It's an exhilarating experience. I don't think I'll ever get tired of this type of flying. That isn't just any patch of ice down there. Before AMTS, the highest altitude at which polar temperatures had been measured was about 30 km, using balloons. It takes advantage of a layer of atomic iron in the mesosphere, the residue of meteors that burned up in this region.
Iron absorbs light and re-emits it at certain wavelengths, giving a bright backscatter signal.
The lasers in the lidar are tuned to two of those wavelengths. As the laser light passes through the iron layer, the resulting glow is detected by the lidar's two telescopes. Our chemical models predicted very low iron densities. If the iron levels in the atmosphere were too low, the returning signal would be too weak for detection. As the investigators flew north, the iron densities dropped even more drastically than expected.