A new study by meteorologist Michael Lockwood of the University of Reading in the United Kingdom and colleagues suggests that space weather is going to worsen over the next 40 to 200 years, increasing the chance of radiation hazards for astronauts and frequent flyers.
Space weather is defined as the amount of energetic particles above the atmosphere: when weather is bad, dangerous particles including protons and ions—known as galactic cosmic rays (GRCs), and similar particles from sun bursts called solar energetic particles (SEPs)— rain down on Earth at near light speed.
The amount of radiation the sun emits fluctuates over centuries and has the biggest impact on space weather; the more radiation the sun emits, the stronger its external magnetic field which acts as a blanket in the solar system against GRCs.
By analyzing ancient ice cores, Lockwood and his colleagues were able to gather data on the variations of GRCs and SEPs reaching Earth over the past hundreds of years. They found that during low solar activity, more GRCs reached Earth, and there were fewer SEP events. They also found however, that fewer SEP events led to an increase in their intensity, which occurred during “middling” solar activity—the period the sun is currently entering.
Dangers are most likely to arise for frequent flyers who take more than five long flights a year, and astronauts headed for the moon or Mars. Although some scientists state that the new predictions need to be tested, Lockwood believes that radiation levels will increase during the sun’s middling transition and cautions that the safe number of flights a year may drop to two, and that the amount of radiation astronauts are exposed to could double.