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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

The Orbits of the Inner Uranian Satellites from Hubble Space Telescope and Voyager observations

This article presents revised orbital elements for theten small Uranian satellites discovered by Voyager 2. The elements have been determined from a fit to astrometric observations made with the Hubble Space Telescope and imaging data acquired by the Voyager 2 spacecraft. An assessment of the accuracy of the orbits represented by the elements is provided as are comparisons with orbits found by previous investigators.

Uranian↗
NASA NTRS2011

Overview of NASA's Carbon Monitoring System Flux-Pilot Project

NASA's space-based observations of physical, chemical and biological parameters in the Earth System along with state-of-the-art modeling capabilities provide unique capabilities for analyses of the carbon cycle. The Carbon Monitoring System is developing an exploratory framework for detecting carbon in the environment and its changes, with a view towards contributing to national and international monitoring activities. The Flux-Pilot Project aims to provide a unified view of land-atmosphere and ocean-atmosphere carbon exchange, using observation-constrained models. Central to the project is the application of NASA's satellite observations (especially MODIS), the ACOS retrievals of the JAXA-GOSAT observations, and the "MERRA" meteorological reanalysis produced with GEOS-S. With a primary objective of estimating uncertainty in computed fluxes, two land- and two ocean-systems are run for 2009-2010 and compared with existing flux estimates. An transport model is used to evaluate simulated CO2 concentrations with in-situ and space-based observations, in order to assess the realism of the fluxes and how uncertainties in fluxes propagate into atmospheric concentrations that can be more readily evaluated. Finally, the atmospheric partial CO2 columns observed from space are inverted to give new estimates of surface fluxes, which are evaluated using the bottom-up estimates and independent datasets. The focus of this presentation will be on the science goals and current achievements of the pilot project, with emphasis on how policy-relevant questions help focus the scientific direction. Examples include the issue of what spatio-temporal resolution of fluxes can be detected from polar-orbiting satellites and whether it is possible to use space-based observations to separate contributions to atmospheric concentrations of (say) fossil-fuel and biological activity

Pawson, Steven↗
NASA NTRS2003

Optimal Inflatable Space Towers with 3 - 100 km Height

Theory and computations are provided for building inflatable space towers up to one hundred kilometers in height. These towers can be used for tourism, scientific observation of space, observation of the Earth's surface, weather and upper atmosphere, and for radio, television, and communication transmissions. These towers can also be used to launch space ships and Earth satellites. These projects are not expensive and do not require rockets. They require thin strong films composed from artificial fibers and fabricated by current industry. The towers can be built using present technology. The towers can be used (for tourism, communication, etc.) during the construction process and provide self-financing for further construction. The tower design does not require work at high altitudes; all construction can be done at the Earth's surface. The transport system for a tower consists of a small engine (used only for friction compensation) located at the Earth's surface. The tower is separated into sections and has special protection mechanisms in case of damage. Problems involving security, control, repair, and stability of the proposed towers are addressed in other publications. The author is prepared to discuss these and other problems with serious organizations desiring to research and develop these projects.

Bolonkin, Alexander↗
NASA NTRS1991

Inner coma imaging of Comet Levy (1990c) with the Hubble Space Telescope

Observations of comet Levy were carried out with the Hubble Space Telescope (HST) on UT 27 Sep. 1990. The comet was imaged with the Wide Field Camera (WFC) through both red and blue filters, which were selected to isolate continuum emission peaking sharply at the nucleus. The longest exposures (4 sec) through the red filter had sufficient signal to noise that image deconvolution could be used to recover virtually the full spatial resolution of HST. These images reveal a fan-shaped inner coma in which the sunward-facing hemisphere is significantly brighter than the tailward hemisphere, consistent with volatile sublimation occurring primarily on the dayside of the nucleus.

Weaver, Harold A.↗
NASA NTRS1987

Dynamics of magnetic clouds in interplanetary space

Magnetic clouds observed in interplanetary space may be regarded as extraneous bodies immersed in the magnetized medium of the solar wind. The interface between a magnetic cloud and its surrounding medium separates the internal and external magnetic fields. Polarization currents are induced in the peripheral layer to make the ambient magnetic field tangential. The motion of a magnetic cloud through the interplanetary medium may be partitioned into a translational motion of the magnetic cloud as a whole and an expansive motion of the volume relative to the axis of the magnetic cloud. The translational motion is determined by two kinds of forces, i.e., the gravitational force exerted by the Sun, and the hydromagnetic buoyancy force exerted by the surrounding medium. On the other hand, the expansive motion is determined by the pressure gradient sustaining the gross difference between the internal and external pressures and by the self-induced magnetic force that results from the interaction among the internal currents. The force resulting from the internal and external currents is a part of the hydromagnetic buoyancy force, manifested by a thermal stress caused by the inhomogeneity of the ambient magnetic pressure.

Yeh, Tyan↗
NASA NTRSDate not supplied

Enhancing NASA Earth Science Data Discovery from Scientific Publications

Earth observations from space borne instruments have evolved explosively in the past decades. Following closely are reanalysis systems assimilating model and observational data, yielding even longer records and larger number of variables. Thanks to advances in internet technology, it is now easier than ever to visualize and analyze these data using web interfaces. On the other hand, it also becomes an increasingly daunting task to build upon the existing knowledge published in various peer reviewed sources, and navigate toward the most relevant data, analysis, and visualization. We present an analysis of a subset of publications that utilized a popular visualization web interface at the NASA Goddard Earth Science Data and Information Services Center. Known as "Giovanni", it allows researchers from wide backgrounds to work with hundreds of variables from space observations and assimilation systems. Since coming online more than a decade ago, Giovanni has been credited in more than 100 papers per year, and the total count now is estimated to be nearly 1,500. Many of these papers contain valuable information about when, where and how Giovanni has been used, and hence forge an opportunity to learn and share the knowledge of which variables were used for what research projects. The purpose of our work is to retrieve the information from the papers and organize it as a knowledge repository which links together datasets, variables, places, dates and phenomena all of which reflect the essence of the published research. Since the publications are unstructured texts, we use natural language processing along with machine learning methods in the retrieval process. One of the challenges is deciphering the dataset names, because in many cases researchers refer to variables, rather than the datasets containing them. To constrain the number of terms, we deploy Earth Science ontologies as dictionaries for the term extraction. We demonstrate that storing these terms and underlying ontologies, along with datasets, variables and papers in the knowledge graph database, enables various linkages between all these entities facilitating the data discovery. Thus, we are setting a qualitatively new stage in improvements of web data interfaces, where machine learning techniques are used to establish and optimize usage-based discovery of data.

Irina V Gerasimov↗
NASA NTRS1992

The structure of the inner arcsecond of R Aquarii observed with the Hubble Space Telescope

The inner arcsec of R Aquarii has been observed with the Faint Object Camera on the Hubble Space Telescope. A simple and reliable linear deconvolution method is used to resolve the two features, designated C1 and C2 from radio observations, into several condensations. C1 is composed of four objects, designated C1a, C1b located at 0.099 arcsec from C1a, C3 at 0.162 arcsec from C1a, and C4 at 0.137 arcsec from C1a. The source C3, detected at 2 cm in the radio and in H-alpha, might be the V = 6-11 Mira variable. The nature of feature C4 is still unknown. Features C1a and C1b have not been resolved by another instrument, and it might be possible that the hot star is one of the two or a nearby nondetected object.

Burgarella, Denis↗
NASA NTRS1972

Radio tracking of solar energetic particles through interplanetary space.

Satellite observations of traveling solar radio bursts provide information about the propagation of energetic solar particles through interplanetary space. This information leads to data on the solar wind density and gross magnetic field configuration over distances of 1 AU. By placing a radio telescope well above the ionosphere it is possible to observe the radio emission down to frequencies that correspond to emission at distances of the order of 1 AU. The observations reported provide the first 'radio picture' over 1 AU of the spiral magnetic field configuration in interplanetary space.

Fainberg, J.↗
NASA NTRS1999

Earth Observing System: Present Capabilities and Promises for the Future

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. During this year 5 EOS science missions are scheduled for launch, representing observations of (i) total solar irradiance, (ii) Earth radiation budget, (iii) land cover & land use change, (iv) ocean processes (vector wind, sea surface temperature, and ocean color), (v) atmospheric processes (aerosol and cloud properties, water vapor, and temperature and moisture profiles), and (vi) atmospheric chemistry (both tropospheric and stratospheric). In succeeding years many more satellites will be launched that will contribute immeasurably to our understanding of the Earth's environment. In this presentation I will describe how scientists intend to use MODIS, an earth-viewing cross-track scanning spectroradiometer to be launched on the Terra satellite in summer 1999, for the remote sensing of cloud and aerosol properties. MODIS will scan a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, sun-synchronous, platform at an altitude of 705 km. In addition, I will describe key elements of other instruments recently launched or planned for flight in the coming months. Finally, I will lay out a plan for the future space-based observing system being planned by NASA and its partners.

King, Michael D.↗
NASA NTRS2011

External Surface Changes Observed on the International Space Station (ISS) Through 2010

Some worse-than-expected materials degradation effects have been observed, but none have created any operational issues and some hardware (as with the anodized aluminum labels) appear to be recovering. Inadvertent materials substitutions have been observed, but none have created any operational issues. Hardware handling contamination effects have been observed, and although none have created operational issues, there is clearly room for improvement in this regard. Even with robust materials selections, space environmental effects will be observed. Be cautious when interpreting on-orbit photography, as lighting conditions and the space environment affect imaging.

Golden, J. L.↗
NASA NTRS1994

Detection of the SO2 atmosphere on Io with the Hubble Space Telescope

Observations of the trailing hemisphere of Io made with the Faint Object Spectrograph of the Hubble Space Telescope (HST) in March 1992 have resulted in the first detection of atmospheric SO2 absorption bands in the ultraviolet. These observations represent only the third positive means of detection of what is widely believed to be Io's primary atmospheric constituent. Below approximately 2130 A the geometric albedo of the satellite is dominated by SO2 gas absorption band signatures, which have been analyzed using models that include the effects of optical thickness, temperature, and spatial distribution. The disk-intergrated HST data cannot resolve the spatial distribution, but it is possible to define basic properties and set constraints on the atmosphere at the time of the observations. Hemispheric atmospheres with average column density N = 6 - 10 x 10(exp 15)/sq sm and T(gas) = 110 - 500 K fit the data, with preference for temperatures of approximately 200 - 250 K. Better fits are found as the atmosphere is spatially confined, with a limit of approximately 8% hemispheric areal coverage and N approximately equal to 3 x 10(exp 17)/sq cm with colder 110 - 250 K temepratures. A dense (N greater than or equal to 10(exp 16)/sq cm), localized component of SO2 gas, such as that possibly associated with active volcanoes, can generate the observed spectral constrast only when the atmosphere is cold (110 K) and an extended component such as Pele is included. The combination of a dense, localized atmosphere with a tenuous component (N less than 10(exp 16)/sq cm, either patchy or extended) also fits the data. In all cases the best fit models imply a disk-averaged column density larger than exospheric but approximately 10 - 30 times less than the previous upper limit from near-UV observations.

Ballester, G. E.↗
NASA NTRS2006

Observing Ice in Clouds from Space

There are many satellite observations of cloud top properties and the liquid and rain content of clouds, however, we do not yet quantitatively understand the processes that control the water budget of the upper troposphere where ice is the predominant phase, and how these processes are linked to precipitation processes and the radiative energy budget. The ice in clouds in the upper troposphere either melts into rain or is detrained, and persists, as cirrus clouds affecting the hydrological and energy cycle, respectively. Fully modeling the Earth's climate and improving weather and climate forecasts requires accurate satellite measurements of various cloud properties at the temporal and spatial scales of cloud processes. These properties include cloud horizontal and vertical structure, cloud water content and some measure of particle sizes and shapes. The uncertainty in knowledge of these ice characteristics is reflected in the large discrepancies in model simulations of the upper tropospheric water budget. Model simulations are sensitive to the partition of ice between precipitation and outflow processes, i.e., to the parameterization of ice clouds and ice processes. One barrier to achieving accurate global ice cloud properties is the lack of adequate observations at millimeter and submillimeter wavelengths (183-874 GHz). Recent advances in instrumentation have allowed for the development and implementation of an airborne submillimeter-wave radiometer. The brightness temperatures at these frequencies are especially sensitive to cirrus ice particle sizes (because they are comparable to the wavelength). This allows for more accurate ice water path estimates when multiple channels are used to probe into the cloud layers. Further, submillimeter wavelengths offer simplicity in the retrieval algorithms because they do not probe into the liquid and near surface portions of clouds, thus requiring only one term of the radiative transfer equation (ice scattering) to relate brightness temperatures to ice. The next step is a satellite mission designed to acquire global Earth radiance measurements in the submillimeter-wave region, thus bridging the measurement gap between microwave sounders and shorter-wavelength infrared and visible sensors. This presentation provides scientific justification and an approach to measuring ice water path and particle size from a satellite platform that spans a range encompassing both the hydrologically active and radiatively active components of cloud systems.

Ackerman, S.↗