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Variability Of The Lower Thermosphere Determined From Satellite Accelerometer Data
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Book Synopsis Variability of the Lower Thermosphere Determined from Satellite Accelerometer Data by : Frank A. Marcos
Download or read book Variability of the Lower Thermosphere Determined from Satellite Accelerometer Data written by Frank A. Marcos and published by . This book was released on 1978 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: An extensive atmospheric density data base has been developed using accelerometer results from four low altitude satellites. The altitude range of the data is from 250 km down to as low as 140 km, with latitude coverage from 90 N to 90 S and local time periods that cover several 24-hr cycles. The data were obtained over a wide range of geomagnetic activity conditions. Solar radiation, as indicated by the 10.7-cm flux, was generally very low. Hence the data base applies mainly to solar minimum conditions. A description of the satellites, the accelerometer experiment, and the data base is given. Density variability is statistically analyzed in relation to selected atmospheric models. Particular attention is given to deviations from a normal distribution. Frequency distribitons of the data are described in terms of the mean value and the second, third, and fourth moments about the mean. This provides a more accurate description of extreme variations. The statistical properties of atmospheric variability are analyzed as a function of geomagnetic activity, latitude, altitude, and local time to develop a quantitative knowledge of unmodeled density variations. The results show that these accelerometer data will permit significant improvement in understanding the variations in the lower thermospheric density.
Book Synopsis Lower-thermosphere Neutral Density Profiles Derived from Satellite Accelerometer Data by : F. A. Marcos
Download or read book Lower-thermosphere Neutral Density Profiles Derived from Satellite Accelerometer Data written by F. A. Marcos and published by . This book was released on 1976 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cannon Ball II and SPADES satellites carried triaxial accelerometer systems for accurate measurement of neutral atmospheric density. Cannon Ball II was launched 6 August 1971 into a polar elliptic orbit in which the initial perigee was at the extremely low altitude of 132 km. SPADES was launched 11 July 1968 into a polar elliptic orbit in which the initial perigee was at 155 km. The data, analyzed to deduce an average density profile for each satellite for summer conditions in the northern hemisphere, are for the altitude region 135 to 250 km, where measurements have heretofore been extremely sparse. Comparisons were made with recent models and experimental data. These results are intended to be supplemented by those of lower-thermosphere studies now being carried out on accelerometer data from the Atmosphere Explorer satellites and a low-altitude Air Force satellite. Comprehensive analyses of accelerometer data low-altitude satellites will allow accurate modeling of the lower thermosphere. These models are required for improving calculation of the trajectories of Air Force systems vehicles and other spacecraft.
Book Synopsis A Global Thermospheric Density Model Based on Satellite Accelerometer Data by : Frank A. Marcos
Download or read book A Global Thermospheric Density Model Based on Satellite Accelerometer Data written by Frank A. Marcos and published by . This book was released on 1982 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements from the accelerometer experiments on four low-altitude satellites (S3-1 and Atmosphere Explorer-C, -D, and -E) have been combined to produce an empirical model of the neutral mass density from 140 to 240 km. Data from over a 8000 orbits are analyzed using the least-squares method of multiple linear regression. The resulting model gives density as a function of solar flux (for flux values 60 to 130 units), geomagnetic activity, day of year, local time, latitude and altitude. It provides a more accurate fit to the measured data than other available atmospheric models. Three commonly used models are evaluated by comparison of their predicted density variations with those of this empirical model.
Book Synopsis Lower-thermosphere Neutral Density Profiles Derived from Satellite Accelerometer Data by : F. A. Marcos
Download or read book Lower-thermosphere Neutral Density Profiles Derived from Satellite Accelerometer Data written by F. A. Marcos and published by . This book was released on 1976 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cannon Ball II and SPADES satellites carried triaxial accelerometer systems for accurate measurement of neutral atmospheric density. Cannon Ball II was launched 6 August 1971 into a polar elliptic orbit in which the initial perigee was at the extremely low altitude of 132 km. SPADES was launched 11 July 1968 into a polar elliptic orbit in which the initial perigee was at 155 km. The data, analyzed to deduce an average density profile for each satellite for summer conditions in the northern hemisphere, are for the altitude region 135 to 250 km, where measurements have heretofore been extremely sparse. Comparisons were made with recent models and experimental data. These results are intended to be supplemented by those of lower-thermosphere studies now being carried out on accelerometer data from the Atmosphere Explorer satellites and a low-altitude Air Force satellite. Comprehensive analyses of accelerometer data low-altitude satellites will allow accurate modeling of the lower thermosphere. These models are required for improving calculation of the trajectories of Air Force systems vehicles and other spacecraft.
Book Synopsis Satellite Density Measurements with the Rotatable Calibration Accelerometer (ROCA) by : Frank A. Marcos
Download or read book Satellite Density Measurements with the Rotatable Calibration Accelerometer (ROCA) written by Frank A. Marcos and published by . This book was released on 1979 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Satellite accelerometer measurements of atmospheric density have provided significant improvement in our understanding of the structure and dynamics of the lower thermosphere. Derivation of accurate data with this technique requires removal of instrument bias from the total sensor output. The ROCA (Rotatable Calibration Accelerometer) experiment was flown to provide and orbital calibration capability on the three-axis stabilized S3-4 satellite. The ROCA sensitive axis could be operated in either of two orientations selectable by ground command. For density measurement (normal operating mode) the sensitive axis was aligned with the satellite velocity vector. For direct measurement of bias, the sensitive axis was aligned perpendicular to the velocity vector. Utilization of the inflight calibration technique showed a dependence of the bias upon the instrument operating temperature. Removal of the bias-temperature component from the total acceleration signal obtained in the normal operating mode permits derivation of accurate density data. Measurements of atmospheric density were obtained during approximately 600 orbits over a five month period. The resulting ROCA data will be utilized for improved satellite ephemeris computations and for detailed studies of the lower thermosphere, particularly those related to energy inputs at high latitudes. (Author).
Book Synopsis Application of the Satellite Triaxial Accelerometer Experiment to Atmospheric Density and Wind Studies by : Frank A. Marcos
Download or read book Application of the Satellite Triaxial Accelerometer Experiment to Atmospheric Density and Wind Studies written by Frank A. Marcos and published by . This book was released on 1982 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new satellite triaxial accelerometer system has been developed. This instrument has been flight-tested on three-axis stabilized satellites and has demonstrated the capability to accurately measure accelerations in the satellite's in-track, cross-track, and radial directions. The in-track data provide direct determination of atmospheric density. These data, obtained during a period of high solar flux, supplement the extensive set of measurements obtained by other accelerometer experiments during low solar flux conditions. The cross-track and radial results permit, for the first time, large-scale measurements of the zonal and, possibly, radial components of neutral atmospheric winds. These simultaneous wind and density data provide an extremely valuable input for the understanding of dynamic processes in the atmosphere and for the improvement of atmospheric models.
Download or read book Instrumentation Papers written by and published by . This book was released on 1978 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fundamentals of Space Systems by : Vincent L. Pisacane
Download or read book Fundamentals of Space Systems written by Vincent L. Pisacane and published by Johns Hopkins University Appli. This book was released on 2005 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Space Systems was developed to satisfy two objectives: the first is to provide a text suitable for use in an advanced undergraduate or beginning graduate course in both space systems engineering and space system design. The second is to be a primer and reference book for space professionals wishing to broaden their capabilities to develop, manage the development, or operate space systems. The authors of the individual chapters are practicing engineers that have had extensive experience in developing sophisticated experimental and operational spacecraft systems in addition to having experience teaching the subject material. The text presents the fundamentals of all the subsystems of a spacecraft missions and includes illustrative examples drawn from actual experience to enhance the learning experience. It includes a chapter on each of the relevant major disciplines and subsystems including space systems engineering, space environment, astrodynamics, propulsion and flight mechanics, attitude determination and control, power systems, thermal control, configuration management and structures, communications, command and telemetry, data processing, embedded flight software, survuvability and reliability, integration and test, mission operations, and the initial conceptual design of a typical small spacecraft mission.
Book Synopsis Report on Research at AFCRL. by : Air Force Cambridge Research Laboratories (U.S.)
Download or read book Report on Research at AFCRL. written by Air Force Cambridge Research Laboratories (U.S.) and published by . This book was released on 1976 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hemispheric Asymmetries Detected from Satellite Ionization Gauge Measurements by : J. P. McIsaac
Download or read book Hemispheric Asymmetries Detected from Satellite Ionization Gauge Measurements written by J. P. McIsaac and published by . This book was released on 1980 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: esults obtained from the S3-1 ionization gauge measurements are statistically examined for hemispheric asymmetries in neutral density behavior. The parameter analyzed in this study is the mean value R, the ratio of the measured density to the Jacchia 71 model value. Over 150,000 values obtained during the period from November 1974 to May 1975 and covering the altitude range from perigee (about 160 km) to 300 km are considered. Results are presented in the form of frequency histograms and graphs of mean ratios vs latitude. Significant hemispherical asymmetries are found and described in detail.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Application of Satellite Accelerometer Data to Improve Density Models by : Frank A. Marcos
Download or read book Application of Satellite Accelerometer Data to Improve Density Models written by Frank A. Marcos and published by . This book was released on 1984 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric density measurements obtained by the satellite accelerometer experiment provide data over a wide range of solar and geophysical conditions. These results are used in a preliminary evaluation of several atmospheric models. The model accuracies are compared by their mean values and standard deviations relative to the accelerometer data. Sources of model uncertainties and problems in reducing them are described. Long-term programs involving coordinated measurements, analyses of available data and theoretical studies are required along with development of more accurate indicators of solar and geomagnetic activity before models can show significant improvement. Keywords include: Satellite, Accelerometers, Atmospheric density measurements, Thermospheric model evaluations, Thermospheric density variability.
Book Synopsis Meteorological and Geoastrophysical Abstracts by :
Download or read book Meteorological and Geoastrophysical Abstracts written by and published by . This book was released on 1996 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamics and Structure of the Quiet Thermosphere by : K. S. W. Champion
Download or read book Dynamics and Structure of the Quiet Thermosphere written by K. S. W. Champion and published by . This book was released on 1974 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The COSPAR International Reference Atmospheres (CIRA) 1972 provides both a Mean International Reference Atmosphere of the thermosphere and a parametric set of models for the region. The models are based on knowledge of the thermosphere as of mid 1971. The differences in the diurnal variations of atmospheric density scale height obtained from satellite drag studies and temperatures obtained from incoherent radar scatter observations are probably due to different diurnal variations of density and temperature and not due to systematic discrepancies in the measurements. The answer to this question should be provided by data obtained from recently launched satellites ESRO IV, AEROS, and AE-C. The second major area of interest involves the absolute number densities and variations with time of day, latitude, and season of the major and minor constituents of the thermosphere. Recent data obtained with mass spectrometers and optical instruments are reviewed in addition to the results of theoretical composition calculations, which include turbulence and other transport effects.
Book Synopsis Atmospheric Infrared Radiance Variability by : C. H. Humphrey
Download or read book Atmospheric Infrared Radiance Variability written by C. H. Humphrey and published by . This book was released on 1981 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data concerning the spatial and temporal inhomogenities of atmospheric density and composition and their implication concerning the atmospheric infrared radiance are reviewed. Preliminary estimates of the variability in the radiance are presented. In addition, the range of scale sizes from small-scale variations is also considered.
Book Synopsis Air Force Surveys in Geophysics by :
Download or read book Air Force Surveys in Geophysics written by and published by . This book was released on 1974 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch Publisher : ISBN 13 : Total Pages :516 pages Book Rating :4.:/5 (31 download)
Book Synopsis Data Bases and Data Base Systems, Related to NASA's Aerospace Program by : United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch
Download or read book Data Bases and Data Base Systems, Related to NASA's Aerospace Program written by United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch and published by . This book was released on 1981 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
