There are two types of aurora: diffuse and discrete. With the former, you'll get a faint flow that might not even be visible at night; with the latter, you'll see that gorgeous, sharply defined band of colorful light most of us associate with the Northern Lights,or Aurora Borealis.
The MICA mission is especially interested in the discrete aurora, particularly one of the possible underlying mechanisms: Alfven waves, created by something in the ionosphere called the Alfven resonator.
It's a long narrow channel in space and the same beam of charged particles from the sun that creates the aurora, also boosts the electrical conductivity in the resonator. And this produces Alfven waves. That's the hypothesis, anyway; MICA's measurements should help validate it.
Marc Lessard of the Univeristy of New Hampshire's Institute for the Study of Earth, Oceans and Space, provided a wonderfully poetic analogy for how this works in the UNH press release, comparing the Alfven resonator to a giant guitar string stretching through space: