established that deal with rural-urban transition problems before they arise.

Goehring, D. R.↗
NASA NTRS1972

Cartographic application of ERTS imagery

There are no author-identified significant results in this report. Results of a quick look of selected ERTS-1 imagery with respect to cartographic applications and products are presented. The term cartographic is applied to graphics that have been related to an accepted reference figure of the earth within a prescribed degree of accuracy. The results are presented in the form of figures covering: (1) nongeometric relative image quality; (2) geometric properties (preliminary); (3) first phase photoimage products; (4) intermediate phase photoimage products; (5) optimum phase orthophotoquad products; and (6) cartographic applications. Because of its unique vantage point of 920 km, ERTS-1 will be a powerful mapping tool by providing extensive and continuous up-to-date data.

Colvocoresses, A. P.↗
NASA NTRS1972

Central Atlantic regional ecological test site: A prototype regional environment information system

The author has identified the following significant results. Prior to the actual testing of data from ERTS-1, the principal scientific results to date are the establishment of a model or design for a regional land use information system based on remote sensor data and a firm establishment of the RB-57 type high altitude aircraft data base as an important tool in land use mapping. Preliminary user evaluations of the resulting land use data have been favorable, and one of the states, Maryland, has adopted the USGS-GAP land use system as a first step towards mapping their entire state. The State is funding an extension (to the west) of the part of Maryland not covered by CARETS (Central Atlantic Regional Ecological Test Site), using the GAP land use classification and mapping procedures.

Alexander, R. H.↗
NASA NTRS1972

Hurricane Preparedness and Control Plan

This plan establishes policy and sets forth guidance, responsibilities and procedures utilized by Federal Electric Corp., communications department in support of the KSC Emergency Preparedness Plan, Annex A, Hurricane Control Plan (GP-355) dated 27 May 1971. This plan covers all FEC communications department personnel, facilities, and equipment situated at the Kennedy Space Center that are the responsibility of FEC contract NAS 10-4967.

Source record↗
NASA NTRS1972

Supernovae studied with a ground level atmospheric fluorescence

A monitoring experiment was undertaken late 1968 to search for photon bursts of extraterrestrial origin. The experiment and the results of the observations to date are summarized. The method of detection employs ground-based photomultiplier tubes which are sensitive to the secondary fluorescence light that would be produced when the primary pulse is absorbed in the atmosphere.

Bertsch, D. L.↗
NASA NTRS1972

Study and evaluation of ferro-cement for use in wind tunnel construction

The structural suitability and cost effectiveness of ferro-cement for large subsonic wind tunnel structures is investigated. This investigation was carried out in the following four main categories: (1) a state-of-the-art survey into the uses, properties, and costs of ferro-cement; (2) an evaluation of those ferro-cement properties critical to construction of large, subsonic wind tunnels, which have not been adequately established to date; (3) a laboratory testing program to determine preliminary values for those properties; and (4) a study to establish cost factors for ferro-cement as related to a preliminary construction scheme for a nacelle and shroud unit.

Larsen, H. J., Jr.↗
NASA NTRS1971

Ar-40/Ar-39 ages and cosmic ray exposure ages of Apollo 14 samples.

We have used the Ar-40/Ar-39 dating technique on eight samples of Apollo 14 rocks (14053, 14310), breccia fragments (14321), and soil fragments (14001, 14167). The large basalt fragments give reasonable Ar-40/Ar-39 release patterns and yield well defined crystallization ages of 3.89-3.95 aeons. Correlation of the Ar-40/Ar-39 release patterns with Ar-39/Ar-37 patterns showed that the low temperature fractions with high radiogenic argon loss came from K-rich phases. A highly shocked sample and fragments included in the breccia yield complex release patterns with a low temperature peak. The total argon age of these fragments is 3.95 aeons. Cosmic ray exposure ages on these samples are obtained from the ratio of spallogenic Ar-38 to reactor induced Ar-37 and show a distinct grouping of low exposure ages of 26 m.y. correlated with Cone crater. Other samples have exposure ages of more than 260 m.y. and identify material with a more complex integrated cosmic age exposure history.

Turner, G.↗
NASA NTRS1971

Installation and integration of transonic transport propulsion systems.

Initial work indicates that a viable aircraft family can be designed for higher subsonic cruise speeds. Studies to date suggest that the propulsion system/nacelle design and the incorporation of noise attenuation into this design will have more influence on the choice of an optimum engine than engine weight and fuel consumption. These studies also suggest the payoff resulting from the incorporation of new technology items such as the internal engine generator and new structural cowl concepts because of the greater sensitivity to drag. These factors, plus the greater interdependency of the transonic aircraft and its propulsion system, point up the importance of a total system approach to propulsion system optimization and design.

Goodmanson, L. T.↗
NASA NTRS1971

The NASA Quiet Engine.

The NASA Quiet Engine Program will incorporate all available noise-reduction technology into a propulsion system suitable for subsonic civil transport aircraft. Full-scale experimental hardware is being built and tested primarily for noise performance. The program is in process, and component tests to date indicate that it is possible to achieve or exceed noise reduction objectives of 15-20 PNdB below the levels of 707/DC-8 long-range transport aircraft.

Kramer, J. J.↗