Threat from space: “killer electrons”

High-energy “relativistic” electrons, known as “killer electrons”, have long been of concern to the satellite industry because of their ability to cause radiation damage. These electrons can disrupt the Earth’s magnetic shield, leading to geomagnetic disturbances and posing a serious threat due to changes in “space weather.” However, a recent study led by Dr. Nigel Meredith of the British Antarctic Survey (BAS) has shed light on the extent of these phenomena and their implications for satellite operators, manufacturers, insurers and governments.

After analyzing 20 years of data from the U.S. GPS satellite, the international team of researchers identified three levels of events: 1 in 10, 1 in 50 and 1 in 100 years. A 1-in-100-year event is defined as an event of such magnitude that it is expected to occur on average once every 100 years. These event levels serve as guidelines for assessing the potential impact of extreme space weather events.

The results of the study have important implications for the satellite industry, which relies heavily on satellites for communications, navigation, Earth observation and defense. As of April 2022, there were more than 5,400 active satellites in Earth orbit, and most of them are exposed to energetic electrons as they orbit. The global space economy generated $386 billion in revenues in 2021, highlighting the economic importance of the satellite industry.

Dr. Nigel Meredith emphasizes the importance of these results to industry and government, stating that they provide the necessary benchmarks for assessing extreme space weather events and their potential impacts. The study will help engineers and operators prepare for the effects of such events and improve the resilience of future satellites. In addition, satellite insurers can use the study to assess realistic catastrophe scenarios and ensure that satellite operators take the necessary steps to mitigate risks.

One notable finding of the study is the difference between 1-in-10-year and 1-in-100-year events, which depends on electron energy and distance from Earth. The differences are greatest at the highest energies and at the greatest distances from the planet, with increases of 3 to 10 times for some of the highest electron energies over 35,000 km from the Earth’s surface. This poses an additional risk to satellites operating in this region.

Space weather, like weather on Earth, is characterized by variations on different time scales. The researchers noted that most of the killer electron events occurred during the decline phases of the 11-year solar cycle, which were observed twice during the 20-year study period. However, the largest event occurred at a different time, emphasizing the unpredictability of extreme space weather events.

Professor Richard Horne, co-author of the study, emphasizes that the space industry is a critical part of the national infrastructure. The research conducted by Dr. Nigel Meredith and his collaborators will help assess the resilience of satellites to severe space weather events, ultimately contributing to the protection and safety of our satellite systems.

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