Core Field Modeling with the Iridium Constellation

Abstract:

The Iridium constellation is being evaluated as a potential space-based data source for producing future World Magnetic Models (WMMs). The WMM is a core field model that is widely used for navigation, and it currently relies on highly-accurate magnetometer measurements from Swarm. This work uses magnetic field data from the engineering magnetometers onboard the Iridium satellites to determine whether a large number of lower-quality measurements can produce satisfactory future WMMs that are comparable to the models derived from a single Swarm spacecraft. Iridium nominally has 66 satellites in high-inclination low-Earth orbit spread evenly across 6 orbit planes, providing excellent spatial and temporal sampling of the Earth’s magnetic field. The magnetometers are primarily used for attitude control, which does not require the resolution, accuracy, and calibration effort that is commonly found on scientific missions such as Swarm. We present magnetic field models derived from Iridium data, and discuss the challenges and solutions to producing models using a large constellation of uncalibrated data.