Spacecraft Heliospheric Observation of Collisions and Kinetic Wave Analysis in Various Environments

Projektbeschreibung

Innovative Ansätze zur Analyse schwacher Schocks in beispielloser Detailtiefe

Plasmaschocks sind im Weltraum allgegenwärtig und entstehen, wenn schnell fließende Plasmen, wie der Sonnenwind, auf Hindernisse wie planetare Magnetfelder oder langsameren Sonnenwind treffen. Die Stärke dieser Schocks hängt von ihrer Mach-Zahl ab, wobei starke Schocks besonders gut untersucht sind, vor allem in der Nähe der Erde. Schwächere Schocks sind jedoch wenig erforscht. Das im Rahmen der Marie-Skłodowska-Curie-Maßnahmen geförderte Projekt SHOCKWAVE plant, mithilfe modernster Raumfahrzeugdaten diese schwächeren Schocks zu untersuchen und dabei den Schwerpunkt auf ihre Wellenaktivität, Jets und Instabilitäten zu legen. Mithilfe eines dreistufigen Ansatzes, der den Vergleich von Schocks in verschiedenen Mach-Bereichen in Erdnähe, die Analyse interplanetarer Schocks und die Untersuchung von Übergängen zwischen schwachen und starken Schocks umfasst, wird die vorgeschlagene Forschung das Verständnis der Schockphysik im Sonnensystem und ihrer Rolle bei geomagnetischen Stürmen verbessern.

Ziel

Plasma shocks are ubiquitous phenomena in space plasmas, emerging when a supersonic and super-Alfvénic plasma flow encounters an obstacle. The solar wind is such a flow with usually high Mach numbers. Solar wind shocks occur due to two obstacles: magnetic fields of planets or much slower solar wind in front of it. The Mach number dictates the shock strength: from strong (roughly > 5) to weak (1-4).

Spacecraft in Earth’s environment allowed us to study the terrestrial shock as an example of a strong shock in increasing detail in the past decades. The availability of shock measurements from other planets is increasing as well. However, most astrophysical shocks are weak, in particular shocks that have little to no in-situ measurements. The lower range of Mach number shocks is underexplored, especially with high resolution data (resolution of several seconds to milliseconds).

Our main goal is to utilize state-of-the-art spacecraft data to explore the lower Mach number range of shocks (including wave activity, jets, instabilities) and crosscheck the universality of our results with available events in the solar system. To tackle this project, we propose a 3-step analysis: 1) Comparing low and high Mach number range at the terrestrial shock, 2) Investigate interplanetary shocks using high-resolution data, and 3) Providing a comprehensive study on the transition of characteristics from low to high Mach number values.

The proposed research will be carried out in a 24-month project at the Queen Mary University of London. This institution hosts well-known international experts on shock physics and space plasma physics, providing outstanding expertise that perfectly matches the proposed efforts. The generated knowledge will deepen our understanding of shock physics with application throughout the solar system as well as general astrophysics. In particular we will apply the knowledge on interplanetary shocks, which are the precursor of strong geomagnetic storms at Earth.