The Sun constantly flings a stream of charged particles—the solar wind—past Earth, and electrons within it behave in ways that scientists still do not fully understand. This matters because the solar wind drives space weather, which can disrupt satellites, power grids, and communications on Earth. Electrons, despite their tiny mass, control much of the solar wind’s heat and pressure, yet the processes that shape their behaviour—such as interactions with electromagnetic waves and collisions between particles—remain poorly understood. The research team built the Electron Analyser System on ESA’s Solar Orbiter, which measures electrons with higher resolution in energy, direction, and time than any previous instrument. They will combine these measurements with a novel analysis technique, already proven in a pilot study, to reveal how wave-particle interactions and collisions sculpt electron populations. If successful, this work will answer fundamental questions about how the solar wind forms, heats, and accelerates to hundreds of kilometres per second. That deeper understanding could improve predictions of hazardous space weather events, protecting the infrastructure that modern society depends on. This is primarily curiosity-driven fundamental science, but similar studies of plasma physics have previously led to advances in fusion energy and spacecraft design.
View original technical description
The Sun’s corona is composed of charged particles, or plasma, which escape into the interplanetary medium as the solar wind and fill the heliosphere. The solar wind drives potentially hazardous ‘Space Weather’ conditions in near-Earth space and is a natural, almost unbounded, laboratory for study of astrophysical plasmas. The understanding of the solar corona and its extension into the solar wind is thus vital to predicting when hazardous conditions may arise and for revealing which fundamental plasma processes lead, for example, to the heating and acceleration (to 100’s km/s) of the solar wind itself. A unique advantage of this natural plasma system is its accessibility to spacecraft, such as ESA’s current Solar Orbiter mission, carrying scientific instruments that directly sample, in situ, its electromagnetic fields and particles. Despite their small mass, electrons play a disproportionate role in processes driving and controlling the solar wind, since they dominate certain contributions to the solar wind thermal energy budget, such as the pressure and heat flux. Understanding processes that influence the nature of the electron populations in the solar wind is thus a major milestone on the road to addressing unanswered questions on the formation, heating and acceleration of the solar wind itself. Our proposed work involves novel analysis of measurements of electrons and electromagnetic fields made in the solar wind by Solar Orbiter as it transits close to the Sun, at increasing latitudes and during different phases of the solar cycle. We lead the Solar Wind Analyser sensor suite on the mission and we built the Electron Analyser System (EAS) to detect and characterize the solar wind electrons. EAS resolves details of the electron populations with higher resolution in energy, arrival direction and time than previously achieved. This enables better understanding of processes that determine the electron properties such as temperature, speed, and density and create, for example, anisotropies and beams in the electron population which mitigate energy exchange of with electromagnetic fields and waves. These processes operate on fast timescales compared to most previous measurements, so EAS measurements open new windows on these processes and their impacts on the solar wind. Combined with a novel analysis technique developed by us and proven in a recent pilot study, we will make important breakthroughs in open science questions relating to how processes such as wave-particle interactions and collisions shape the solar wind electron populations and what implications these have on the global heliosphere.
Plain English summaries and category classifications on this site are generated by AI and may not perfectly reflect the original research.
Is something wrong? Let us know