A growing dent in Earth’s magnetic field over the South Atlantic is letting damaging solar radiation reach satellites in low-Earth orbit, and no one can reliably predict how it will change. This dent, called the South Atlantic Anomaly (SAA), is currently expanding and deepening. It threatens the thousands of satellites that underpin weather forecasting, navigation, communications, banking, and internet access. The anomaly originates in the churning liquid iron of Earth’s outer core, where the geodynamo generates the planet’s protective magnetic field. But existing computer models cannot simulate the core’s true conditions, leaving scientists unable to explain the SAA’s behaviour or forecast its future. The researchers will build a new type of geodynamo model that combines fundamental physics with machine learning and high-resolution data from the recently launched MSS-1 spacecraft. This will allow them to map the SAA from space, image the dynamics inside the core, and predict how the global magnetic field—and the space weather hazard it creates—will evolve. If successful, the models could improve the magnetic-field maps embedded in billions of mobile phones via Google and Apple Maps. They would also help satellite operators design and position spacecraft to survive the radiation risk in the SAA—a critical concern as plans call for launching up to 100,000 new satellites in the next decade.
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Context: Earth’s magnetic field shields our planet from harmful solar radiation, protecting our atmosphere in which life has thrived, and sheltering modern electrical infrastructure such as satellites and power grids from space weather. Yet our planetary magnetic shield has a dent, or low intensity zone, called the south Atlantic anomaly (SAA), a vast area of space currently between South Africa and Chile, in which spacecraft in low-Earth orbit are exposed to damaging radiation. The SAA is currently growing and deepening, which might have major implications for the sustainability of satellites, underpinning diverse technologies such as weather forecasting, navigation, communication, television, banking transactions and internet provision. The origin of the SAA lies deep within Earth’s liquid outer core, where a churning ball of liquid metal generates the Earth’s global magnetic field through a process termed the geodynamo. However, due to severe computational challenges, current numerical models of this geodynamo cannot faithfully describe the correct conditions of the core, a situation that is unlikely to change in the foreseeable future. Major gaps are left in our understanding of how the global magnetic field is created, which means that we cannot predict the future of the SAA and the associated environment at low-Earth orbit. The challenge: The challenge is to develop a new type of model of Earth’s dynamo, leveraging recent advances in observational data and data-driven machine learning methods. These models will obey all the appropriate physics while matching high resolution satellite data, providing an unprecedented opportunity to image the dynamics inside the core. Data from the recently launched MSS-1 spacecraft provide a unique opportunity to map and, based on the new models, predict the environment within the SAA. Aims and objectives: We aim to: Create new maps of the SAA from space using the data from MSS-1. Create new models of Earth’s core that explain the dynamics of SAA and how the geodynamo operates in the present-day. Predict the future structure of the global field, including the SAA and its associated space weather hazard. Potential applications and benefits: Our new models will answer fundamental questions about the deep-Earth. For the first time, we will be able to identify how the geodynamo operates, why we have a SAA and whether it might have occurred in the past. Furthermore, our models will allow us to gain new insights into the planetary evolution of Earth, such as constraining the thermo-chemical structure of the deep mantle and how global magnetic reversals occur. More broadly, because the fundamental physics is thought to be the same in all planetary dynamos, our new understanding for the Earth will directly inform the interpretation of magnetic fields in other planets. Better forecasts of the global magnetic field will improve the magnetic field orientation and navigation models embedded in billions of mobile devices worldwide via Google and Apple Maps. Predictions of the near-Earth space environment will inform satellite operators and designers about the risk from the south Atlantic anomaly. This has the potential to be globally impactful in view of current plans to launch up to another 100,000 satellites in the next decade (Zhang et al., 2022), mainly in large, interconnected but poorly shielded satellite constellations such as Starlink (SpaceX). These constellations will all be in low-Earth orbit, and at risk from space weather.
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