Science@NASA: Mission to Study Terrestrial Gamma-ray Flashes

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RJN
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Science@NASA: Mission to Study Terrestrial Gamma-ray Flashes

Post by RJN » Sat Jan 30, 2010 1:49 am

http://science.nasa.gov/headlines/y2010 ... list113284

I wonder if the phenomena that cause these TGFs occur elsewhere in the universe, including outside of planetary atmospheres.

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Science@NASA: Are TGFs Hazardous to Air Travelers?

Post by bystander » Thu Feb 11, 2010 12:14 am

Are TGFs Hazardous to Air Travelers?
Science@NASA - 2010 Feb 10
Instruments scanning outer space for cataclysmic explosions called gamma-ray bursts are detecting intense flashes of gamma-ray energy right here in the friendly skies of Earth. These terrestrial gamma-ray flashes, or TGFs, blast through thunderstorms close to the altitude where commercial airliners fly.

In fact, they could be too close for comfort.

In a recent study,* scientists estimated that airline passengers could be exposed to 400 chest X-rays worth of radiation by being near the origin of a single millisecond blast. Joe Dwyer of the Florida Institute of Technology took part in that research, which used observations from NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager, or RHESSI, to estimate the danger TGFs pose.

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Space Telescope Sifts Earth Storms for Radiation Flashes

Post by bystander » Fri Feb 19, 2010 4:33 pm

Space Telescope Sifts Earth Storms for Radiation Flashes
Space.com - 2010 Feb 19
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 rare, but deadly, threat to high-flying commercial airliners.

NASA's Fermi Gamma-Ray Space Telescope has joined the search for mysterious gamma-ray flashes above thunderstorms which are ultra-brief, 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 jet airliner to the same level of radiation as 400 chest X-rays, according to a recent study.

Fermi, which NASA originally 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.

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NS: Thundercloud gamma rays hint at origins of lightning

Post by bystander » Fri Jun 18, 2010 5:06 pm

Thundercloud gamma rays hint at origins of lightning
New Scientist | Physics & Math | 18 June 2010
MYSTERIOUS gamma ray bursts that occur in the first moments of a storm, as lightning jumps between clouds, hint at where lightning comes from.

It is even possible that passengers in planes flying above storms could be bathed in dangerous radiation.

Terrestrial gamma ray flashes (TGFs) were discovered in 1994 emanating from the tops of thunderclouds. To explore their origin, Xuan-Min Shao of Los Alamos National Laboratory, New Mexico, and David Smith of the University of California, Santa Cruz, compared TGFs detected by the RHESSI satellite with time lines of lightning. They confirmed the bursts were associated with intra-cloud lightning. Such lightning is more common than intense ground strikes, says Smith1.

The pair also found that TGFs occur in the first few milliseconds of strikes. This is backed up by Steven Cummer of Duke University in North Carolina and colleagues. They link TGFs to the initial "leader" of lightning flowing upwards between charged clouds2.

Morris Cohen of Stanford University, California, says that the studies give a clue to how lightning gets started. Electric fields in clouds often initiate a spark despite being apparently too weak to do so. "Lightning happens earlier than it should," says Cohen.
  1. A closer examination of terrestrial gamma-ray flash-related lightning processes
  2. Lightning mapping observation of a terrestrial gamma-ray flash