NASA Mission Looks to Decode Lightning

NASA has launched a new mission specifically designed to unlock some of the mysteries surrounding the formation and effects of lightning.

A collaboration between the space agency and the National Science Foundation in partnership with the US Department of Defense, FireStation will orbit the Earth for an entire year attached to the outside of the International Space Station. During this time, its instruments will collect data as it moves over thunderstorms in hopes of decoding the answer between lightning and gamma rays.

"Somewhere in the atmosphere momentarily there's just an incredible amount of energy release and what happens in that region is something of a witch's brew," Doug Rowland, principal investigator for FireStation at NASA's Goddard Space Flight Center in Greenbelt, said in a statement.

"You get antimatter created in the Earth's atmosphere during this interaction," Rowland explained, "you get energetic neutrons that basically you never see in the quiet atmosphere, that you only associate with nuclear reactions, that are happening in our atmosphere whenever these things go off."

In a thunderstorm, clouds charge as ice crystals rub together, causing them to separate by electrical charge and weight. What's unclear, however, is what exactly triggers this process in the first place.

One theory points to a chain reaction called a seeded avalanche breakdown, in which an outside energy source sets off a few energetic-free electrons within the Earth's electron field.

"The idea is that you get a cosmic ray coming in that has a million electron volts of energy and it can serve to trigger another breakdown mechanism that generates gamma rays," Rowland said.

These short bursts of gamma rays are seen as terrestrial gamma ray flashes (TGFs), lasting mere milliseconds but packing as much as 100 million electron volts.

"I always thought this was a really weird idea," Rowland said, "that your local weather, that your lightning depends on a cosmic ray that's traveled for 150 thousand light years or a million light years from some exploding star that just set off your lightning stroke over your head."

By measuring these lightning and gamma ray flash events simultaneously, FireStation will help researchers determine if TGFs are generated by the electric fields during thunderstorms, and what kinds of lightning produce gamma ray flashes.

"We are measuring lightning flashes -- which has been done before -- and we are measuring gamma ray flashes -- which has been done before -- but we are doing it on the same platform, so that we can see for the same event the lighting and the gamma rays it produces," Rowland said. "You can imagine a case where if you don't know exactly where the events and the signals were traveling at different speeds, you might reverse the cause and effect. So having it in the same platform is new and very helpful."