Studying Earth's magnetosphere with energetic particles

Earth’s magnetosphere is the region of space surrounding Earth that is under the influence of Earth’s magnetic field and embedded in the Sun’s field. Interactions between Earth’s magnetic field and the Sun’s field lead to many complicated interactions and processes in Earth’s magnetosphere. Studying the magnetosphere will help us understand space weather, illustrate the effect of space weather on both satellites and Earth’s surface, and can provide a real life test of plasma physics outside a laboratory.

Because the magnetosphere is so close to the Earth’s surface, we can launch satellites to study it locally. This means that we can measure particles, magnetic and electric fields, and waves directly where the satellite is located. Having satellites in the magnetosphere allows us to measure energetic particles. These are electrons and ions with more energy than the general plasma population and are produced in specific conditions. In this work, we first observed energetic electrons near the boundary of the magnetosphere facing the sun and linked them to reconnection, a process that releases energy stored in magnetic fields. Then we compared energetic electron observations in different locations on the side of the magnetosphere facing away from the sun to see that when these particles travel from deep on the nightside towards Earth, the most energetic particles are not always able to travel the full distance to the inner magnetosphere. Finally, we looked at a location where electrons and ions are accelerated on the nightside and found that a commonly used simple method of explaining this acceleration is not generally accurate in every case, meaning that either some process beyond the expected acceleration mechanism is occurring or some common assumptions about the plasma are not always valid.