Cosmic rays emanating from ultra-powerful sources in the distant universe can pose a risk to people on Earth — particularly frequent air travelers who are routinely exposed to the high altitudes of commercial flights. Now, astronomers have used inexpensive radiation detectors to begin mapping the radiation environment across African skies, in the first steps to ensure the safety of aircrew flying over that continent.
cosmic rays constantly bombard us from all directions. But the “rays” aren’t exactly well named. Although the astronomers who first discovered cosmic rays thought they were a new form of radiation like X-rays and gamma rays, further investigation revealed that cosmic rays are actually made up of subatomic particles that are almost identical to the Speed ​​of Light.
These cosmic rays typically come from the extremely distant universe, from ultra-strong events such as supernovae And quasars.
Related: The supernova “wreck” emits cosmic rays into space
A typical cosmic ray particle has the same kinetic energy as a fastball. That may not seem like a lot, but squeezed down to the subatomic level, this amount of energy packs a real punch. Cosmic rays can mess up electronic devices, damage data storage devices, and even cut up DNA. When DNA is cleaved, it can lead to replication errors and even tumors. Scientists estimate that cosmic radiation causes a few percent of all cancers worldwide.
Fortunately, our planet offers multiple layers of protection against these threats. The first is The Earth’s magnetic field – the strongest among the rocky planets in the solar system – this simply deflects the lower-energy cosmic rays. However, the more energetic ones shoot right through and end up in our planet’s atmosphere.
But that’s where the cosmic rays usually encounter a nitrogen or oxygen molecule and release their energy in a shower of other particles. At sea level, cosmic rays, or their lower-energy showers, penetrate the human body at a rate of about once per second.
The risks of cosmic rays
This happens at sea level; Cruising altitude for scheduled flights is a different matter entirely. Without those tens of thousands of feet to provide protection, passengers and crew are exposed to far higher levels of cosmic ray bombardment. With higher rates comes a greater risk of DNA or cell damage and a corresponding increase in cancer rates.
Even the plane’s metal hull doesn’t do much to stop the microscopic damage. While the metal effectively blocks the cosmic rays themselves, once they collide with an atom, they morph into a shower of subatomic particles that blast through the cabin. This shower is almost as damaging as cosmic rays themselves.
The only effective remedy is to limit exposure. Casual travelers need not worry as their accumulated radiation dose is not significantly different from what they experience on the ground. But frequent travelers, particularly crews, are at increased radiation risk from their time at high altitude.
The governments of the United States and Europe have mandated safety standards that limit the total exposure that aircraft crews may have over a lifetime. Combined with frequent monitoring of the high-altitude radiation environment, airlines can protect their crews.
Monitoring must be frequent because the cosmic ray environment is constantly changing depending on many factors such as the Earth’s magnetic field, the activity of the Sun, and random cosmic fluctuations.
unknown dangers
However, this surveillance program only covers the skies over North America and Europe. We have relatively little knowledge of the radiation environment over Africa. Although fewer flights cross this continent, we cannot quantify the risk to flight crews until we understand the cosmic ray environment.
A team of astronomers has taken the first steps towards solving this problem and has detailed their findings in an article accepted for publication in the Journal of Space Weather and Space Climate (opens in new tab). Setting it up was incredibly easy. They designed a dosimeter using a Raspberry Pi computer to measure radiation exposure in any environment. They then brought the device on board on two long-haul flights – one from Johannesburg, South Africa, to Frankfurt, Germany, and another from Munich to Johannesburg.
The researchers showed that their simple setup could accurately measure in-flight radiation levels. They hope to extend the use of these simple devices to as many passenger planes as possible to build a network of monitoring devices that constantly map and update the cosmic ray environment. From there, they hope to work with African governments to develop safety standards for their airlines.
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