Scientists pilot NASA plane into storms to study gamma rays

The capabilities of the aircraft are also useful in studying thunderstorms which typically occur in the lowest layers of the atmosphere up to 56,000 feet (17,068 meters) at their maximum but can also have some regions that extend into the lower layers of the stratosphere up to 164,000 feet (49,987 meters).

Gamma rays from thunderstorms

Thunderstorms are not just a source of lightning but also intense gamma rays. The powerful updrafts and downdrafts of winds inside thunderstorms are capable of accelerating wind and water at very high speeds. At these high speeds, ice crystals can be stripped of electrons and generate electric fields around them, responsible for the lightning we see.

At times, these electrons can also emit gamma rays, creating a glow within the thundercloud. This glow can last from a few minutes to a few hours. Researchers know that there are two types of gamma radiation emitted from thunderstorms, flashes and glows, and they are trying to understand how they are formed.

They are also keen to understand the relationship of this radiation with the terrestrial gamma-ray bursts which occur at specific points with the thundercloud.

Studying gamma rays

The researchers worked together as part of the Airborne Lightning Observatory for Fly’s Eye GLM Simulator and Terrestrial gamma-ray flashes (ALOFT) mission based in Tampa, Florida.

The ER-2 aircraft was flown at an altitude of nearly 60,000 feet (18,288 meters) for over 60 hours over areas of Central America and the Caribbean and was equipped with some of the most advanced lightning instrumentation to study the thunderclouds.

This included the gamma-ray detector dubbed the University of Bergen-Bismuth-Germanium-Oxide (UIB-BGO) for its origin, which not only collected data from the thunderclouds but also relayed them in real-time. This allowed researchers to instruct the ER-2 pilots to return to a thundercloud if it was emitting gamma rays.

NASA's Marshall and Goddard Space Flight Centers, contributed to the program with their instrumentation to capture other wavelengths emitted by the clouds. Called Fly’s Eye GLM Simulator (FEGS), the instrument captures near-infrared and ultraviolet radiation from lightning which is not captured by satellites.

Optical sensors on the FEGS can capture smaller lense-dense flashes, which are known to be precursors to storms turning severe. This could be useful and helpful in predictions about intensifying storms and aid in keeping people safe from lightning, the press release added.