I’m not sure the wording in the 1967 treaty categorically prohibits establishing large scale (even permanent) physical presence on celestial bodies, or exploiting resources there for economic gain.
From one viewpoint, an authorized space entrepreneur could mine ore on Mars, and (whether economically viable or not) melt down ingots and sell them on earth. He and his crew could live on Mars.
The treaty simply prohibits claiming sovereign ownership. In modern terrestrial society, establishing sustained physical presence and harvesting resources might seem like sovereign ownership, but space is like an undeveloped frontier – somewhat like the US west in the late 1700s or early 1800s.
If an early western pioneer and his intrepid band camped in the wilderness, cut down some trees and burned the firewood on unclaimed, unowned land, he is not laying claim to the land, just scavenging materials. He might even haul the firewood back to civilization and sell it, but he’s no more claiming the land than an offshore fisherman claims the ocean when hauling in a catch from international waters.
Likewise when the crew on a gigantic offshore oil platform occupies a region of the ocean for years, they aren’t staking a sovereign claim on the ocean itself – they are just working and living there: http://energy-cg.com/EandP_pics/DeepWaterSemi-GulfOfMexico-BOEMOPA.jpg
Most oil platforms are build within the 200 mile “Exclusive Economic Zone” from shore, but in theory they could be outside that: Oil rigs: Cities at sea | The Week
You could then argue that the late 17th century frontier explorer was at least claiming ownership over the wood he scavenged. But does the 1967 Outer Space Treaty prohibit claiming ownership over geological fragments of celestial bodies? If it does, then what legal basis did the US government have to haul nearly 1/2 ton of moon rocks back to earth and claim ownership over them – at a time when they had already signed and ratified the 1967 treaty?
In the western frontier case, even though during certain periods nobody had unassailable sovereign ownership of the land, there was some risk of conflicting claims. In theory Napoleon Bonaparte could have challenged the wood-cutting explorer, saying the wood belongs to France.
However in the space case, the 1967 treaty has already prohibited sovereign ownership. So by treaty nobody can complain if someone takes tons of ore off the moon or Mars, because they signed the treaty and agreed to not claim or contest sovereign, territorial ownership. By that viewpoint, deep space is simply “first come, first served” – provided you don’t plant a flag and claim sovereign, territorial ownership.
https://www.cnbc.com/2016/08/29/private-exploration-moving-faster-than-law-in-new-space-race.html