Recently the MagQuest competition on improving the measuring of the Earth’s magnetic field announced that the contestants in the final phase have now moved on to launching their satellites within the near future. The goal here is to create a much improved World Magnetic Model (WMM), which is used by the World Geodetic System (WGS). The WGS is an integral part of cartography, geodesy and satellite-based navigation, which includes every sat nav, smartphone and similar with built-in GNSS capabilities.
Although in this age of sat navs and similar it can seem quaint to see anyone bother with using the Earth’s magnetic field with a compass, there is a very good reason why e.g. your Android smartphone has an API for estimating the Earth’s magnetic field at the current location. After your sat nav or smartphone uses its magnetometer, the measurements are then corrected so that ‘north’ really is ‘north’. Since this uses the WMM, it’s pertinent that this model is kept as up to date as possible, with serious shifts in 2019 necessitating an early update outside of the usual five-year cycle.
Goal of the MagQuest competition is thus to find a method that enables much faster, even real-time updates. The three candidate satellites feature three different types of magnetometers: a scalar-vector magnetometer (COSMO), a nitrogen-vacancy (NV) quantum sensor, and the Io-1 satellite containing both a vector fluxgate and atomic scalar magnetometer.
The NV quantum magnetometer is quite possibly the most interesting one, featuring a new, quantum-level approach for magnetic sensing. This effectively uses a flaw in a diamond’s carbon matrix to create a quantum spin state that interacts with magnetic fields and can subsequently be read out. The advantage of this method is its extreme sensitivity, which makes it an interesting sensor for many other applications where measuring the Earth’s magnetic field is essential.
I find it odd that they would still be using fluxgates (temperature sensitive, power hungry, requires calibration, intermittent readout) instead of an Overhauser (fundamentally converts magnetic field directly to frequency, less power hungry, continuous readout)
Could it be the mass required for a strong enough signal to be generated using the Overhauser effect is too high relative to using fluxgates ?
Or that the shielding required to sufficiently attenuate RF from other sources causes interferes with the magnetic field strength measurements due to hysteresis effects ?
I don’t know if would be applicable or not, but in the early phases of GWOT, when the pentagon was throwing money of defense startups left and right, there was a company that was using the Earth’s magnetic field to measure the distance a 40 mm shell traveled. It was on one of those “future weapons” kind of shows that the Discovery channel was heavy into in the early 00s.
The weapons platform (Bofors Mk4? shooting a 40x365mm) measured the distance to the target, programmed that distance into the round, and fired. The sensor in the round then counted the number of magnetic field bands it passes through on its way to the target. x-number of bands equals y-number of meters. When the desired distance is reached the round does its thing; air burst, detonation after penetration, sing happy birthday or whatever.
No idea if it ever made it into production, but I thought it was pretty cool. If its sensitive and robust enough enough to fuse a cannon shell then it should be useful for this application.
“magnetic field bands”?
Something got lost in translation, methinks.
Probably just Discovery TV nonsense.
It’s not like AI actually invented hallucinating; it was already a thing in wide use I’d say.
That, and this was close to 20 years ago. I have been hit on the head a few times since then and could be combining memories. They did have a round that counted the number of times it spun and extrapolated from there distance traveled.
I will say the Mk38 Mod2 GPS and gyro sensors were garbage. Not a fan of BAE.
From that android link:
” This class currently uses WMM-2020 which is valid until 2025, but should produce acceptable results for several years after that. Future versions of Android may use a newer version of the model.”
valid until 2025
And: may use a newer version.