A week ago, while you were safely tucked up in bed, a group of NASA scientists up in Alaska were preparing to launch a rocket into the Northern Lights.

The Auroral Spatial Structures Probe was a mid-sized rocket, launched 30 miles into the thermosphere to study the electromagnetic energy that heats the atmosphere during the aurora borealis. According to NASA:

The ASSP carried seven instruments to study the electromagnetic energy that can heat the thermosphere—the second highest layer of the atmosphere—during auroral events. The interaction of waves and particles from the solar wind, Earth’s magnetosphere, and the upper atmosphere can cause “Joule heating.” Essentially, the electrical currents on the edge of space run into a resistant media (the air in the atmosphere) and generate heat in a process similar to that of a toaster coil or electric stove. This heating can expand the atmosphere upward and increase the friction, or drag, on spacecraft and satellites.

Image credit:NASA Earth Observatory