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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Interactive analysis of a large aperture Earth Observations Satellite

A system level design and analysis has been conducted on an Earth Observation Satellite (EOS) system using the Interactive Design and Evaluation of Advanced Spacecraft (IDEAS) computer-aided design and analysis program. The IDEAS program consists of about 40 user-friendly technical modules and an interactive graphics display. The reflector support system and feed mast of the EOS spacecraft are constructed with a box-truss structural concept, a lattice configuration which can be packaged for delivery in a single Shuttle flight and deployed in orbit. The deployed spacecraft consists of a 120-m by 60-m parabolic reflector, a 120-m-long support structure, and a 30-m feed arc beam on the focal axis. The spacecraft was modeled for structural, thermal, and control systems analysis and structural elements were designed. On-orbit dynamic and thermal loading analyses were conducted and spacecraft weights were determined.

Wright, R. L.↗
NASA NTRS1991

Satellite observations of variations in tropical cyclone convection caused by upper-tropospheric troughs

Satellite observations and numerical model results have been used to study the relationship between upper-tropospheric forcing and the oscillation of convection of tropical cyclones Florence (1988) and Irene (1981) during their mature stage over open warm oceans (SST greater than or equal to 26 C). It is suggested that the initiation and maintenance of intense convective outbreaks in tropical cyclones are related to the channeling and strengthening of their outflow by upper-tropospheric troughs. It is possible to enhance the convection in response to the outflow jet-induced import of eddy relative angular momentum and ascending motion associated with the thermally direct circulation. Both Florence and Irene are found to intensify after the onset of these convective episodes. It is also suggested that the cessation in the convection of the two tropical cyclones occurs when the upper-tropospheric troughs move near or over the tropical cyclones, resulting in the weakening of their outflow and the entrainment of dry upper-tropospheric air into their inner core.

Rodgers, Edward B.↗
NASA NTRS1992

Multi-satellite observations of plasmoids - IMP 8 and ISEE 3

An examination of IMP 8 and ISEE 3 magnetotail data during the 1983 Geotail Mission yielded one plasmoid event which was observed by both satellites and two other possible cases. These are the first multisatellite observations of plasoids. These observations provide a unique opportunity to examine how plasmoid characteristics change as plasmoids propagate downtail and they show that plasmoids are very stable structures.

Moldwin, Mark B.↗
NASA NTRS1974

Direct satellite observations on bremsstrahlung radiation as a technique to investigate its role in meteorological processes

Satellite observations on bremsstrahlung produced in the atmosphere by precipitating energetic electrons are reported. This type of observation affords the possibility of directly monitoring the bremsstrahlung energy input to the lower atmosphere over large segments of the earth and at frequent intervals. From comparison of the ion production rates from cosmic rays with those calculated for bremsstrahlung from precipitating energetic electrons, it is concluded that bremsstrahlung is a negligible contributor to the ionization near the 300-mb level.

Johnson, R. G.↗
NASA NTRS1980

The continuous spectrum of Markarian 421 during periods of X-ray satellite observations

New UBVRI photometry of Mrk 421 obtained during periods of X-ray satellite observations are presented. An X-ray light curve for 1977 November from the HEAO A-1 experiment is also given. The decomposition of the UBVR fluxes into a compact nonthermal component and an extended galactic component shows that there are coordinated variations in the optical nonthermal and X-ray emission. The data are consistent with the hypothesis that the mini-BL Lac object is emitting by the synchrontron-self-Compton process. The host galaxy of this composite source has properties like those of a giant elliptical.

Mufson, S. L.↗
NASA NTRS1972

Corrections to star catalogues from satellite observations.

Theoretical investigation of the possibility of obtaining systematic corrections to star catalogs from observations of artificial satellites. A model is established to represent the system of equations formed when such corrections are determined simultaneously with corrections to the geocentric position of the observer. An analytical expression for the covariance matrix is set up for the two-dimensional (planar) case. The resulting correlations and weights are discussed. Since this method presents an independent way of obtaining the systematic errors in star catalogs, apart from the orientation to the equatorial system, it is related to the measurement of all quantities which depend on star positions. This institutes a completely new principle of obtaining systematic corrections to star catalogs. It is based not on rotation, but on comparing the angle subtended at the satellite by two stars to the angle subtended at the satellite by two points on the surface of the earth.

Williams, C. A.↗
NASA NTRS1994

Extreme ultraviolet explorer satellite observation of Jupiter's Io plasma torus

We present the first Extreme Ultraviolet Explorer (EUVE) satellite observation of the Jupiter system, obtained during the 2 day period 1993 March 30 through April 1, which shows a rich emission-line spectrum from the Io plasma torus spanning wavelengths 370 to 735 A. The emission features correspond primarily to known multiplets of oxygen and sulfur ions, but a blended feature near 372 A is a plausible Na II transition. The summed detected energy flux of (7.2 +/- 0.2) x 10(exp -11) ergs/sq cm(s) corresponds to a radiated power of approximately equal to 4 x 10(exp 11) W in this spectral range. All ansa emissions show a distinct dawn-dusk brightness asymmetry and the measured dusk/dawn ratio of the bright S III lambda-680 feature is 2.3 +/- 0.3, significantly larger than the ratio measured by the Voyager spacecraft ultraviolet (UV) instruments. A preliminary estimate of ion partitioning indicates that the oxygen/sulfur ion ratio is approximately equal to 2, compared to the value approximately equal to 1.3 measured by Voyager, and that (Na(+))/(e) greater than 0.01.

Hall, D. T↗
NASA NTRS2017

Experiences in Applying Earth Observing Satellite Technology in SERVIR Regions with an Emphasis on Disasters: Successes, Lessons and Paths Forward

Earth observing satellites offer a unique perspective of our environment from the vantage point of space. Repeated measurements of the Earths subsystems such as the biosphere, atmosphere, lithosphere, hydrosphere, and of humans interactions with their environments, allow for a better understanding of Earth system processes, and they can provide input for decision making in areas of environmental management and disaster risk reduction. SERVIR is a joint initiative of the US National Aeronautics and Space Administration (NASA) and the US Agency for International Development (USAID) that began in 2005 and has been active in applying Earth observations for sustainable development in many regions around the world, recently the Lower Mekong and West Africa regions. This talk will highlight some successes achieved and lessons learned through SERVIR in Central America, Eastern Southern Africa, and the Hindu Kush-Himalaya region, focusing on disasters. We will also present opportunities for enhanced decision making with Earth observations and geospatial technologies in the Lower Mekong region.

SERVIR↗
NASA NTRS1981

The state of the atmosphere as inferred from the FGGE satellite observing systems during SOP-1

Data assimilation experiments were performed to test the influence of different elements of the satellite observing systems. Results from some of the experiments are presented. These findings show that the FGGE satellite systems are able to infer the three-dimensional motion field and improve the representation of the large-scale state of the atmosphere. Preliminary results of the forecast impact of the FGGE data sets are also presented.

Halem, M.↗
NASA NTRS2003

Scheduling Earth Observing Satellites with Evolutionary Algorithms

We hypothesize that evolutionary algorithms can effectively schedule coordinated fleets of Earth observing satellites. The constraints are complex and the bottlenecks are not well understood, a condition where evolutionary algorithms are often effective. This is, in part, because evolutionary algorithms require only that one can represent solutions, modify solutions, and evaluate solution fitness. To test the hypothesis we have developed a representative set of problems, produced optimization software (in Java) to solve them, and run experiments comparing techniques. This paper presents initial results of a comparison of several evolutionary and other optimization techniques; namely the genetic algorithm, simulated annealing, squeaky wheel optimization, and stochastic hill climbing. We also compare separate satellite vs. integrated scheduling of a two satellite constellation. While the results are not definitive, tests to date suggest that simulated annealing is the best search technique and integrated scheduling is superior.

Globus, Al↗
NASA NTRS1975

Micropulsations in the morning sector. II - Satellite observations of 10to 45-s waves at synchronous orbit, ATS 1

A study of 13 wave events having 10- to 45-s periods and observed by ATS 1 in the morning sector reveals that these events, which have been called band-limited pulsations and are thought to be related to Pi 1, appear actually to be Pc 3. Digital power-spectral and coherency analysis was used to determine the characteristics of the wave activity. The average peak frequency of the events (about 0.04 Hz) and their generally narrow-band nature correspond closely with the characteristics of Pc 3. The local-time distribution of the events (peaking at 0900 LT) and their less than complete association with substorms also correspond more closely with Pc 3 characteristics. The orientation of the major axis of the polarization ellipse for these events was predominantly azimuthal, which agrees more closely with the east-west polarization of Pi 1 observed on the ground. However, some examples of radial orientation were observed in the satellite data.

Arthur, C. W.↗
NASA NTRS1982

The use of stereoscopic satellite observation in the determination of the emissivity of cirrus

The feasibility of determining cirrus 'emissivity' from combined stereoscopic and infrared satellite observations in conjunction with radiosounding data is investigated for a particular case study. Simultaneous visible images obtained during SESAME-1979 from two geosynchronous GOES meteorological satellites were processed on the NASA Goddard interactive system (AOIPS) and were used to determine the stereo cloud top height Z sub C as described by Hasler (1981). Iso-contours of radiances were outlined on the corresponding infrared image. Total brightness temperature T sub B and ground surface brightness temperature T sub S were inferred from the radiances. The special SESAME network of radiosoundings was used to determine the cloud top temperature T sub CLD at the level defined by Z sub C. The 'effective cirrus emissivity' NE where N is the fractional cirrus cloudiness and E is the emissivity in a GOES infrared picture element of about 10 km x 10 km is then computed from T sub B, T sub S and T sub CLD.

Szejwach, G.↗