{"id":30,"date":"2026-07-06T07:45:35","date_gmt":"2026-07-06T07:45:35","guid":{"rendered":"https:\/\/teams.issibern.ch\/stellarwindplasmaturbulence\/?page_id=30"},"modified":"2026-07-06T14:38:31","modified_gmt":"2026-07-06T14:38:31","slug":"scientific-rationale","status":"publish","type":"page","link":"https:\/\/teams.issibern.ch\/stellarwindplasmaturbulence\/scientific-rationale\/","title":{"rendered":"Scientific Rationale"},"content":{"rendered":"

The heliosphere is the vast region of space dominated by the Sun’s magnetic field, encompassing the planets that orbit the Sun. The interplanetary space is filled with the solar wind<\/strong>, a continuous collisionless plasma flow emitted by the Sun. Interestingly, the existence of the solar wind was first inferred indirectly by observing its effect on solar system objects, e.g., aurorae and cometary ion tail dynamics [Biermann 1951], and ascertained later theoretically [Parker 1958] and by in-situ spacecraft observations [e.g., Neugebauer & Snyder 1962]. Since then, several space missions have been devoted to studying solar wind properties and its influence on planetary dynamics.<\/p>\n

Observations from spacecraft missions have revealed that the solar wind is turbulent<\/strong>, meaning that fluctuations over a broad range of spatial and temporal scales populate it [Bruno & Carbone 2013]. Turbulence is a process through which fluids, including plasmas, dissipate energy in their flows into heat [Yordanova et al. 2021]. This happens through complex, multiscale, nonlinear interactions among fluctuations, forming vortices and shears [Marino & Sorriso-Valvo 2023]. Besides solar wind heating, turbulence affects other prominent nonlinear processes in the solar wind and astrophysical plasmas<\/strong>. Turbulence (i) favors the onset of magnetic reconnection and promotes energy dissipation in reconnection outflows [Pucci et al. 2017, Stawarz et al. 2024], (ii) generates and amplifies magnetic fields through dynamo processes [Rincon et al. 2016], (iii) is responsible for the acceleration of energetic particles and their transport [Dundovic et al. 2020, Comisso & Sironi 2022], and (iv) influences the dynamics of collisionless shocks [Trotta et al. 2021]. All these results suggest that solar wind turbulence should play a prominent role in planetary dynamics<\/strong> where these nonlinear processes are present.<\/p>\n

In parallel to in-situ spacecraft exploration and following the constant increase in computational power due to technological advancement, the study of space plasmas has been strongly supported by the development of numerical simulations that include the physics at play. Global numerical <\/strong>simulations<\/strong>, able to describe the entire spatial interaction of the solar wind with any compact object (like comets or planets), are nowadays routinely used to study the interaction between solar wind and solar-system planets<\/strong> [e.g., Von Alfthan et al. 2014].<\/p>\n

At all solar system planets and under usual solar wind conditions, the solar wind is a supersonic and superalv\u00e9nic flow that produces a bow shock when interacting with an obstacle. Given the solar wind’s collisionless nature, the shock is itself collisionless, and its thickness is of the order of the ion gyroscale. Therefore, kinetic effects are crucial to describe heliospheric shocks.<\/strong> Nowadays, real-scale kinetic simulations of small planets (Mercury, Venus, Mars, and the Earth) are becoming computationally accessible.<\/p>\n

Although global codes have been used for decades, the existence of turbulence in the solar <\/strong>wind has been overlooked due to modeling constraints<\/strong>. Consequently, most of our theoretical knowledge around the key aspects of solar wind\u2013magnetosphere interaction (e.g., boundaries shape and positions) is built assuming stable, laminar initial conditions, albeit observations reveal a much richer scenario. The standard modeling approach solves the plasma equations in the planet reference frame. This has the advantage of allowing for a static simulation domain but has the drawback of limiting the description of the solar wind dynamics, which in most applications has been described as laminar. Recently, the novel code Menura was developed to overcome the mentioned limitation and to simulate a fully turbulent solar wind<\/strong> [Behar et al. 2022, 2023]. This was enabled by changing the reference frame from the planet to the solar wind. Subsequent work has successfully tested this methodology on a global planetary magnetosphere simulation [Behar et al. 2024].<\/p>\n

These new numerical capabilities opened the door to novel studies of the interaction between the turbulent solar wind and planetary magnetospheres using a synergistic approach of global modeling and in-situ observations. Indeed, the investigation of the effect of solar wind turbulence on magnetospheric dynamics is an exceptional challenge also from the point of view of observational studies<\/strong>, as it requires a multi-spacecraft or even multi-mission approach that should include a solar wind \u2018\u2019monitor\u2019\u2019 and simultaneous observations in the magnetospheric region of interest.<\/p>\n

This ISSI team aims to gather interdisciplinary expertise to uncover the role of turbulence in planetary dynamics. The team will combine state-of-the-art global simulations that include turbulence in the solar wind with in-situ observations of heliospheric missions and explore the role of stellar wind turbulence in exoplanetary dynamics.<\/strong><\/span><\/p>\n

The team will meet to work on research tasks, which will be tackled using numerical simulations and observational data synergistically. The following research tasks will serve as a guideline for developing joint research projects.<\/p>\n

1)<\/strong> Establish how turbulence influences shock position and dynamics.<\/em> The presence of turbulence changes the local ram pressure of the solar wind, producing shock wavefront oscillations that are larger than in the laminar solar wind case (see Figure above, top-left). We will use numerical simulations to test how the global shock dynamics change under different upstream solar wind conditions. In-situ data (see Spacecraft Data Availability section below) will provide the relevant parameters to model the upstream conditions.<\/p>\n

2)<\/strong> Establish how turbulence modifies the foreshock and magnetosheath dynamics<\/em>. Solar wind turbulence makes the magnetic topology in the ion-foreshock region much more complex than in the laminar case (see Fig. 1, top row). We will study the properties of the ion foreshock beam (the ion population formed upstream of collisionless shocks) in numerical simulations and compare its occurrence and properties with available observations. We will also study turbulence properties (correlation length, structure functions, intermittency), including plasma instabilities, upstream and downstream of the bow-shock in simulations and compare the results with available observations.<\/p>\n

3)<\/strong> Explore the effect of turbulence on exoplanetary magnetospheres<\/em>. Using numerical simulations, we will explore the impact of turbulence on exoplanetary magnetospheres. Table 1 reports the typical stellar wind parameters for a few planets inside and outside the heliosphere [Vidotto et al. 2015, Halekas et al. 2017, Milillo et al. 2020]. We will explore whether turbulence in stellar wind may
\nproduce effects that can be detected from remote observations.<\/p>\n

Spacecraft Data availability<\/strong>. To assess the solar wind turbulence at different distances from planetary magnetospheres, we will use missions such as Parker Solar Probe [Fox et al. 2016] and Solar Orbiter [M\u00fcller et al. 2020] and missions at L1, namely WIND and ACE [Stone et al. 1998]. These missions will serve as solar wind monitors combined with magnetospheric observations. At Earth, MMS [Burch et al. 2016], Cluster [Escoubet, Schmidt & Goldstein 1997] and THEMIS [Angelopoulos 2008] provide multi-spacecraft observations of magnetospheric regions, and they also sample the solar wind close to the bow shock. At Mercury, we will use data from the MESSENGER [Solomon et al. 2007] and, if already available, BepiColombo [Benkhoff et al. 2021] missions. Observations at Mars (MAVEN [Jacosky et al. 2015] and MGS [Cunningham et al. 1996] missions) will also be considered.<\/p>\n

\"\"<\/p>\n

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