[ RadSafe ] The Effects of Space Weather on Aviation

JPreisig at aol.com JPreisig at aol.com
Mon Oct 28 11:05:46 CDT 2013

     There have been articles in Health Physics Journal  and perhaps 
elsewhere about Bonner Neutron Spectrometer measurements made of  neutron flux 
density versus neutron energy in flying airplanes.  This  work was done by 
Goldhagen and perhaps other people.  You can read about  the work of Hess and 
(in balloons???) in Patterson and Thomas's book on Accelerator Health  
Physics, if you can find a copy.
     Joe Preisig
In a message dated 10/28/2013 12:43:45 A.M. Eastern Daylight Time,  
slgawarecki at gmail.com writes:

*Oct.  25, 2013:*  The next time you step onto an airplane, consider  the
following:  In any given year, the pilot of your aircraft probably  absorbs
as much radiation as a worker in a nuclear power plant.

And  you are about to follow him wherever he goes.

The FAA classifies pilots  as "occupational radiation workers."  Flying high
above Earth with  little atmosphere to protect them, they can absorb
significant doses of  cosmic rays and solar radiation. During a typical
polar flight from Chicago  to Beijing, for instance, a pilot is exposed to
the equivalent of two chest  x-rays.  Multiplied over the course of a
career, this can cause  problems such as increased risk of cancer and
possibly  cataracts.

Passengers have reason to be concerned, too.

"A  100,000 mile frequent flyer gets about 20 chest x-rays," points out
Chris  Mertens, a senior research scientist at NASA Langley Research Center.
"This  is true regardless of the latitude of the flights."

It’s worth noting  that even people on the ground absorb some radiation.
Cosmic rays and their  by-products are so powerful, they can reach all the
way down to Earth’s  surface, giving a person at sea level the equivalent of
one chest x-ray  every 10 days or so.

On a plane, however, dose rates increase 10-fold  or more.  The exposure
depends on factors ranging from the altitude  and latitude of the flight
path (polar routes are irradiated most) to  sunspot counts and solar
activity (a powerful solar storm can boost  radiation levels a
hundredfold).  To help airline companies safeguard  passengers and
personnel, NASA is developing an experimental tool to  predict exposures in
real time.  Mertens is the PI of the system,  called NAIRAS--short for
"Nowcast of Atmosphere Ionizing Radiation for  Aviation Safety."

Mertens notes that the number of flights over the  poles has skyrocketed in
recent years.  Airlines prefer polar routes  for international travel
because they are shorter and have reduced head  winds, creating fuel savings
of tens of thousands of dollars per  flight.

However, Earth's poles are where the radiation problem can be  most severe.
Our planet's magnetic field funnels cosmic rays and solar  energetic
particles over the very same latitudes where airlines want to  fly.  On a
typical day when the sun is quiet, dose rates for  international flights
over the poles are 3 to 5 times higher than domestic  flights closer to the

If a flight controller wants to know  the situation around the poles *right
now*, NAIRAS can help.  It is,  essentially, an online global map of
radiation dose rates for different  flight paths and altitudes.  Maps are
produced in near real-time by a  computer at Langley, which combines
cutting-edge physics codes with  realtime measurements of solar activity and
cosmic rays.

“We are  still in an experimental phase,” he says.  “The ultimate goal of
the  NAIRAS effort is to adopt a paradigm similar to terrestrial  weather

The value to the airlines is clear.  The  ability to fly over the poles can
save $35,000 to $40,000 per flight in  fuel costs alone.  On the other hand,
altering course to avoid a polar  radiation storm can cost as much as
$100,000.   A forecasting  tool like NAIRAS can help the airlines make the
right decision.

Of  even greater importance to Mertens is the human factor.  “Back in  2004,
I went to a workshop on space weather and aviation. A pilot from  American
Airlines stood up to address the audience: ‘Look,’ he said, ‘we  are
classified as radiation workers, we are the most exposed than any  other
group, yet we know the least of all the groups.’  That was a  turning point
for me.  I wanted to do something to help pilots better  understand what
they are flying into.” And so NAIRAS was  born.

Mertens and colleagues are about to publish a paper in the  journal *Space
Weather* comparing NAIRAS predictions to actual radiation  measurements
onboard airplanes.  “The results are encouraging,” he  says, “but we still
have work to do.”

For graphics & video,  see:


**Susan  Gawarecki*

ph: 865-494-0102
cell:   865-604-3724
SLGawarecki at gmail.com
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