What is E-RAD?

July 4,  2018: E-RAD is a new model of aviation radiation from Spaceweather.com and Earth to Sky Calculus. It can predict how much cosmic radiation a passenger will absorb flying on any commercial jet across the USA.

Researchers have long known that cosmic rays penetrate the hulls of commercial aircraft. At typical cruising altitudes, pilots, flight attendants and passengers typically receive a dose rate 40 to 70 times higher than natural radiation on the ground below. The higher a plane flies, the more radiation it receives. This has prompted the International Commission on Radiological Protection (ICRP) to classify pilots as occupational radiation workers–just like nuclear power plant engineers.

Image result for cosmic rays aviation radiation

Most people stepping onboard an airplane have no idea they are about to encounter cosmic rays–much less do they know what the dose rate might be. And that is where E-RAD comes in. Enter a flight number and voila!–E-RAD predicts your exposure to cosmic rays.

This new model has been years in the making. Since Jan. 2015, Spaceweather.com and the students of Earth to Sky Calculus have been monitoring cosmic rays in airplanes. Our method is simple: We board planes carrying the same cosmic ray payload we routinely fly to the stratosphere on space weather balloons. Inside the airplane we measure X-rays, gamma-rays and neutron dose rates, along with GPS altitude, latitude and longitude.

flightpaths
Above: Flight paths forming the basis of our aviation radiation study. 2015-2017

Our data set is impressive. So far we have gathered 18,518 GPS-tagged radiation measurements during 72 flights over 2 oceans and 5 continents. We have spent 276.6 hours onboard planes taking data. These numbers are increasing rapidly with new flights every month.

The E in E-RAD stand for “Empirical.” In other words, the model is based on real-life measurements, not theoretical calculations that might be wrong. Moreover, our data-set is fresh. Because it is constantly being updated, E-RAD naturally keeps up with variables that affect cosmic rays–for instance, the waxing and waning of the solar cycle and changes in Earth’s magnetic field.

At the moment, the bulk of our data (70%) are concentrated over the continental USA, and that is where our predictions are best. For instance, here is a flight from Eugene, OR, to San Francisco, CA, in January 2018:

comparison

The orange curve traces radiation dose rates actually observed inside the airplane, while the blue curve is E-RAD’s prediction. The two agree within 20% for most of the flight. These errors are constantly shrinking as we add new readings to our database.

We are also improving our model outside the continental USA. Recent trips to Nepal and Hong Kong have added thousands of data points in southeast Asia. And later this month we will gather more than 100 hours of measurements over the South Pacific, Australia and New Zealand.

Stay tuned for updates from 35,000 feet.

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