The Wind spacecraft is a critical element in NASA’s Heliophysics System Observatory (HSO) – a fleet of spacecraft created to understand the dynamics of the sun-Earth system – owing to the combination of its longevity (>25 years in service), its diverse compliment of instrumentation, and high resolution and accurate measurements. Wind has over 55 selectable public data products with over ~1100 total data variables (including OMNI data products) on SPDF/CDAWeb alone. These data have led to paradigm shifting results in studies of statistical solar wind trends, magnetic reconnection, large-scale solar wind structures, kinetic physics, electromagnetic turbulence, the Van Allen radiation belts, coronal mass ejection topology, interplanetary and interstellar dust, the lunar wake, solar radio bursts, solar energetic particles, and extreme astrophysical phenomena such as gamma-ray bursts. This review introduces the mission and instrument suites then discusses examples of the contributions by Wind to these scientific topics that emphasize its importance to both the fields of heliophysics and astrophysics.

While not specifically designed as a planetary mission, NASA’s Parker Solar Probe (PSP) mission uses a series of Venus gravity assists (VGAs) in order to reduce its perihelion distance. These orbital maneuvers provide the opportunity for direct measurements of the Venus plasma environment at high cadence. We present first observations of kinetic scale turbulence in the Venus magnetosheath from the first two VGAs. In VGA1, PSP observed a quasi-parallel shock, $\beta\sim1$ magnetosheath plasma, and a kinetic range scaling of $k^{-2.9}$. VGA2 was characterised by a quasi-perpendicular shock with $\beta\sim 10$, and a steep $k^{-3.4}$ spectral scaling. Temperature anisotropy measurements from VGA2 suggest an active mirror mode instability. Significant coherent waves are present in both encounters at sub-ion and electron scales. Using conditioning techniques to exclude these electromagnetic wave events suggests the presence of developed sub-ion kinetic turbulence in both magnetosheath encounters.

The solar wind is a continuous outflow of plasma from the Sun, which expands into the space between the planets in our solar system and forms the heliosphere. The solar wind is inherently turbulent and characterised by kinetic micro-instabilities on a range of scales. The Sun also intermittently ejects mass (coronal mass ejections; CMEs) or solar energetic particles (SEPs) which change their trajectory or energy due to their interactions with the solar wind. When these violent particle events hit the Earth’s magnetosphere, they can cause “space weather” with both long- and short-term impacts on our natural and technological environment. This presentation investigates the behaviour and the effects of kinetic instabilities in a turbulent plasma with particular emphasis on energy transfer processes. We utilise the unprecedented observations from ESA’s Solar Orbiter spacecraft, launched in February 2020, to advance our understanding of the Sun, the solar wind, and space weather. Large-scale compressions (ubiquitous in solar-wind turbulence) create conditions for proton, alpha-particle and electron microinstabilities, which then transfer energy to small-scale fluctuations. These instability-driven small-scale fluctuations, including those driven by turbulence and other sources of free energy (e.g. particle beams, differential flows, heat fluxes, temperature anisotropies), make a significant contribution to the fluctuation spectrum at kinetic scales, where energy dissipation occurs. We consider instabilities driven by turbulence in the plasma by using statistical methods to analyse the Solar Orbiter data and characterise the turbulence at the relevant scales and amplitude. Specifically, we evaluate the processes by which turbulence combined with temperature anisotropy causes instability, comparing theoretical calculations with the high resolution data available from the Solar Orbiter MAG and SWA instruments.