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  • 1
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    Particle sightings by the infrared telescope on Spacelab 2 (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Part of the objective of the cooled infrared telescope on Spacelab 2 was to determine the particle environment around the Space Shuttle. The telescope scanned the sky in six wavelength bands ranging from 2 to 100 microns with high time resolution. Dust particles could be identified from their particular signature in the data stream. Particle data from about 4 h early in the mission were analyzed in terms of size, color temperature, velocity, and time. The 1100 particles that were seen were slow moving and ranged in color temperature from 190 to 350 K with a few much hotter. The minimum detectable diameter is between 5 and 13 microns, depending on temperature. The size distribution resembles sample distributions collected at a Shuttle preparation facility. Although particle detection rates varied widely with time, no specific events were identified to be associated with particle production. It was not possible to determine the particle composition, although it was probably not ice.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 30; 2; p. 216-221.
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  • 2
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    Infrared forbidden lines in H II regions and planetary nebulae (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Emissivity coefficients are calculated as functions of electron density and temperature for the IR forbidden lines between 2 and 300 microns of the elements and ionization stages most abundant in H II regions and planetary nebulae. The effect of self-absorption is investigated, and a method is presented for estimating when self-absorption may be important. The IR line spectrum of the Orion Nebula is predicted using the emissivity coefficients, and ionic abundances are derived for the Ar III, S IV, and Ne II forbidden lines in a number of planetary nebulae. The sulfur abundance and sulfur/oxygen ratio are discussed for H II regions and planetary nebulae. The average sulfur/oxygen ratio is found to be about 0.05 for gaseous nebulae.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 39; 1, Fe; Feb. 197
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  • 3
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    An FIR cooled grating spectrometer for the Kuiper Airborne Observatory (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The design and performance of a liquid-He-cooled spectrometer being developed for the Kuiper Airborne Observatory (KAO) to study FIR lines originating in the interstellar medium are discussed. Currently, the spectrometer contains six Ge:Ga photoconductor detectors mounted in integrating cavities and cooled to about 3 K; the collimator focal plane has space for 39 such detectors. The instrument achieves a maximum resolving power of 6000 by means of a 45-cm long echelle grating and is optically capable of operating in the spectral range 25-300 microns. A laboratory spectrum of water vapor, an atmospheric water absorption feature measured from the KAO with Mars as a source, and the forbidden O(2+) emission from W51-IRS1 are shown.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Infrared Physics (ISSN 0020-0891); 25; 513-515
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  • 4
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    Spectrum of the Kleinmann-Low nebula from 29 to 125 micrometers (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The infrared spectrum of the Kleinmann-Low nebula in M42 has been measured from 80 to 350 kaysers (approximately 29 to 125 microns) with a Michelson interferometer aboard the NASA Kuiper Airborne Observatory. The frequency spectrum peaks at about 185 kaysers. A simple model of the emission implies that the temperature is in the range 70-95 K and that the optical depth is at least 0.2 at the peak frequency. A possible absorption is seen at about 176 kaysers. Thermal emission by dust at a temperature of 71 K, with the absorption cross section proportional to frequency, provides a good fit to the data. Other thermal-emission models can also fit the spectrum. The data are compared with previous broad-band measurements. Upper limits are placed on expected line emission from the surrounding H II region at the position of the nebula.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 5
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    The far-infrared spectrum of the core of Sagittarius B2 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A Michelson interferometer aboard NASA's Kuiper Airborne Observatory has been used to measure the spectrum of Sgr B2 from 40 to 200 kaysers with 5-kayser resolution in a 1.4-arcmin beam. The measured spectrum is smooth and featureless with a broad maximum at about 85 kaysers. The data can be fitted analytically with a model corresponding to thermal emission by a uniform sla of dust filling the beam, with an average temperature of approximately 32 K, an optical depth at 100 microns of about 1.6, and a spectral index of the dust emissivity about 1.5. The absence of features implies either that the source is optically thick or that the emission spectrum of the individual grains is smooth in the passband. The possible physical significance of this model is discussed.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 216
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  • 6
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    Effect of the Shuttle contaminant environment on a sensitive infrared telescope (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A sensitive IR telescope on the Space Shuttle Orbiter will be limited in its performance by fluctuations in the IR radiation from the natural environment and the contaminant atmosphere. Models of the Orbiter's contaminant atmosphere were used to predict its spectral radiance from 3 to 300 microns. At 350 km, statistical fluctuations in the radiation from a water vapor column, and a noise equivalent power were measured. This noise is somewhat smaller than the expected contribution from zodiacal light from 5 to 30 microns. The column density of all IR emitting molecules can be kept low only if restrictions on rocket firings and liquid vents are maintained. The relatively low frequency of particle sightings from Skylab, coupled with improvements in Orbiter venting techniques, indicate that sightings of particles 2 microns and larger in radius will not seriously hamper telescope performance provided that liquid vents and rocket firings are properly restricted.
    Keywords: ASTRONOMY
    Type: Applied Optics; 16; Aug. 197
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  • 7
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    Models of four highly obscured compact H II regions (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Models are constructed for three stars in order to determine their properties and elemental abundances through comparisons of model predictions and observations. By comparing predicted line fluxes with those observed, it is noted that oxygen is apparently enhanced by a factor of 2 in W3A, and of 4 in G75.84 + 0.40A and G29.9 - 0.0. The first two cases are based on the premise that the O(++)-emitting regions are as clumped as those of S(++). The H II regions all need more than one main sequence star or one unusually large star to provide the observed radio luminosity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 184-193
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  • 8
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    Mars - Far-infrared spectra and thermal-emission models (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Spectra of Mars from 100 to 360 kaysers were obtained during three different observation periods from NASA's Kuiper Airborne Observatory. Also, a new thermal model was constructed for the surface of Mars, and synthetic spectra were computed from the models to compare with the observations. The models include the effects of a dusty atmosphere which absorbs, scatters, and reradiates energy. The synthetic spectra show significant effects on disk-averaged brightness temperatures, as well as absorption features due to silicate dust. The spectra of Mars, which are ratios of Mars to the moon, do not fit the synthetic spectra unless the surface emissivities of Mars and the moon have different dependencies on wavelength. A possible explanation for this behavior is a difference in soil particle-size distributions between Mars and the moon, with Mars being depleted in large particles compared to the moon. Small particles are consistent with clay minerals which have been suggested elsewhere as constituents of the Martian surface.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 48; Nov. 198
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  • 9
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    Far infrared spectrophotometry of Jupiter and Saturn (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Infrared spectral measurements of Mars, Jupiter, and Saturn were obtained from 100 to 470 kaysers and, by taking Mars as a calibration source, brightness temperatures of Jupiter and Saturn were determined with approximately 5 kayser resolution. Internal luminosities were determined from the data and are reported to be approximately 8 times 10 to the minus tenth power of the sun's luminosity for Jupiter and approximately 3.6 times 10 to the minus tenth power of the sun's luminosity for Saturn. Comparison of data with spectra predicted by models suggests the need for an opacity source in addition to gaseous hydrogen and ammonia to help explain Jupiter's observed spectrum in the vicinity of 250 kaysers.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 35; July 197
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  • 10
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    The mean Jovian temperature structure derived from spectral observations from 105 to 630 cm kaysers (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Far infrared observations of the thermal emission of Jupiter are used to determine the temperature at 1 bar. High-altitude observations of the whole-disk brightness temperature of Jupiter in the range of 100 to 347 kaysers were inverted to obtain a P-T profile between 1.5 and 0.06 atm, assuming as opacity sources the H2 collisionally induced continuum and the rotation inversion bands of ammonia. The P-T profile derived from the spectrum reproduces the main features of the observed spectrum, with a slightly improved fit if the effects of ammonia haze opacity or NH3 supersaturation in the saturated region are taken into account. The Jovian temperature is found to be 160 + or - 7 K at 1 bar, and 105 + or - 3 K at the inversion level at 0.15 bar. The 1-bar temperature is shown to be consistent with Jovian interior models which match the observed gravitational moment.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 40; Oct. 197
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