https://en.wikipedia.org/wiki/5D_optical_data_storage
5d is a bit dramatic but it is a femtosecond laser writing of quartz crystal that should, in theory, be stable for billions of years and can hold hundreds of terabytes.
Seems to be just what is needed.
https://www.scientificamerican.com/article/data-saved-quartz...
https://en.wikipedia.org/wiki/5D_optical_data_storage
5d is a bit dramatic but it is a femtosecond laser writing of quartz crystal that should, in theory, be stable for billions of years and can hold hundreds of terabytes.
Seems to be just what is needed.