Grant Stephens

The Earth’s magnetic field forms a protective cocoon from the solar wind called the magnetosphere. The magnetosphere is not a static structure and reacts to changes in the solar wind. For example, the Sun will occasionally emit a large bundle of magnetized plasma termed a coronal mass ejection or CME. When a CME sweeps past the Earth it can trigger a large magnetic disturbance throughout the magnetosphere called a geomagnetic storm. Another type of disturbance, substorms, occurs when a large amount of magnetic energy is stored on the nightside of the Earth which is suddenly released, accelerating particles toward the poles and lighting the night sky with the aurora. Both storms and substorms are important aspects of space weather and can have profound impacts on both spacecraft and astronauts. Grant Stephens’ research involves describing these events using data-driven models of the magnetosphere’s magnetic field and electric current systems. He employs data-mining methods to extract information on the dynamics of these systems from decades of spacecraft magnetometer measurements which then gets ingested into the model, forming a global picture of storms and substorms. Additionally, Grant has developed similar models for other planets such as Mercury and Saturn.