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A marginal stability criterion for ion acoustic waves is applied to the analysis of five thin bow shock crossings observed by OGO-5; the observations began with the satellite in the magnetosheath. The assumption of marginally stable ion acoustic wave generation in the shock ramp provides the basis for determining the thickness of the magnetic gradients for subcritical, quasi-perpendicular shock features.
Density measurements made by OGO-5 during the period from March 1968 to May 1969 were used to locate enhanced light ion abundances in the midst of ion-depleted regions in the plasmasphere. Such abundances were found to be more frequent on the night side. As a possible mechanism for the observed light ion distribution, convection electric fields and subsequent thinning and corotation of plasma tails are considered. Attention is given to wave-particle interactions, especially as influenced by a magnetic field (both during plasmaspheric magnetic storms, and magnetospheric substorms).
Scientific results from OGO-5 and OGO-6 experiments are summarized and approximately 200 citations are included to update the 1975 OGO bibliography. Personal author, subject, and corporate source indexes are included. The supplement follows the same format as that of the OGO Program Summary; it does not repeat the finalized information in the original publication, which should be consulted for indexes of experiments, experimenters, institutions, and the glossary of abbreviations and acronyms.
Solar-wind data obtained by the OGO-5 and IMP-7-8 earth satellites show a positive correlation between the ratio of helium to hydrogen tempeatures, and the velocity difference between the two ions. Although this result disagrees with the Prognoz-1 results reported earlier in this journal, it is consistent with the expected control by Coulomb collisions when the solar-wind density is high.
After a review of the properties and predictions of the closed and open models of the magnetopause, OGO-5 magnetometer data are used to illustrate various observed signatures of the magnetopause current layer and the adjacent plasma boundary layer. Among the topics touched upon are: fluctuations, diamagnetic effects, and field aligned currents in the boundary layer; one dimensionality of the magnetopause; presence and absence of a magnetic field component perpendicular to the magnetopause; finite ion gyroradius effects. A brief summary is given of existing Vlasov theory for the description of tangential, rotational, and contact discontinuities. Special attention is paid to the tangential momentum balance and the jump conditions at a rotational discontinuity. Low frequency fluctuations are discussed with emphasis on the signatures of the tearing mode.
Holzer and Slavin (1978) have found that the transfer of magnetic flux to and from the dayside magnetosphere as inferred from observed displacements of the magnetopause surface is correlated with both the magnitude of the auroral zone magnetic index AL and the incident flux of southward IMF. Empirical expressions specifying the rate at which magnetic flux is eroded in terms of interplanetary parameters and the rate of magnetic flux return as a function of AL have been developed. These relations are then used to predict magnetotail magnetic field enhancements from interplanetary and ground based data during an interval of substorm activity. The total magnetic flux in the tail is increased during intervals when the amount of flux transferred into its volume by dayside erosion exceeds the flux lost to the dayside by magnetospheric convection. Using Ogo-5 tail observations it is found for the sample events considered that these magnetic field enhancements can be described by empirical expressions for the magnetic flux transfer rates.
The paper investigates possible chorus generation mechanisms by means of simultaneous OGO-5 measurements of chorus, energetic (79 + or - 23 keV) electron fluxes and pitch angle distributions, and ambient magnetic fields. Further, the solar wind data during high-latitude dayside chorus events are examined. It is reported that the highly eccentric orbit had an apogee of 24 earth radii and an inclination of 30 deg to the geographic equator.
The University of Chicago cosmic ray electron detector was launched aboard the ISEE-3 spacecraft on August 12, 1978. The energy spectrum of electrons measured in 1978 is nearly identical to that measured in 1968 by OGO-5. During the period of our investigation we observe quiet time increases in the electron flux which are of Jovian origin. These increases are restricted to energies below about 25 MeV but appear to have an energy dependence that peaks around 15 MeV.
According to the Rankine-Hugoniot jump conditions, the magnetic field strength increases in passing from upstream to downstream of a magnetohydrodynamic shock. At the earth's bow shock the magnetic field often increases significantly more than is required by the Rankine-Hugoniot conditions before decaying in an oscillatory fashion to its downstream average value. Recent OGO-5 and ISEE studies, together with the realization that overshoots also occur in the bow shocks of Venus, Jupiter, and Saturn have focussed attention on these phenomena. It is found that none of the nonlinear dispersive wave theories in the shock literature can account for the overshoot. The present investigation documents the dependence of the overshoot amplitude and thickness on solar wind parameters. Magnetic field overshoots are found to be characteristic of supercritical quasi-perpendicular shocks. The overshoot thickness scales as the ion Larmor radius based upon the solar wind speed and magnetic field.
The spectra of strong bursts observed at low frequencies by OGO-5 during 1968-1970 are presented. They usually exhibit an intense main peak between 100 kHz and 1 MHz, and sometimes a less intense secondary peak between 1 and 3.5 MHz. Main peaks of 10 to the -12th W per sq m per Hz or more were obtained in very strong events, but because of antenna calibration problems those could be one or two orders of magnitude too high. Recently published work supports the finding that type III bursts at low frequencies can be at least four orders of magnitude more intense than at ground-based frequencies of observation. It is found that the energy received at the earth increases with decreasing frequency approximately as f to the -n, where n is between 3 and 4.
Recent advances in the techniques and instruments of cometary research are described. Consideration is given to the development of the first space-based platforms for cometary observations in the 1970s, including the OGO-5 and OAO-2 ultraviolet satellites, as well as IRAS. The expectations for the scientific return from space missions in the 1980s and 1990s are also discussed, with attention given to the Giotto flyby; the Soviet VEGA missions; and two Japanese spacecraft missions Sakigake and Suise. The imaging and spectroscopic experiments to be carried out during the Giotto mission are described in detail.
Triaxial electron spectrometer, mounted on OGO-E SPACECRAFT, measures flux and energy distributions of electrons, noting electron multiplier
Integrated set of three detectors for galactic and solar ray studies of OGO-E and OGO-G