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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Spectroscopic observations of winds on Venus. I - Technique and data reduction

Methods of measurement and reduction of high-dispersion photographic spectra of Venus are presented. Preliminary results are consistent with slow direct or no rotation at the level sample, and disagree strongly with a 4-day retrograde rotation. A serious systematic error, which affects much published work, is due to blending of solar lines in the sky with those reflected from the planet. This always tends to produce a spurious retrograde 'rotation'. Only data obtained in a dark sky, or daytime observations from which the sky lines have been accurately subtracted, can be relied upon. All such data give low wind speeds.

Young, A. T.↗
NASA NTRS1980

Review of spectroscopic data for measurement of stratospheric species

The role of various infrared techniques in measurements of trace gases in the stratosphere were surveyed. Particular emphasis was placed on the role of instruments exhibiting ultrahigh resolution (i.e., less than or equal to 0.00/cm) such as laser heterodyne spectrometers.

Goldman, A.↗
NASA NTRS1980

A spectroscopic study of intermediates in the condensation of refractory smokes: Matrix isolation experiments SiO

The infrared and Raman spectra of N2 matrix isolated silicon oxides are investigated. The vibrational frequencies of SiO, Si2O2, and Si3O3 were identified and assigned on the basis of normal coordinate analyses. Heating the solid to 50 K (evaporating the matrix) leaves a residue whose infrared spectrum is identical to that of a smoke condensed at ambient temperatures. Further heating of the sample to 500 K leads to significant changes in the band shapes. Investigations of the infrared spectra at several stages of the diffusion process result in the proposal of a mechanism for the transition from molecular properties to those of the residue (bulk) material, which is characterized as Si2O3.

Khanna, R. K.↗
NASA NTRS1980

Spectroscopic evidence for two achondrite parent bodies - Asteroids 349 Dembowska and 4 Vesta

A Fourier spectrometer was used to obtain IR spectra of asteroids 349 Dembowska and 4 Vesta. The spectrum of Dembowska shows olivine and pyroxene with an olivine/pyroxene abundance ratio greater than 2, and possibly as high as 10. This is probably an unsampled achondritic composition, similar to the unique achondrite ALHA 77005. Dembowska's mineralogy therefore appears related to the achondrites; pyroxene and plagioclase feldspar are seen, with a pyroxene/feldspar abundance ratio between 1.5 and 2.0. Time-resolved observations over one-half of the rotation period indicate compositional homogeneity; both 349 Dembowska and 4 Vesta can be considered as candidates for the parent bodies of igneous meteorites.

Feierberg, M. A.↗
NASA NTRS1980

High dispersion spectroscopic observations of Venus near superior conjunction. IV - Results for the carbon dioxide bands in the IV-N photographic region

Phase curves for the CO2 bands at 7883, 7820, and 8689 A are presented. While the weaker bands at 7820 and 7883 A show a definite 'inverse phase effect,' the band at 8689 A shows a more normal phase curve; it also exhibited much larger day-to-day variations in the CO2 abundance near superior conjunction in 1971. Because the variation of the phase curves with band strength is comparable to temporal variations on Venus, simultaneous observations of strong and weak bands are still needed to determine the dependence on band strength accurately.

Young, L. D. G.↗
NASA NTRS1980

Ultraviolet spectroscopic observations of VV Cephei

Observations with the International Ultraviolet Explorer satellite (IUE) of the recent egress of the eclipsing binary VV Cep(M2Iabep + B) are presented. Egress in the ultraviolet lagged behind the visible egress by 2 to 3 months, as a result of higher opacity of the M star atmosphere in the ultraviolet. Shortly after visible egress, the low-dispersion spectrum from 1200-1900 wavelengths was dominated by fluorescent emission lines arising in the atmosphere of the M star and excited by the ultraviolet continuum of the hot companion. High-dispersion spectra show a hot continuum blanketed by absorption lines, some of which weaken or disappear as the egress continues. A year after eclipse, the absorption spectrum is still too complex to permit determination of a spectral type for the hot companion. The Mg II h and k lines both exhibit asymmetric double-peaked emission features indicative of an expanding chromosphere in the M supergiant.

Hagan, W.↗
NASA NTRS1980

Spectroscopic study of the effect on an EHD contact of trichloroethane addition to a traction fluid

Addition of trichloroethane to a traction fluid was studied in a ball/diamond plate EHD apparatus by infrared emission spectroscopy of the radiation transmitted through the plate. Small concentrations of an organic chloride at first increased infrared radiance, then decreased it. Large concentrations caused a rapid decrease. During running, the infrared spectrum showed an increase of aromatics and olefins. A polymeric deposit formed on the plate. X-ray examination of the ball surface showed the presence of chlorine. Reuse of the same ball with fresh fluid resulted in similar chain of events, indicating that adsorbed chloride could promote fluid deterioration.

Lauer, J. L.↗
NASA NTRS1980

Design and use of a servo-controlled high pressure window bomb in spectroscopic studies of solid propellant combustion

The feasibility of using a high pressure window bomb as a laboratory scale model of actual motor conditions. The design and operation of a modified high pressure window bomb is discussed. An optical servocontrol mechanism has been designed to hold the burning surface of a propellant strand at a fixed position within the bomb chamber. This mechanism permits the recording of visible and infrared emission spectra from various propellants. Preliminary visible emission spectra of a nonmetalized and metalized propellant are compared with spectra recorded using the modified bomb.

Goetz, F.↗
NASA NTRS1980

Spectroscopic determination of the in-situ composition of epoxy matrices in glass fiber reinforced composites

Computerized infrared analysis is applied to the characterization of a glass-reinforced crosslinked polyester. The method of factor analysis determines the number of independent components which constitute the polymeric matrix. Subsequently, the spectra of those components are fitted by a least-squares criterion to spectra of the multicomponent matrix, or, if the glass spectrum is included as an additional component, to the spectra of composites. The least-squares coefficients yield the matrix composition in terms of the initial reactant composition and the extent of crosslinking.

Antoon, M. K.↗
NASA NTRS1980

A matrix-isolation-infrared spectroscopic study of the reactions of nitric oxide with oxygen and ozone

An investigation of the oxidation of NO to NO2 by trapping the products of the gas-phase reactions with excess oxygen and ozone identified the transient species by their infrared spectra. The primary products of the NO + NO2 reactions were NO2, N2O3(A), N2O3(B), N2O4, and peroxy nitrate (OONO). The primary products of the NO + O3 reactions were NO2 and peroxy NO3 with the higher nitric oxides in low concentrations compared with the NO + O2 reactions. Isotopic oxygen and ozone were used to identify the infrared absorption frequency of the peroxy nitrate.

Bhatia, S. C.↗
NASA NTRS1980

Spectroscopic observations of the optical counterpart of Centaurus X-4

The optical spectrum of the transient X-ray burst source Centaurus X-4 was observed about 5 weeks after the source reached its maximum. The brightness of the optical counterpart had decreased to V = 18.2, and the star had become appreciably redder (B - V = 0.7) compared to its color at maximum. The spectrum of Centaurus X-4 is similar to that of cataclysmic variables showing strong emission lines of H-1 and weaker lines of He-1 and He-2. The N03 lambda 4640 line is not visible. The continuum energy distribution of Centaurus X-4 shows the presence of a main-sequence star in the system, with spectral type between K3 and K7. This is consistent with the orbital period of 8.2 hr proposed by Kaluzienski et al (1980), if the main-sequence star is close to filling its Roche lobe.

Van Paradijs, J.↗
NASA NTRS1980

Spectroscopic and polarimetric observations of NGC 1333 and the surrounding dark cloud complex

Spectroscopy and polarimetry of several very red stars, noted on Near Infrared Photographic Sky Survey photographs in the region of NGC 1333, have yielded a 'map' suggesting the extent of polarization arising from a two-cloud structure in the region. Spectral types and color indices of the stars make it possible to infer that grain radii in the clouds exceed typical interstellar medium values and, further, that they increase with optical depth into the cloud. The present observations indicate that the cloud structure is far more extensive than previously realized.

Turnshek, D. A.↗
NASA NTRS1981

A spectroscopic study of intermediates in the condensation of refractory smokes - Matrix isolation experiments of SiO

The infrared and Raman spectra of N2 matrix-isolated silicon oxides were investigated. The vibrational frequencies of SiO, Si2O2, and Si3O3 were identified and assigned on the basis of normal coordinate analyses. Heating the solid to approximately 50 K (evaporating the matrix) leaves a residue whose infrared spectrum is identical to that of a smoke condensed at ambient temperatures. Further heating of the sample to approximately 500 K leads to significant changes in the band shapes. Investigations of the infrared spectra at several stages of the diffusion process enable a mechanism to be proposed for the transition from molecular properties to those of the residue (bulk) material, which has been characterized as Si2O3.

Khanna, R. K.↗
NASA NTRS1981

Spectroscopic determination of the in-situ composition of epoxy matrices in glass-fiber-reinforced composites

Computerized infrared analysis is applied to the characterization of a glass-reinforced crosslinked polyester. The method of factor analysis determines the number of independent components which constitute the polymeric matrix. Subsequently, the spectra of those components are fitted by a least-squares criterion to spectra of the multicomponent matrix, or, if the glass spectrum is included as an additional component, to the spectra of composites. The least-squares coefficients yield the matrix composition in terms of the initial reactant composition and the extent of crosslinking.

Antoon, M. K.↗
NASA NTRS1981

Spectroscopic evidence for aqueous alteration products on the surfaces of low-albedo asteroids

The spectral reflectances of primary components of the carbonaceous chondrite matrix materials (CCMM) and their secondary alteration products are compared with new observations of low-albedo asteroids. It is shown that the spectral differences between C-type asteroids and carbonaceous chondrites are consistent with differing degrees of aqueous alteration of CCMM.

Feierberg, M. A.↗