From:
https:// www.cia.gov/library/readingroom/docs/CIA-RDP80-00810A007800290007-1.pdf
Radioisotopes to measure thickness.
Red October?
Our military vehicles, tanks and ships glow in the dark? Can be detected by satellite?
"glow in the dark" is a figure of speech. Radioactivity is not in the visible spectrum but is detectable with proper equipment. Perhaps by satellite.