A World without Low Earth Orbit High-Precision Magnetometry: the next assessment

High-precision magnetometry with absolute accuracy is crucial for monitoring the Earth’s magnetic field and advancing our understanding of core, lithospheric, and magnetospheric dynamics. Missions such as Ørsted, CHAMP (CHAllenging Minisatellite Payload), and ESA’s Swarm constellation have demonstrated the unique value of high-precision vector field and scalar magnetometer measurements carried out with absolute accuracy in Low Earth Orbit (LEO). Now imagine a world in which dedicated geomagnetic missions in LEO reach the end of their operational lifetimes, expected or otherwise, with no replacements in place. Without the insights provided by missions like Ørsted, CHAMP, and Swarm, we would lose a critical high-resolution view of Earth’s magnetic environment, leaving many variations unresolved. Moreover, data from dedicated magnetic missions are integral for calibrating platform magnetometers aboard satellites not designed for magnetic measurements. While such instruments remain operational, they lack the precision to capture fine-scale signals. Furthermore, without absolute-accuracy reference measurements, platform magnetometer data become less reliable, leading to increased inconsistencies across datasets.Here, we examine the consequences of losing high-precision magnetometry with absolute accuracy in LEO for the calibration of platform magnetometers on satellites not dedicated to magnetic measurements. While reference geomagnetic information could still be derived from less accurate sources, such as ground-based observatory networks, these alternatives lack the spatial and temporal resolution uniquely provided by LEO observations and suffer from uneven global coverage, particularly over the oceans and other remote regions where observatories are sparse. Consequently, geomagnetic field models derived from such data would exhibit reduced resolution and accuracy, limiting their reliability and scientific scope. These deficiencies would propagate directly into the calibration of platform magnetometers, degrading their precision and consistency. This cascading effect would significantly impair our ability to monitor, understand, and model the dynamic geomagnetic field, including contributions from the core, lithosphere, and magnetosphere. Maintaining accurate, high-precision magnetometry in LEO is therefore essential to preserve the integrity of geomagnetic science and to support its wide range of scientific and practical applications.