Earth

The Iridium communications satellites form a network with 66 satellites in Low Earth Orbit at 780 km, with 11 satellites in each of six orbit planes. They carry commercial grade magnetometers for attitude correction. By themselves, these magnetometers are not useful for scientific investigations of the Earth’s magnetic field due to their coarse resolution. However, together, they form a dense network that samples each point on Earth every nine minutes. This vast amount of repeated sampling significantly increases the signal to noise ratio allowing us to measure the dynamics of Earth’s internal as well as external magnetic fields.