Our Sun drives the interplanetary environment and its interactions with the objects within. The gusty, magnetized solar wind provides the upstream environment for all planetary interactions. Naturally we know most about the Earth's interaction, with the solar wind important upstream driving reconnection at the magnetopause and in the tail, and the ionosphere as the inner region as a source of particles. The interaction of other objects depends on their nature - from unmagnetized Venus, Mars and the Moon with small-scale crustal fields, with some similarities to comet interactions, small, magnetized Mercury and the giant, rapidly rotating magnetospheres of Saturn and Jupiter enveloping mainly icy moons, especially Titan and Enceladus at Saturn, and Ganymede, Io, Europa and Callisto at Jupiter. Here we take a tour of the planetary and moon interactions, concentrating on'space weather' effects.

The proposed JUICE (JUpiter ICy moons Explorer) mission will provide the first detailed exploration of Ganymede during its orbital mission, and will also study the plasma interaction with Europa and Callisto, as well as exploring Jupiter's equatorial and mid-latitude magnetosphere, affording enhanced views of Jupiter's polar regions. In this paper we will give a brief summary of the mission, and will discuss the plasma-related objectives in plasma-moon interactions and Jupiter's magnetosphere as summarised below.
Related to plasma-moon interactions, JUICE will: (i) Investigate Ganymede's internal, induced, and magnetospheric field components, and how they are modulated by the Jovian magnetosphere, (ii) Identify the magnetic field and particle populations near the moons and their interaction with Jupiter's magnetosphere, including the moon footprint aurora in Jupiter's atmosphere, (iii) Study the particle interaction with the surface of Ganymede, (iv) Contribute to our understanding of the atmospheres of the icy satellites, their origin and evolution Related to Jupiter's magnetosphere, JUICE will: (i) Investigate the global configuration and dynamics of Jupiter's magnetodisc, (ii) Study the electrodynamic coupling between Jupiter’s magnetosphere and the satellites, (iii) Assess the global and local acceleration of particles within the giant magnetosphere and (iv) Investigate the magnetospheric region between the orbits of Ganymede and Europa

Solar spectral irradiance variations in the UV/EUV are important for the detailed modeling of the Earth's upper atmosphere. For the past decades very valuable data are available, however they lack a full temporal and spatial coverage, which is important for investigating and monitoring its effect on the Earth's atmosphere. Therefore, the need of robust and reliable models to reconstruct the irradiance for the full temporal and spectral range is very important. Here, we present the reconstruction of the EUV for specific time intervals for validation. These intervals will then be extended to the full Solar Cycle 23. First, we employ the decomposition of images taken with the Precision Solar Photometric Telescope (PSPT) and SOHO/EIT, deriving the area coverage of brightness features from the chromosphere to the corona. Second, synthetic spectra are calculated for each component for different positions on the solar disk and weighted by their area coverage. This leads to a time-dependent EUV spectrum which is compared with available observations.

The work presents the results of a statistical study on solar energetic particles (SEPs) during solar cycle 23. Among the data sample, 2/3 is associated with flares (of X and M-class) and coronal mass ejections coming from western heliolongitues and 1/3 originated from the eastern hemisphere. We carry out a comprehensive analysis on the link between SEPs and their parent solar activity, by studying the electromagnetic signatures of flares and coronal mass ejections in the corona and IP space. We revisit the topic of predicting SEPs at 1 AU by observations of solar radio emission and focus on the appearance and timing of metric-to-decametric radio bursts with respect to the SEP onset time and profile. Additionally, we include in the analysis the association rate of SEPs with large-scale coronal EUV-disturbances. We discuss the possible application of radio and EUV coronal signatures to the SEP forecasting methods.

The relative locations of the STEREO, SOHO, SDO and Venus Express spacecraft in August 2010 provide an opportunity for unique multi-spacecraft observations of two CMEs originating from the same solar source region. On 7 August 2010, a halo CME originating from NOAA AR11093 is observed remotely by STEREO B. Seven days later this active region erupts again, and a halo CME is observed remotely by STEREO A on 14 August 2010.

We show that both eruptions are associated with reverse S-shaped flux rope structures and display a number of typical large-scale features relating to CMEs, including coronal dimmings and EUV waves. By combining remote sensing and in situ observations of the ejecta, we consider the structure and heliospheric evolution of these CMEs and their interplanetary counterparts.

Our estimate of the dimensionless expansion rate of the 14 August 2010 magnetic cloud suggests that this structure may be perturbed by a high speed stream, likely to originate from a coronal hole. Consequently, we address the influence of the surrounding solar wind on the in situ observations of both ICMEs. Additionally, a comparison of the orientations of the axes of the erupting flux ropes near the Sun and in interplanetary space reveals that both CMEs appear to undergo significant rotation as they expand into the heliosphere.

We compare and contrast many aspects of these two eruptions from a remote sensing and in situ perspective, before discussing the evolutionary implications of the similarities and differences between the ejecta.

Because the atmospheric escape is strongly linked to the solar activity, it is an important point of the Planetary Space Weather. Although several mechanisms have proven to contribute, the atmospheric escape remains an open question. The escape of the atmosphere of Mars is still not fully understood. Its comprehension would give important insights on the other planetary atmospheres.
In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly energetic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy.
The goal of this study is to assess the impact of the doubly-charged ions in the escape of CO2 dominated planetary atmospheres and to compare it to the escape of thermal photo-ions. We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO2++ for a simplified single constituent atmosphere of a case-study planet. We compute the escape of fast ions using a Beer-Lambert approach.
We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering ...), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished and even contribute only marginally to this loss. We show that with these 2 mechanisms, the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible.When simulating the hot Jupiter HD209458b, the two processes cannot explain the measured escape flux of C+
This study shows that the dications may constitute a source of the escape of planetary atmospheres which had not been taken into account until now. This source, although marginal, is not negligible. The influence of the photoionization is of course large, but cannot explain alone the loss of Mars' atmosphere nor the atmospheric escape of HD209458b.

Development of prediction methods for ICME arrival at Mars is important in a space weather context for two main reasons. (1) It will be useful for future Mars exploration, and (2) it may increase our understanding of the structure and heliospheric propagation of ICME's in general, thereby potentially improving our ability to predict ICME arrival at Earth. We use ~6 years of observations from the MAG/ER instrument onboard the Mars Global Surveyor in the previous solar cycle to identify events of significantly enhanced solar wind dynamic pressure and a set of ICME events encountering Mars. We investigate the occurrence pattern of the events relative to the heliospheric current sheet and relative to near Earth observations of ICME's. When the solar source of the ICME's can be identified we employ two existing models of ICME propagation: The global MHD model ENLIL and the drag-based model DBM. These are compared with the observations in order to identify key parameters for a successful prediction. The presented work has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no 263252 [COMESEP] and no 218816 [SOTERIA].

The solar particle events and solar flares impose extreme conditions on the lower thermospheres of planets.
As example, the ionization rate in these atmospheric layers can be enhanced by an order of magnitude, leading to the creation of a dominant ion layer at these altitude. The heating also modifies the local structure of the thermosphere. On Earth, the effect is complicated by the presence of the magnetosphere, therefore, it is interesting to compare Earth with objects without magnetospheres, hence Mars, Venus, and Titan when it is outside the magnetosphere of Saturn.

We have modeled the ion and excited species productions in the atmospheres of these bodies with several models, for a solar flare event, and a solar particle event. We computed the resulting effects that can be, or have been, observed in the thermosphere of Mars, Venus, Earth, and Titan.