The interest in trying to understand red sprites partially comes from the unknown. When they were first discovered, it was because somebody was testing a camera, pointed it at the horizon, pressed record and went home for the evening. And when they came back and looked at their footage, they found these flashes of light in the sky where there shouldn’t have been any. That was in 1990. That, all by itself, triggered interest in red sprites.
Now, why are we actually interested in studying red sprites? It’s a good question because they start at maybe 40 kilometres altitude, which is above aeroplane heights, and they got to about 85 kilometres altitude, which is above most things’ heights.
Some of the interest has come from space travel, so most of the time when you’re travelling in space, you’re at 350 kilometres altitude or above if you’re orbiting the Earth. But to get there, you have to pass through the rest of the atmosphere. And if you’re launching from many parts of the world where we launch spacecraft, which are close to the equator, there’s also lots of lightning, thunderstorms there. So there’s a real possibility that you might fly through a sprite on your way to space or on your way back from space.
The probabilities aren’t high, but one of the questions was would this be bad for you? And if you go back not so long ago, the space shuttleColumbiawas lost on re-entry as it was coming back from space. It broke up into millions of pieces, the astronauts died and one of the first questions that was asked was did they fly through a sprite? They didn’t, but one of the first questions that was asked was could a sprite have been responsible?
Associate Professor Craig Rodger, University of Otago, Department of Physics
Diagram of blue jets and ELVE, courtesy of Abestrobi Creative Commons 3.0 license