Triggering of plasma resonance by Whisper sounder on distant Cluster Spacecraft in Solar Wind

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Radiants of the Leonids 1999 and 2001 Obtained by LLTV Systems Using Automatic Software Tools

International audienceBoth amateur and professional meteor groups are more frequently using Low-Light level TV (LLTV) systems to record meteors. Double-station observations can yield orbit data. However, data analysis normally is still done by hand and thus time consuming. This paper addresses the question of whether available automated tools can be used to determine reasonably accurate orbits with minimum human intervention. The European Space Agency performed several observing campaigns to observe the Leonid meteor stream. In November 1999, the ESA meteor group was stationed at two locations in Southern Spain, in November 2001 at two stations close to Broome in North-Western Australia. Double-station observations with LLTV systems were conducted. The data was recorded on S-VHS video tapes. The tapes were processed using automatic detection software from which meteor heights, velocities and radiants were computed. This paper shows the results for the two maximum nights. The radiants determined in 1999 show a very large scatter due to unfortunate observing geometry and inaccurate position determination since one of the cameras was moving because of the wind. The 2001 data is excellent and the radiant was determined to be at RA = 153.96°±0.3° and Dec = 21.09°±0.2°. The error bars for individual meteor radiants are about 0.2° to 0.4°. This demonstrates that is indeed possible to determine good radiant positions using totally automated tools. Orbits, on the other hand, are not well defined due to the fact that the velocity of individual meteors shows large errors. Reasons for this are described

Latitudinal extension of the sources of continuum radiations

International audienceThe electromagnetic radio emissions known as 'continuum radiation' are widelyobserved for decades in planetary magnetospheres. Although their main sourcelocation is well identified for Earth in the vicinity of the equatorial plasmapause andits generation mechanism generally associated with electrostatic emissions arisingbetween half harmonics of the electron gyro harmonics, many details of theircharacteristics and source are still missing. Recent observations had suggested newfeatures in their description. For example, studies based on the Whisperinstruments have shown that continuum sources can also be located at mid latitudesand can be generated at exact harmonics of the electron frequency. The higherperigee of the present phase of the Cluster extended mission allows the spacecraftto skim the sources regions close to the plasmapause and to explore their latitudinalextension thanks to its polar orbit. This higher perigee also allows to get Peace data,seldom available at the lower perigees earlier in the mission, to characterize theelectrons populations at the origin of these emissions. We present here the firstanalysis of the best events observed so far

Titan's induced magnetosphere from plasma wave and magnetometer observations

International audiencePlasma wave observations are combined with the magnetometer measurements to investigate Titan's induced magnetosphere. Electric field emissions close to Titan are identified as upper hybrid resonance emissions and therefore can provide a density estimate of Titan's cold plasma. Some of Titan's flybys show a very strong asymmetry between two flybys performed in similar geographical conditions. Good examples are the Ta and Tb flybys, which have a similar trajectory in the Titan interaction coordinate system and even though they have the same illumination conditions, the density profiles present major differences. Thermal plasma observations are displayed for the nominal mission flybys in a draping coordinate system where the average ambient magnetic field, the ideal flow direction and the motional electric field correspond to the main axis of the system. This coordinate system organizes the cold plasma observations and provides information on the envelop of the induced magnetosphere and its global asymmetry

Titan's induced magnetosphere from plasma wave, particle data and magnetometer observations

International audienceThe Magnetometer (MAG) measurements, the particle data (CAPS) are combined with the Radio and Plasma Wave Science (RPWS) observations to provide an overall and organized description of the electron plasma environment and the pickup ion distribution around Titan. RPWS observations are used to measure the electron number density of the thermal plasma close to Titan. This data set is combined with CAPS-ELS electron number density in Saturn's magnetosphere and Titan's environment. A relatively good correspondence between the number density estimated from CAPS-ELS and RPWS are most of the time observed between 0.1 - 1 cm-3. Combining both ELS and RPWS data allows deducing a continuous electron density profile going from Saturn's magnetosphere to Titan's ionosphere leading to a global electron density map in Titan's vicinity. The MAG observations are used to derive information about the ambient magnetic field environment in the vicinity of Titan and also to emphasize the bipolar tail region. Ion information such the mass composition of the plasma and ion distribution function for specific time intervals are determined from CAPS-IMS. Pick-up ions have been identified from their energy signature and mass composition for few flybys. These observations also emphasized a ring distribution, characteristic of pick-up ions. The pick-up observations, in the DRAP coordinate system, are found to be located in the E=-vxB hemisphere as expected

The RPW Low Frequency Receiver (LFR) on Solar Orbiter: in-situ LF electric and magnetic field measurements of the solar wind expansion

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The Search-Coil Magnetometer (SCM) of the Radio and Plasma Waves Investigation (RPWI) onboard the ESA JUICE mission

International audienceThe JUpiter ICy moons Explorer (JUICE) mission is the first large-class (L1) mission of ESA Cosmic Vision. JUICE will be launched in April 2023 with an arrival at Jupiter in 2031 and at least four years making detailed observations of Jupiter’s magnetosphere and of three of its largest moons (Ganymede, Callisto and Europa). The Radio and Plasma Wave Investigation (RPWI) consortium will carry the most advanced set of electric and magnetic fields sensors ever flown in Jupiter’s magnetosphere, which will allow to characterize the radio emission and plasma wave environment of Jupiter and its icy moons. Here we present the scientific objectives and the technical features of the Search Coil Magnetometer (SCM) of RPWI. SCM will provide for the first time three-dimensional measurements of magnetic field fluctuations in the frequency range 0.1 Hz – 20 kHz within Jupiter’s magnetosphere. High sensitivity (~10 fT / √Hz at 1 kHz) will be assured by combining an optimized (20 cm long) magnetic transducer with a low-noise (4 nV / √Hz) ASIC pre-amplifier. Perturbations by the spacecraft are strongly reduced by accommodating SCM at about 10 m away from the spacecraft on the JUICE magnetometer boom. The combination of high sensitivity and high cleanliness of SCM measurements will allow unpreceded studies of electromagnetic fluctuations down to plasma kinetic scales, in particular in key regions such as the magnetopause, the auroral region and the magnetotail current sheet of Ganymede’s own magnetosphere which JUICE will orbit for many months. This will lead to important advances in understanding how fundamental plasma processes such as magnetic reconnection, turbulence and particle energization occur in Jupiter’s plasma environment