The second pair of satellites in the European Space Agency's Cluster II mission were successfully launched Aug. 9, bringing with them imaging electron spectrometers developed at Los Alamos National Laboratory in New Mexico. Over their two-year mission, the four satellites will study the interaction of charged particles from the sun with the Earth's magnetic field. As part of the Research with Adaptive Particle Imaging Detectors instrument package, the spectrometers will measure very energetic electrons in the magnetosphere in three dimensions. The mission will collect information about the phenomena that produce auroras and -- in extreme conditions -- that can cause power outages, disrupt telecommunications networks and satellites, and that may lead to climatic changes.