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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Naked-eye acquisition of visible near-earth satellites

This paper develops visual sighting criteria for observing artificial near-earth satellites with the naked eye, and summarizes the mathematics needed to predict visibility efficiently from a set of mean orbital elements. It reports on a successful application of the sighting criteria and visibility-prediction mathematics, and shows that successful visual acquisition depends as much upon the observer's skill in recognizing the constellations as it does upon accurate visibility predictions.

Mansfield, Roger L.↗
NASA NTRS2016

The Matsu Wheel: A Cloud-Based Framework for Efficient Analysis and Reanalysis of Earth Satellite Imagery

Project Matsu is a collaboration between the Open Commons Consortium and NASA focused on developing open source technology for cloud-based processing of Earth satellite imagery with practical applications to aid in natural disaster detection and relief. Project Matsu has developed an open source cloud-based infrastructure to process, analyze, and reanalyze large collections of hyperspectral satellite image data using OpenStack, Hadoop, MapReduce and related technologies. We describe a framework for efficient analysis of large amounts of data called the Matsu "Wheel." The Matsu Wheel is currently used to process incoming hyperspectral satellite data produced daily by NASA's Earth Observing-1 (EO-1) satellite. The framework allows batches of analytics, scanning for new data, to be applied to data as it flows in. In the Matsu Wheel, the data only need to be accessed and preprocessed once, regardless of the number or types of analytics, which can easily be slotted into the existing framework. The Matsu Wheel system provides a significantly more efficient use of computational resources over alternative methods when the data are large, have high-volume throughput, may require heavy preprocessing, and are typically used for many types of analysis. We also describe our preliminary Wheel analytics, including an anomaly detector for rare spectral signatures or thermal anomalies in hyperspectral data and a land cover classifier that can be used for water and flood detection. Each of these analytics can generate visual reports accessible via the web for the public and interested decision makers. The result products of the analytics are also made accessible through an Open Geospatial Compliant (OGC)-compliant Web Map Service (WMS) for further distribution. The Matsu Wheel allows many shared data services to be performed together to efficiently use resources for processing hyperspectral satellite image data and other, e.g., large environmental datasets that may be analyzed for many purposes.

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NASA NTRS1980

Satellite Earth resources data, module U-3

Satellite data image products potentially useful in solving Earth resource and environmental problems are described. Sources for satellite data and user information are given. Recommendations for suitability of use of data from each satellite are presented. Satellite sources of Earth resources data are summarized for satellites launched since 1965 and those projected for launch through the late 1980s. The sensors of interest on each satellite, the wavelength or frequency of operation, and the resolution are given. Color ranges are illustrated and compared. The form and utility of aircraft and LANDSAT images are compared. Data from the Gemini-Apollo photography, Skylab, meteorological satellites, the Heat Capacity Mapping Mission, the Coastal Zone Color Scanner, Seasat, LANDSAT, and projected future satellites are briefly described.

Source record↗
NASA NTRS1976

Attenuation of propagation through rain for an earth-satellite path correlated with predicted values using radar

During the summer of 1974 and spring of 1975, measurements of attenuation of propagation through rain were made at Wallops Island, VA, using 13 and 18 GHz transmitters operating in the uplink mode toward the ATS-6 satellite. Simultaneously, rain reflectivity levels were measured along the earth-satellite path using a high resolution (0.4 deg beamwidth) S-band radar having a scanning antenna. Four rain-gages and two disdrometers were also located in the vicinity of the transmitters. The radar and disdrometer data were used in a modelling program to predict attenuation levels which were subsequently compared to the directly measured fades over nearly simultaneous time intervals. Predicted attenuation levels were obtained for three drop size distributions. Comparisons between predicted and measured attenuation levels showed the APL dropsize distribution gave the smallest rms difference of 1.3 dB at 13 and 18 GHz although the rms difference corresponding to Marshall-Palmer was close to this value. The good agreement suggests the validity of using radar to model path attenuation to obtain attenuation statistics.

Goldhirsh, J.↗
NASA NTRS1976

On the nature of the radial and cross track errors for artificial earth satellites

The paper discusses the analysis of the radial and cross track errors of artificial earth satellites in terms of the interference of two one-dimensional celestial mechanical wave trains. The resulting equations for these tracking errors describe the behavior of the uncertainties in the orbital parameters as oscillatory in nature, with a rapidly oscillating term, which is a function of the sum of the observed and computed orbital frequencies, modulated in amplitude by a slowly varying oscillation. This latter term is itself a function of either the difference between these orbital frequencies or between the values of the computed and observed right ascensions, depending upon whether it is the radial or cross track case under consideration. Results indicate that the cross track calculation describes the behavior of uncertainties in the right ascension of the ascending node and the inclination, while the radial calculation gives information on uncertainties in the semi-major axis, the eccentricity, and the argument of perigee.

Bonavito, N. L.↗
NASA NTRS1976

The elimination of short and intermediate period terms from the problem of a high altitude earth satellite

The Delaunay-Similar elements of Scheifele (1976) are applied to the problem of an earth satellite that is perturbed by the sun, moon, and J2. All three effects are assumed to be the same order of magnitude. Since the external body terms depend explicitly on time, the time element appears as an additional angle variable. Also, the eccentric anomaly is used as a noncanonical auxiliary variable. A solution to the first Von Zeipel equation allows simultaneous elimination of short- and intermediate-period terms. The canonical transformation to mean elements is defined by a generating function that is a series involving Bessel coefficients.

Graf, O. F., Jr.↗
NASA NTRS1972

GPS early-orbit subsystem for earth satellites

The early-orbit capability of the Goddard Trajectory Determination System, which determines starting vectors for earth satellites from angles-only or range-angles observations, is described and documented. Early-orbit results obtained from a variety of satellites, data types and methods of solution are also presented.

Laczo, V. T.↗
NASA NTRS1988

First estimates of the diurnal variation of longwave radiation from the multiple-satellite Earth Radiation Budget Experiment (ERBE)

First results for diurnal cycles derived from the Earth Radiation Budget Experiment are presented for the combined Earth Radiation Budget Satellite and NOAA-9 spacecraft for April 1985. Regional scale longwave radiation data are analyzed to determine diurnal variations for the total scene (including clouds) and for clear-sky conditions. The longwave diurnal range was found to be greatest for clear desert regions (up to about 70 W/sq m) and smallest for clear oceans (less than 5 W/sq m). Local time of maximum longwave radiation occurs at a wide range of times throughout the day and night over oceans, but generally occurs from noon to early afternoon over land and desert regions.

Harrison, Edwin F.↗