Firefly Sees Electrons Populate the Radiation Belts

The small satellite, with a big mission, is appropriately named "Firefly." Sponsored by the National Science Foundation (NSF), the pint-sized satellite will study the most powerful natural particle accelerator on Earth - lightning - when it launches from the Marshall Islands aboard an Air Force Falcon 1E rocket vehicle next year. In particular, Firefly will focus on Terrestrial Gamma-ray Flashes (TGFs), a little understood phenomenon first discovered by NASA's Compton Gamma-Ray Observatory in the early 1990s.

Although no one knows why, it appears these flashes of gamma rays that were once thought to occur only far out in space near black holes or other high-energy cosmic phenomena are somehow linked to lightning.fly's instruments, Goddard scientist Doug Rowland and his collaborators - Universities Space Research Association in Columbia, Md., Siena College, located near Albany, N.Y., and the Hawk Institute for Space Studies in Pocomoke City, Md. - hope to answer what causes these high-energy flashes. In particular, they want to find out if lightning triggers them or if they trigger lightning. Could they be responsible for some of the high-energy particles in the Van Allen radiation belts, which damage satellites? Firefly is expected to observe up to 50 lightning strokes per day, and about one large TGF every couple days.