Fermi Gamma-ray Telescope Turns Its Attention to Earth

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A NASA space telescope hunting for the most powerful explosions in the universe is turning its eye on Earth to hunt for tiny flashes of radiation to determine if they pose a potential hazard to passengers aboard high-flying airliners.

NASA’s Fermi Gamma-Ray Space Telescope has joined the search for mysterious gamma-ray flashes above thunderstorms, which are ultrabrief but could be a concern for air travelers, researchers said.

Just one millisecond blast of the so-called terrestrial gamma-ray flashes (TGFs) could expose passengers and crew aboard a nearby jetliner to the same level of radiation as 400 chest X-rays, according to a recent study.

Fermi, which NASA launched to seek out gamma-ray bursts — immensely powerful explosions in deep space, usually from a dying star — joined in the hunt several months ago to possibly uncover more about when and how TGFs occur around thunderstorms and lightning.

To do that, scientists are using one of the telescope’s monitoring sensors.

“Fermi-GBM [Gamma-Ray Burst Monitor] has the broadest energy coverage and highest sensitivity of any instruments that have observed, or will observe TGFs,” said Jerry Fishman, an astrophysicist at NASA’s Marshall Space Flight Center in Huntsville, Ala.

Scientists first discovered the existence of TGFs by accident, when the Compton Gamma-Ray Observatory detected a flash in 1991. But they still do not know if it is lightning that triggers the phenomenon or whether TGFs provide the quick burst of electrons that may spark a lightning strike.

Research findings by Fishman and his team are expected to be published in the coming weeks by the American Geophysical Union.