[defrost]

Complex?

Seems straightforward enough in the geophysical instrumentation domain.

Exotic? Radiometric mapping has been around for 50+ years - Australia has mapped the entire country (size of mainland contiguous USofA) from aircraft with ~200m line spacing in that time (along with surveying other countries, Mali, Fiji, India|Pakistan border, elsewhere), Russia, South Africa, Finland, USofA also have radiometric survey teams.

It's handy for finding drums of radioactive waste in a Finnish forrest near the Russia border, for example, which was an actual contest | exercise some years ago.