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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Dayglow forbidden O I 6300 and 5577 A lines in the early morning ionosphere.

Data on a developing morning ionosphere have been obtained by rocket measurement of the atomic oxygen red- and green-line airglow emissions and of the composition of the neutral and ionized constituents of the upper atmosphere. The use of tilting-filter photometers for the optical measurements resulted in reliable and accurate height profiles of the airglow intensity from below 100 to 245 km. The roles of the excitation of both O(super 1 D) and O(super 1 S) atoms by the dissociative recombination of O2(+) and electron impact were studied by using the 6300- and 5577-A data in conjunction with the ion composition measurements. The component of photodissociative excitation of O(super 1 D) by solar radiation in the Schumann-Runge continuum of O2 absorption was assessed as being approximately twice that determined for a previous rocket experiment.

Schaeffer, R. C.↗
NASA NTRS1992

Comparison of measured and modeled solar EUV flux and its effect on the E-F1 region ionosphere

Two different photochemical schemes are used to investigate the response of the E-F1 region ionosphere to different solar EUV flux models, and the results are compared with incoherent scatter radar electron density measurements taken at Millstone Hill. The latest EUV flux model (Tobiska, 1991), which incorporates more recent measurements, has generally more flux at short wavelengths compared to the Hinteregger et al. (1981) flux model based on AE-E satellite data. This results in better agreement with the measurements in the E-F1 region and above. The Tobiska flux model gives a smaller E region peak density, due to the influence of low Ly-beta flux in the November 10, 1988 rocket measurements of Woods and Rottman (1990). The photoionization and photoabsorption cross sections of Conway (1988) give results in somewhat better agreement with observations than the cross sections of Torr et al. (1979). For the zenith angles considered (daytime conditions), the Chapman function method for calculating photoabsorption yields results in satisfactory agreement with a more rigorous calculation method using a formula from Rees (1989).

Buonsanto, M. J.↗
NASA NTRS1966

Nitric oxide in the upper atmosphere.

Aerobee rocket measurement of nitric oxide in upper atmosphere, noting fluorescence in airglow layer, emission rate factors and NO densities

EMISSION SPECTRUM↗
NASA NTRS1989

Solar activity influence on climatic variations of stratosphere and mesosphere in mid-latitudes

The direct modulation of temperature of the mid-latitude mesosphere by the solar-cycle EUV variation, which leads to greater heat input at higher solar activity, is well established. Middle atmosphere temperature modulation by the solar cycle is independently confirmed by the variation of reflection heights of low frequency radio waves in the lower ionosphere, which are regularly monitored over about 30 years. As explained elsewhere in detail, these reflection heights depend on the geometric altitude of a certain isobaric surface (near 80 k), and on the solar ionizing Lyman-alpha radiation flux. Knowing the solar cycle variation of Lyman-alpha how much the measured reflection heights would be lowered with the transition from solar minimum to maximum can be calculated, if the vertical baric structure of the neutral atmosphere would remain unchanged. An discrepancy between expected and observed height change must be explained by an uplifting of the isobaric level from solar minimum to maximum, caused by the temperature rise in the mesosphere. By integrating the solar cycle temperature changes over the height region of the middle atmosphere, and assuming that the lower boundary (tropopause) has no solar cycle variation, the magnitude of this uplifting can be estimated. It is given for the Lidar-derived and for the rocket-measured temperature variations. Comparison suggests that the real amplitude of the solar cycle temperature variation in the mesosphere is underestimated when using the rocket data, but probably overestimated with the Lidar data.

Taubenheim, J.↗
NASA NTRS1980

An empirical determination of the production efficiency for auroral 6300-A emission by energetic electrons

Auroral data from the soft particle spectrometer and the red line photometer on board the Isis satellite are presented as a data base for electron energy flux and optical auroral emission and are used to derive production efficiencies for 6300 A emission. Data obtained during a single orbit in which an aurora was observed is corrected by integrating the precipitating flux observed in four energy bands over the loss cone and eliminating the effects of airglow and albedo in the optical emission measurements. A regression analysis of the corrected data from 12 orbits is used to determine 6300 A production coefficients for the 5-60 eV, 60-300 eV, 0.3-1 keV and 1-15 keV electron energy bands. Production coefficients are shown to be in good agreement with theoretical calculations and rocket measurements in conjugate photoelectrons, and applications of the method to other data sets are discussed.

Shepherd, G. G.↗
NASA NTRS1976

A study of a sector spectrophotometer and auroral O+(2P-2D) emissions

The metastable O+(2P-2D) auroral emission was investigated. The neighboring OH contaminants and low intensity levels of the emission itself necessitated the evolution of an instrument capable of separating the emission from the contaminants and having a high sensitivity in the wavelength region of interest. A new type of scanning photometer was developed and its properties are discussed. The theoretical aspects of auroral electron interaction with atomic oxygen and the resultant O+(2P-2D) emissions were examined in conjunction with N2(+)1NEG emissions. Ground based measurements of O+(2P-2D) auroral emission intensities were made using the spatial scanning photometer (sector spectrophotometer). Simultaneous measurements of N2(+)1NEG sub 1,0 emission intensity were made in the same field of view using a tilting photometer. Time histories of the ratio of these two emissions made in the magnetic zenith during auroral breakup periods are given. Theories of I sub 7319/I sub 4278 of previous investigators were presented. A rocket measurement of N2(+)1NEG sub 0,0 and O+(2P-2D) emission in aurora was examined in detail and was found to agree with the ground based measurements. Theoretical examination resulted in the deduction of the electron impact efficiency generating O+(2P) and also suggests a large source of O+(2P) at low altitude. A possible source is charge exchange of N+(1S) with OI(3P).

Swenson, G. R.↗
NASA NTRS1989

Plasma phenomena observed in the MAP/WINE campaign

The wealth of plasma data gathered in the MAP/WINE campaign allows insight into the generation of electron densities on a large, and the nature of the ions on a small scale. The associated measurements of winds and charged particles help to understand the morphology of the midlatitude ionization which turns out to correlate poorly with geomagnetic activity, but at least slightly with the prevailing winds. A somewhat clearer connection seems to exist between stratospheric warmings and radio wave absorption minima. On the local scale the interpretation of the rocket measurements of positive ions was helped by simultaneous observations of temperatures and atomic oxygen. The relevance of the description winter anomaly for high latitude electron density profiles are examined.

Friedrich, M.↗
NASA NTRS1988

The OI 989 and 1173 A multiplets in the dayglow

Sounding rocket measurements of the O-I 989-A dayglow obtained in 1978, 1980, and 1985 are discussed. The 989-A intensity and multiplet ratios are consistent with total branching losses (to atomic states other than the ground state) of 1.5-4 x 10 to the -4th. It is found that the 1173/989 intensity ratio is dependent only on the 1173/989 branching ratio and the atomic oxygen concentration when viewing upward from rocket altitudes.

Morrison, M. D.↗
NASA NTRS1983

Mesopheric turbulence intensities measured with a HF radar at 35 deg S. Part 2

A theory was developed for extracting turbulence energy dissipation rates from spectra measured with a radar. It is shown that factors apart from turbulence contribute to the observed spectral widths, and that these factors must be considered if accurate estimates of energy dissipation rates are to be obtained. In particular, beam-width broadening and shear broadening are important. The first results obtained with this theory are presented. The rules were obtained using the large HF array at Adelaide, Australia, primarily during the Southern Hemisphere winter of 1981. Results are consistent with rocket measurements of turbulence, with typical values varying between 0.01 and 1/0.2 W kg at 80-90 km altitude.

Hocking, W. K.↗
NASA NTRS2001

Acoustical and Flowfield Characterization of a Scaled Tabletop Rocket

An analysis of the acoustical and flowfield environment for the scaled 1-pound-force (lbf) thrust tabletop motor was performed. This tabletop motor from NASA Stennis Space Center Is composed of Plexiglas burning In gaseous oxygen with a graphite insert for the nozzle portion. The nozzle has a throat diameter of 0.2 inch and an exit diameter of 0.38 Inch. With a chamber pressure at 55 pounds per square Inch absolute (psia), a normal shock is formed immediately downstream of the nozzle exit plane as the combustion products exhaust into the ambient at atmospheric pressure. The jet characterization Is based on computational fluid dynamics (CFD) in conjunction with Kirchhoff surface integral formulation and compared with correlations developed for measured rocket noise and a pressure fluctuation scaling (PFS) method. Predictions and comparisons are made for the overall sound pressure levels (OASPL's) and spectral dependence of sound pressure level (SPL). The overall objective of this effort is to develop methods for scaling the acoustic and flowfield environment of rockets with a wide range of thrust (1 lbf to 1 million lbf).

Kandula, Max↗
NASA NTRS1983

Solar irradiance variations. II - Analysis of the extreme ultraviolet measurements onboard the Atmosphere Explorer E satellite

Five of the extreme ultraviolet channels (L-alpha, L-beta, He I, He II, Fe XV) measuring irradiance fluctuations on board the AE-E satellite between 1977 and 1980 have been studied in detail. It is shown that the daily variations correspond very closely to the daily variations in solar radio emission (F10.7), but that the UV data are afflicted with serious and to date unrecognized calibration changes during the period of operation of the instruments. In order to correct for these changes, a statistical analysis is carried out, and a set of corrections to the raw data is suggested. The resulting, now uniform, data are then compared with rocket measurements (L-alpha) and data acquired onboard the AE-C satellite (L-beta). Finally the remaining discrepancies are discussed. After concluding that they are below the overall level of uncertainties, a first-order 10-year run of EUV irradiances derived from F10.7 data is proposed. This estimate includes the ratio of irradiance levels between the maxima of solar cycles 20 and 21 and the intervening minimum.

Oster, L.↗
NASA NTRS1973

Daytime ion chemistry of N2+.

Rocket measurements of the emission of the (0, 0) first negative band of N2+ at 3914 A in the day airglow have been made between 120 and 300 km. The solar zenith angle at the time of the flight was 60 deg, and the zenith intensity above 120 km was 1.6 kR averaged over both legs of the flight. The data are compared with a model in which charge exchange of N2 with metastable O+(2D) ions is included as an additional source of N2 ionization. Above 240 km this mechanism is dominant over the photoionization of N2 by solar extreme ultraviolet radiation. The derived N2+ density is consistent with the results of rocket-borne mass spectrometric observations.

Feldman, P. D.↗
NASA NTRS1964

Aerospace group

Rocket measurements of ionospheric absorption and Faraday rotation for determination of D layer electron collision frequency

FARADAY ROTATION↗