Has science discovered a new threat to air travel?

Graphic courtesy of  NASA/Robert Kilgore

Physicists in America have just made an alarming discovery about electrical storms and jet airliners.

They were looking at data from the Fermi satellite, a gamma ray telescope scanning deep space for insights into how cataclysmic blasts of cosmic radiation are emitted by dying stars and from the enigmatic edges of “black holes” where time itself slows to a near standstill and matter vanishes.

And they found incredibly brief bursts of gamma rays hitting the satellite not from deep space, from tens to hundreds of thousands of light years away, but from below, from earth.

“It’s amazing,” Jerry Fishman, a co-investigator for the Gamma-ray Burst Monitor on the satellite was quoted as saying.

“They come blasting right through the whole Fermi spacecraft and light up all of our detectors. Very few cosmic gamma-ray bursts manage to do this!”

Terrestrial gamma ray bursts or TGBs weren’t even known to science nor glimpsed by satellites until 1994, when the first instruments capable of studying them from orbit were switched on. Those early searches, like most of the work that followed, were directed at objects no closer than the sun, and the flashes accidentally picked up from earth were treated like irrelevant anomalies.

The Fermi data changes this perception. It confirms the origin of TGBs  in thunderstorms, with an intensity equivalent to as much as 400 chest X-rays delivered in a millisecond at the point of origin, which is approaching drop-dead intensity.

Because major electrical storms occur at the altitudes used by jet airliners, a light went on in the minds of a team of Fermi researchers in the US.

They have authored a paper, Estimation of high-energy electron bursts produced by thunderclouds and the resulting radiation doses received in aircraft, which is about to appear in the niche publication the Journal of Geophysical Research (Atmospheres).

However, there are reasons to be wary of any tabloid linkage between this research and air travel, a point the lead author, Dr Joe Dwyer, has already made.

Jet airliners do not deliberately fly near giant electrical storms, not because of gamma ray risks that no airline has heard of before now, but fierce windshear zones where abrupt changes of speed and direction by high velocity air cells can exceed the structural limits of wings and their variable control surfaces.

For some combination of reasons, Air France flight AF447 appears to have flown into such a towering storm cell last June over the mid-Atlantic, killing all 228 people on board the Airbus A332, which was on its way from Rio de Janeiro to Paris.

And the intensity of gamma ray bursts is rapidly dispersed and diminished in the atmosphere by distance and can be either sustained, or deflected, by the extent or shape of the magnetic fields generated by electrical storms.

Directed energy (or death ray) weapons research is preoccupied by the technological barriers to throwing tightly focused beams of  gamma radiation over long distances.

The biggest issue for air travel may well be the risk TGBs pose at altitudes above 20 kilometres, or higher than Concorde cruised, but clearly there are potential issues to explore in relation to current jets as the skies become more crowded, and flight paths flirt with routes that pass over or near rapidly forming thunderheads.

Gamma rays are produced in abundance in stars, nebulas and black holes, and in man-made particle accelerators and nuclear detonations. They are the most energetic form of light, but paradoxically invisible to the naked eye and cannot be reflected by mirrors.

Building telescopes able to “see” and then understand the universe in the ultra-high-frequency bandwidth of gamma radiation has thus been one of the major challenges of  modern physics and astronomy.

Being more aware of natural “local” bursts of gamma rays from storm clouds may well become a part of airline operations in the near future.