Scientists pinpoint how shock waves scramble electrons around Earth
Researchers using NASA satellites discovered that electrostatic waves are the primary driver of electron disorder at Earth's bow shock—the magnetic boundary where solar wind slams into our planet's magnetosphere. The finding could improve forecasting of space weather events that disrupt satellites, power grids, and communications, with direct implications for space infrastructure protection strategies.
Originaltitel: Statistical Study of Electron Kinetic Entropy Generation at Earth's Quasi-Perpendicular Bow Shock
<p>We use the Magnetospheric Multiscale mission to study electron kinetic entropy across Earth's quasi-perpendicular bow shock. We perform a statistical study of how the change in electron entropy depends on the different plasma parameters associated with a collisionless shock crossing. The change in electron entropy exhibits strong correlations with upstream electron plasma beta, Alfv & eacute;n Mach number, and electron thermal Mach number. We investigate the source of entropy generation by correlating the change in electron entropy across the shock to the measured electric and magnetic field wave power strengths for different frequency intervals within different regions in the shock transition layer. The electron entropy change is observed to be greater for higher electric field wave power within the shock ramp and shock foot for frequencies between the lower hybrid frequency and electron cyclotron frequency, suggesting electrostatic waves are important for electron kinetic entropy generation at Earth's quasi-perpendicular bow shock. Any eventual cross-shock potential contribution to the electron entropy generation has not been considered in this study.</p>