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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Reflectance measurements of cotton leaf senescence altered by mepiquat chloride

Spectrophotometric reflectance measurements were made on plant-attached leaves to evaluate growth chamber-grown cotton leaf (Gossypium hirsutum L.) senescence (chlorophyll degradation as criterion) that was delayed by mepiquat chloride (1,1-dimethylpiperidinium chloride) rates of 0, 10, 40, 70, and 100 g a.i./ha. Mepiquat chloride (MC increased both chlorophyll and leaf water contents as compared with that of untreated leaves. Reflectance was inversely and linearly correlated (r = -0.873**) with eater content at the 1.65 micrometer wavelength and was inversely correlated (r = -0.812**) with chlorophyll concentration at the 0.55 micrometer wavelength but best fit a quadratic equation. Either wavelength measurement might be useful to remotely detect cotton leaf senescence or fields of MC-treated cotton plants.

Gausman, H. W.↗
NASA NTRS1984

FTIR-spectrometer-determined absorption coefficients of seven hydrazine fuel gases - Implications for laser remote sensing

The absorption spectra of three hydrazines and four of their air-oxidation products were measured in the 9-12-micron spectral region with a Fourier transform infrared (FTIR) spectrometer with a 0.05-kayser resolution to determine absorption coefficients at CO2 and tunable diode laser wavelengths. The measurements agreed well with published CO2 laser determinations for many of the absorption coefficients, except where the published values are thought to be in error. The coefficients were then used to estimate the sensitivity for remote detection of these gases using CO2 and tunable diode lasers in long-path differential absorption measurements.

Molina, L. T.↗
NASA NTRS1986

The discrimination between crude-oil spills and monomolecular sea slicks by an airborne lidar

Airborne lidar measurements were performed over a deployed monomolecular oleyl alcohol surface film ('slick'), the physicochemical characteristics of which are known to be similar to biogenic organic compounds secreted by plankton and fish, and adjacent 'clean' sea surfaces in the North Sea. In the presence of the slick, the suppression of the Raman backscatter at 381 nm and of two spectral bands indicative of water column fluorescent organic material at 414 and 482 nm were observed. This effect is explained by two possible mechanisms giving rise to a modification of the transmission or coupling of the laser beam into the water column: (1) the damping of capillary and short gravity water waves by the oleyl alcohol slick, and (2) the modification of the uppermost water layer by the oleyl alcohol film. The results obtained in the presence of a slick are compared with data measured over a Murban crude-oil spill with the same lidar system off the coast of the U.S.A. The consequences of the lidar-monomolecular film experiments with regard to the remote detection of crude-oil spills and oil-thickness measurements with an airborne laser fluorosensing system will be discussed.

Huehnerfuss, H.↗
NASA NTRS1987

Remote sensing of the earth's biosphere - A tool for studies of the global atmospheric environment

Recent advances in remote sensing technology and its use for global studies of the biospheric processes are described. Special consideration is given to research related to two issues: (1) quantifying the impacts of natural vegetation and its changing patterns of occurrence on the atmospheric CO2 budget and (2) assessing wetlands (such as the swamps and marshes of Florida's Everglades) as sources of atmospheric CH4. The results include the data from NOAA-AVHRR sensors and from experiments in remote detection of plant growth rate.

Bartlett, David S.↗
NASA NTRS1987

Estimating key forest ecosystem parameters through remote sensing

Forest canopy chemistry and biomass indicators of ecosystem photosynthesis and decomposition processes are presently studied in view of Airborne Imaging Spectrometer data, which generated spectra from averaged 3 x 3 pixel areas for each of 20 sites for mutual qualitative comparison. Vegetation spectra were strongly differentiated from other cover types by an apparent absorption feature at 1500-1700 nm. Preliminary work with stepwise regression suggests that lignin may play a role in canopy reflectance, and that there is potential for remote detection of forest canopy lignin.

Wessman, Carol A.↗
NASA NTRS1989

The heliospheric neutral hydrogen density profile in the presence of a solar wind shock

The effect of a postulated nearby solar wind shock on the radial density profile of the cold inflowing neutral hydrogen atoms is studied. It is found that a nearby solar wind shock strongly affects the neutral hydrogen breeze. Model calculation reveals that the strongly perturbed hydrogen atom distribution beyond a solar wind shock can be remotely detected by observation of the radial dependence of the backscattered UV glow from the deep space probes Pioneer 10/11 and Voyager 1/2.

Gangopadhyay, P.↗
NASA NTRS1990

Analysis of aircraft performance during lateral maneuvering for microburst avoidance

Aircraft response to a severe and a moderate three-dimensional microburst model using nonlinear numerical simulations of a Boeing 737-100 is studied. The relative performance loss is compared for microburst escape procedures with and without lateral maneuvering. The results show that the hazards caused by the penetration of a microburst in the landing phase are attenuated if lateral escape maneuvers are applied in order to turn the aircraft away from the microburst core rather than flying straight through. If the lateral escape maneuver is initiated close to the microburst core, high bank angles tend to deteriorate aircraft performance. Lateral maneuvering is also found to reduce the advanced warning required to escape from microburst hazards but requires that information of the existence and location of the microburst is available (i.e., remote detection) in order to avoid an incorrect turn toward the microburst core.

Avila De Melo, Denise↗
NASA NTRS1990

Flow downstream of the heliospheric terminal shock. I - Irrotational flow

Recent reports of remote detection of the heliospheric terminal shock place it near 50 AU. These conflict with standard models which, when combined with current data on the local interstellar medium, place the shock beyod 100 AU. Resolution of this discrepancy has led to hypotheses that invoke cosmic ray pressure, momentum exchange with interstellar neutrals, and magnetic field effects between the shock and the contact discontinuity dividing the solar wind from interstellar plasma. These hypotheses depend not only on properties of the interstellar medium, but also on the downstream three-dimensional flow between the shock and the contact discontinuity, in the region called the 'heliosheath'. The downstream flow field in the absence of magnetic fields is examined here under the assumptions that the flow everywhere outside the shock can be approximated as irrotational and incompressible. It is found, in particular, that the distance between the terminal shock and the contact discontinuity is less than the heliocentric distance to the terminal shock, effectively eliminating magnetic field effects in the heliosheath as being dynamically important.

Suess, Steven T.↗
NASA NTRS1990

The heliopause

A Pioneer or Voyager spacecraft will soon pass through one of the last major frontiers in the solar system - the heliospheric terminal shock. Some unknown, but perhaps small, distance beyond the terminal shock is the heliopause, marking the final boundary between solar-wind and Galactic plasmas and the final goal of these spacecraft. This occasion offers an opportunity to obtain a wealth of information on the properties of the Galaxy, the interstellar medium, and the large-scale interactions of that medium with stellar winds. Several tentative remote detections of the shock place it just beyond the present spacecraft locations. However, uncertainties in the physical processes and parameters that determine the location of the boundary lead to equal uncertainties in predicting which of the spacecraft will reach it first.

Suess, Steven T.↗
NASA NTRS1992

Numerical simulations of bursty radio emissions from planetary magnetospheres

One-dimensional electromagnetic particle simulations are used to investigate the characteristics of radiation from electron beams with a large temperature anisotropy, in order to identify the origin of the smooth and bursty radio emissions from Uranus and Neptune observed by the Voyager spacecraft. It is shown that these electron beams, which would typically originate from the sporadic or impulsive injections of energetic electrons, can generate electromagnetic radiation which should be able to escape into the solar wind despite the growth of the electrostatic instability. The amount of radiation with frequencies above the local x mode cutoff increases with the beam speed. It is also proposed that some of the radiation generated below the local x mode cutoff may also be able to escape the plasma and be detected remotely via mode conversion between regions where field-aligned currents produce local perturbations in the magnetic field.

Winglee, R. M.↗
NASA NTRS1992

Solar-generated disturbances in the heliosphere

It has long been known that disturbances can propagate from Sun to Earth with periods of a few days following large solar flares. Other disturbances re-occur with the solar rotation rate implying that they are more or less stably generated by a specific region on the solar surface. At the Sun some of these disturbances are readily observed in coronagraphs and against the solar disk. Several techniques have been used to remotely detect and follow different disturbances in the interplanetary medium as they propagate outward from the Sun. These techniques include interplanetary scintillation, kilometric radio and Helios photometer observations. In situ, spacecraft can mark the passage of disturbances by direct measurement along the column convected past the observation point. As probes of the heliospheric magnetic field and disturbances in themselves, particles above the energy of the thermal plasma traverse the heliosphere and indicate the extent of its structures. Both the basic physics, as well as the spatial and temporal evolution of disturbances, can be confused as they propagate through the interplanetary medium largely because of the data coverage limitations. However, as their basic physics becomes better known through more complete observations and theory, the extent and accuracy of these disturbances can be better described.

Jackson, B. V.↗
NASA NTRS1998

Compositional Variation in Lunar Regolith Samples: Vertical

Some techniques for measuring composition and mineralogy remotely detect only the upper few micrometers to millimeters of material. Is this a serious concern for lunar regolith studies? Here it is shown the centimeter-scale variation with depth in the composition of lunar regolith based on results of the studies of regolith cores taken on the Apollo missions. In short, the compositional variation of lunar regolith with depth over tens of centimeters is equivalent to that observed laterally at the surface over kilometers. On average, however, the composition of material in the upper half centimeter is probably reasonably representative of the upper half meter or more (the depth of most Apollo cores), particularly for measurements made from orbit that integrate over a large surface area.

Korotev, Randy L.↗
NASA NTRS1997

Comparison of interplanetary type 2 radio burst observations by ISEE-3, Ulysses, and WIND with applications to space weather prediction

Interplanetary (IP) type 2 radio bursts are produced by IP shocks driven by solar ejecta, presumably involving shock acceleration of electrons that leads to radio emission. These radio bursts, which can be detected remotely by a sensitive spacecraft radio receiver, provide a method of tracking the leading edge of solar ejecta moving outward from the sun. Consequently, observations of these bursts sometimes provide advance warning of one or more days prior to the onset of geomagnetic activity induced by the solar ejecta. A robust lower limit on the fraction of intense geomagnetic storms, that are preceded by IP type 2 bursts, is provided. It is shown that 41 percent of the geomagnetic storms occurring during the interval September 1978 to February 1983 were preceded by type 2 events in this catalog, and reasons why the fraction is not larger are addressed. Differences in the observing capabilities of the International Sun-Earth Explorer (ISEE) 3, Ulysses, and WIND, to explain why each of these similar spacecraft radio investigations provides a different perspective of IP type 2 emissions are reviewed.

MacDowall, R. J.↗
NASA NTRS2000

Describing and Measuring the Chemical Signatures of Life

Here we discuss an approach to remotely detecting extraterrestrial life forms on other planets or their moons by detection of specific types of organic molecules. The life entities to be detected would be presently active life forms, or those that are only recently dormant. The only place beside Earth's moon where humans have actually examined surface soils for the presence of organic molecules is Mars. This was accomplished using mass-spectrometry during the Viking mission, and results were negative. The lack of organic moieties, if they ever were present, probably resulted form their destruction over geologic time frames by the extraordinarily reactive surface soils found there. Thus, on Mars, detection of organic signatures of life probably would be possible only in subsurface soils, or perhaps in polar regions.

Crawford, R. L.↗
NASA NTRS2002

Determining the Compositions of Extraterrestrial Lava Flows

The primary purpose of this research project has been to develop techniques that allow the emplacement conditions of volcanic landforms on other planets to be related to attributes that can be remotely detected with available instrumentation. The underlying assumption of our work is that the appearance of a volcano, lava flow, debris avalanche, or exhumed magmatic intrusion can provide clues about the conditions operating when that feature was first emplaced. Magma composition, amount of crustal heat flow, state of tectonic stress, and climatic conditions are among the important variables that can be inferred from the morphology and texture of an igneous body.

Fink, Jonathan H.↗
NASA NTRS1999

Subsurface Microsensors for Assisted Recertification of TPS (SmarTPS)

Commercialization of a competitive reusable launch vehicle (RLV) is a primary goal for both NASA and the U.S. aerospace industry. To expedite achievement of this goal, the Bantam-X Technology Program is funding development of innovative technologies to lower costs for access to space. Ground operations is one area where significant cost reduction is required. For the Shuttle fleet, ground operations account for over 80% of the life cycle costs, and TPS recertification accounts for 27% of the operation costs ($4.5M per flight). Bantam Task TPS-7, Subsurface Microsensors for Assisted Recertification of TPS (SmarTPS), is a joint effort between NASA centers and industry partners to develop rapid remote detection and scanning technology for inspection of TPS and detection of subsurface defects. This short paper will provide a general overview of the SmarTPS concept.

Pallix, Joan B.↗
NASA NTRS1998

A remotely interrogatable sensor for chemical monitoring

A new type of continuously operating, in-situ, remotely monitored sensor is presented. The sensor is comprised of a thin film array of magnetostatically coupled, magnetically soft ferromagnetic thin film structures, adhered to or encased within a thin polymer layer. The polymer is made so that it swells or shrinks in response to the chemical analyte of interest, which in this case is pH. As the polymer swells or shrinks, the magnetostatic coupling between the magnetic elements changes, resulting in changes in the magnetic switching characteristics of the sensor. Placed within a sinusoidal magnetic field the magnetization vector of the coupled sensor elements periodically reverses directions, generating magnetic flux that can be remotely detected as a series of voltage spikes in appropriately placed pickup coils. one preliminary sensor design consists of four triangles, initially spaced approximately 50 micrometers apart, arranged to form a 12 mm x 12 mm square with the triangle tips centered at a common origin. Our preliminary work has focused on monitoring of pH using a lightly crosslinked pH sensitive polymer layer of hydroxyethylmethacrylate and 2-(dimethylamino) ethylmethacrylate. As the polymer swells or shrinks the magnetostatic coupling between the triangles changes, resulting in measurable changes in the amplitude of the detected voltage spirits.

Non-NASA Center↗
NASA NTRS2005

Then Why Do They Call Earth the Blue Planet?

While the most common photographs of Earth taken from space show the planet covered in blue water, NASA has managed to produce detailed color images, using satellite imagery, that show the remarkable variation of colors that actually make up the oceanic surface. An ocean s color is determined by the interaction of surface waters with sunlight, and surface waters can contain any number of different particles and dissolved substances, which could then change the color. Then Why Do They Call Earth the Blue Planet? The particles are mostly phytoplankton, the microscopic, single-celled ocean plants that are the primary food source for much marine life. Remote detection of phytoplankton provides information about the uptake and cycling of carbon by the ocean through photosynthesis, as well as the overall health of the water. Inorganic particles and substances dissolved in the water also affect its color, particularly in coastal regions. Satellite images can be used to calculate the concentrations of these materials in surface waters, as well as the levels of biological activity. The satellites allow a global view that is not available from ship or shore. NASA s orbiting satellites offer a unique vantage point for studying the oceans. By resolving the biological, chemical, and physical conditions in surface waters, they have allowed the oceanographic community to make huge leaps in its understanding of oceanographic processes on regional and global fronts. The study of ocean color, in particular, has been integral in helping researchers understand the natural and human-induced changes in the global environment and establishing the role of the oceans in the biochemical cycles of elements that influence the climate and the distribution of life on Earth.

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