Wednesday

THOR (Turbulence Heating ObserveR) is one of the three candidates for selection as the next ESA M-class mission (M4). If selected, THOR will be the first mission flown in space that is fully dedicated to study turbulent fluctuations and the associated plasma energisation mechanisms. Turbulent fluctuations are ubiquitous in space and astrophysical plasmas and reach up scales as large as stars, stellar winds and galaxy clusters. However, most of the irreversible energy dissipation associated with turbulent fluctuations occurs at very small scales, the so-called kinetic scales, where the plasma no longer behaves as a fluid and the properties of individual plasma species (electrons, protons, and other ions) become important. THOR will explore the kinetic plasma processes that determine the fundamental behaviour of plasma in the universe. It will enable an understanding of the basic plasma heating and particle acceleration mechanisms, of their effect on different plasma species and of their relative importance in different turbulent regimes. THOR will achieve this by making detailed in situ measurements of the closest available dilute and turbulent magnetised plasmas in near-Earth space (solar wind, foreshock, bow shock, magnetosheath) at unprecedented temporal and spatial resolution. Here we present THOR’s science and summarise the results of the mission and payload studies that finished earlier this year.