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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Latitude measures of Jupiter in the 0.89-micron methane band.

Jupiter has been photographed by the Lunar and Planetary Laboratory in the 0.89-micron methane band since October 1968. A photometric evaluation of these photographs has not yet been carried out, but a visual study of this collection and a comparison with the color records has been made. This comparison, together with diameter and latitude measures of the methane records, shows that the albedos and latitudes of most features shown at 0.89 micron vary with time and that there is no simple correlation between the visual color and/or intensity of a feature and its intensity in the methane band. The latitudes of the Red Spot and South Tropical Zone have remained unchanged, while those of the Equatorial Zone, North Tropical Zone, and South Polar Hood have changed.

Minton, R. B.↗
NASA NTRS1973

Reflection spectra, 2.5-7 microns, of some solids of planetary interest

Reflection spectra of 42 compounds of possible planetary interest were run from 2.5 to 7 microns. They were supplemented by some transmission spectra extending the wavelength coverage to 15 microns. The spectra were organized according to their constituent radicals and an attempt was made at the identification of the absorption features.

Fink, U.↗
NASA NTRS1974

Estimation of sea surface temperature from remote sensing in the 11-13 micron window region

The Nimbus 3 and 4 IRIS spectral data in the 11-13 micron water vapor window region are analyzed to determine the sea surface temperature (SST). The high spectral resolution data of IRIS are averaged over approximately 1 micron wide intervals to simulate channels of a radiometer to measure the SST. Three channels are utilized to measure SST over cloud-free oceans. However, two of these channels are sufficient in routine SST determination. The differential absorption properties of water vapor in the two channels enable one to determine the water vapor absorption correction without detailed knowledge of the vertical profiles of temperature and water vapor. The feasibility of determining the SST is demonstrated globally with Nimbus 3 data where cloud-free areas can be selected with the help of albedo data from the MRIR experiment on board the same satellite.

Prabhakara, C.↗
NASA NTRS1973

Broad-band 20-micron photometry of 76 stars

Observations in the 16 to 28 micron spectral band made with an infrared photometer mounted at the Cassegrain f/10 focus of a 2.24-m telescope are discussed. The stars observed belonged to classes B through M and included several carbon and S stars. Most of them are Mira, semiregular, or irregular variables. The remaining 12 stars are nonvariable objects of which the brightest (both in the visible and infrared) are alpha-Boo and alpha-Tau. Since 16 of the Mira stars varied during the period of observation, it is concluded that they are probably intrinsic variables at 20 microns. There is no conclusive evidence for variation of any other star. Because the variation at this wavelength originates largely in circumstellar shells for most of these stars, the nonvariability suggests that these shells are stable phenomena, at least on a time scale of a year.

Morrison, D.↗
NASA NTRS1973

The size of NGC 1068 at 10 microns

The data presented show that a majority of the 10-micron emission from NGC 1068 comes from an area with a diameter of about 60 pc. The measurements described were made at 10 microns on two nights at the 200-inch Hale telescope. The data obtained agree with the results obtained by Stein et al. (1973). An approach to reconcile the new data with the variability observed by Rieke and Low (1972) is also discussed.

Becklin, E. E.↗
NASA NTRS1975

A simple method to incorporate water vapor absorption in the 15 microns remote temperature sounding

The water vapor absorption in the 15 micron CO2 band, which can affect the remotely sensed temperatures near the surface, are estimated with the help of an empirical method. This method is based on the differential absorption properties of the water vapor in the 11-13 micron window region and does not require a detailed knowledge of the water vapor profile. With this approach Nimbus 4 IRIS radiance measurements are inverted to obtain temperature profiles. These calculated profiles agree with radiosonde data within about 2 C.

Dallu, G.↗
NASA NTRS1974

A 1.4-4-micron high-energy angle-tuned LiNbO3 parametric oscillator

The performance characteristics of a widely tunable infrared source that can be rapidly and conveniently angle tuned over the entire 1.4-4.4 micron range are reported. It is significant that the source requires only one set of optics and a single LiNbO3 crystal to tune the entire range. Conversion efficiencies of 15% and an operating amplitude stability of better than 3% have been demonstrated. The availability of large 15-mm-diam by 5-cm-long 47-deg cut LiNbO3 crystals makes possible oscillator operation at up to 2 J of 1.06-micron input pulse energy.

Herbst, R. L.↗
NASA NTRS1974

Observations of the Orion nebula at 100 microns

The Orion nebula spectrum was obtained using an airborne cooled grating spectrometer in the spectral range from 80 to 125 microns at a resolution of 8 microns. The spectrum, corrected for instrument profile and atmospheric water vapor absorption, could be fit by the 60 and 100 K black body curves. The results are in good agreement with those of Erickson et al. (1973) and are consistent with a thermal emission spectrum produced by cool interstellar grains radiating at a wavelength much longer than the grain size.

Ward, D. B.↗
NASA NTRS1974

10-micron heterodyne stellar interferometer

A spatial interferometer for 10-micron wavelength which uses two independent telescopes separated by 5.5 m, heterodyne detection of the infrared radiation, and path equalization by a variable-length RF cable, has given interference fringes from radiation of the planet Mercury. Continuous fringe observations during 4000 sec indicate remarkable stability in the optical-path difference through the atmosphere and the two telescopes, fluctuations between 20-sec averages being about 1/6 of the 10-micron wavelength.

Johnson, M. A.↗
NASA NTRS1975

Heterodyne spectroscopy of astronomical and laboratory sources at 8.5 microns using diode laser local oscillators

The first 8.5 microns infrared heterodyne spectrometer has been constructed using tuneable semiconductor (PbSe) diode lasers and was used to measure absorption line profiles of N2O in the laboratory, as well as black-body emission from the moon and from Mars. Spectral information was recorded over a 200 MHz bandwidth using an 8-channel filter bank. The resolution was 25 MHz (6 millionths of a micron), and the minimum detectable (black-body) power was approximately 1 times 10 to the minus 16th power W for 8 min of integration. The results demonstrate the usefulness of heterodyne spectroscopy for the study of remote and local sources in the infrared.

Mumma, M.↗
NASA NTRS1975

The thermal structure of Jupiter. II - Observations and analysis of 8-14 micron radiation

Observations of Jovian limb structure at 8.11 and 8.45 microns are reported. These are used along with other limb structure and spectral data in the 8-14 micron region to derive a model of the thermal and cloud structure within the 1.0-0.01 bar pressure regime. The temperature is about 165 K at 1.00 bar, 108 K at 0.10 bar, and 143 K at 0.03 bar. In zones, an optically opaque cloud of NH3 exists near the 143 K (0.60 bar) level. A partly transparent haze of solid NH3 particles overlies the cloud. Belts are free of the cloud and have a much lower abundance of NH3 haze than the zones. The data are consistent with an NH3 gas abundance defined by saturation equilibrium, with a mixing ratio of 0.00015 deep in the atmosphere, and with a CH4 mixing ratio of 0.002, about three times the currently accepted value.

Orton, G. S.↗
NASA NTRS1976

Remote sensing of the surface emissivity at 9 microns over the globe

The infrared spectral measurements made by the Nimbus 4 infrared interferometer spectrometer (Iris) for a period of about 10 months are used to study the surface emissivity properties over the globe. It is found that the surface emissivity at 9 microns, as measured by Iris with a circular field of view of about 100-km diameter, is significantly less than unity over arid and semiarid areas. The spectral features in the 8-12-micron window observed over these lands reveal emissivity characteristics essentially due to quartz (SiO2). It is found that these emissivity features are significantly weakened by the presence of clay, clay horizons, or pedogenic horizons in the soil. Low emissivity is observed over sandy or sandy loam areas (psamments) with no clay or pedogenic horizons.

Prabhakara, C.↗
NASA NTRS1976

Nonthermal 10 micron CO2 emission lines in the atmospheres of Mars and Venus

Mechanisms are examined for excitation of strong 10-micron CO2 emission lines seen on Mars and Venus. Line absorption of near-infrared solar flux directly by CO2 or H2O with collisional transfer of energy to CO2 are proposed as likely excitation mechanisms. Altitudes for peak 10-micron emission are estimated to be near 80 km for Mars and 120 km for Venus.

Johnson, M. A.↗
NASA NTRS1977

Observations of Jupiter and Saturn at 5-8 micron

Moderate-resolution spectrophotometry (about 0.015) has shown the effects of known atmospheric constituents (NH3, CH4, C2H6) on the 5-8 micron spectrum of Jupiter. Broadband observations of Saturn at 6.5 micron are also reported.

Russell, R. W.↗
NASA NTRS1977

Observations of the unidentified 3.3 micron emission feature in nebulae

Spectrophotometric observations from 2.1 to 4.1 microns of a variety of objects exhibiting the 3.3-micron emission feature (first detected in NGC 7027) are reported. The characteristics of the feature, the various environments in which it is found, and possible emission mechanisms are discussed in light of all the available observations of the feature to date. A resonance feature in solids is the most probable emission mechanism; however, no satisfactory identification has yet been made on the basis of infrared spectroscopy of terrestrial materials.

Russell, R. W.↗
NASA NTRS1978

Identification of the 3.9 micron absorption band in carbon stars

With a 1.7% spectral-resolution filter-wheel spectrometer, 1.2-5.2-micron spectra have been obtained for a sample of carbon stars. The previously unidentified 3.9-micron band is attributed to a combination of CS and C2H2. The first observation of SiO in a carbon star is also reported.

Bregman, J. D.↗
NASA NTRS1978

The light curve at 10 microns of Algol near secondary minimum

Observations of Algol (Beta Persei) at 10 microns are presented which are of relevance to the system's behavior around the time of its secondary minimum. No evidence is found for a significant excess at 10 microns. The data show a smooth decline by 0.3 mag which starts at about phase 0.42, while the limited data obtained at phases greater than 0.50 are consistent with a symmetrical curve about phase 0.50.

Nadeau, D.↗
NASA NTRS1979

Two-micron spectrophotometry of the galaxy NGC 253

A very strong Brackett-gamma hydrogen emission line, and the 2.3 micron CO stellar absorption feature were measured in NGC 253. The presence and strength of the CO feature indicates that late type giant stars produce most of the 2.2 micron continuum emission, while the rate of ionization implied by strength of the Brackett-gamma line indicates that much, perhaps all, of the luminosity detected at far infrared wavelengths originates from a large number of OB stars. As compared to the corresponding region of the Galaxy, the number of massive young stars in the central 200 pc of NGC 253 is thirty times greater, but the total mass of stars is roughly the same.

Wynn-Williams, C. G.↗