(disclaimer I work on climate/methane mapping) Companies do survey from the ground, and for large facilities there is often permanent monitoring. Detecting me

(disclaimer I work on climate/methane mapping) Companies do survey from the ground, and for large facilities there is often permanent monitoring. Detecting methane from the ground still requires an expensive instrument, and it covers a very tiny area. Having said that, a lot of methane leaks are from abandoned well heads, and in many places there just are no economic incentives to care about it. Anyway, satellites are not cheap from a capex standpoint, but they are surprisingly cheap in terms of $/m^2. A camera moving over the earth at 7km/s mapping a 200km swath can cover a million square km for O($1000). Getting a team with expensive equipment into the field for a day on one site could easily be more than that.