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The Moon has small scale regions of strong magnetic fields scattered over its surface, known as crustal fields. Coexisting with some of the strongest crustal fields are peculiar markings in the lunar soil, called lunar swirls, which are suggested to be formed by magnetosphere-like interactions between the crustal fields and the solar wind plasma. This interaction depends on the lunar phase and the Interplanetary Magnetic Field (IMF) among many other parameters (e.g. solar wind dynamic pressure). The focus of this thesis is on a localized crustal field on the lunar near side known as Reiner Gamma, which has distinct swirl patterns that will be visited by NASA's Lunar Vertex mission in 2024. We study the solar wind plasma interaction with Reiner Gamma for two lunar phases and IMF directions for a constant solar wind dynamic pressure using a hybrid plasma model (kinetic ions, fluid electrons). We analyze steady state outputs from the simulations in the ParaView visualization software and self-made Python scripts and present detailed maps of the plasma environment above Reiner Gamma from 10 km up to 100 km above the surface. From this, we show that a mini-magnetosphere forms from the interaction. Furthermore, we establish that the solar wind interaction with Reiner Gamma's crustal fields is affected by the lunar phase and IMF direction. The magnetic field intensity and the solar wind ion flux are shown to be largely influenced by the IMF direction, and the electric fields are affected by the lunar phase. Finally, we find that the strongest radial and tangential components of the electric fields are the electron inertial and hall terms.

Waves in the mHz frequency range are a prominent feature in the terrestrial magnetosphere. In this frequency range the waves have wavelengths comparable to the lengths of the geomagnetic field lines. The waves are then standing waves along closed field lines with endpoints in the southern and northern ionosphere. Waves play an important role in the distribution of energy in the magnetosphere and mHz waves can accelerate electrons to MeV energies and have been proposed as a driver of auroral arcs. They can also be used as a diagnostic tool for determining the plasma density. There are two important classes of these low frequency waves. One has large azimuthal wavelength and is usually associated with driving mechanisms outside the magnetosphere, such as the Kelvin-Helmholtz instability at the magnetopause. The other has small azimuthal wavelength and is associated with plasma instabilities inside the magnetosphere. Both types of waves are studied in this thesis with an emphasis on the small azimuthal wavelength waves. For the type of wave with large azimuthal wavelength there is however, a considerable debate about the driving mechanism. One recently suggested driver is coherent magnetohydrodynamic waves in the solar wind. Part of this thesis studies this experimentally and we conclude that, at least on some occasions, this driving mechanism come into play. The Cluster satellites are used to study the morphology of the waves. We demonstrate the ability of Cluster to determine the azimuthal wave number of the waves and also how the structure along the magnetic field lines can be determined. This gives information regarding the harmonic number of the standing waves, which in turn says something about the driver of the waves. We also look at possible excitation mechanisms for the small azimuthal wavelength waves. / QC 20101129

When the solar wind reaches the Mars obstacle, mass loading by planetary ions slows down the solar wind and raises the bow shock. The Martian atmosphere is undergoing the a scavenging by the solar wind without the protection of a global magnetic field. Atmospheric escape is an important process for the evolution of the Martian climate. For present Mars, the dominant escape of atmospheric neutrals is through four channels: Jeans escape, photochemical reactions, sputtering and electron impact ionization. Ions above the exobase get accelerated by the solar wind electric field and can escape. We here apply a new method for estimating heavy ion (O+, O+2, and CO+2) escape rates at Mars, which combines a hybrid model and observations. We use observed upstream solar wind parameters as input for a hybrid plasma model, where the total ion upflux at the exobase is a free parameter. We then vary this ion upflux to find the best fit to the observed bow shock location. This method gives us a self-consistent description of the Mars-solar wind interaction, which can be used to study other properties of the solar wind interaction besides escape. / När solvinden stöter på Mars så tyngs den ner av joner från planeten, vilket bromsar solvinden och expanderar bogshocken. Mars atmosfär eroderas av solvinden eftersom planeten saknar ett globalt magnetfält. Atmosfärsförlust är en viktig process i hur Mars klimat förändras. För nuvarande Mars är det fyra dominerande processer för förlust av neutrala atomer: Jeans förlust, fotokemiska reaktioner, sputtering och elektronkollisionsjonisering. Joner ovan exobasen accelereras av solvinden och kan förloras. Här använder vi en ny metod för att uppskatta förlusten av tunga joner (O+, O+2 , and CO+2) vid Mars, som kombinerar en hybridmodell och observationer. Vi använder observerade solvindsparametrar som indata till en hybrid plasmamodell, där totalt jonuppflöde vid exobasen är en fri parameter. Vi varierar sedan detta jonuppflöde för att hitta bästa passningen till den observerade positionen för bogshocken. Metoden ger en självkonsistent beskrivning av Mars växelverkan med solvinden, som kan användas till att studera andra egenskaper av växelverkan, förutom jonförlust.

It is known that AGWs strongly interact with Traveling Ionospheric Disturbancescalled TIDs (e.g. Kirchengast et al., 1996). Vlasov et al., 2011 presented a statisticalstudy for AGWs-TIDs events with the EISCAT dataset. Our study is follow-up study of this one, and our goals are to discuss statistically AGWs-TIDs features such as the amplitude, the dominant frequency, and frequency of the events with outer factors like magnetic activities. We succeeded to project AGWs-TIDs features with the Butterworth filter for the dataset on 6 September 1988, on 11 November 2018, and on 2 March 2022. However, in our projection process, we found several problems worth to discuss further. In this report, we show you the examples of the projections, and share to you our difficulties and problem as well as our possible solutions for these matters.

Saturn's rings have long been thought to provide the planetary atmosphere with infalling material, affecting both its chemical composition and physical properties (e.g. temperature). As in-situ measurements of this material have been realized during the Grand Finale orbits of the Cassini spacecraft, icy grains falling from the innermost, D ring, towards the planet have been detected. In this work we are simulating the trajectories of these grains, starting from the D ring, moving under the influence of the planetary magnetic and gravitational fields. The atmospheric drag force that acts on them while traveling through the Saturn's atmosphere is also implemented and the grains apart from losing kinetic energy, are also getting sublimated. Our results suggest that in a constant electric potential of typical values for the ambient plasma around Saturn, the grains tend to move towards the southern hemisphere, with the negatively charged ones ending up in low to mid latitudes, whereas the positive ones follow a spiraling motion and fall close to the south pole.

This study investigates the lunar plasma environment and its implications for the safety and success of future crewed missions to the Moon. The Moon’splasma environment, formed by the solar wind, galactic cosmic rays and solar flare particles, presents potential hazards to human life and property. The study focuses on simulating the lunar plasma environment at various points along the Moon’s orbit, particularly in regions behind the Earth, such as the bow shock, magnetotail, and magnetosheath, using a self-consistent 3D quasineutral hybrid model. The findings of this work reveal significant variations in plasma characteristics, such as density, temperature and velocity. This thesis identifies potential risks to human health, surface infrastructure and spacecraft systems due to these dynamic plasma conditions, especially in regions with increased plasma density and temperature. By analysing the simulation results, this research aims to enhance the understanding of the plasma environment’s effects on human resources and life, ultimately contributing to the safety and success of future crewed missions to the Moon.

The Rosetta spacecraft orbited around comet 67P/Churyumov-Gerasimenko from 2014 to 2016. During this time, several thousands of cometary jets occurred and were photographed by the onboard cameras. Since the spacecraft slowly orbited around the comet nucleus and assuming an angular spread of 20º for the jets, it can be assumed that sometimes Rosetta flew through some of them. The dust particles ejected from the jet travel radially outward virtually unaffected by gravity, but as the jet is ongoing for several hours and as the comet nucleus rotates, the dust trace forms a spiral-like trajectory shape in space. Tracking the spacecraft's position around the times the jets were photographed, and checking whether it was within the dust cone, we found that Rosetta travelled across 181 out of the 3946 listed jets. Then, we looked into the plasma density and spacecraft potential data for every jet, finding some interesting events that could give rise to a further study into plasma interactions between jets and surrounding plasma in the cometary coma.

Earth-space traversing electromagnetic waves become attenuated as they propagate through the atmosphere. The sources of attenuation are weather phenomena in the Troposphere, and scintillation and absorption in the Ionosphere. On behalf of Arctic Space Technologies AB, an empirical model based on data from the last decade was built in Python, in order to estimate the level of attenuation and provide a better picture of the frequency environment at the site in Piteå. By utilizing recommendations from the International Telecommunication Union Radiocommunication Sector, and constraining the project to only consider the case where the satellite is at an 5° apparent elevation in Piteå, and a range of weather phenomena a nuanced picture can be obtained. It was found that the attenuation from the Ionosphere in typical satellite frequency bands is not of significance, and therefore only the Tropospheric sources were considered. The results showed that the S-band is the most reliable band to utilize, since little to no changes were observed for a range of weather scenarios. For the X-band, larger changes in the level of attenuation were observed for higher levels of precipitation, yet not as severe as for the Ku- and Ka- bands. However, for the Ku- and Ka-bands, large fluctuations in the attenuation were observed for different cases. In conclusion, the attenuation at Arctic space's site in Piteå for the S- and X-bands are the lowest and least effected by changes in weather. On the other hand, the Ku- and Ka-bands should be used predominantly under good weather circumstances.

High speed plasma flows (jets) are ubiquitous phenomena in the universe. For example, they carry energy from the most powerful sources (e.g active galactic nucleï AGN) to the medium at rest surrounding them. When the plasma at rest encounters the front of the fast flow, it gains energy via conversion from magnetic field energy to particle heating and acceleration. High speed plasma flows are also common in planetary magnetospheres including the Earth's magnetotail. In particular the fast Earthward magnetic reconnection outflows in the Earth's magnetotail provide a laboratory to address some of the open questions related to plasma jet fronts and the associated energy conversion. In this thesis, we use the four Magnetospheric Multiscale (MMS) spacecraft to investigate current sheet flapping, particle heating and particle acceleration associated with the fast magnetotail flows. In paper I, we investigate a short-period kink-like flapping motion of an ion scale current sheet in the wake of a plasma jet front. We show that the kink-like motion propagates along the current direction toward the flank of the magnetosphere, and that the prediction of the wavelength of the drift-kink instability of a thin current sheet agrees with our estimation of the wavelength of the observed kink-like current sheet. In paper II, we investigate particle acceleration at turbulent Earthward jet fronts during a moderately active substorm. We show that a proton with a gyroradius smaller than the scale of the Earthward convected structures gain energy from the bulk flow. On the other hand, we show that, depending on the time scale of the electromagnetic fluctuations with respect to the proton scale, protons with larger gyroradius get accelerated via resonant interaction with the jet front or via direct acceleration by the dawn-dusk electric field in a spatially limited electric field pulse.