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We present observations of "lion roars" obtained in the magnetosheath by the Spectrum Analyser (SA) of the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment aboard Cluster. STAFF-SA calculates, in near real time, the complete auto- and cross-spectral matrix derived from three magnetic and two electric components of the electromagnetic field at 27 frequencies in the range of 8 Hz to 4 kHz. This allows the study of the properties of whistler mode waves and more particularly, the properties of "lion roars", which are intense, short-duration, narrow-banded packets of whistler waves. Their presence is favoured by the magnetic field troughs associated with mirror mode structures. During two short periods of well-defined mirror modes, we study the depth δB/B of the magnetic troughs, and the direction of propagation of the lion roars. During the first period, close to the magnetopause, deep magnetic troughs pass the satellites. Lion roars are then observed to propagate simultaneously in two directions, roughly parallel and anti-parallel to the magnetic field: this probably indicates that during this period, the satellites were within the successive source regions of lion roars. For the second period, far from the magnetopause, the magnetic troughs are less deep. Lion roars are propagating in only one direction, roughly anti-parallel to the magnetic field, suggesting that the source regions are more distant and predominantly on one side of the satellites.Key words. Magnetospheric physics (magnetosheath; plasma waves and instabilities) Radio science (radiowave propagation)

For the first time the evolution of interplanetary rotational discontinuities (RDs) are observed in the solar wind, in the magnetosheath and in the dayside magnetosphere by the ISEE 1-2-3 spacecraft. Interaction of a RD with the bow shock builds up a transient density event (TDE) in the magnetosheath, displaying two density peaks anticorrelated to the magnetic field modulus. TDEs are convected from the bow shock to the dayside magnetopause without spreading. The duration of a TDE is around 15 s and two close TDEs can merge in a single structure. The density in a TDE exceeds the surrounding level by a factor of about 35%, while the field modulus can decrease by a large amount. The interaction of a TDE with the magnetopause is analyzed in terms of impulsive penetration process. The element of plasma injected in the magnetosphere is filamentary, its signature is different from the signature of a flux transfer event or a surface wave.

We analyze the high time-resolution profiles of the electron density and of the magnetic field and the plasma parameters recorded by ISEE 1 and 2 during a crossing of the Earth's magnetosheath at 1430 LT. Compressive and Alfven ion cyclotron modes (AIC modes) are identified by comparing the measured magnetic polarization and electron parallel compressibility with the results of calculations in an unstable kinetic linear model. A criterion to discuss the accuracy of the wave vector direction of mirror modes is established; an efficient method to disentangle mirror and AIC modes is presented and applied. From the bow shock to the inner sheath we identify successively (1) compressive modes and AIC modes in the oblique shock, (2) a pure AIC mode region of circularly and elliptically polarized waves in a layer 0.3 RE thick adjacent to the undershoot, (3) a mixed region 2 RE thick where both mirror modes and AIC modes are observed, (4) a pure mirror mode region. The nature of the dominant mode appears to be controlled by the depth in the magnetosheath, more than by the local values of βp and the proton temperature anisotropy Tp⊥/Tp‖. In the outer sheath the unusual identification of a pure Alfvenic region for a large average proton beta βp = 13 and a moderate proton temperature anisotropy could be explained by a relatively low density of α particles. The mirror modes are three-dimensional structures with their major axis along the magnetic field and with their minor axis nearly perpendicular to the magnetopause surface. We estimate the dimensions of ordered structures observed in the middle of the magnetosheath for a βp around 7 ± 1 and Tp⊥/Tp‖ around 1.5; the minor axis of regular mirror modes is typically between 1300 and 1900 km long; the intermediate dimension is larger than either 2200 or 2700 km, while the major axis is larger than either 2700 or 3400 km. For the first time the measured parallel compressibility of the pure mirror modes is shown to be in relatively good agreement with the linear model predictions for 4 < βp < 11. The absence of AIC modes in the inner sheath suggests that these modes cannot grow or propagate in regions where mirror modes are well developed and that AIC wave energy is not transferred across a large-amplitude mirror mode region.

The ISEE radio wave propagation electron density experiment allowed the determination of the integrated electron density between the ISEE 1 and ISEE 2 satellites at the relatively high rate of 8 or 32 Hz. When the component of the spacecraft separation vector in the direction of the normal to the magnetopause is significantly smaller than the thickness of the current layer, this data set allows the internal structure of the magnetopause to be studied and compared with theoretical predictions. For a particular triple subsolar magnetopause crossing with high magnetic shear, an electron density overshoot is observed in the current layer adjacent to the magnetosheath. The similarity of the three crossings indicates that the internal structure of the magnetopause does not change dramatically during the time interval considered. A superposed epoch analysis of these crossings is consistent with the density profile obtained from kinetic simulations. The general relationship between magnetic field asymmetry, magnetic field rotation angle and electron density overshoot is discussed. It is concluded that a density overshoot could be a typical feature of the subsolar magnetopause with high magnetic shear. This conclusion is supported by two other dayside magnetopause crossings for which high time resolution electron density data are available.

International audience; Radio waves undergo angular scattering when they propagate through a plasma with fluctuating density. We show how the angular scattering coefficient can be calculated as a function of the frequency spectrum of the local density fluctuations. In the Earth's magnetosheath, the ISEE 1-2 propagation experiment measured the spectral power of the density fluctuations for periods in the range 300 to 1 s, which produce most of the scattering. The resultant local angular scattering coefficient can then be calculated for the first time with realistic density fluctuation spectra, which are neither Gaussian nor power laws. We present results on the variation of the local angular scattering coefficient during two crossings of the dayside magnetosheath, from the quasi-perpendicular bow shock to the magnetopause. For a radio wave at twice the local electron plasma frequency, the scattering coefficient in the major part of the magnetosheath is b(2fp) ? 0.5 – 4 × 10–9 rad2/m. The scattering coefficient is about ten times stronger in a thin sheet (0.1 to1RE) just downstream of the shock ramp, and close to the magnetopause.

The Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment is one of five experiments which together comprise the Wave Experiment Consortium (WEC). STAFF consists of a three-axis search coil magnetometer to measure magnetic fluctuations at frequencies up to 4 kHz, and a spectrum analyser to calculate in near-real time aboard the spacecraft, the complete auto- and cross-spectral matrices using the three magnetic and two electric components of the electromagnetic field. The magnetic waveform at frequencies below either 10 Hz or 180 Hz is also transmitted. The sensitivity of the search coil is adapted to the phenomena theo be studied: the values 3 × 10-3 nT Hz-1/2 and 3 × 10-5 nT Hz-1/2 are achieved respectively at 1 Hz and 100 Hz. The dynamic range of the STAFF instruments is about 96 dB in both waveform and spectral power, so as to allow the study of waves near plasma boundaries. Scientific objectives of the STAFF investigations, particularly those requiring four point measurements, are discussed. Methods by which the wave data will be characterised are described with emphasis on those specific to four-point measurements, including the use of the Field Energy Distribution function.

This paper describes the RETE (Research on Electrodynamic Tether Effects) experiment mounted on board the TSS (Tethered-Satellite System) satellite which was deployed on a cable from the space Shuttle Atlantis during the TSS mission flown in August 1992. The experiment layout and its modes of operation are described in detail. To give an idea of RETE capabilities and actual performance during the mission, samples of measurements are also presented.

The Ulysses spacecraft encountered the planet Jupiter in February 1992, on its journey towards high heliospheric latitude. During the approach to the planet, as well as on the outbound pass, while receding from the Jovian bow shock, the Plasma Frequency Receiver that is part of the Unified Radio and Plasma Wave experiment (URAP) recorded bursts of plasma waves in the frequency range of a few kHz. These emissions, first observed by the PWS experiment onboard the Voyager spacecraft, have been identified as upstream electron plasma waves. In this paper, we present the first analysis of the characteristics of these emissions, which are very similar to those found in the Earth's electron foreshock, upstream of the Earth's bow shock. These bursty emissions, with a peak frequency very close to the local electron plasma frequency Fpe, have a typical electric field amplitude in the range 0.01–0.1 mV m−1, with some bursts above 1 mV m−1. The frequency bandwidth over which significant power can be found above the instrument background noise ranges from below 0.2 Fpc to about 2 Fpc. On the basis of our present knowledge of similar emissions observed at Earth, we suggest that the broadband emissions are triggered by suprathermal (a few tens of eV) electrons, streaming back from Jupiter's bow shock.

The Space Physics Archive Search and Extract (SPASE) project has developed an information model for interoperable access and retrieval of data within the Heliophysics (also known as space and solar physics) science community. The diversity of science data archives within this community has led to the establishment of many virtual observatories to coordinate the data pathways within Heliophysics subdisciplines, such as magnetospheres, waves, radiation belts, etc. The SPASE information model provides a semantic layer and common language for data descriptions so that searches might be made across the whole of the heliophysics data environment, especially through the virtual observatories.

The Unified Radio and Plasma Wave (URAP) experiment has produced new observations of the Jupiter environment, owing to the unique capabilities of the instrument and the traversal of high Jovian latitudes. Broad-band continuum radio emission from Jupiter and in situ plasma waves have proved valuable in delineating the magnetospheric boundaries. Simultaneous measurements of electric and magnetic wave fields have yielded new evidence of whistler-mode radiation within the magnetosphere. Observations of aurorallike hiss provided evidence of a Jovian cusp. The source direction and polarization capabilities of URAP have demonstrated that the outer region of the lo plasma torus supported at least five separate radio sources that reoccurred during successive rotations with a measurable corotation lag. Thermal noise measurements of the lo torus densities yielded values in the densest portion that are similar to models suggested on the basis of Voyager observations of 13 years ago. The URAP measurements also suggest complex beaming and polarization characteristics of Jovian radio components. In addition, a new class of kilometer-wavelength striated Jovian bursts has been observed.

The radio receiver of the Unified Radio and Plasma experiment aboard the Ulysses spacecraft records spectra of the quasi-thermal plasma noise. The interpretation of these spectra allows the determination of the total electron density Ne and of the cold (core) electron temperature Tc in the solar wind. A single power law does not fit the variations of Ne which result from the contribution from different solar wind structures. The distribution of the values of Tc suggests that, on the average, the solar wind is nearly isothermal.

ISEE1 and 2 high resolution electron density and magnetic field measurements have been used to study characteristic structures, identified as FTEs, observed inside the magnetosphere close to the magnetopause. We investigate new properties: a volcano-like signature in the magnetic field strength, a thin sheet structure at the leading edge, and a wake. The plasma compressibility is analysed through the structure. Auto and cross spectral analysis of the data reveal the signature of compressive modes in the wake of the FTE.

The four-satellite Cluster mission investigates the small-scale structures and physical processes related to interaction between the solar wind and the magnetospheric plasma. The Cluster Active Archive (CAA) (URL: http://caa.estec.esa.int) will contain the entire set of Cluster high-resolution data and other allied products in a standard format and with a complete set of metadata in machine readable format. The total amount of the data files in compressed format is expected to exceed 50 TB. The data archive is publicly accessible and suitable for science use and publication by the world-wide scientific community. The CAA aims to provide user-friendly services for searching and accessing these data and ancillary products. The CAA became operational in February 2006 and as of Summer 2008 has data from most of the Cluster instruments for at least the first 5 years of operations (2001–2005). The coverage and range of products are being continually improved with more than 200 datasets available from each spacecraft, including high-resolution magnetic and electric DC fields and wave spectra; full three-dimensional electron and ion distribution functions from a few eV to hundreds of keV; and various ancillary and browse products to help with spacecraft and event location. The CAA is continuing to extend and improve the online capabilities of the system and the quality of the existing data. It will add new data files for years 2006–2009 and is preparing for the long-term archive with complete coverage after the completion of the Cluster mission.

Non-thermal continuum (NTC) radiation is, with auroral kilometric radiation (AKR), one of the two electromagnetic emissions generated within the Earth's magnetosphere and radiated into space. The location of the source of NTC has been sought for several decades, with only limited success. The constellation formed by the four CLUSTER spacecraft provides the possibility of triangulation in the vicinity of the source, thus allowing progress in source localisation, while simultaneously revealing the beaming properties of NTC radio sources. We present a case event showing two beams localised on opposite sides of the magnetic equator. At any selected frequency, triangulation points to a single region source of small size. Its position is compatible with the range of possible loci of sources predicted by the radio window theory of Jones (1982) in a frame of constraints relaxed from the simple sketch proposed in early works. The analysis of similar observations from the Dynamics Explorer 1 by Jones et al. (1987) enabled the authors to claim validation of the radio window theory. CLUSTER observations, however, reveal a large beaming cone angle projected onto the ecliptic plane, a feature unobservable by Dynamics Explorer which had a different spin axis orientation. According to the radio window theory, such a large observed cone angle can only be formed by a series of point sources, each beaming in a narrow cone angle. This study demonstrates the difficulty of validating NTC linear generation mechanisms using global beaming properties alone.

We report on radio signatures observed at Saturn by the Cassini RPWS experiment which are strikingly similar to the Jovian “energetic events” observed by Galileo. They consist of sudden intensifications of the auroral radio emission (SKR) followed by the detection of a periodic narrowband radiation which most likely originates from Saturn's plasma disk. About ten “events” have been observed in 2006, showing on average temporal scales ∼3 times longer than their Jovian counterparts. We analyze the conditions of generation and the visibility of the narrowband radiation and conclude that the Kronian “events” are most likely associated with plasma evacuation from the disk. These observations provide new insights on the role of internal energy releases in Saturn's magnetosphere, known from other observations to be mainly driven by the solar wind.

The Cluster STAFF Spectral Analyser measures the magnetic and electric power spectral densities (PSD) δB2 and δE2 in the magnetosheath between 8 Hz and 4 kHz, i.e. between about the lower hybrid frequency and 10 times the proton plasma frequency. We study about 23 h of data on four different days. We do not consider the whistler waves and the electrostatic pulses (which are not always observed) but the underlying permanent fluctuations. Paper 1 (Mangeney et al., 2006) shows why the permanent PSD at a given frequency f depends strongly on the angle ΘBV between the magnetic field B and the flow velocity V: this is observed for the electromagnetic (e.m.) fluctuations, δB2 and δEem2, below the electron cyclotron frequency fce, and for the electrostatic (e.s.) fluctuations δEes2 at and above fce. This dependence is due to the Doppler shift of fluctuations which have a highly anisotropic distribution of the intensity of the wave vector k spectrum, and have a power law intensity ∝k−ν with ν≃3 to 4. In the present paper, we look for parameters, other than ΘBV, which control the intensity of the fluctuations. At f≃10 Hz, δB2 and δE2em increase when the solar wind dynamic pressure PDYNSW increases. When PDYNSW increases, the magnetosheath PDYNMS∝N V2 also increases, so that the local Doppler shift (k.V) increases for a given k. If V increases, a given frequency f will be reached by fluctuations with a smaller k, which are more intense: the variations of δB2 (10 Hz) with PDYNSW are only due to the Doppler shift in the spacecraft frame. We show that the e.m. spectrum in the plasma frame has an invariant shape I1D∝Aem (kc/ωpe)−ν related to the electron inertial length c/ωpe: the intensity Aem does not depend on PDYN, nor on the electron to proton temperature ratio Te/Tp, nor on the upstream bow shock angle θBN. Then, we show results of 3-D MHD numerical simulations of the magnetosheath plasma, which map the regions where the angle ΘBV is ≃90°. The e.m. fluctuations are more intense in these magnetosheath regions, in the spacecraft frame where they are observed in the "whistler" range; and the e.s. fluctuations are less intense in these same regions, in the spacecraft frame where they are observed in the "ion acoustic" range. We conclude that the intensity of the permanent fluctuations in the e.m. range only depends on the Doppler shift, so that from day to day and from place to place in the magnetosheath, the k spectrum in the plasma frame has an invariant shape and a constant intensity. This is observed on scales ranging from kc/ωpe≃0.3 (50 km) to kc/ωpe≃30 (500 m), i.e. at electron scales smaller than the Cluster separation.

We analyse the power spectral density δB2 and δE2 of the magnetic and electric fluctuations measured by Cluster 1 (Rumba) in the magnetosheath during 23 h, on four different days. The frequency range of the STAFF Spectral Analyser (f=8 Hz to 4 kHz) extends from about the lower hybrid frequency, i.e. the electromagnetic (e.m.) range, up to about 10 times the proton plasma frequency, i.e. the electrostatic (e.s.) range. In the e.m. range, we do not consider the whistler waves, which are not always observed, but rather the underlying, more permanent fluctuations. In this e.m. range, δB2 (at 10 Hz) increases strongly while the local angle ΘBV between the magnetic field B and the flow velocity V increases from 0° to 90°. This behaviour, also observed in the solar wind at lower frequencies, is due to the Doppler effect. It can be modelled if we assume that, for the scales ranging from kc/ωpe≃0.3 to 30 (c/ωpe is the electron inertial length), the intensity of the e.m. fluctuations for a wave number k (i) varies like k−ν with ν>≃3, (ii) peaks for wave vectors k perpendicular to B like |sinθkB|µ with µ>≃100. The shape of the observed variations of δB2 with f and with ΘBV implies that the permanent fluctuations, at these scales, statistically do not obey the dispersion relation for fast/whistler waves or for kinetic Alfvén waves: the fluctuations have a vanishing frequency in the plasma frame, i.e. their phase velocity is negligible with respect to V (Taylor hypothesis). The electrostatic waves around 1 kHz behave differently: δE2 is minimum for ΘBV>≃90°. This can be modelled, still with the Doppler effect, if we assume that, for the scales ranging from k λDe>≃0.1 to 1 (λDe is the Debye length), the intensity of the e.s. fluctuations (i) varies like k−ν with ν>≃4, (ii) peaks for k parallel to B like |cosθkB|µ with µ>≃100. These e.s. fluctuations may have a vanishing frequency in the plasma frame, or may be ion acoustic waves. Our observations imply that the e.m. frequencies observed in the magnetosheath result from the Doppler shift of a spatial turbulence frozen in the plasma, and that the intensity of the turbulent k spectrum is strongly anisotropic, for both e.m. and e.s. fluctuations. We conclude that the turbulence has strongly anisotropic k distributions, on scales ranging from kc/ωpe≃0.3 (50 km) to kλDe≃1 (30 m), i.e. at electron scales, smaller than the Cluster separation.

[1] On June 30, 2001, around 0530 UT, Cluster was moving along the magnetopause with spacecraft on both sides of the discontinuity. The configuration was ‘quasi-ideal’ with magnetic field and plasma flow almost aligned in the magnetosheath and nearly anti-parallel to the magnetospheric field. Cluster observed several perturbations with leading and trailing edges corresponding respectively to tangential and rotational discontinuities. They present a complex 3D topology, consistent with the inter-linking of flux tubes resulting from reconnections occurring at different sites.

The Cassini radio and plasma wave investigation is designed to study radio emissions, plasma waves, thermal plasma, and dust in the vicinity of Saturn. Three nearly orthogonal electric field antennas are used to detect electric fields over a frequency range from 1 Hz to 16 MHz, and three orthogonal search coil magnetic antennas are used to detect magnetic fields over a frequency range from 1 Hz to 12 kHz. A Langmuir probe is used to measure the electron density and temperature. Signals from the electric and magnetic antennas are processed by five receiver systems: a high frequency receiver that covers the frequency range from 3.5 kHz to 16 MHz, a medium frequency receiver that covers the frequency range from 24 Hz to 12 kHz, a low frequency receiver that covers the frequency range from 1 Hz to 26 Hz, a five-channel waveform receiver that covers the frequency range from 1 Hz to 2.5 kHz in two bands, 1 Hz to 26 Hz and 3 Hz to 2.5 kHz, and a wideband receiver that has two frequency bands, 60 Hz to 10.5 kHz and 800 Hz to 75 kHz. In addition, a sounder transmitter can be used to stimulate plasma resonances over a frequency range from 3.6 kHz to 115.2 kHz. Fluxes of micron-sized dust particles can be counted and approximate masses of the dust particles can be determined using the same techniques as Voyager. Compared to Voyagers 1 and 2, which are the only spacecraft that have made radio and plasma wave measurements in the vicinity of Saturn, the Cassini radio and plasma wave instrument has several new capabilities. These include (1) greatly improved sensitivity and dynamic range, (2) the ability to perform direction-finding measurements of remotely generated radio emissions and wave normal measurements of plasma waves, (3) both active and passive measurements of plasma resonances in order to give precise measurements of the local electron density, and (4) Langmuir probe measurements of the local electron density and temperature. With these new capabilities, it will be possible to perform a broad range of studies of radio emissions, wave-particle interactions, thermal plasmas and dust in the vicinity of Saturn.

One of the objectives of the Cluster mission is to study sources of various electromagnetic waves using the four satellites. This paper describes the methods we have applied to data recorded from the STAFF spectrum analyser. This instrument provides the cross spectral matrix of three magnetic and two electric field components. This spectral matrix is analysed to determine, for each satellite, the direction of the wave normal relative to the Earth’s magnetic field as a function of frequency and of time. Due to the Cluster orbit, chorus emissions are often observed close to perigee, and the data analysis determines the direction of these waves. Three events observed during different levels of magnetic activity are reported. It is shown that the component of the Poynting vector parallel to the magnetic field changes its sense when the satellites cross the magnetic equator, which indicates that the chorus waves propagate away from the equator. Detailed analysis indicates that the source is located in close vicinity of the plane of the geomagnetic equator. Key words. Magnetospheric physics (plasma waves and instabilities; storms and substorms); Space plasma physics (waves and instabilities)

The Whisper instrument yields two data sets: (i) the electron density determined via the relaxation sounder, and (ii) the spectrum of natural plasma emissions in the frequency band 2–80 kHz. Both data sets allow for the three-dimensional exploration of the magnetosphere by the Cluster mission. The total electron density can be derived unambiguously by the sounder in most magnetospheric regions, provided it is in the range of 0.25 to 80 cm-3 . The natural emissions already observed by earlier spacecraft are fairly well measured by the Whisper instrument, thanks to the digital technology which largely overcomes the limited telemetry allocation. The natural emissions are usually related to the plasma frequency, as identified by the sounder, and the combination of an active sounding operation and a passive survey operation provides a time resolution for the total density determination of 2.2 s in normal telemetry mode and 0.3 s in burst mode telemetry, respectively. Recorded on board the four spacecraft, the Whisper density data set forms a reference for other techniques measuring the electron population. We give examples of Whisper density data used to derive the vector gradient, and estimate the drift velocity of density structures. Wave observations are also of crucial interest for studying small-scale structures, as demonstrated in an example in the fore-shock region. Early results from the Whisper instrument are very encouraging, and demonstrate that the four-point Cluster measurements indeed bring a unique and completely novel view of the regions explored.Key words. Space plasma physics (instruments and techniques; discontinuities, general or miscellaneous)

In this paper we present an analysis of the satellite current-voltage (I-V) characteristics observed during the TSS-IR mission. The satellite I-V curves were compared with the predictions by two theoretical models: the first one [Parker and Murphy, 1967] considers the channeling effect of the terrestrial magnetic field as the dominating process in the current collection, whereas the second one [Alpert et al., 1965] neglects the magnetic field and assumes an isotropic spherical geometry. Even though neither of the two theories reproduces rigorously the TSS experimental situation, as they neglect both the motion of the body and possible anomalous collisions, we find that both the models, in certain conditions, could reproduce theoretical curves in agreement with the data. However we suggest that, when the effect of the plasma turbulence is considered, the data could be better interpreted on the basis of the Alpert formulation.

Ulysses spacecraft radio and plasma wave observations indicate that some variations in the intensity and occurrence rate of electric and magnetic wave events are functions of heliographic latitude, distance from the sun, and phase of the solar cycle. At high heliographic latitudes, solartype Ill radio emissions did not descend to the local plasma frequency, in contrast to the emission frequencies of some bursts observed in the ecliptic. Short-duration bursts of electrostatic and electromagnetic waves were often found in association with depressions in magnetic field amplitude, known as magnetic holes. Extensive wave activity observed in magnetic clouds may exist because of unusually large electron-ion temperature ratios. The lower number of intense in situ wave events at high latitudes was likely due to the decreased variability of the high- latitude solar wind.

There have been many reports of the terrestrial foreshock as a source of freely propagating electromagnetic (e.m.) radiation1–7, identified as plasma emission at twice the solar-wind plasma frequency, 2fp. The 2fp source is close behind the curved surface defined by the interplanetary magnetic field lines tangent to the Earth's bow shock. Electrons accelerated at the shock over a wide range of energies propagate along these field lines where, from a time-of-flight effect6, they have a distribution that is unstable to the production of Langmuir waves6,8. These Langmuir waves9,10 and the unstable electron distributions11,12 have been observed. The mechanism suggested for generating the 2fp radiation5,6,13,14 by the terrestrial foreshock is closely related to present models of type III solar radio emission and rely on some of the energy in the Langmuir waves converting to e.m. waves. The e.m. emission of type III bursts is known to be produced in the solar wind at both the fundamental and second harmonic15, and whether fundamental emission is produced in the terrestrial foreshock is of considerable interest. Comparison of nearby fundamental and harmonic emissions and the Langmuir wave energy density in the source will help discriminate between the different conversion models8,14,16. We present here unambiguous measurements made with the sounder experiment aboard the International Sun–Earth Explorer-1 (ISEE-1) and the radio experiment on ISEE-3 of simultaneous fundamental and second harmonic e.m. emission from the Earth's foreshock.

Data from three ISEE experiments has been analyzed during several periods of turbulence observed in the solar wind upstream of the earth's quasi-parallel bow shock. Radio observations are used to validate a shock model, which is subsequently used to compute various geometrical parameters during all the periods studied. One typical 9-hour period on November 4, 1977, is discussed in some detail to illustrate the parameters studied and the correlations found. It is shown that during this period, the radio noise spectrum has two components, one centered around the local electron plasma frequency and the other at somewhat lower frequencies; the latter component has a shorter wavelength and correlates with the level of MHD turbulence. A multivariate canonical statistical analysis of particle and MHD data during a 2-week period shows that the proton anisotropy and turbulence level correlate well with the minimum backstreaming proton parallel velocity pmin which, as defined here, is a purely geometrical parameter. Trivariate analysis shows that the correlation of particles and turbulence with the angle between the magnetic field and the shock normal have their sense reversed when allowance is made for the strong correlations with pmin. A very good correlation has been found between power and compressibility in magnetic fluctuations.

We have performed auto and cross spectral analysis of the electron density and vector magnetic field fluctuations recorded aboard ISEE 1 and 2 in the magnetosheath close the Earth's bow shock when in quasiperpendicular configuration. The analysis shows the characteristic signatures of mirror type modes downstream of the undershoot of the shock. copyright American Geophysical Union 1989

The French electron density experiment aboard the ISEE 1 and 2 satellites really consists of two separate, but complementary, experiments to measure the total electron density by means of radio techniques. Both experiments are new: one flew above the ionosphere for the first time on the satellite GEOS, launched in April 1977, while the other takes advantage of the unique ISEE feature of having two spacecraft which are always relatively close together. The principles and the realization of both experiments are described.

The authors review the techniques available for finding out the location and polarization of a radio source using antennas with low directivity, that is, electric or magnetic antennas with dimensions less than the wavelength. The use of such antennas is imposed by the combination of the low frequency of observation and of the dynamical constraints upon the antenna length particularly in the case of planetary probes. First they summarize the relationship of an arbitrary antenna to the parameters describing the radiation field, emphasizing the importance of the antenna polarization vector. The application of these results defines precisely the limited information available using short electric antennas. In principle, it is possible to determine the direction (except for the sense) and also the polarization of a point source, using either three such antennas on a three-axis stabilized spacecraft or two antennas on a spinning spacecraft. With a single antenna which is neither parallel nor perpendicular to the spin axis it is possible to determine the source direction with a πambiguity but not its complete polarization. If the single antenna is perpendicular to the spin axis (as is usually the case) only the great circle containing the source direction and the spin axis can be obtained, and this at the expense of assumptions about the source polarization. Source localization requires, in addition to the direction, either observations from another spacecraft or some assumption about the source mechanism and the spatial distribution of the relevant plasma parameters. The application of these methods to the observations of solar radio bursts and terrestrial kilometric radiations is presented.

Plasma, electric-field and magnetic-field data from several experiments on board the spacecraft ISEE 1 and 2 have been analysed in the interaction region upstream of the Earth's bow shock. Upstream waves which are known to be associated with diffuse distributions of backstreaming protons are shown to correlate also with variability in the distribution of the incoming solar-wind protons. Both phenomena are also clearly connected with the presence of enhanced electric-field turbulence. On the basis of these relations, a preliminary discussion can be given of the complex nonlinear plasma processes occurring in the foreshock region.

Summary The case records of two brothers suffering from Lignac-Fanconi disease are given in detail. Two further siblings probably suffered from the disease. The results of certain special investigations are discussed. In a mineral balance we have not been able to prove that the hypophosphataemia in one of the cases was due to an excessive excretion of phosphorus. In both brothers the glutamic acid level in the serum was found to be raised. This supports the view that a disorder of aminoacid metabolism is the underlying cause of the disease. It is suggested that the large quantity of aminoacids passed by the kidneys has a nephrotoxic action. The pathogenesis of other features of the disease can be explained by dysfunction of tubular reabsorption caused by this action, and the ultimate onset of renal failure can be explained by the same action involving the glomeruli. With alkali therapy the general condition of both boys has improved, although a normal plasma CO2 combining power could not be reached in either case. High vitamin D dosage has produced some healing of the skeletal changes, but attention is drawn to the possibly dangerous effects of this treatment. One case died from heart failure secondary to renal failure after three months treatment. The genetics of the disease are discussed. The evidence presented from our cases seems to confirm the theory of a recessive inheritance.

The receiver in the satellite UK-2 is briefly described. Interference-free data received where the satellite is near the apogee of its orbit is of interest for astronomical and ionospheric work, and typical samples of such data are shown, the salient features being pointed out. Among the tatter are the ionospheric noise bands, and the propagation of waves in the i-mode. The method of determination of the orientation of the satellite at any given time is described, and the consequent conclusions about the polarisation of the signals are stated.

The iterative solution of Hallen's integral equation for the current distribution on a lossless dipole transmitting antenna is studied from first principles, and a general solution in terms of an expansion function is derived. In this new solution even the zero-order approximation gives a reasonable representation of both the quadrature and the in-phase current distributions. The choice of an expansion function is discussed. At each stage the approximations which must be made in order to obtain earlier iterative solutions are clearly described. Three low order solutions are derived in detail: the zero-order solution using both a constant expansion parameter and a simple expansion function, and the rst-order solution using a constant expansion parameter. The results are compared and special attention is paid to the very short antenna, although the results are good for lengths up to and including the half-wave dipole. The results are presented in such a way that the first-order admittance of any given antenna may be readily calculated.

SUMMARY The fatty acid composition of erythrocyte and liver mitochondrial lipids was readily and drastically altered by varying the fatty acid content of the diet. Nonessential polyunsaturated fatty acids were found in these tissues when the tissue level of linoleic acid fell below 10% of the total fatty acids. In essential fatty acid deficiency, two isomeric eicosatrienoic acids appeared, except when the diet supplied other more highly unsaturated nonessential fatty acids. Although brain mitochondrial lipids were relatively less affected by dietary manipulations, their fatty acid compositions could be significantly altered by variations of dietary fat; nonemential polyunsaturated fatty acids from cod liver oil were also incorporated into these lipids. It is postulated that such dterations in the polyunsaturated fatty acid content of phospholipids, other lipid complexes, or both, may be of importance in metabolism.