The Effects of Space Weather on Aviation   
       
   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.   
       
   http://www.youtube.com/watch?v=UHYbnv6O1Go   
       
   A new ScienceCast video explores the effects of solar storms and cosmic rays   
   on aviation. Play it   
       
   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."   
       
   Auroras Underfoot (signup)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.   
       
   Nairas   
   A NAIRAS model shows radiation levels over the northern hemisphere on Oct. 25,   
   2013. MoreHowever, 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 equator.   
       
   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.   
       
   http://sol.spacenvironment.net/~nairas/Dose_Rates.html   
       
   "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   
   forecasting."   
       
   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."   
       
   Credits:   
       
    Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.96   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)