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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 127 records · Page 7
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NASA NTRS1975

Measurement of the spectrum of the submillimeter cosmic background

The spectrum of the night sky has been measured in the wave number range from 3 to 40 per cm using a fully calibrated liquid-helium-cooled balloon-borne spectrophotometer at an elevation of 39 km. A model based on the known molecular parameters was used to subtract the atmospheric emission. In the range from 4 to 17 per cm, the spectrum of the background radiation is that of a blackbody with a temperature of about 2.99 K.

Woody, D. P.↗
NASA NTRS1975

Evaluation of the gravity independent miniature analytical system

The miniature fast analyzer is an automated, analytical instrument developed for potential use for biochemical analyses conducted in space flight. The gravity independent fast analyzer system is described which consists of a 17 place rotor type spectrophotometer and computerized data acquisition system weighing only 30 pounds and occupying a volume of 1 cubic foot.

Wallace, L. D.↗
NASA NTRS1976

Literature review of some selected types of results and statistical analyses of total-ozone data

The depletion of ozone in the stratosphere is examined, and causes for the depletion are cited. Ground station and satellite measurements of ozone, which are taken on a worldwide basis, are discussed. Instruments used in ozone measurement are discussed, such as the Dobson spectrophotometer, which is credited with providing the longest and most extensive series of observations for ground based observation of stratospheric ozone. Other ground based instruments used to measure ozone are also discussed. The statistical differences of ground based measurements of ozone from these different instruments are compared to each other, and to satellite measurements. Mathematical methods (i.e., trend analysis or linear regression analysis) of analyzing the variability of ozone concentration with respect to time and lattitude are described. Various time series models which can be employed in accounting for ozone concentration variability are examined.

Myers, R. H.↗
NASA NTRS1976

Development of a high efficiency thin silicon solar cell

One hundred thin (120 microns to 260 microns) silicon-aluminum solar cells were fabricated and tested. Silicon slices were prepared, into which an aluminum alloy was evaporated over a range of temperatures and times. Antireflection coatings of tantalum oxide were applied to the cells. Reflectance of the silicon-aluminum interfaces was correlated to alloy temperature (graphs are shown). Optical measurements of the rear surface-internal reflectance of the cells were performed using a Beckman spectrophotometer. An improved gridline pattern was evaluated and stability tests (thermal cycling tests) were performed. Results show that: (1) a high-index, high-transmittance antireflection coating was obtained; (2) the improved metallization of the cells gave a 60 percent rear surface-internal reflectance, and the cells displayed excellent fill factors and blue response of the spectrum; (3) an improved gridline pattern (5 micron linewidths compared to 13 micron linewidths) resulted in a 1.3 percent improvement in short circuit currents; and (4) the stability tests showed no change in cell properties.

Lindmayer, J.↗
NASA NTRS1975

Spectral signature selection for mapping unvegetated soils

Airborne multispectral scanner data covering the wavelength interval from 0.40-2.60 microns were collected at an altitude of 1000 m above the terrain in southeastern Pennsylvania. Uniform training areas were selected within three sites from this flightline. Soil samples were collected from each site and a procedure developed to allow assignment of scan line and element number from the multispectral scanner data to each sampling location. These soil samples were analyzed on a spectrophotometer and laboratory spectral signatures were derived. After correcting for solar radiation and atmospheric attenuation, the laboratory signatures were compared to the spectral signatures derived from these same soils using multispectral scanner data. Both signatures were used in supervised and unsupervised classification routines. Computer-generated maps using the laboratory and multispectral scanner derived signatures resulted in maps that were similar to maps resulting from field surveys. Approximately 90% agreement was obtained between classification maps produced using multispectral scanner derived signatures and laboratory derived signatures.

May, G. A.↗
NASA NTRS1976

Nitric oxide gamma band emission in an aurora

Emission of the NO gamma (1,0) band at 2150 A has been observed by a rocket-borne spectrophotometer in an IBC II(+) aurora. The nu-prime progression of the gamma-system does not appear in the spectrum. The observed emission rate of the 2150 A feature increases relative to N2(+) first negative band emission with increasing altitude. We suggest radiative recombination of NO(+) ions with electrons as a possible excitation mechanism compatible with the data.

Feldman, P. D.↗
NASA NTRS1975

Intercomparison of ground based and satellite pictures of the sun

Using NASA facilities in space (OSO-7) and on the ground (Goddard multi-channel spectrophotometer at Sacramento Peak, New Mexico) an active region has been mapped. By combining these ultraviolet, X-ray, and visible data, a physical picture of this structured region was constructed from the photosphere to the corona, corresponding to temperature regimes from 4500 K to 4,000,000 K. The morphology of the active region was studied by comparing grey-shaded images in which fine details stand out more clearly than in the contour plots. One result of the study is that gross similarities persist from the low photosphere up to high in the transition region, while some changes occur in the corona.

Chapman, R. D.↗
NASA NTRS1976

EUV flux variations with solar rotation observed during 1974-1976 from AE satellites C, D, and E

Solar EUV fluxes in the spectral range from 140 to 1850 A have been observed by spectrophotometers on the satellites AE-C, D, and E. Variations over the long period of one or two years cannot be verified quantitatively, as the observed small variations are of the same magnitude as possible variations of instrumental sensitivities and estimated uncertainties of absolute values from the rocket experiment which established the calibration of the AE-C instrument. Fortunately, no similar difficulty exists for the interpretation of observed EUV variations within smaller time periods up to that of a full solar rotation. Results from AE-C observations for many different wavelength groups for the year 1974 are shown by some detail and compared with some recent observations made by the AE-D and AE-E instruments.

Hinteregger, H. E.↗
NASA NTRS1976

EUV absorption analysis of thermospheric structure from AE-satellite observations of 1974-1976

Atmospheric absorption characteristics at various selected wavelengths of solar EUV emission have been observed by spectrophotometers on the Atmosphere Explorer satellites. Two levels of results are defined as (A) results independent of any cross section values and involving no specific atmospheric model assumptions, and (B) results expressed in terms of particle concentrations, mass density, and other aeronomical parameters. The present report will mostly deal with results of type B, with emphasis on molecular oxygen. Studies of EUV-derived results in correlation with results of other simultaneous experiments on the same satellite are expected soon to improve the assessment of technique-peculiar errors, possible errors in the various EUV cross sections or accommodation coefficients, and lead to the design of a 'correlative approach' based on the use of mixed inputs of the most reliable aspects of one and the other types of observations, respectively.

Hinteregger, H. E.↗
NASA NTRS1976

Carbon production in comet West 1975n

Rocket-ultraviolet spectra of comet West 1975n are reported which were obtained with scanning spectrophotometers in the wavelength range from 1200 to 1300 A. The principal emission features observed include lines of C, O, and C(+), as well as bands of OH, CO, CO(+). The estimated fluxes of the C, O, H, CO, and OH features are found to be consistent with a photodissociation source in which the CO evaporation rate is about one-third that of water. The presence of a large number of carbon atoms in the metastable 1D state is indicated and taken to suggest that dissociative recombination is important near the cometary nucleus, that CO must originate in the nucleus, and that CO is the primary carbon constituent of the comet.

Feldman, P. D.↗
NASA NTRS1977

Comparison of ozone measurement techniques using aircraft, balloon, and ground-based measurements

In order to verify the ultraviolet absorption technique used in the Global Atmospheric Sampling Program, two flight experiments were conducted employing several techniques, both in situ and remote, for measuring atmospheric ozone. The first experiment used the NASA CV-990 equipped with an ultraviolet absorption ozone monitor and an ultraviolet spectrophotometer, a balloon ozonesonde, and a Dobson station for determining and comparing the ozone concentration data. A second experiment compared ozone data from an automated sampling system aboard a B-747 with data from a manned system installed on the NASA CV-990 during a cross-country flight with both aircraft following the same flight path separated by 32 kilometers.

Briehl, D.↗
NASA NTRS1976

EUV fluxes in the solar spectrum below 2000 A

The list of EUV fluxes presented at the 1969 IAGA review in Madrid (Hinteregger, 1970) has served as a useful reference in many aeronomical studies, leading to a wide range of opinions regarding both the absolute values in that reference list and the question of estimating EUV fluxes from the only routinely obtained data, i.e., the solar 10.7 cm flux. Advances made since 1969 will be reviewed including previously unpublished observations of the variability of solar EUV for the period from January 1974 to May 1975 which were obtained from the EUV spectrophotometer experiment on the AE-C satellite. The review is concluded by a discussion of current and future needs of solar EUV flux measurements for aeronomical applications.

Hinteregger, H. E.↗
NASA NTRS1976

Studies of molecular nitrogen bands from airborne auroral spectroscopy

Absolute auroral emission rates of several bands of the 1 PG (first positive), 2 PG, and Vegard-Kaplan systems of N2 and of the 1 NG (first negative) system of N2(+) were obtained from simultaneous spectral scans of two Ebert spectrophotometers mounted on board the NASA CV 990 aircraft. Analysis of these bands emitted during a 2-min auroral event leads to some conclusions regarding the excitation mechanisms of the C(3)Pi, B(3)Pi, and A(3)Sigma levels: the v' = 0 to v' = 3 levels of the C(3)Pi electronic state are populated by electron impact; the cross sections predict absolute emission rates that are in good agreement with the observations. Cross sections for excitation of the v' = 4 to v' = 8 levels, derived from laboratory measurement of the optical excitation functions, predict well the 1 PG bands observed in the auroral event.

Rees, M. H.↗
NASA NTRS1977

Measurements of line emission in quiescent prominences - Ca/+/, H and He

The paper presents observations of Ca(+) H, K, and infrared-triplet integrated line intensities, as well as H-beta, H-gamma and He 5876-A throughout eight quiescent prominences. The data were obtained with a multichannel coronal spectrophotometer system. The presently available theoretical models appear to be insufficient to provide a consistent basis for the interpretation of the data.

Landman, D. A.↗
NASA NTRS1976

The remarkable chemical uniformity of Apollo 16 layered deep drill core section 60002

Atomic absorption and colorimetric spectrophotometers were used to determine major- and minor-element abundances in 12 samples from layered section 60002 of the Apollo 16 deep drill core. It is suggested that gardening of a relatively thick local unit produced the layering in this section in such a manner that the proportions of materials of different compositions remained virtually unchanged.

Nava, D. F.↗
NASA NTRS1977

Problems in the use of interference filters for spectrophotometric determination of total ozone

An analysis of the use of ultraviolet narrow-band interference filters for total ozone determination is given with reference to the New Zealand filter spectrophotometer under the headings of filter monochromaticity, temperature dependence, orientation dependence, aging, and specification tolerances and nonuniformity. Quantitative details of each problem are given, together with the means used to overcome them in the New Zealand instrument. The tuning of the instrument's filter center wavelengths to a common set of values by tilting the filters is also described, along with a simple calibration method used to adjust and set these center wavelengths.

Basher, R. E.↗
NASA NTRS1978

Abrasion-resistant antireflective coating for polycarbonate

Following plasma-polymerization technique, treatment in oxygen glow discharge further enhances abrasion resistance and transmission. Improvement in abrasion resistance was shown by measuring percentage of haze resulting from abrasion. Coating samples were analyzed for abrasion using standard fresh rubber eraser. Other tests included spectra measurements and elemental analysis with spectrometers and spectrophotometers.

Wydeven, T. J.↗
NASA NTRS1979

Instrument measures many optical properties in visible and IR

Electro-optical system measures reflectance, reflectance ratio, transmission, absorption, refractive index, and absorption coefficient in both visible and infrared (IR) spectral regions. System effectively combining capabilities of ellisometer, reflectometer, and spectrophotometer is expected to find application in environmental and material composition testing fields.

Batten, C. E.↗