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The mechanism involved in the transfer of energy, momentum and plasma from the solar wind to any planetary magnetosphere is considered one of the more important topics in space plasma physics. With the use of the Mercury spacecraft MESSENGER’s (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) data, it has been possible to study these processes in an environment different, yet similar, to Earth’s. These data have resulted in unprecedented investigations advancing not only the extraterrestrial space plasma research, but also the general space physics field. This work aims to investigate the Kelvin-Helmholtz (KH) instability at Mercury’s magnetopause, which is believed to be one of the main drivers for the transfer of matter and energy into Earth’s magnetosphere, and the low- latitude boundary layer (LLBL) which is in direct connection to the magnetopause. The studies use data from MESSENGER’s magnetometer (MAG) and fast imaging plasma spectrometer (FIPS) instruments during the first three years in orbit. Results show that KH waves are observed almost exclusively on the duskside magnetopause, something that has not been observed at Earth. In contrast, the LLBL shows an opposite asymmetry as it occurs more often on the dawnside. Both the KH instability and the LLBL are observed mainly during northward interplanetary magnetic field. This, together with the distinct opposite asymmetry, suggests that the KH instability and LLBL are somehow connected. Previous theoretical studies, simulations and observations have shown or indicated that the sodium ions have a large impact on the Hermean magnetospheric environment, including the boundary layer where the KH instability arises. One possibility is that the sodium ions also induce the observed dawn-dusk asymmetry in the LLBL. Another explanation could be that the LLBL on its own influences the KH wave occurrence by reducing the KH wave growth rates on the dawnside where most of the LLBLs are observed. Furthermore, observations agree with some formation mechanisms that should give rise to the observed dawn-dusk LLBL asymmetry. The processes responsible for the dawn-dusk occurrence asymmetry in both the KH instability and the LLBL are yet to be confirmed. Future work may also include determination of the contribution of KH waves to the energy and plasma transfer from the solar wind to the Hermean magnetosphere. / <p>QC 20151005</p>

The Cassini mission to Saturn carries a wide variety of instruments to investigate Saturn and its surroundings. Since Cassini is an orbiter, the spatial coverage of this mission far exceeds the few flybys made by earlier spacecraft. We focus on just one of the instruments, and conduct a preliminary analysis of data from five-channel waveform receiver (WFR) which is a part of the Radio and Plasma Wave Science instrument (RPWS). Two electric and three magnetic field components are measured in the 3 Hz to 2.5 kHz band and recorded in the time domain. Interference from other systems of the spacecraft severely complicates interpretation of the electric field spectrum below about 1 kHz. To mitigate this problem we have applied a Blackman-Harris window with a strong sidelobe attenuation, but parts of our analysis is restricted to frequencies above 1 kHz. Various algorithms have been applied to detect and discard erroneous measurements. By analyzing the data we have produced maps of spatial variations in the measured power. The region inside about 9 Saturn radii was found to be particularly active, especially in the electric field measurements. Phenomena that have been seen in the data include dust impacts, electromagnetic whistler-mode hiss and chorus, and electrostatic electron-cyclotron harmonic (ECH) emissions.

In this study density variations in the solar wind are examined based on data from the Cluster Mission. The data are originating from the stream outside the bowshock and thus they are spanning in an interval of three to four months for each mission year up to 2006. As the data are examined, variations above the relative electron density threshold of 1.3 are archived. The variations are analyzed in terms of position, orientation, magnetic field perturbation and scale sizes. The magnetic field perturbations are exhibiting diamagnetic and paramagnetic behavior and a possible link to similar observations inside the magnetosphere is attempted through the impulsive penetration mechanism. The final conclusion of the report is that plasma density enhancements, similar to those identified from previous studies inside the magnetosphere, are also evident in the free solar wind stream close to earth.

Electric propulsion is gaining popularity in space industry. This type of propulsion is replacing chemical propulsion for different maneuvers. But it deeply modifies the ambient plasma that surrounds the satellites and can affect the operation of satellites. Modelling the interactions arising from electric propulsion is then critical. In the frame of SPIS, a simulation software designed to simulate plasma-spacecraft interactions, European Space Agency (ESA) started the AISEPS project which aimed at modelling these interactions. Here, we report the development of new features for SPIS during the last phase of the AISEPS project, how they operate and were tested. Using these developments, a complete spacecraft is modelled and the variation of its floating potential resulting from its solar array rotation is reproduced.

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