Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “OGO”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Ogo 6 measurements of supercooled plasma in the equatorial exosphere.

Plasma measurements performed on Ogo 6 reveal electron and ion temperature values that on occasion appear to be well below the expected neutral gas temperature. The phenomenon is observed only at night above 500 km near the magnetic equator. It is suggested that the expansion cooling of the plasma is accomplished by downward motions of the F region plasma induced by winds or diffusion, by outward E x B drift, or more probably by the upward flow of plasma during interhemisphere transport along magnetic field lines. It is also suggested that preferential cooling of electrons because of their greater thermal conductivity should tend to give ion temperatures greater than electron temperatures during the postsunset cooling of the plasmasphere when photoelectrons are absent.

Hanson, W. B.↗
NASA NTRS1973

Role of gas-surface interactions in the reduction of Ogo 6 neutral particle mass spectrometer data.

Data obtained with the quadrupole mass spectrometer aboard the Ogo 6 satellite show the effects of significant surface interaction processes, including nearly complete recombination of incoming atomic oxygen on the walls of the instrument antechamber plus adsorption and desorption of oxygen and carbon monoxide. The observed data are fit by solving the time-dependent continuity equations accounting for production and loss of atomic oxygen, molecular oxygen, and (in the case of mass 28) carbon monoxide. The surface parameters that best fit the data are selected and applied to the determination of ambient densities and their estimated errors.

Hedin, A. E.↗
NASA NTRS1973

The detection of 'intermediate' size magnetic anomalies in Cosmos 49 and OGO 2, 4, 6 data.

Benkova, Dolginov and Simonenko have recently reported the presence of intermediate size magnetic anomalies from Cosmos 49 data and hypothesized a crustal and/or upper mantle origin for these. We have examined the spherical harmonic models of the internal potential function, based on the OGO 2, 4 and 6 data and verified the locations and amplitudes of those anomalies with wavelengths of approximately 4000 km. The patterns of delta-F so computed were then compared with the IZMIRAN maps and also were analyzed statistically, in both the spatial and frequency domains, using residuals computed from the raw Cosmos 49 data. The two sets of data were thus derived from completely independent sets of observations and field references. The two patterns are shown to agree very well over the whole earth surface up to the 50 deg latitude limit of Cosmos 49.

Regan, R. D.↗
NASA NTRS1973

Electron concentrations calculated from the lower hybrid resonance noise band observed by Ogo 3.

A noise band at the lower hybrid resonance (LHR) is often detected by the VLF and ELF receivers on Ogo 3, using the electric antenna. In some cases the noise band is at the geometric mean gyrofrequency as measured by the Goddard Space Flight Center (GSFC) magnetometer, and local LHR in a dense H(+) plasma is indicated; in such cases, electron concentration can be calculated, if it is assumed that heavy ions are negligible. Observations at midlatitudes and altitudes of a few earth radii show local concentrations as low as 1.4 electrons/cu cm. In one case the concentrations obtained from the LHR noise band agree with those measured simultaneously by the GSFC ion mass spectrometer within a factor of 2. In another case the concentration is observed to fall by a factor of 2 in 150 km and then to decrease roughly as R to the minus fourth power, in agreement with whistler measurements outside the plasmapause.

Burtis, W. J.↗
NASA NTRS1973

An atlas of low-latitude 6300-A forbidden O I night airglow from Ogo 4 observations.

The atomic oxygen emission line at 6300 A as measured in the nadir direction by a photometer on the polar-orbiting satellite Ogo 4 has been plotted between 40 deg N and 40 deg S latitude on a series of maps for the moon-free periods between Aug. 30, 1967, and Jan. 10, 1968. Readily apparent are the longitudinal and local time variations that occur during the northern fall-winter season. The northern tropical arc is more widespread; the southern arc is not present at all longitudes. The arcs in early evening are strong and distinct, separated by very low emission rates at the magnetic equator. The arcs lie generally along magnetic parallels, move toward the magnetic equator as the night progresses, and, in the early morning hours, decrease in emission rate and degenerate into patches.

Reed, E. I.↗
NASA NTRS1973

A magnetospheric field model incorporating the OGO 3 and 5 magnetic field observations.

A magnetospheric field model is presented in which the usually assumed toroidal ring current is replaced by a circular disk current of finite thickness that extends from the tail to geocentric distances less than 3 earth radii. The drastic departure of this model from the concept of the conventional ring current lies in that the current is continuous from the tail to the inner magnetosphere. This conceptual change was required to account for the recent results of analysis of the OGO 3 and 5 magnetic field observations. In the present model the cross-tail current flows along circular arcs concentric with the earth and completes circuit via surface currents on the magnetopause. Apart from these return currents in the tail magnetopause, Mead's (1964) model is used for the field from the magnetopause current. The difference scalar field, Delta B, defined as the difference between the scalar field calculated from the present model and the magnitude of the dipole field, is found to be in gross agreement with the observed Delta B.

Sugiura, M.↗
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 NTRS1973

Measurements of VLF polarization and wave normal direction on OGO-F

A major achievement of the F-24 experiment on OGO 6 was a verification of the theory of the polarization of proton whistlers. As predicted, the electron whistler was found to be right-hand polarized and the proton whistler left hand polarized. The transition from right- to left-hand polarization was found to occur very rapidly. Thus it appears that the experimental technique may allow great accuracy in the measurement of the cross-over frequency, a frequency that provides information on the ionic composition of the ionosphere.

Helliwell, R. A.↗
NASA NTRS1973

Variation with interplanetary sector of the total magnetic field measured at the OGO 2, 4, and 6 satellites

Variations in the scalar magnetic field (delta B) from the polar orbiting OGO 2, 4, and 6 spacecraft are examined as a function of altitude for times when the interplanetary magnetic field is toward the sun and for times when the interplanetary magnetic field away from the sun. This morphology is basically the same as that found when all data, irrespective of interplanetary magnetic sector, are averaged together. Differences in delta B occur, both between sectors and between seasons, which are similar in nature to variations in the surface delta Z found by Langel (1973c). The altitude variation of delta B at sunlit local times, together with delta Z at the earth's surface, demonstrates that the delta Z and delta B which varies with sector has an ionospheric source. Langel (1973b) showed that the positive delta B region in the dark portion of the hemisphere is due to at least two sources, the westward electrojet and an unidentified non-ionospheric source(s). Comparison of magnetic variations between season/sector at the surface and at the satellite, in the dark portion of the hemisphere, indicates that these variations are caused by variations in the latitudinally narrow electrojet currents and not by variations in the non-ionospheric source of delta B.

Langel, R. A.↗
NASA NTRS1974

Reduction and analysis of data from cosmic dust experiments on Mariner 4, OGO 3, and Lunar Explorer 35

The analysis of data from the cosmic dust experiment on three NASA missions is discussed. These missions were Mariner IV, OGO III, and Lunar Explorer 35. The analysis effort has included some work in the laboratory of the physics of microparticle hypervelocity impact. This laboratory effort was initially aimed at the calibration and measurements of the different sensors being used in the experiment. The latter effort was conducted in order to better understand the velocity and mass distributions of the picogram sized ejecta particles.

Source record↗
NASA NTRS1974

A comparison of electric and magnetic field data from the OGO-6 spacecraft

Electric and magnetic field disturbance characteristics from OGO-6 were studied. Examination of simultaneous patterns of disturbance below 600 km over the summer polar cap showed that pattern changes in electric field and in the disturbance in magnetic field magnitude are highly correlated. This correlation extends to pattern shapes boundary locations, and to the amplitudes of the correlated quantities. In the winter hemisphere, at altitudes above 800 km, correlations between boundaries exist, pattern correlations are present, and amplitude correlations are essentially absent. Below 600 km the region of positive delta B, from 2200 to 1000 MLT, has a significant contribution from ionospheric and nonionospheric sources. Above 800 km the nonionospheric sources dominate.

Langel, R. A.↗
NASA NTRS1973

A catalog of ionospheric F region irregularity behavior based on Ogo 6 retarding potential analyzer data

Review of in situ data obtained with the aid of the retarding potential analyzer on board Ogo 6 which reveal the nature of ionospheric irregularities in the total ion concentration above 400 km. Except for the high-latitude regions, the ionosphere is usually observed to be very smooth in the daytime, but considerable structure is observed at night, particularly near the equator and at Atlantic longitudes. Although most of the irregularities observed appear to be stochastic in nature, many nearly monochromatic waveforms are observed near the equator. The topics discussed include the midlatitude scintillation boundary, large-amplitude equatorial irregularities, the fluctuation spectrum of typical F-region irregularities, the lower edge of the equatorial F region, sinusoidal waveforms, ground glass irregularities, breaking wave irregularities, and regions of smooth and irregular ionization inside the polar cap.

Mcclure, J. P.↗
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

Spatial and temporal behavior of atomic oxygen determined by Ogo 6 airglow observations

Maps are produced of the atomic oxygen density near 97 km showing a strong variation in latitude, longitude, universal time, and time of year. These densities are deduced from atomic oxygen green nightglow observations carried out from Ogo 6. Meridional wind patterns needed to support the asymmetries observed in local oxygen production and loss rates are deduced.

Donahue, T. M.↗
NASA NTRS1974

Cosmic gamma-ray burst detected with an instrument on board the OGO-5 satellite

Gamma-ray bursts of cosmic origin have recently been detected by instruments on the Vela satellites. We now confirm the detection of the June 30, 1971 event with an instrument on board the OGO-5 satellite. The intensity of this burst is calculated to be approximately 100-200 photons per sq cm/sec for photons of energy greater than 150 keV with an upper limit of 50 photons per sq cm/sec for the intensity above 5 MeV. An upper limit of one-third of the intensity of the June 30, 1971 event is set for 10 other events studied.

Lheureux, J.↗
NASA NTRS1974

The global distribution of natural and man-made ionospheric electric fields at 200 kHz and 540 kHz as observed by Ogo 6

An experiment on the polar-orbiting Ogo 6 spacecraft yielded real-time analog data in several broadband channels and essentially continuous tape-recorded data from two narrow-band (200-Hz) receivers operating at 200 and 540 kHz. The results show that the worldwide distributions of signals at 200 and 540 kHz falls into a number of different categories: (1) naturally generated broadband (auroral) hiss at polar latitudes with typical 200-kHz intensities of around 0.1 microvolt per meter per Hz to the 1/2 power, maximum intensities of up to several microvolt per meter per Hz to the 1/2 power, and generally lower intensities at 540 kHz; (2) nighttime midlatitude enhancements of a few microvolts per meter, which probably result either from a superposition of signals from a number of 200- and 540-kHz stations or from interference from intense signals of much higher frequencies; (3) well-defined signal peaks associated with individual ground stations operating at 200 kHz; (4) striking signal enhancements in the conjugate region of a low-latitude 200-kHz station (Ashkhabad), suggesting propagation in the whistler mode to the opposite hemisphere; and (5) occasional signal enhancements at the magnetic equator.

Laaspere, T.↗
NASA NTRS1974

Plasma tail interpretations of pronounced detached plasma regions measured by Ogo 5

Measurements of the light ion thermal plasma distribution in the magnetosphere frequently show apparent isolated patches of enhanced plasma density in the trough region beyond the main plasmasphere. These patches of light ions viewed along a satellite orbit appear detached from the main plasmasphere. By using a simple time-dependent convection model to determine the length of time a magnetic flux tube has been closed and in daylight (a rough indicator of the expected equatorial plasma density variation), the most prominent 'detached' regions measured by the mass spectrometer on Ogo 5 in the noon-dusk quadrant are seen on a global scale to be readily interpreted as filamentary extensions of the plasmasphere, called plasma tails. Hence on a global scale the pronounced detached regions may be attached to the main plasmasphere.

Chen, A. J.↗