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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Complementary information between UV and IR for remote sensing of total ozone

When infrared and ultraviolet measurements are available simultaneously with the same field of view, it is possible to minimize some of the errors in measuring the total ozone. The addition of the infrared technique to Total Ozone Mapping Spectrometer (TOMS) operation can aid in getting measurements of ozone in the nighttime and during the polar night. A radiometer with a channel in the window region around 11 microns, a channel in the 9-6 micron O sub 3 band, and three channels in the 15 micron CO sub 2 band should be adequate to retrieve total ozone. Such a radiometer could be designed to do cross track scanning. This combination of ultraviolet and infrared instruments could be flown on a geostationary or polar orbiting satellite.

Cuddapah, Prabhakara↗
NASA NTRS1988

CANOZE measurements of the Arctic ozone hole

In CANOZE 1 (Canadian Ozone Experiment), a series of 20 ozone profile measurements were made in April, 1986 from Alert at 82.5 N. CANOZE is the Canadian program for study of the Arctic winter ozone layer. In CANOZE 2, ozone profile measurements were made at Saskatoon, Edmonton, Churchill and Resolute during February and March, 1987 with ECC ozonesondes. Ground based measurements of column ozone, nitrogen dioxide and hydrochloric acid were conducted at Saskatoon. Two STRATOPROBE balloon flights were conducted on February 26 and March 19, 1987. Two aerosol flights were conducted by the University of Wyoming. The overall results of this study will be reported and compared with the NOZE findings. The results from CANOZE 3 in 1988, are also discussed. In 1988, as part of CANOZE 3, STRATOPROBE balloon flights were conducted from Saskatchewan on January 27 and February 13. A new lightweight infrared instrument was developed and test flown. A science flight was successfully conducted from Alert (82.5 N) on March 9, 1988 when the vortex was close to Alert; a good measurement of the profile of nitric acid was obtained. Overall, the Arctic spring ozone layer exhibits many of the features of the Antarctic ozone phenomenon, although there is obviously not a hole present every year. The Arctic ozone field in March, 1986 demonstrated many similarities to the Antarctic ozone hole. The TOMS imagery showed a crater structure in the ozone field similar to the Antarctic crater in October. Depleted layers of ozone were found in the profiles around 15 km, very similar to those reported from McMurdo. Enhanced levels of nitric acid were measured in air which had earlier been in the vortex. The TOMS imagery for March 1987 did not show an ozone crater, but will be examined for an ozone crater in February and March, 1988, the target date for the CANOZE 3 project.

Evans, W. F. J.↗
NASA NTRS1989

Uranus - Beneath that bland exterior

Findings made by the Voyager missions regarding the atmosphere, magnetic field, rings, and satellites of Uranus are reviewed. The reasons for the bland appearance of the planet are addressed, and the use of radio and infrared instruments to determine the rotational speeds of the planet and atmosphere, the equatorial radius, and the atmospheric temperature is discussed. The corkscrew magnetic field and the dark, almost dust-free rings are described. The most significant features of the largest Uranian moons are mentioned.

Simpson, Richard A.↗
NASA NTRS1991

Infrared remote sensing of cometary parent volatiles from the ground, air, and space

A balanced view of the present generation of infrared instruments for cometary compositional studies is presented. Ground-based instruments are compared with airborne and spaceborne capabilities. An attempt to give examples of the unique science achievable with each is made, and particular emphasis is on the unique aspects of a dedicated Cometary Composition Telescope in earth orbit for investigating the chemical and structural heterogeneity of the cometary nucleus.

Mumma, Michael J.↗
NASA NTRS1990

Laboratory measurements of NO2 line parameters near 1600/cm for the interpretation of stratospheric spectra

Tunable diode laser laboratory measurements of infrared spectral parameters of selected NO2 lines near 1600/cm have been made to assess the contribution of uncertainties in these parameters to stratospheric measurements of NO2 made using the Balloon-Borne Laser In-Situ Sensor (BLISS) tunable diode laser spectrometer. Relative line intensities are measured to accuracies of better than 2 percent, with a root-sum-squared uncertainty in the absolute linestrengths of 4.5 percent. Air-broadening coefficients have been determined from measurements at total pressures in the range 20-100 Torr, at temperatures of 293 K and 214 K. These results are also discussed in the light of the discrepancies between infrared instruments flown in the 1982 and 1983 Balloon Intercomparison Campaigns.

May, R. D.↗
NASA NTRS1991

Infrared astronomy takes center stage

Characteristics of infrared astronomy, including the ability to detect cool matter, explore the hidden universe, reveal a wealth of spectral lines, and reach back to the beginning of time are outlined. Ground-based infrared observations such as observations in the thermal infrared region are discussed as well as observations utilizing infrared telescopes aboard NASA aircraft and orbiting telescopes. The Space Infrared Telescope Facility and the Stratospheric Observatory for Infrared Astronomy are described, and it is pointed out that infrared astronomers can penetrate obscuring dust to study stars and interstellar matter throughout the Milky Way galaxy. Application of various infrared instruments to the investigation of stars and planets is emphasized, and focus is placed on the discovery of clouds or disks of particles around mature stars and acquisition of high-resolution spectra of the gaseous and solid materials orbiting on the fringes of the solar system.

Gillett, Frederick C.↗
NASA NTRS1990

Infrared spectroscopic remote sensing from the Cassini orbiter

An infrared spectroscopy instrument for infrared remote sensing from the Cassini orbiter is being breadboarded in the laboratory. The Composite Infrared Spectrometer (CIRS) consists of a pair of Fourier Transform Spectrometers (FTS) which together cover the range from 10 - 1400/cm with a spectral resolution up to 0.5/cm. The far-infrared FTS is a polarizing interferometer covering the 10 - 300/cm range. The mid-infrared FTS is a conventional Michelson FTS covering 200 - 1400/cm in three spectral channels. CIRS will retrieve information on the atmospheres of Titan and Saturn with good vertical resolution, from deep in their tropospheres to high in their stratospheres, and into the upper few centimeters of the regoliths of icy objects. The science objectives and design of CIRS are discussed.

Kunde, V.↗
NASA NTRS1992

FET's Perform Well At Cryogenic Temperatures

New metal-oxide-semiconductor field-effect transistors designed for source-follower preamplifiers operating at liquid-helium temperatures in conjunction with infrared detectors. Lower thresholds and offset give CryoFET's greater dynamic range and linearity than conventional MOSFET's at low temperatures and facilitates pair balancing to reduce offsets in output. Reduces heat loading of cryogenic system, extending life, reliability, and performance of cryogenic infrared instruments.

Sclar, N.↗
NASA NTRS1993

Development Of Multilayer Metallic Mesh Low-Pass Infrared Filters

Prototype filters exhibit desired transmissivity vs. wavelength. Etched-metallic-film low-frequency-pass (long-wavelength-pass) filters with relatively sharp cut-on at wavelengths of 30 to 40 micrometers developed for use in infrared instruments. Filters particularly useful in observing astronomical bodies exhibiting wide temperature dynamic range. Reduction in signal dynamic range (due to temperature extremes) accomplished by blocking short-wavelength radiance by using low-pass metallic mesh filters.

Mobasser, Sohrab↗
NASA NTRS1992

Separation of temperature and emittance in remotely sensed radiance measurements

The remote determination of surface temperature and surface spectral emittance by use of airborne or satellite-borne thermal infrared instruments is not straightforward. The radiance measured is a function of surface temperature, the unknown surface spectral emittance, and absorption and emission in the intervening atmosphere. With a single measurement, the solution for temperature and spectral emittance is undedetermined. This article reviews two of the early approximate methods which have been fairly widely used to approach this problem.

Kahle, Anne B.↗
NASA NTRS1992

Measurements and model calculations of HCl column amounts and related parameters over McMurdo during the austral spring in 1989

Solar spectra obtained from a ground-based Fourier transform infrared instrument at McMurdo (Antarctica) in the spring of 1989 have been analyzed to determine total HCl column amounts. A one-dimensional photochemical model was used to simulate the rate of recovery of HCl in the springtime. Low column amounts (about 1 x 10 exp 15 molecules/sq cm) were observed in early September and may be attributed to the heterogeneous conversion of HCl to active chlorine species during the polar night. The rate of recovery of HCl is consistent with its production by chlorine atoms reacting with methane and is dependent on concentrations of active chlorine species and NO molecules in the altitude region from 12 to 22 km. High HCl column amounts (about 7 x 10 exp 15 molecules/sq cm) were observed following recovery in late October, suggesting that the lower stratosphere in the polar region had descended relative to mid-latitudes and that the degree of dechlorination of the transported air was very small.

Liu, X.↗
NASA NTRS1994

The Two Micron All Sky Survey

The Two Micron All Sky Survey (2MASS) will provide a uniform survey of the entire sky at three near-infrared wavebands: J(lambda(sub eff) = 1.25 micrometers), H(lambda(sub eff) = 1.65 micrometers), and K(sub s)(lambda(sub eff) = 2.16 micrometers). A major goal of the survey is to probe large scale structures in the Milky Way and in the Local Universe, exploiting the relatively high transparency of the interstellar medium in the near-infrared, and the high near-infrared luminosities of evolved low- and intermediate-mass stars. A sensitive overview of the near-infrared sky is also an essential next step to maximize the gains achievable with infrared array technology. Our assessment of the astrophysical questions that might be addressed with these new arrays is currently limited by the very bright flux limit of the only preceding large scale near-infrared sky survey, the Two Micron Sky Survey carried out at Caltech in the late 1960's. Near-infrared instruments based on the new array technology have already obtained spectra of objects 1 million times fainter than the limit of the TMSS! This paper summarizes the essential parameters of the 2MASS project and the rationale behind those choices, and gives an overview of results obtained with a prototype camera that has been in operation since May 1992. We conclude with a list of expected data products and a statement of the data release policy.

Kleinmann, S. G.↗
NASA NTRS2000

High Resolution Spectroscopy to Support Atmospheric Measurements

The major research activities performed during the cooperative agreement enhanced our spectroscopic knowledge of molecules of atmospheric interest such as carbon dioxide, water vapor, ozone, methane, and carbon monoxide, to name a few. Measurements were made using the NASA Langley Tunable Diode Laser Spectrometer System (TDL) and several Fourier Transform Spectrometer Systems (FTS) around the globe. The results from these studies made remarkable improvements in the line positions and intensities for several molecules, particularly ozone and carbon dioxide in the 2 to 17-micrometer spectral region. Measurements of pressure broadening and pressure induced line shift coefficients and the temperature dependence of pressure broadening and pressure induced line shift coefficients for infrared transitions of ozone, methane, and water vapor were also performed. Results from these studies have been used for retrievals of stratospheric gas concentration profiles from data collected by several Upper Atmospheric Research satellite (UARS) infrared instruments as well as in the analysis of high resolution atmospheric spectra such as those acquired by space-based, ground-based, and various balloon-and aircraft-borne experiments. Our results made significant contributions in several updates of the HITRAN (HIgh resolution TRANsmission) spectral line parameters database. This database enjoys worldwide recognition in research involving diversified scientific fields.

Benner, D. Chris↗
NASA NTRS2000

High Resolution Spectroscopy to Support Atmospheric Measurements

The major research activities performed during the cooperative agreement enhanced our spectroscopic knowledge of molecules of atmospheric interest such as carbon dioxide, water vapor, ozone, methane, and carbon monoxide, to name a few. Measurements were made using the NASA Langley Tunable Diode Laser Spectrometer System (TDL) and several Fourier Transform Spectrometer Systems (FTS) around the globe. The results from these studies made remarkable improvements in the line positions and intensities for several molecules, particularly ozone and carbon dioxide in the 2 to 17-micrometer spectral region. Measurements of pressure broadening and pressure induced line shift coefficients and the temperature dependence of pressure broadening and pressure induced line shift coefficients for infrared transitions of ozone, methane, and water vapor were also performed. Results from these studies have been used for retrievals of stratospheric gas concentration profiles from data collected by several Upper Atmospheric Research satellite (UARS) infrared instruments as well as in the analysis of high resolution atmospheric spectra such as those acquired by space-based, ground-based, and various balloon- and aircraft-borne experiments. Our results made significant contributions in several updates of the HITRAN (HIgh resolution TRANsmission) spectral line parameters database. This database enjoys worldwide recognition in research involving diversified scientific fields.

Benner, D. Chris↗
NASA NTRS2003

Strategies to Support Exploration of Mars' Surface

Surface Visible infrared spectroscopy has a long history of providing fundamental compositional discoveries in the solar system. However, we are entering a new era of Mars exploration in which missions will take place nearly every 2 years.The visible infrared spectral community thus faces a more rapid influx in data volume and variety than it has previously handled.Visible- infrared instruments are on the 1996 Mars Global Surveyor, 2001 Mars Odyssey 2003 Mars Exploration Rovers, 2003 Mars Express, 2005 Mars Reconnaissance Orbiter; and likely on the 2007 and 2009 missions. Interpretations of those data sets provide a critical foundation for geologic and climatic interpretations as well as an opportunity to select landing sites.

Kirkland, L.↗
NASA NTRS2004

Polycyclic Aromatic Hydrocarbons and Infrared Astrophysics with Spitzer

PAH spectral features are now being used as new probes of the ISM. PAH ionization states reflect the ionization balance of the medium while PAH size and structure reflect the energetic and chemical history of the medium. This paper will focus on recent applications of the NASA Ames PAH IR spectral Database to interpret astronomical observations made by the Spitzer Space telescope and other space based infrared instruments. Examples will be given showing how changes in the spectral characteristics of different objects reveal interstellar PAH characteristics such as structure, size and composition, as well as provide insight into the chemical history and physical nature of the emission zones.

Allamandola, L. J.↗
NASA NTRS2007

Detectors for the James Webb Space Telescope Near-Infrared Spectrograph I: Readout Mode, Noise Model, and Calibration Considerations

We describe how the James Webb Space Telescope (JWST) Near-Infrared Spectrograph's (NIRSpec's) detectors will be read out, and present a model of how noise scales with the number of multiple non-destructive reads sampling-up-the-ramp. We believe that this noise model, which is validated using real and simulated test data, is applicable to most astronomical near-infrared instruments. We describe some non-ideal behaviors that have been observed in engineering grade NIRSpec detectors, and demonstrate that they are unlikely to affect NIRSpec sensitivity, operations, or calibration. These include a HAWAII-2RG reset anomaly and random telegraph noise (RTN). Using real test data, we show that the reset anomaly is: (1) very nearly noiseless and (2) can be easily calibrated out. Likewise, we show that RTN affects only a small and fixed population of pixels. It can therefore be tracked using standard pixel operability maps.

Rauscher, Bernard J.↗