Newswise — High-powered 'relativistic' electrons - referred to as "deadly" electrons - pose a substantial threat to satellites as they cause radiation harm. Consequently, comprehending their activity patterns holds immense importance. Intense surges of charged particles and magnetic fields originating from the Sun have the capability to rupture the Earth's magnetic field, leading to geomagnetic storms. Within such occurrences, the population of lethal electrons within the outer radiation belt can experience exponential growth, emerging as a significant space weather peril.
Dr. Nigel Meredith of BAS spearheaded a global consortium that scrutinized two decades' worth of data obtained from a US GPS satellite, with the objective of ascertaining the occurrence levels of events at the 1 in 10, 1 in 50, and 1 in 100-year intervals. A 1 in 100-year event denotes an incident of such magnitude that, on average, it will be equaled or surpassed once every 100 years.
Stakeholders such as satellite operators, manufacturers, insurers, and governments must proactively prepare for and mitigate the hazards presented by these electrons. The dependence of society on satellites for diverse applications such as communication, navigation, Earth observation, and defense has grown significantly. By April 2022, there were 5,465 functional satellites orbiting the Earth, and a majority of them experience exposure to high-energy electrons during certain parts of their orbit. In 2021, the global space industry as a whole generated revenues totaling $386 billion, indicating a four percent growth compared to the previous year.
The significance of these discoveries cannot be overstated for the satellite industry, as engineers and operators necessitate accurate assessments of the most substantial electron fluxes encountered within GPS orbit. This information enables them to effectively plan for the consequences of extreme events and enhance the resilience of upcoming satellites. The findings also hold crucial value for satellite insurers, enabling them to verify that satellite operators are taking appropriate measures to mitigate risk and evaluate plausible disaster scenarios realistically.
The disparity between a 1 in 10-year event and a 1 in 100-year event is subject to fluctuation based on the electron energy and the distance from Earth. The dissimilarities are most pronounced at the highest energies and farthest distances from the planet. For certain electrons with energies surpassing 35,000 km from the Earth's surface, these discrepancies can range from a factor of 3 to 10. Such substantial increases in event frequency pose a significant additional risk to satellites operating within this particular region.
Similar to weather patterns on Earth, space weather exhibits significant variations over short time intervals, spanning minutes, days, seasons, and the 11-year solar cycle. The researchers discovered that the majority of killer electron events took place during the declining phases of the solar cycle, which were observed twice within the 20-year timeframe they examined. However, the largest event occurred at a different phase, highlighting the fact that extreme events can transpire unpredictably at any given time.
In 2011, severe space weather was included in the UK National Risk Register of Civil Emergencies, recognizing its potential impact. The consequences of space weather on satellites can vary from temporary service disruptions to complete loss of functionality. An example of the severity of such events occurred in 2003 when a significant storm led to anomalies in 47 satellites, with more than 10 satellites being non-operational for over a day, and one satellite being completely destroyed or rendered inoperable. These incidents highlight the substantial risks posed by space weather to satellite operations.
Extreme Relativistic Electron Fluxes in GPS Orbit: Analysis of NS41 BDD-IIR Data by Nigel P. Meredith, Thomas E. Cayton, Michael D. Cayton, Richard B. Horne is published in the journal Space Weather
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