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A six-axis electron spectrometer for the ISEE-1 spacecraft is described and some typical early results presented. This instrument, designed for three-dimensional plasma distribution function studies in the solar wind, magnetosheath, outer magnetosphere, and near tail regions, has three energy ranges: 7.5-512 eV, 11-2062 eV, and 109-7285 cV, respectively. Two channel electron multipliers are used at the output of each of six cylindrical electrostatic analyzers. The total mass of two sensors and a data processing unit is 4.9 kg and the power comsumption is 3.5 W. Two hundred information bits/s telemetry rate is required.

An investigation using a novel ion mass spectrometer for measuring the ionic composition of the solar wind from the ISEE-C spacecraft is described. The resolution and dynamic range of the instrument are sufficient to be able to resolve up to twelve individual ions or groups of ions. This will permit the solution of a number of fundamental problems related to solar abundances and the formation of the solar wind. The spectrometer is composed of a stigmatic Wien filter and hemispherical electrostatic energy analyzer. The use of curved electric field plates in the filter results in a substantial saving of weight with respect to a conventional filter of the same resolution and angular acceptance. The spectrometer is controlled by a microprocessor based on a special purpose computer which has three modes of operations: full and partial survey modes and a search mode. In the search mode, the instrument locks on to the solar wind. This allows four times the time resolution of the full survey mode and yields a full mass spectrum every 12.6 min.

Two plasma regimes were observed in the Venus wake, one characterized by negative-going anisotropies accompanied by high bulk speeds and low magnetic variance, and the other characterized by positive-going anisotropies accompanied by low bulk speeds and high magnetic variance. The two modes alternate in time in a stochastic bimodal fashion as interplanetary magnetic field discontinuities propagate past Venus and switch on the positive anisotropies. The positive mode probably represents enhanced planetary ion pickup which results in instabilities, the damping of which energizes the electrons in the distant wake.

A concept for a near-earth interplanetary mission in the mid-eighties is described. The proposed objectives would be to determine the composition of the interplanetary constituents and its dependence on source-conditions and to investigate energy and momentum transfer processes in the interplanetary medium. Such a mission would accomplish three secondary objectives: (1) provide a baseline for deep space missions, (2) investigate variations of the solar wind with solar activity, and (3) provide input functions for magnetospheric studies.

Two nightside encounters with Mercury's magnetosphere by Mariner 10 revealed bow shock and magnetosheath signatures in the plasma electron data that are entirely consistent with the geometry expected for an interaction between a planet-centered magnetic dipole and the solar wind. The geometrically determined distance between the planet's center and the solar wind stagnation point is 1.4 plus or minus 0.1 R sub M. Both diffuse and sharp shock crossings were observed on the two magnetosphere encounters.

Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure.

The performance of an upconversion system is examined for observation of astronomical sources in the low to middle IR spectral range. Theoretical values for the performance parameters of an upconversion system for astronomical observations are evaluated in terms of the conversion efficiencies, spectral resolution, field of view minimum detectable source brightness, and source flux. Experimental results of blackbody measurements and molecular absorption-spectrum measurements using a lithium niobate upconverter with an argon-ion laser as the pump are presented. Estimates are given of the expected optimum sensitivity of an upconversion device that may be built with presently available components.

Using observations of the solar wind by Explorers 34 and 43, the relationship is confirmed between the relative abundance of helium n sub alpha/n sub p and the bulk speed U of the wind, recently described by Hirschberg, Asbridge and Robbins. Use of this relationship n sub alpha/n sub p = a(t)+bU allows the dependence of the relative abundance of helium upon solar activity to be separated from its bulk speed dependence. The proportion of helium in the solar wind at a given bulk speed is found to increase with increasing sunspot number, averaged over the period of observation. It is shown that the relationship between average relative abundance and temperature, deduced using the bulk speed - temperature relation, is consistent with the data. The relative abundance of helium is not found to increase with increasing solar wind flux. This confirms the result of Hirschberg et al, and contradicts the theoretical prediction of Geiss.

Consideration of observed interplanetary shocks leads to the conclusion that a corotating forward shock has not been unambiguously identified at 1 AU. A reverse shock identified in September 1967 is a likely candidate for a corotating structure.

Description of studies of electrons between 10 eV and 9.9 keV in the solar wind. The transport of energy in the rest frame of the plasma is evaluated and shown to be parallel to the interplanetary magnetic field. The presence of electrons from solar events causes this energy-flux density to exceed the heat flow due to thermal electrons. In one such event, the observations are shown to be consistent with the solar-electron observations made at higher energies. When observations are made at a point connected to the earth's bow shock by an interplanetary-field line, a comparatively large energy flux along the field toward the sun is observed, but the heat flow remains outwardly directed during this time interval. In either situation the heat flow is found to be consistent with measurements made on Vela satellites by a different method. These values, less than .01 ergs/sq cm/sec, are sufficiently low to require modifications to the Spitzer-Harm conductivity formula for use in solar-wind theories.

Magnetospheric substorms relationship to interplanetary magnetic field and solar wind plasma parameters, noting dominant effect of interplanetary southward component

A compact mass energy spectrometer to be flown aboard the IMP-H spacecraft is described. Scientific aims include determination of the relative and absolute fluxes of He-4(2+), He-4 (+), 0(6+), and 0(7+), and He-3(2+).

Helium and hydrogen bulk speeds in solar wind

Magnetic field and electron plasma observations near dawn magnetopause by triaxial spectrometer and fluxgate magnetometer on satellite OGO 5

Short duration proton energy increases observation by Explorer 34, considering interpretation as acceleration associated interplanetary shocks

Comments on waves and discontinuities in solar wind

Magnetic and thermal pressures in solar wind from Explorer 34 data

Measuring energy transfer at colliding streams in solar wind based on data from Explorer 34 and Vela 4B satellites

Solar wind flow behind shock fronts from Mariner 5 and Explorer 34 spacecraft

Magnetic and kinetic pressures in solar wind

Magnetic field and electron flux observations near magnetopause via magnetometer and triaxial electron spectrometer on OGO-E

Acceleration of protons by interplanetary shocks

Solar wind heating, determining roles of various energy sources from Explorer 34 observations

Hydromagnetic fluid model of solar wind for interpreting discontinuities in plasma and magnetic field, interaction with atmosphere, heating mechanism and chemical composition

Solar wind plasma effects on lunar wake umbral and penumbral interplanetary magnetic field anomalies, evaluating roles of electrons and ions

Shock discontinuities in solar wind measured by magnetic field and plasma instruments on Explorer 34, applying Rankine-Hugoniot relations

Explorer 34 observations of hydrogen and He ions in solar wind, noting number density variations and tentative association with geomagnetic storms

Plasma experiments on Explorer 34 satellite to study fluid properties of solar wind

Worldwide changes in geomagnetic field, determining causes by examining magnetic field and plasma data for solar wind and classifying as SSC or SI

Proton heating and velocity of solar wind

Microscale fluctuations in interplanetary magnetic field, considering proton thermal energy and magnetic field energy densities

Worldwide changes in earth magnetic field determined by examination of magnetic field and interplanetary plasma data for solar wind near earth

Solar plasma observations during magnetic storms, discussing shocks and tangential discontinuities, geomagnetic variations and He

Magnetosheath-solar wind boundary discontinuous transitions in proton spectrum, flow direction and magnetic flux from Explorer 34 satellite data

Spaceborne mass-energy spectrometer to study solar wind He-H ions ratio, ion temperatures and ion flux angular distributions

Auroral electron energy spectra measured from 180 to 250 km using electrostatic analyzer and channeltron detector, discussing electron flux

Crossed field velocity selector, calculating particle paths

Electron measurements near weak aurora during rocket flight

Three curved plate energy analyzers coupled with three electron multiplier tubes detect and measure low energy electron flux in several directions simultaneously.

Triaxial electron detector differential energy analyzer for use in sounding rockets

Experiments on solar particles noting abundance of solar cosmic rays, energy region, spectrum of solar protons, sudden commencement, etc

Detector-analyzer for studying proton and ion energy distribution in interplanetary space at satellite altitudes

Intensities and energies of solar cosmic ray particles detected near earth

Solar cosmic ray event - september 26, 1960

Electron temperature measurements taken by a triaxial electron analyzer on Ogo 5 in the solar wind and in the magnetosheath are interpreted. In the interplanetary medium, observations made on the bow shock connected lines of magnetic force have been separated from those made on non-bow-shock connected lines. The dependence of electron thermal properties on the local field geometry is discussed together with features of electron temperature and density discontinuities across the bow shock. The velocity distribution function is characterized together with temperature and density variations in a part of the dawn magnetosheath.

When it is averaged on a time scale of several solar rotations, the solar wind proton temperature T increases monotonically with the bulk speed V (Hundhausen et al., 1970; Burlaga and Ogilvie, 1970). This macroscale T-V relation does not change appreciably with solar cycle. The temperatures corresponding to intervals of increasing speed are only 15% higher than those corresponding to decreasing speeds, and thus it is indicated that the macroscale T-V relation is not appreciably affected by stream interactions. On a time scale of a tenth of a solar rotation there are time dependent T(t)-V(t) relations that are closely related to the stream profiles, as was noted by Hundhausen (1973). These T(t)-V(t) relations can meaningfully be resolved into two components - the macroscale T-V relation and systematic time dependent deviations from the macroscale relation.