Unobtanium in the 21st century

I was watching this old PBS NOVA program (the lip synch is off) about the Earth's magnetic field.




source: https://www.youtube.com/watch?v=NJUTUFAWfEY

At about 10 minutes into the show there is a brief sequence with Mario Acuna at NASA Goddard mentioning how magnetic fields are measured.  At about 13 minutes he shows what appears to be a fluxgate magnetometer which is a toroid wound with an excitation coil with another sense coil wound over the toroid.

Doing a little searching I found this page:

https://science.nasa.gov/technology/technology-highlights/rediscovering-the-lost-art-of-fluxgate-magnetometer-cores

Also this page:

https://gi.copernicus.org/articles/8/227/2019/

It sounds like the quantities in question are so small that no one can justify having the people on hand to keep making these cores.  I wonder how many other projects there are like this ?

I wish I knew more about this stuff.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm