Making Ultra-fast Electron Measurements in Multiple Directions to Reveal the Secrets of the Aurora

In the design of APES, one major trade-off had to be made.  For the magnetic field geometry to work properly, the instrument can only observe in one direction. This concept works well if the goal is just to measure the precipitating (downgoing) electrons in the aurora that ultimately hit the atmosphere.  However, we know that electrons in the aurora also move in other directions; in fact, these electrons contain a lot of information about other physical processes happening farther out in space.