APRIL 14, 2026 – At the center of our planet, a core of conductive iron alloys swirl, radiating heat and electrical currents. This effect generates a magnetic field that extends from the center of the Earth out into the reaches of space, powerful enough to prevent solar winds from stripping the atmosphere from the planet.
While the magnetic field deflects the hazards of space, its impacts are felt at the terrestrial level as well. The field has proven particularly useful for navigation — from migrating birds to humans sailing the seven seas. For centuries, however, this important navigational aid was a source of frustration. Mariners quickly learned their compass needles pointed not to the geographic North Pole, but to a magnetic pole — and it was moving. The angular difference between true north and magnetic north, known as declination, varied unpredictably across the globe and over time. A chart that was true one year could lead a vessel to ruin the next.
This challenge spurred a centuries-long quest to map and understand the Earth’s shifting magnetism, an undertaking that would require generations of collective scientific knowledge and take geomagnetic observation from the seas into space.
Today, the National Geospatial-Intelligence Agency continues the pursuit of geomagnetic study, using data gathered from seabed to space to craft models that help billions safely navigate our world – building upon the legacy of the explorers and scientists that came before.
Pioneers of the Unseen
One of the first major leaps in geomagnetic study came at the turn of the 18th century. Famed astronomer Edmond Halley — years before the comet that bears his name would make its predicted return — took command of the HMS Paramour, departing on a series of voyages. Backed by the British Crown, his mission was to chart the magnetic declination of the Atlantic Ocean. The resulting charts were the first of their kind, providing scientific verification that the magnetic field was not static. However, these charts did not solve the issue that a single survey, no matter how accurate, was only a fleeting snapshot.
While the practical applications and limitations of magnetic navigation were being explored, it ultimately took another century for German mathematician Carl Friedrich Gauss to unlock the science behind it. He theorized that the magnetic field was primarily generated from within the planet and ultimately provided the fundamental theoretical tools and mathematical frameworks still used by scientists today to model its complex behavior. While Halley had charted the problem and Gauss provided the theory, it was an American scientist who would fuse these concepts into a global, operational mission.
Louis A. Bauer, the first director of the United States’ Carnegie Institution’s Department of Terrestrial Magnetism, made it his life’s work to elevate the study of geomagnetism, recognizing that a precise, unified model was essential for safe navigation and scientific progress.
In 1905, his department commissioned its first vessel, theGalilee. However, the ship’s iron fastenings created too much magnetic interference. To achieve the precision he required, Bauer convinced the Carnegie Institution to fund a vessel unlike any other: a ship built to be almost entirely non-magnetic.
Constructed from wood, copper and bronze, the Carnegieset sail in 1909. On its maiden voyage, theCarnegieretraced Halley’s path from 200 years prior, determining that if they had followed Halley’s original compass headings, they would have landed in Scotland instead of their intended destination in England — a clear demonstration of the ever-shifting magnetic field.
TheCarnegie’s seven voyages produced an unprecedented volume of magnetic data, dramatically improving the accuracy of the world’s navigational charts. However, Bauer’s grand endeavor came to a tragic halt in 1929 when theCarnegiewas sunk after a refueling explosion in Samoa, killing its captain and destroying its contents. Though this ended the program, most of the gathered data had been copied and sent to Washington, preserving its scientific advancements.
The Final Frontier
Following the loss of the Carnegie, dedicated U.S. magnetic data collection paused for several decades before resuming in the 1950s with the military’s Project Magnet. This survey program outfitted specialized aircraft with magnetometers, flying extensive missions across the globe to gather the vital data needed for military charts and navigation.
The dawn of the space age offered a revolutionary new vantage point, and by the turn of the millennia, the satellite era of geomagnetic research began in earnest. Early missions, such as the Danish Ørsted satellite and the German CHAMP satellite, laid the foundation for modern satellites such as the European Space Agency’s Swarm constellation. These orbital platforms could gather a continuous stream of precise, global data with a previously impossible speed, consistency and scale.
This satellite-derived data now fuels the modern World Magnetic Model. The U.S. National Geospatial-Intelligence Agency and the U.K. Defence Geographic Centre sponsor the WMM, and the U.S. National Oceanic and Atmospheric Administration and the British Geological Survey produce it. Updated every five years to account for the planet’s shifting field, the WMM is one of the world’s premiere geomagnetic models.
Today, the U.S. Department of War, the U.K. Ministry of Defence, the North Atlantic Treaty Organization and the Federal Aviation Administration, and many other major organizations and countries use the WMM. It is also part of the dataset that makes up the World Geodetic System, which is used in countless navigation systems, including the GPS, in billions of smartphones and vehicles.
The Next Evolution
This widespread reliance on magnetic data creates a pressing need for an advanced and sustainable data source. To meet this challenge, NGA looks to the future with MagQuest, a competition designed to stimulate innovation in geomagnetic data collection. The initiative challenges solvers from industry and academia to develop new, independent and cost-effective methods for collecting the data needed to maintain and update the WMM. By accelerating the development of novel solutions, such as constellations of small, highly accurate nanosatellites, MagQuest drives technological innovation, harnessing private-sector industry to deliver cutting-edge technologies. Additionally, it is a vital national security imperative. By fostering a domestic capability for geomagnetic data collection, NGA ensures that the U.S. and its allies maintain their decisive navigational edge — receiving the most accurate and timely geomagnetic data available.
The tools may have evolved from canvas sails to satellites, but the fundamental mission remains unchanged: to precisely chart the Earth’s dynamic magnetic field and guarantee navigational accuracy for U.S. forces, allies and civilian users worldwide.
Story by National Geospatial-Intelligence Agency
National Geospatial-Intelligence Agency