Field notes
A $399 research-grade magnetometer, and the 400-station problem
By Ross Day2 min read
There are roughly 400 science-grade magnetometer stations on Earth. That's the entire global ground truth for a phenomenon that knocks GPS out of tolerance.
What the sun does to GPS
Geomagnetic storms degrade GNSS in ways most users never attribute correctly — ionospheric scintillation, timing error, position drift during the exact events when position and timing matter most. The grid operators know. The aviation people know. Most everyone else experiences it as “GPS was weird today.”
The resilient PNT conversation is mostly about jamming and spoofing right now, and it should be. But the sun doesn't need an adversary's budget to degrade your timing signal.
A $399 instrument
I built NextMAG partly because that instrumentation gap is absurd. A 3-axis magnetometer with GPS-disciplined timing, 2.7 nT at 1 Hz, for $399 instead of several thousand. Put it in a few hundred classrooms and the map gets denser than the professional network that exists today.
Open the lid and $399 of research-grade geophysics is three parts. A Raspberry Pi. A 3-axis magnetometer good to 2.7 nT at 1 Hz. A GPS receiver that disciplines every timestamp — the same timing rigor the big observatories use.
In plain terms, every reading of the field, in all three axes, carries a GPS-disciplined timestamp. That is what lets one classroom's data line up with a reading from anywhere else on the map. The incumbent instruments cost $3,000 and up. We build NextMAG with Nextage LLC.
In the classroom
Students can build this. NextMAG ships assembled, or as a kit that makes the instrument itself the lesson. Eight weeks of NGSS-aligned curriculum ships with it (MS-PS2-3, MS-ETS1-2). One unit runs a full lab section as teams rotate through.
Both are middle-school standards. MS-PS2-3 is about the factors that affect the strength of electric and magnetic forces. MS-ETS1-2 covers evaluating competing design solutions against the criteria and constraints of a problem.
Classrooms join a live map alongside the roughly 400 science-grade stations that exist worldwide. That is how the map gets denser.
A research university just bought our entire first production run. Not a pilot. Not two units for a lab. All of them.