Three-dimensional Multispecies Simulation of the Solar Wind Interaction with Mars Under Different Interplanetary Magnetic Field Orientations

Without the intrinsic magnetic field, the solar wind interaction with Mars can be significantly different from the interaction with Earth and other magnetized planets. In this paper, we investigate how a global configuration of the magnetic structures, consisting of the bow shock, the induced magnetosphere, and the magnetotail, is modulated by the interplanetary magnetic field (IMF) orientation. A 3D multispecies numerical model is established to simulate the interaction of solar wind with Mars under different IMF directions. The results show that the shock size including the subsolar distance and the terminator radius increases with Parker spiral angle, as is the same case with the magnetotail radius. The location and shape of the polarity reversal layer and inverse polarity reversal layer in the induced magnetotail are displaced to the y < 0 sector for a nonzero flow-aligned IMF component, consistent with previous analytical solutions and observations. The responses of the Martian global magnetic configuration to the different IMF directions suggest that the external magnetic field plays an important role in the solar wind interaction with unmagnetized planets.

Steepening of magnetosonic waves in the inner coma of comet 67P/Churyumov–Gerasimenko

We present a statistical survey of large-amplitude, asymmetric plasma and magnetic field enhancements detected outside the diamagnetic cavity at comet 67P/Churyumov–Gerasimenko from December 2014 to June 2016. Based on the concurrent observations of plasma and magnetic field enhancements, we interpret them to be magnetosonic waves. The aim is to provide a general overview of these waves' properties over the mission duration. As the first mission of its kind, the ESA Rosetta mission was able to study the plasma properties of the inner coma for a prolonged time and during different stages of activity. This enables us to study the temporal evolution of these waves and their characteristics. In total, we identified ∼ 70 000 steepened waves in the magnetic field data by means of machine learning. We observe that the occurrence of these steepened waves is linked to the activity of the comet, where steepened waves are primarily observed at high outgassing rates. No clear indications of a relationship between the occurrence rate and solar wind conditions were found. The waves are found to propagate predominantly perpendicular to the background magnetic field, which indicates their compressional nature. Characteristics like amplitude, skewness, and width of the waves were extracted by fitting a skew normal distribution to the magnetic field magnitude of individual steepened waves. With increasing mass loading, the average amplitude of the waves decreases, while the skewness increases. Using a modified 1D magnetohydrodynamic (MHD) model, we investigated if the waves can be described by the combination of nonlinear and dissipative effects. By combining the model with observations of amplitude, width and skewness, we obtain an estimate of the effective plasma diffusivity in the comet–solar wind interaction region and compare it with suitable reference values as a consistency check. At 67P/Churyumov–Gerasimenko, these steepened waves are of particular importance as they dominate the innermost interaction region for intermediate to high activity.

Magnetosphere-Ionosphere-Thermosphere Coupling study at Jupiter Based on Juno First 30 Orbits and Modelling Tools

&lt;p class=&quot;western&quot; lang=&quot;en-US&quot; align=&quot;justify&quot;&gt;The dynamics of the Jovian magnetosphere is controlled by the complex interplay of the planet&amp;#8217;s fast rotation, its solar-wind interaction and its main plasma source at the Io torus. At the ionospheric level, these MIT coupling processes can be characterized by a set of key parameters which include ionospheric conductances, currents and electric fields, exchanges of particles along field lines and auroral emissions. Knowledge of these key parameters in turn makes it possible to estimate the net deposition/extraction of momentum and energy into/out of the Jovian upper atmosphere. In this talk we will extend to the first thirty Juno science orbits the method described in Wang et al. (JGR 2021, under review) which combines Juno multi-instrument data (MAG, JADE, JEDI, UVS, JIRAM and WAVES), adequate modelling tools and data bases to retrieve these key parameters along the Juno magnetic footprint and across the north and south auroral ovals. We will present preliminary distributions of conductances, electric currents and electric fields obtained from these orbits and will compare them with model predictions.&lt;/p&gt;

Magnetosphere-Ionosphere-Thermosphere Coupling study at Saturn Based on Cassini high-latitude and Grand Finale Orbits and Modelling Tools

&lt;p class=&quot;western&quot; lang=&quot;en-US&quot; align=&quot;justify&quot;&gt;The dynamics of the Kronian magnetosphere is controlled by the complex interplay of the planet&amp;#8217;s fast rotation, its solar-wind interaction and its main plasma sources at Enceladus and other moons. At the ionospheric level, these MIT coupling processes can be characterized by a set of key parameters which include ionospheric conductances, currents and electric fields, exchanges of particles along field lines and auroral emissions. Knowledge of these key parameters in turn makes it possible to estimate the net deposition/extraction of momentum and energy into/out of the Kronian upper atmosphere. In this talk we will apply to Cassini high-inclination, F-ring and Grand Finale orbits the method developed and tested by Wang et al. (JGR 2021, under review) for Juno studies. We will combine Cassini multi-instrument data (MAG, CAPS, MIMI, UVIS and RPWS) with adequate modelling tools and data bases to retrieve these key parameters along the Cassini magnetic footprint and across the north and south auroral ovals. We will present preliminary distributions of conductances, electric currents and electric fields obtained from these orbits and will compare them with model predictions.&lt;/p&gt;

The Comet Interceptor Mission

&lt;p&gt;Comets are undoubtedly extremely valuable scientific targets, as they largely preserve the ices formed at the birth of our Solar System. In June 2019, the multi-spacecraft project Comet Interceptor was selected by the European Space Agency, ESA, as its next planetary mission, and the first in its new class of Fast (F) projects [Snodgrass, C. and Jones, G. (2019) Nature Comms. 10, 5418]. The Japanese space agency, JAXA, will make a major contribution to Comet Interceptor. The mission&amp;#8217;s primary science goal is to characterise, for the first time, a yet-to-be-discovered long-period comet (LPC), preferably one which is dynamically new, or an interstellar object. An encounter with a comet approaching the Sun for the first time will provide valuable data to complement that from all previous comet missions, which visited short period comets that have evolved over many close approaches to the Sun. The surface of Comet Interceptor&amp;#8217;s LPC target will be being heated to temperatures above the its constituent ices&amp;#8217; sublimation point for the first time since its formation.&lt;/p&gt; &lt;p&gt;Following launch, in 2029, the spacecraft will be delivered with the ESA Ariel mission to the Sun-Earth L2 Lagrange Point , a relatively stable location suitable for later injection onto an interplanetary trajectory to intersect the path of its target. This allows a relatively rapid response to the appearance of a suitable target comet, which will need to cross the ecliptic plane in an annulus which contains Earth&amp;#8217;s orbit.&lt;/p&gt; &lt;p&gt;A suitable new comet would be searched for from Earth prior to launch, and after launch if necessary, with short period comets serving as a backup destinations. With the advent of powerful facilities such as the Vera Rubin Observatory, the prospects of finding a suitable comet nearing the Sun are very promising. The possibility may exist for the spacecraft to encounter an interstellar object if one is found on a suitable trajectory.&lt;/p&gt; &lt;p&gt;An important consequence of the mission design is that the spacecraft must be as flexible as possible, i.e. able to cope with a wide range of target activity levels, flyby speeds, and encounter geometries. This flexibility has significant impacts on the spacecraft solar power input, thermal design, and dust shielding that can cope with dust impact speeds ranging from around 10 to 70 km/s, depending on the target comet&amp;#8217;s orbital path.&lt;/p&gt; &lt;p&gt;Comet Interceptor has a multi-spacecraft architecture: it is expected to comprise a main spacecraft and two probes, one provided by ESA, the other by JAXA, which will be released by the main spacecraft when approaching the target. The main spacecraft, which would act as the primary communication point for the whole constellation, would be targeted to pass outside the hazardous inner coma, making remote and in situ observations on the sunward side of the comet. The two probes will be targeted closer to the nucleus and inner coma region.&lt;/p&gt; &lt;p&gt;Planned measurements of the target include its nucleus surface composition, shape, and structure, its dust environment, and the composition of the gas coma. A unique, multi-point &amp;#8216;snapshot&amp;#8217; measurement of the comet- solar wind interaction region is to be obtained, complementing single spacecraft observations made at other comets.&lt;/p&gt; &lt;p&gt;We shall describe the science drivers, planned observations, and the mission&amp;#8217;s instrument complement, to be provided by consortia of institutions in Europe and Japan.&lt;/p&gt;