GPS: A Constellation Mission Measuring Solar Energetic Protons and the Electron Radiation Belts

The outer reaches of the Earth’s magnetic field play an important role in shielding satellites, the International Space Station, and aircraft from harmful radiation. Variations in the solar wind can change the shape and strength of the magnetic field which in turn affect its ability to deflect the incoming radiation. Direct measurements of this shielding have, so far, only used single satellites with resolution of hours. By contrast, the Global Positioning System (GPS) constellation has more than 20 satellites equipped with energetic particle instruments that are distributed across 6 orbital planes. This operational constellation samples the energetic particle population across a wide range of magnetic latitude (or McIlwain L) and magnetic local time. Energetic particle data collected on GPS satellites, brought to more than 200 satellite-years of data with the most recent release, has been made publicly available providing an unprecedented resource for study of solar energetic protons within the magnetosphere and the electron radiation belt. We demonstrate some of the capabilities of these publicly-available, cross-calibrated measurements, using recent observations of solar energetic particle events, long-term radiation belt dynamics, and the fusion of distributed satellite data with numerical modeling for understanding large-scale magnetospheric dynamics.