Michael Denton, an NMC researcher, and Lauren Blum, a scientist with NASA’s Goddard Space Flight Center, have been awarded a NASA grant to study plasma structure and composition as a driver of wave growth in the inner magnetosphere.
Why is this important in space science research? Electromagnetic (EM ) waves accelerate electron particles to high energies which can cause damage to satellites. Electromagnetic Ion-Cyclotron (EMIC) waves are a specific type of EM wave that is known to cause the loss of electrons. Scientists don’t fully understand this phenomenon, but are working to understand where EMIC waves occur in order to know where electrons may be lost and predict this loss in the future.
Thus, understanding EM waves is important for the prediction and mitigation of the potentially damaging environment that satellites operate in.
Recent studies of EMIC waves reveal a dependence of the waves’ spatial extent on magnetic local time (MLT), wave frequency, and L shell around Earth. Various hypotheses have been proposed to explain some of these patterns, including different sources (and spatial extents) of ion anisotropy on the day versus night side, compositional variations throughout the inner magnetosphere, or cold plasma density structure.
Denton and colleagues seek to understand how these things all tie in together. Composition, or the density of the hydrogen/oxygen/helium ions, is predicted to play a big role in growth of the waves. This work aims to link the composition changes up with the patterns seen in the waves, and subsequently in the electron distributions. This is something that has not been explored yet.
Multipoint measurements in the inner magnetosphere, such as from satellite missions like the NASA Van Allen Probes, can allow the spatial and temporal evolution of various particle populations and wave modes to be better understood.