Reply To: NIMBY FUD
The Focus Fusion Society › Forums › Dense Plasma Focus (DPF) Science and Applications › World running out of helium – so make some with a DPF › Reply To: NIMBY FUD
zapkittybenf wrote: Yeah, I wouldn’t want to see the moon with a sad face >:(
On average helium-4 is 28 ppm of lunar regolith. 3He is from 1 to 50 ppb and is not considered further here.
About 1.07 billion metric tons of regolith would need to be processed to yield the 30,000 tons of helium mined on Earth annually.
Earthside mining handles vastly more material than than that annually and that’s in a fragile ecosystem… unfortunately.
“The smallest lunar features we can distinguish with the naked eye are about 200 km across.”
And regolith is about 3 tons per cubic meter. A reasonable depth for mining would be about 4 meters. So a trench 1000 meters wide and 1000 meters long and 4 meters deep would yield 4,000,000 cubic meters or 12,000,000 tons of material which in turn yields ~336 tons of 4He.
A trench a kilometer wide and about 90 kilometers long processed and refilled for each year?
… and the lunar surface area is 37.8 million square km.
The folks on Earth looking up will notice lunar space stations and perhaps lights from the surface installations of lunar cities and not much else.