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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Measurements of the earth's airglow in the vacuum ultraviolet

A valuable by-product of the OAO-2 astronomy mission has been the first extensive set of measurements of the earth's airglow between 1000 and 3000 A. These measurements, made with the Wisconsin experiment package, provide clues to the structure and chemistry of the upper atmosphere. The most significant results from these observations are: (1) the detailed altitude profile of the emissions from the dark and sunlit earth limb; and (2) the confirmation of recent theories concerning the source of the dayglow radiation between 1350 and 1700 A.

Waters, C. R.↗
NASA NTRS1971

Simultaneous measurements of the hydrogen airglow emissions of Lyman alpha, Lyman beta, and Balmer alpha.

Comparison of Lyman-alpha, 740- to 1050-A, and Balmer-alpha airglow measurements made at 134 deg solar-zenith angle on Oct. 13, 1969, with resonance-scattering models of solar radiation. Model comparison with Lyman-alpha data fixes the hydrogen column abundance over 215 km to 2 x 10 to the 13th per cu cm within a factor of 2. Differences between the Lyman-alpha model and data indicate a polar-equatorial departure from spherical symmetry in the hydrogen distribution. A Lyman-beta model based on the hydrogen distribution found to fit the Lyman-alpha data fits the spatial variation of the 740- to 1050-A data well from 100 to 130 km, but it does not fit the data well at higher altitudes; thus the presence of more rapidly absorbed shorter-wavelength radiation is indicated. This same resonance-scattering model yields Balmer-alpha intensities that result in good spatial agreement with the Balmer-alpha measurements, but a fivefold increase in the measured solar line center Lyman-beta flux is required (as required for the Lyman-beta measurement). The intensity ratio of Lyman-beta and Balmer-alpha at night is found to be a simple measure of the hydrogen optical depth if measurements with good accuracy can be made in the visible and ultraviolet spectrum.

Weller, C. S.↗
NASA NTRS1971

Vacuum ultraviolet spectra of the late twilight airglow.

Evaluation of sounding rocket spectra of the late twilight (solar-zenith angle of 120 deg) ultraviolet airglow between 1260 and 1900 A. The only observed features are O I 1304 and 1356. When the instrument looked at an elevation of 17 deg above the western horizon, the brightnesses were 70 and 33 rayleighs, respectively. The upper limits on the total intensity of the Lyman-Birge-Hopfield and Vegard-Kaplan systems of N2 were 26 plus or minus 26 and 55 plus or minus 55 rayleighs, respectively. An estimate shows that a large part of the O I emissions may be due to excitation by conjugate-point electrons.

Buckley, J. L.↗
NASA NTRS1972

Airglow fluctuations at 2.2 microns.

The OH airglow has been observed in the infrared, from high altitude sites, with a bandpass filter from 2.0 to 2.5 microns. An average spatial fluctuation of plus or minus 4% and an average time fluctuation of plus or minus 3% are found about the mean nightly level. The evening fluctuations are more pronounced than the morning ones. The brightness and fluctuations are such as to preclude ground-based observation of the zodiacal light with wide-band photometry at this wavelength.

Peterson, A. W.↗
NASA NTRS1973

Measurements of the Michigan Airglow Observatory from 1971 to 1973 at Ester Dome Alaska

The Michigan Airglow Observatory (MAO) was located at Ester Dome Observatory, College, Alaska (latitude: 64 deg 53'N, longitude: 148 deg 03'W) since October, 1971. The MAO houses a 6-inch Fabry-Perot interferometer, a 2-channel monitoring photometer and a 4-channel tilting filter photometer. The Fabry-Perot interferometer was used extensively during the winter observing seasons of 1971-72 and 1972-73 to measure temperature and mass motions of the neutral atmosphere above approximately 90 kilometers altitude. Neutral wind data from the 1971-72 observing season as measured by observing the Doppler shift of the gamma 6300 A atomic oxygen emission line are presented.

Mcwatters, K. D.↗
NASA NTRS1973

Auroral data from Michigan airglow payload launch

Auroral studies are presented of flight data analysis from the Michigan airglow payload. Analysis of the stellar occultation data and results from the twilight flight are reported. Optical emissions from bottled aurora and an electron analyzer for measurement of distributions in energy of electrons along a beam are also presented. A list of related publications is included.

Hays, P. B.↗
NASA NTRS1973

Far ultraviolet spectra and altitude profiles of the dawn airglow.

The far ultraviolet spectrum of the dawn airglow was observed with a scanning Ebert spectrophotometer aboard an Aerobee 170 rocket launched from White Sands, New Mexico, on January 25, 1971, at 0727 MST. Altitude profiles were obtained between 100 and 244 km for the brightest spectral features, HI 1216, OI 1304, and OI 1356. The OI 1356 column intensity is used to estimate a 1356 intensity of about 10 R at the unilluminated magnetic conjugate point; this procedure is consistent with recent observations.

Rottman, G. J.↗
NASA NTRS1973

An observation of polar auroral and airglow from the ISIS-II spacecraft.

This is a preliminary but comprehensive report on coordinated data obtained with the ISIS-II spacecraft, fourth in the ISIS series, launched 1 April 1971, into a near circular 1400 km orbit. The capabilities of the ISIS-I spacecraft have been extended in a number of ways, including the global mapping of the 3914, 5577 and 6300 A emissions. Data obtained during a 30-min pass over the south pole depict the nightside oval and polar cap, as well as mid-latitude airglow effects; these data are described and discussed.

Shepherd, G. G.↗
NASA NTRS1973

Photometer for detection of sodium day airglow.

Description of a photometer for daytime ground-based measurements of sodium airglow emission. The photometer described can be characterized by the following principal features: (1) a narrow (4.5-A) interference filter for initial discrimination; (2) cooled photomultiplier detector to reduce noise from dark current fluctuations and chopping to eliminate the average dark current; (3) a sodium vapor resonance cell to provide an effective bandpass comparable to the Doppler line width; (4) separate detection of all light transmitted by the interference filter to evaluate the Rayleigh and Mie components within the Doppler width of the resonance cell; and (5) temperature quenching of the resonance cell to evaluate and account for instrumental imperfections.

Mcmahon, D. J.↗
NASA NTRS1973

Distribution of atomic oxygen in the upper atmosphere deduced from Ogo 6 airglow observations.

The atomic oxygen distribution as a function of altitude between 80 and 120 km and as a function of latitude has been deduced from Ogo 6 557.7-nm airglow photometer data obtained between August 1969 and April 1970. The results indicate that the density ranges from 15 to 50 billion per cu cm at 120 km; that there is a semiannual variation by a factor of 3 in the global average density near 100 km in phase with the satellite drag semiannual effect; and that large latitudinal variations occur with maximums between 40 and 60 deg in the winter hemisphere and sometimes deep minimums in the tropics. The implication of these results for meridional and vertical transport patterns is discussed.

Donahue, T. M.↗
NASA NTRS1974

Laboratory studies on the excitation and collisional deactivation of metastable atoms and molecules in the aurora and airglow

The aeronomy group at the University of Pittsburgh is actively engaged in a series of coordinated satellite, sounding rocket, and laboratory studies designed to expand and clarify knowledge of the physics and chemistry of planetary atmospheres. Three major discoveries have been made that will lead ultimately to a complete and dramatic revision of our ideas on the ionospheres of Mars, Venus, and the Earth and on the origin of their vacuum ultraviolet airglows. The results have already suggested a new generation of ionosphere studies which probably can be carried out best by laser heterodyning techniques. Laboratory studies have also identified, for the first time, the physical mechanism responsible for the remarkable nitric oxide buildup observed in some auroral arcs. This development is an important break-through in auroral physics, and has military ramifications of considerable interest to the Department of Defense. This work may also shed some light on related NO and atomic nitrogen problems in the mesosphere.

Zipf, E. C.↗
NASA NTRS1974

Global temperature distributions from OGO-6 6300 A airglow measurements

The OGO-6 6300 A airglow temperature measurements have been used to develop models of the global temperature distributions under solstice and equinox conditions for the altitude region from 240 to 300 km and for times ranging from dawn in this altitude region to shortly after sunset. The distributions are compared with models derived from satellite orbital decay and incoherent scatter sounding. The seasonal variation of the temperature as a function of latitude is shown to be very different from that derived from static diffusion models with constant boundary conditions.

Blamont, J. E.↗
NASA NTRS1974

Twilight airglow. II - N2/+/ emission at 3914 A

One of the experiments aboard a rocket flight carrying instruments to measure the dawn airglow, the ion and electron densities, and the photoelectron spectrum is reported. For a solar zenith angle of 90 deg the emission at 3914 A from N2(+) peaks at about 260 km. The integrated intensity from model calculations suggests that resonance scattering of 3914-A solar photons off N2(+) produces 90% of the emission, whereas simultaneous photoionization excitation of N2(+) produces less than 10% of the emission. Photoelectron impact excitation is found to contribute about 1%.

Sharp, W. E.↗
NASA NTRS1974

The 6300 A O/1-D/ airglow and dissociative recombination

Measurements of night-time 6300 A airglow intensities at the Arecibo Observatory have been compared with dissociative recombination calculations based on electron densities derived from simultaneous incoherent backscatter measurements. The agreement indicates that the nightglow can be fully accounted for by dissociative recombination. The comparisons are examined to determine the importance of quenching, heavy ions, ionization above the F-layer peak, and the temperature parameter of the model atmosphere. Comparable fits between the observed and calculated intensities are found for several available model atmospheres. The least-squares fitting process, used to make the comparisons, produces comparable fits over a wide range of combinations of neutral densities and of reaction constants. Yet, the fitting places constraints upon the possible combinations; these constraints indicate that the latest laboratory chemical constants and densities extrapolated to a base altitude are mutually consistent.

Wickwar, V. B.↗
NASA NTRS1977

Excitation of the Venus night airglow

The strongest spectral features in the Venus night airglow between 3000 and 8000 A are identified as the Herzberg II bands of molecular oxygen. These bands have been produced in a laboratory afterglow by the recombination of oxygen atoms in the presence of carbon dioxide molecules. It is hypothesized that the same mechanism produces this emission in the upper atmosphere of Venus.

Lawrence, G. M.↗
NASA NTRS1977

Mariner 10 ultraviolet spectrometer - Airglow experiment

An extreme ultraviolet airglow spectrometer was flown on Mariner 10 to examine the atmosphere of Venus and Mercury. An objective grating spectrometer was used with channel electron multipliers at fixed positions in the image plane to continuously monitor the resonance-scattered emission rate of expected atomic atmospheric constituents He, H, A, Ne, O and C. A mechanical collimator placed in the entrance aperture of the spectrometer provided spectral separation of 19 A over the wavelength range from He/+/ at 304 A to C at 1657 A and provided spatial separation of 0.125 deg consistent with the spacecraft and trajectory capabilities. The calibration techniques are discussed.

Broadfoot, A. L.↗