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At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

The radiation environment of OSO missions from 1974 to 1978

Trapped particle radiation levels on several OSO missions were calculated for nominal trajectories using improved computational methods and new electron environment models. Temporal variations of the electron fluxes were considered and partially accounted for. Magnetic field calculations were performed with a current field model and extrapolated to a later epoch with linear time terms. Orbital flux integration results, which are presented in graphical and tabular form, are analyzed, explained, and discussed.

Stassinopoulos, E. G.↗
NASA NTRS1973

Ultrahigh Energy Gamma-rays

An analysis is made of the interactions of very high energy cosmic ray protons with the relict radiation in extragalactic space. Two situations are examined: gamma rays derived from neutral pions -mesons produced in collisions in a nonevolutionary situation and gamma rays from electron pairs produced at early epochs. It is shown that the ultrahigh energy gamma rays could conceivably be of high enough intensity to be detected. The flux of gamma rays from the second process is not far from the diffuse background that was reported.

Strong, A. W.↗
NASA NTRS1973

The Deuterium Puzzle in the Symmetric Universe

The examination of the experimental data concerning the reaction antiproton + He-4 yields pions + nuclei shows that the low abundance of D 2 can be explained only by assuming a low He abundance at the beginning of the radiative era. This is a completely independant confirmation of the evasion of neutrons (and antineutrons) from the emulsion before the end of the epoch where nucleogenesis might have taken place, and leads to an estimate of the size of the emulsion when T = 1 MeV.

Leroy, B.↗
NASA NTRS1973

Smithsonian Astrophysical Observatory Reference System Bulletin, no. 1

The reference system is described which involves timing, scale, coordinate systems and their transformations, and observations of the rotation of the earth. Timing (epochs) and STADAT timing corrections are discussed. The coordinates for locations, and MSL height are listed for each observing station.

Source record↗
NASA NTRS1972

Primordial turbulence and the formation of galaxies.

The development of turbulence at early epochs in a Friedmann universe is studied, giving primary attention to the density fluctuations generated by vortical turbulence. Aspects of turbulence theory in a cosmogonical context are discussed together with a theory of turbulence in an expanding universe. It is suggested that small-amplitude density fluctuations generated by primordial turbulence before decoupling, rather than by the onset of supersonic turbulence after decoupling, can best account for the formation of galaxies. On the other hand, the requisite amount of angular momentum per unit mass to account for the rotation of galaxies is well explained by the turbulence parameters.

Silk, J.↗
NASA NTRS1973

Energy losses of galactic cosmic rays in the interplanetary medium.

Using realistic models of cosmic-ray propagation in interplanetary space we present, for electrons, protons and helium nuclei of a given energy near earth, calculations of their distribution in energy before entering the solar cavity and their mean energy loss. Interplanetary conditions appropriate for the epochs 1965 and 1969 have been used. Cosmic-ray energies in the range of 20 to 1000 MeV/nucleon have been considered.

Urch, I. H.↗
NASA NTRS1973

Solar neutrinos, Martian rivers, and Praesepe.

Some recent papers on solar neutrinos, Martian rivers, and Praesepe stars are reviewed. Possible causes of solar neutrino detection rates being below theoretical expectations are quoted. The widespread presence of sinuous dendritic channels on Mars is noted. The occurrence of earth-like epochs on Mars is indicated as a plausible explanation for many such channels in terms of surface liquid water flows. The roughly uniform distribution of the Praesepe stars through the main sequence width is viewed as the indication that the excursion time off the main sequence is comparable to the time between mixings.

Sagan, C.↗
NASA NTRS1973

A correlation between colors of Jovian clouds and their 5-micron temperatures.

Observations of Jupiter at 5 microns by Keay, Low, and Rieke were compared with color photographs by Minton and Kutoroff taken near the same epoch. A strong correlation is evident between the 5-micron temperature distribution on the Jupiter disk and the cloud colors. Further comparison is made with photographs in the .888-micron CH4 absorption band. Strong correlations exist for features in System II latitudes at all three wavelegths but not for those that move with System I. This is attributed to more intensive convection in the Equatorial Zone. Owen's suggestion that colors may result from at least two mechanisms appears valid; a third appears responsible for blue features only.

Minton, R. B.↗
NASA NTRS1973

Radiation hazards to synchronous satellites: The IUE (SAS-D) mission

The ambient trapped particle fluxes incident on the IUE (SAS-D) satellite were studied. Several synchronous elliptical and circular flight paths were evaluated and the effect of inclination, eccentricity, and parking longitude on vehicle encountered intensities was investigated. Temporal variations in the electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model extrapolated to a later epoch with linear time terms. Orbital flux integrations were performed with the latest proton and electron environment models using new improved computational methods. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 MeV, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗
NASA NTRS1972

Jupiter's decametric rotation period and the source-A emission beam

Determinations of the average decametric rotation period for the planet Jupiter are discussed. Mean rotation periods for a twelve year span are plotted as a function of the mean epochs. Two lesser peaks in the longitude histograms were resolved in addition to the main peak. The three peaks, which are believed to result from emission beams oriented in different directions relative to the corotating magnetic field of the planet, are designated Sources A, B, and C in decreasing order of prominence at frequencies in the vicinity of 18 MHz.

Carr, T. D.↗
NASA NTRS1973

Space radiation incident on SATS missions

A special orbital radiation study was conducted in order to evaluate mission encountered energetic particle fluxes. This information is to be supplied to the project subsystem engineers for their guidance in designing flight hardware to withstand the expected radiation levels. Flux calculations were performed for a set of 20 nominal trajectories placed at several altitudes and inclinations. Temporal variations in the ambient electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model, extrapolated to the tentative SATS launch epoch with linear time terms. Orbital flux integrations ware performed with the latest proton and electron environment models, using new computational methods. The results are presented in graphical and tabular form. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 Mev, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗
NASA NTRS1974

Radiation environment for ATS-F

The ambient trapped particle fluxes incident on the ATS-F satellite were determined. Several synchronous circular flight paths were evaluated and the effect of parking longitude on vehicle encountered intensities was investigated. Temporal variations in the electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model extrapolated to a later epoch with linear time terms. Orbital flux integrations were performed with the latest proton and electron environment models using new improved computational methods. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 Mev, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗
NASA NTRS1972

The inner zone electron model AE-5

A description is given of the work performed in the development of the inner radiation zone electron model, AE-5. A complete description of the omnidirectional flux model is given for energy thresholds E sub T in the range 4.0 E sub T/(MeV) 0.04 and for L values in the range 2.8 L 1.2 for an epoch of October 1967. Confidence codes for certain regions of B-L space and certain energies are given based on data coverage and the assumptions made in the analysis. The electron model programs that can be supplied to a user are referred to. One of these, a program for accessing the model flux at arbitrary points in B-L space and arbitrary energies, includes the latest outer zone electron model and proton model. The model AE-5, is based on data from five satellites, OGO 1, OGO 3, 1963-38C, OV3-3, and Explorer 26, spanning the period December 1964 to December 1967.

Teague, M. J.↗
NASA NTRS1973

Investigation of the responses of the general circulation at 700 mb to solar-geomagnetic disturbance

The Northern Hemisphere 700 mb contour heights from 20 N to 70 N for the period 1947-1970 are studied in conjunction with 272 key days, where the daily increase of the Ci index equals or exceeds 1.0. The superposed epoch method is applied from 33 days before to 66 days after the key day for a variety of zonal and meridional indices. It is shown that the 700 mb height difference between 20 N and 55 N increases significantly in winter 4 days following geomagnetic disturbance (in summer a less prominent but statistically significant increase is found 2 days earlier). The effect is most clear in winter in the quadrant 90-175 W and corresponds to a 7% increase in the mean geostrophic westerly flow. The statistical significance of the results is established by applying Student's t-test to the difference of each daily mean from the continuum.

Stolov, H. L.↗
NASA NTRS1973

A correlation between colors of Jovian clouds and their 5 micron temperatures

Observations of Jupiter at 5 micron by Keay, Low, and Rieke were compared with color photographs by Minton and Kutoroff taken near the same epoch. A strong correlation is evident between the 5 micron temperature distribution on the Jupiter disk and the cloud colors. Further comparison is made with photographs in the .888 micron CH4 absorption band. Strong correlations exist for features in System 2 latitudes at all three wavelengths but not for those that move with System 1. This is attributed to more intensive convection in the Equatorial Zone. Owen's suggestion that colors may result from at least two mechanisms appears valid; a third appears responsible for blue features only.

Minton, R. B.↗
NASA NTRS1973

New two-metric theory of gravity with prior geometry

A Lagrangian-based metric theory of gravity is developed with three adjustable constants and two tensor fields, one of which is a nondynamic 'flat space metric' eta. With a suitable cosmological model and a particular choice of the constants, the 'post-Newtonian limit' of the theory agrees, in the current epoch, with that of general relativity theory (GRT); consequently the theory is consistent with current gravitation experiments. Because of the role of eta, the gravitational 'constant' G is time-dependent and gravitational waves travel null geodesics of eta rather than the physical metric g. Gravitational waves possess six degrees of freedom. The general exact static spherically-symmetric solution is a four-parameter family. Future experimental tests of the theory are discussed.

Lightman, A. P.↗
NASA NTRS1973

Topographical coordinates from Mariner 9 observations of the Martian surface

Results of Mariner 9 determinations of the coordinates of selected topographical features on Mars. An attempt is made to project uncertainties in such determinations, together with uncertainties in spin-rate and in the inertial orientation of the spin axis of Mars, to some epoch in the distant future, and, to examine the impact of further imaging data from a Mars synchronous orbiter in reducing the uncertainty of the location of any given surface feature on the planet relative to the orbiter. The effect of residual navigational uncertainties, and uncertainties in celestial orientation of the imaging system, on such determinations is discussed.

Mohan, S. N.↗