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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 343 records · Page 19
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NASA NTRS2023

The Eruption of a Magnetic Flux Rope Observed By Solar Orbiter and Parker Solar Probe

Magnetic flux ropes are a key component of coronal mass ejections, forming the core of these eruptive phenomena. However, determining whether a flux rope is present prior to eruption onset and, if so, the rope’s handedness and the number of turns that any helical field lines make is difficult without magnetic field modelling or in-situ detection of the flux rope. We present two distinct observations of plasma flows along a filament channel on 4 and 5 September 2022 made using the Solar Orbiter spacecraft. Each plasma flow exhibited helical motions in a right-handed sense as the plasma moved from the source active region across the solar disk to the quiet Sun, suggesting that the magnetic configuration of the filament channel contains a flux rope with positive chirality and at least one turn. The length and velocity of the plasma flow increased from the first to the second observation, suggesting evolution of the flux rope, with the flux rope subsequently erupting within ∼5 hours of the second plasma flow. The erupting flux rope then passed over the Parker Solar Probe spacecraft during its Encounter 13, enabling in-situ diagnostics of the structure. Although complex and consistent with the flux rope erupting from underneath the heliospheric current sheet, the in-situ measurements support the inference of a right-handed flux rope from remote-sensing observations. These observations provide a unique insight into the eruption and evolution of a magnetic flux rope near the Sun.

Dynamics↗
NASA NTRS1998

Bidirectional Reflectance Factors used in Lidar Calibration

Many atmospheric remote sensing applications of infrared lidar systems require that the backscatter signal be radiometrically calibrated. These systems are usually monostatic, consequently the reflected radiance from hard targets used in calibration will include the diffuse and the retroreflectance characteristics of the material. Radiometers which are part of orbiting sensors frequently contain onboard calibration subsystems. The onboard calibrator often utilizes onboard reflectance panels which are deployed at particular orbital locations to use the reflected sun light to calibrate the radiometers. To meet the need for correlative calibration of these remote sensing techniques a physically derived model could be used to extend the angular range and to improve the angular resolution of the measured reflectance properties of the calibration materials. A modified version of the B. Hake and E. Wells model has been adapted and will be described.

Haner, David A.↗
NASA NTRS2007

Efficient Dual Head Nd:YAG 100mJ Oscillator for Remote Sensing

A diode pumped, Nd:YAG laser producing 100 mJ Q-switched pulses and employing a dual-pump head scheme in an unstable resonator configuration is described. Each head contains a side pumped zig-zag slab and four 6-bar QCW 808 nm diodes arrays which are de-rated 23%. Denoting 'z' as the lasing axis, the pump directions were along the x-axis in one head and the y-axis in the other, producing a circularized thermal lens, more typical in laser rod-based cavities. The dual head design's effective thermal lens is now corrected with a proper HR mirror curvature selection. This laser has demonstrated over 100 mJ output with high optical efficiency (24%), good TEM(sub 00) beam quality, and high pointing stability.

Coyle, Donald B.↗
NASA NTRS1981

Moon - Near-infrared spectral reflectance, a first good look

Spectral reflectance contains direct information on the mineralogy of the surface soils and rocks. A problem concerning the employment of remote spectral-reflectance sensing techniques for mineralogical studies is related to the lack of photometrically precise spectra of planetary surfaces in the region from 1.0 to 2.5 micrometers, where additional important mineral absorptions occur. Recently, a new instrument was developed, and an observational program is underway to provide the required near-infrared spectra. The first, comprehensive near-infrared spectroscopic results for the moon are presented. It is shown that it is equally possible to derive quantitative mineralogical information about the lunar surface by using remotely sensed reflectance spectra as it is by using laboratory reflectance measurements of lunar samples.

Mccord, T. B.↗
NASA NTRS1998

Environmental Remote Sensing: New Development and Applications

The term 'scale', both in space and time, is central to remote sensing and geographic information systems (GIS). The emergency and widespread use of GIS technologies, including remote sensing, has generated interest in addressing scale as generic Issue, and in the development and implementation of techniques for dealing explicitly with the vicissitudes of scale as a multidisciplinary issue. Traditionally, the paper map has been used as the primary conveyor of 'scale', represented by the ratio between the distance as measured between pairs of points on the map and distance as measured between the same pairs of points on the Earth's surface. GIS and remote sensing, however, have expanded upon the paper map and now provide opportunities for representing multiscale representations; that is databases or models that contain spatial and temporal data that have been obtained and stored at different scales.

Quattrochi, Dale A.↗
NASA NTRS1999

Remote Sensing of Volcanic Clouds: Sulfur Gases and Plume Top Topography

New absorption line parameters for H2S were published and submitted to the Gestion et Etude des Informations Spectroscopiques Atmospheriques (GEISA) and high resolution transmission molecular absorption (HITRAN) databases. These new absorption line parameters will make it possible to use observations from the future Tropospheric Emission Spectrometer (TES) instrument [Earth Observing System (EOS) Chemistry Mission (CHEM) platform] to make more accurate H2S measurements if it observes an H2S-rich volcanic cloud. H2S is the second most abundant volcanic sulfur gas, and like SO2, it also converts to H2SO4 aerosols and can have a climate impact. A paper on the Moderate-resolution Imaging-Spectroradiometer (MODIS) SO2 alert is being revised. New aspects in the revision include verification of the SO2 alert during the EOS mission; factors affecting SO2 detection at thermal infrared, ultraviolet, and microwave wavelengths; radiative transfer tests; more description of satellite instruments; and thermal surface alert installed for MODIS. Her research involves the use of remote sensing to generate maps of plume top altitude. This parameter is important for models of volcanic eruption, aircraft hazards, and climate impact. The topographic shape of the top surface of a volcanic plume can provide information necessary to understand the physics controlling the injection and dispersal of a volcanic plume in the atmosphere. Glaze et al. describe the application of a photoclinometric technique to volcanic plumes. The software algorithm has been improved to account for more general plume and illumination geometries and for easily extracting position information directly from Advanced Very High-Resolution Radiometer (AVHRR) level 1B data. Testing of the algorithm has focused on acquiring AVHRR data for a variety of volcanic plumes in an effort to identify problems with the software as well as model sensitivities. The plumes chosen were erupted from volcanoes at a variety of latitudes, at different times of day, and in different seasons. Another important issue that is being investigated is the importance of plume opacity. A diagram illustrates the method for deriving phi, the angle a wind-blown plume makes with the horizontal, in the direction perpendicular to the remote sensing scan. A figure shows a sample output of the algorithm, a wire mesh map of plume top topography. Additional information is contained in the original.

Crisp, Joy A.↗
NASA NTRS2000

On The Genesis of Tropical Cyclones: Role of Mesoscale Interactions

Before the last decades of the 20th century, observations were rarely adequate to assess the role of mesoscale circulations in the formation of tropical cyclones. Recent developments in remote-sensing technology have allowed routine collection of measurements that reveal the small- and mesoscale structure of forming tropical cyclones. Additional information is contained in the original extended abstract.

Ritchie, Elizabeth↗
NASA NTRS2002

Geologist's Field Assistant: Developing Image and Spectral Analyses Algorithms for Remote Science Exploration

We are developing science analyses algorithms to interface with a Geologist's Field Assistant device to allow robotic or human remote explorers to better sense their surroundings during limited surface excursions. Our algorithms will interpret spectral and imaging data obtained by various sensors. Additional information is contained in the original extended abstract.

Gulick, V. C.↗
NASA NTRS1986

Method and apparatus for a Fabry-Perot multiple beam fringe sensor

A method and, in one embodiment of the invention, the resulting apparatus for implementing a unique multiple beam fringe sensor that is adapted to be interfaced with a low cost, compact fiber optic transmission system in order to provide an accurate digital representation of a physical parameter (e.g. temperature) of a remote sample. The sensor is fabricated so as to include a Fabry-Perot gap formed between the ends of two mated optical fibers. By examining the optical characteristics of light that is transmitted through the Fabry-Perot sensor gap, an indication of gap width can be ascertained. Accordingly, a change in Fabry-Perot sensor gap width is related to a change in the particular physical parameter to be measured. In another embodiment of the invention, a second unique multiple beam fringe sensor having a Fabry-Perot gap is disclosed that is also adapted to provide an accurate digital representation of a physical parameter (e.g. temperature) of a remote sample. The sensor may be fabricated in two segments. A fiber containing segment includes each of a driving optical fiber for supplying incident light signals to the Fabry-Perot gap and a sensing optical fiber for receiving output light signals that have been transmitted twice through the Fabry-Perot gap, the optical characteristics of which output signals provide an indication of the parameter to be sensed. A transducer segment includes the Fabry-Perot gap formed therein and means responsive to the physical parameter for changing the width of the Fabry-Perot gap and, accordingly, the optical characteristics of the light signals passing therethrough.

James, Kenneth A.↗
NASA NTRS2008

Geologic Mapping of the Meridiani Region, Mars

The light toned bedrock that has been observed at the Mars Exploration Rover Opportunity landing site is an upper layer in a sequence >600 m thick in places. These outcrops contain mineral and textural signatures that require interaction of, and possibly formation from, water. Many distinct layers are visible in the remote sensing data (e.g. Figure 1) and no work has ever characterized the full set of these materials that cover an area >3 105 km2 spanning 20 of longitude. Thus, whatever water-related process( es?) altered, and possibly formed, the rocks at the Opportunity landing site extended over a vast region of Mars. Yet many questions remain to be answered, such as: (1) in what capacity did water form and alter the deposits?, (2) what are the temporal and spatial relations with other major events known from ancient Mars?, and (3) would this type of environment have been conducive to the development of life? To address these questions we are completing a detailed geologic, stratigraphic, and thermophysical properties study of this widespread terrain. Specifically, we are drafting a 1:2M-scale geological map covering the full extent of these water-related deposits. In tandem with the mapping, Hynek and Phillips [1] have conducted a preliminary stratigraphic analysis of the stack of materials. After mapping is complete, we will study the thermophysical properties of the varied layers to derive possible compositional information of the materials. These tasks serve several purposes including gaining an understanding of the complex nature of these materials, their potential source region(s), and their timing of emplacement. All of these efforts are necessary to place the observations by the Opportunity Rover in a broader context and prepare for potential future landed missions to the region. Understanding the large-scale paleohydrology of Mars is central to NASA s goals and vital for determining if life ever arose on the planet.

Hynek, B. M.↗
NASA NTRS2020

Harmonization of global land use change and management for the period 850–2100 (LUH2) for CMIP6

Human land use activities have resulted in large changes to the biogeochemical and biophysical properties of the Earth's surface, with consequences for climate and other ecosystem services. In the future, land use activities are likely to expand and/or intensify further to meet growing demands for food, fiber, and energy. As part of the World Climate Research Program Coupled Model Intercomparison Project (CMIP6), the international community has developed the next generation of advanced Earth system models (ESMs) to estimate the combined effects of human activities (e.g., land use and fossil fuel emissions) on the carbon–climate system. A new set of historical data based on the History of the Global Environment database (HYDE), and multiple alternative scenarios of the future (2015–2100) from Integrated Assessment Model (IAM) teams, is required as input for these models. With most ESM simulations for CMIP6 now completed, it is important to document the land use patterns used by those simulations. Here we present results from the Land-Use Harmonization 2 (LUH2) project, which smoothly connects updated historical reconstructions of land use with eight new future projections in the format required for ESMs. The harmonization strategy estimates the fractional land use patterns, underlying land use transitions, key agricultural management information, and resulting secondary lands annually, while minimizing the differences between the end of the historical reconstruction and IAM initial conditions and preserving changes depicted by the IAMs in the future. The new approach builds on a similar effort from CMIP5 and is now provided at higher resolution (0.25°×0.25°) over a longer time domain (850–2100, with extensions to 2300) with more detail (including multiple crop and pasture types and associated management practices) using more input datasets (including Landsat remote sensing data) and updated algorithms (wood harvest and shifting cultivation); it is assessed via a new diagnostic package. The new LUH2 products contain > 50 times the information content of the datasets used in CMIP5 and are designed to enable new and improved estimates of the combined effects of land use on the global carbon–climate system.

land use land cover change↗
NASA NTRS1984

The future of satellite remote sensing: A worldwide assessment and prediction

A frame-work in which to assess and predict the future prospects for satellite remote sensing markets is provided. The scope of the analysis is the satellite-related market for data, equipment, and services. It encompasses both domestic and international markets and contains an examination of the various market characteristics by market segment (e.g., Federal Government, State and Local Governments, Academic Organizations, Industrial Companies, and Individuals) and primary applications areas (e.g., Geology, Forestry, Land Resource Management, Agriculture and Cartography). The forecasts are derived from an analysis of both U.S. and foreign market data. The evolution and current status of U.S. and Foreign markets to arrive at market growth rates is evaluated. Circumstances and events which are likely to affect the future market development are examined. A market growth scenario is presented that is consistent with past data sales trends and takes into account the dynamic nature of the future satellite remote sensing market. Several areas of current and future business opportunities available in this market are discussed. Specific worldwide forecasts are presented in three market sectors for the period 1980 to 1990.

Spann, G. W.↗
NASA NTRS1990

Remote sensing of Earth terrain

The layered random medium model is used to investigate the fully polarimetric scattering of electromagnetic waves from vegetation. The vegetation canopy is modeled as an anisotropic random medium containing nonspherical scatterers with preferred alignment. The underlying medium is considered as a homogeneous half space. The scattering effect of the vegetation canopy are characterized by 3-D correlation functions with variances and correlation lengths respectively corresponding to the fluctuation strengths and the physical geometries of the scatterers. The strong fluctuation theory is used to calculate the anisotropic effective permittivity tensor of the random medium and the distorted Born approximation is then applied to obtain the covariance matrix which describes the fully polarimetric scattering properties of the vegetation field. This model accounts for all the interaction processes between the boundaries and the scatterers and includes all the coherent effects due to wave propagation in different directions such as the constructive and destructive interferences. For a vegetation canopy with low attenuation, the boundary between the vegetation and the underlying medium can give rise to significant coherent effects.

Kong, Jin AU↗
NASA NTRS1990

Analysis of pressure-broadened ozone spectra in the 3 micron region

The Molecular Spectroscopy Lab at NASA-Langley has been involved in a long term effort to carefully characterize the infrared spectra of small molecules of atmospheric interest, including methane, water vapor, ozone, and their isotopic counterparts. High resolution gas phase infrared spectra are obtained using both a tunable diode laser system, and the McMath Fourier transform spectrometer at the Kitt Peak Solar Observatory. Spectra are obtained at various pressures and temperatures for pure gas samples, and for samples containing mixtures of the species of interest in nitrogen, oxygen, or air. From these spectra, using a nonlinear least squares fitting technique, spectral parameters of position, intensity, and half-width were determined for varying laboratory conditions that approximate atmospheric conditions experienced in remote sensing situations. These parameters are of interest in theoretical studies of these species, as well as in allowing more accurate interpretation of remote sensing data. The current work involves the analysis of a series of McMath FTIR spectra of ozone broadened by mixing with air, nitrogen, or oxygen. Each spectrum covers the region from 2396 to 4057/cm. Each vibrational band is analyzed by first diving its region into small intervals containing a few well isolated absorption lines of reasonable intensity. Each of these small intervals is fit by multiple iterations of the nonlinear least square program until residuals are minimized to a reasonable value which corresponds to the noise level of the measured spectrum. Intervals for the 3 nu(sub 3) ozone band in the region from 3000 to 3060 wavenumbers are being examined.

Prochaska, Eleanor S.↗
NASA NTRS1983

A sun acquisition sensor for spacecraft guidance and control

The combination of a strap-down analog sun acquisition sensor (AS) and an on-board digital programmable signal processor results in a versatile guidance and control system. The combination can orient the rotation axis of a spin-stabilized spacecraft to the sun no matter what the initial attitude of the spacecraft. During the sun orientation process, spacecraft spin rate can be sensed and supplied as an input to the control algorithm. If needed, the AS-signal processor combination can be used to perform a rhumb-line turn maneuver. In case of unexpected spacecraft operating conditions, or unplanned pointing directions, the signal processor program can be updated via earth-based transmission of another program to cover the new situation. Using only three radiation-hard cadmium-sulfide detectors, containing no moving parts, needing only a few microwatts of power, included in a volume of 550 cubic cm (a redundant pair), and weighing only 540 grams, the AS is a small, simple, sturdy sensing device.

Birnbaum, M. M.↗
NASA NTRS1972

Circuit model for characterizing the nearly linear behavior of avalanche diodes in amplifier circuits

A nonlinear circuit model for avalanche diodes is proposed. The model was derived by assuming that the bias dependence of the elements in a known small-signal equivalent-circuit model for existing diodes arises in a manner consistent with the theory of an idealized Read-type device. The model contains a nonlinear R-L branch, a controlled source, and a linear depletion capacitance. The model is used in the nearly linear sense to predict intermodulation distortion and gain compression in avalanche diode amplifiers. Computed results for amplifiers with existing diodes are shown to be in good agreement with experiment.

Penfield, P., Jr.↗
NASA NTRS1999

GPS Ocean Reflection Experiment on Spartan 251

It has recently been demonstrated that the GPS signal which has reflected from the ocean surface contains useful geophysical data from which the sea surface wind speed and other parameters can be extracted. This can be used for remote sensing, similar to present day use of radar altimeters or scatterometers, but with significantly smaller instrumentation because of the utilization of the existing GPS broadcast signal for illumination. Several campaigns of aircraft experimentation have been completed demonstrating this technique and reflected GPS data has been reliably collected from 25 km altitude on a balloon. However, there has not yet been a demonstration that the reflected GPS signal can be detected from orbit with sufficient signal to noise ratio (SNR) to make useful remote sensing measurements. A technology demonstration experiment is planned for a Space Shuttle flight in the late 2000 using the Spartan 251 recoverable carrier. This experiment will be also be the first flight validation of the PiVoT GPS receiver developed in house at the Goddard Space Flight Center. The open-architecture, design of this receiver allows the software modifications to be made which control code-correlator spacing to map out the shape of the reflected signal waveform, which is the most basic data product generated by this instrumentation. A moderate gain left-hand circularly polarized antenna, constructed from an array of off-the-shelf hemispherical antennas will be used to give approximately 6dB of additional gain. Preliminary SNR predictions have been done indicating that this antenna will offer sufficient gain to record waveform measurements. A system level description of the experiment instrumentation, including the receiver, antenna and data storage and retrieval will be given. The visibility of GPS reflections over the mission duration of several hours will be studied, including the effects of the limited beamwidth of the antenna. Additionally, because of the small size of this instrumentation, several other space flight opportunities are being considered in the near term. If these missions materialize, they will be described in the paper as well.

Garrison, James L.↗
NASA NTRS1999

GPS Ocean Reflection Experiment on Spartan 251

It has recently been demonstrated that the GPS signal which has reflected from the ocean surface contains useful geophysical data from which the sea surface wind speed and other parameters can be extracted. This can be used for remote sensing, similar to present day use of radar altimeters or scatterometers, but with significantly smaller instrumentation because of the utilization of the existing GPS broadcast signal for illumination. Several campaigns of aircraft experimentation have been completed demonstrating this technique and reflected GPS data has been reliably collected from 25 km altitude on a balloon. However, there has not yet been a demonstration that the reflected GPS signal can be detected from orbit with sufficient signal to noise ratio (SNR) to make useful remote sensing measurements. A technology demonstration experiment was planned for a Space Shuttle flight in the late 2000 using the Spartan 251 recoverable carrier. This experiment would also have been the first flight validation of the PiVoT GPS receiver developed in house at the Goddard Space Flight Center. The "open-architecture" design of this receiver would allow the software modifications to be made which control code-correlator spacing to map out the shape of the reflected signal waveform, which is the most basic data product generated by this instrumentation. A moderate gain left-hand circularly polarized antenna, constructed from an array of off-the-shelf hemispherical antennas was to be used to give approximately 3 to 6 dB of additional gain. Preliminary SNR predictions have been done indicating that this antenna would offer sufficient gain to record waveform measurements. A system level description of the experiment instrumentation, including the receiver, antenna and data storage and retrieval will be given. The visibility of GPS reflections over the mission duration of several hours will be studied, including the effects of the limited beamwidth of the antenna. Spartan 251 has now been postponed with the earliest opportunity in the year 2002. The results of this study however, have been 2 used to further the define the requirements and expected performance of reflected GPS receivers in orbit. Several other space flight opportunities are being considered based upon this new information.

Garrison, James L↗