SPACE IS AN OPPORTUNITY TO RETHINK PROPERTY RIGHTS: HERE'S WHAT COULD HAPPEN WHEN JOHN LOCKE AND HENRY GEORGE GO TO THE MOON.

• Author: Lowe, Rebecca

DISPLAYED NEAR A triceratops skull in a small gallery in Cambridge, England, you can find a bit of moon rock on sale for just under $40,000--or you could have found it for sale, if only you'd arrived sooner. A red "sold" sticker is attached to the label that identifies the rock as a "lunar sphere."

Never mind, you think--there's plenty more where that came from.

It's not as simple as that. That space rock represents a rare opportunity, similar to a vegetarian making a moral exception for roadkill. It wasn't deliberately extracted from the moon by someone claiming it for themself or planning to sell it to you. Something randomly bashed into the moon approximately 4.5 billion years ago, and a particular bit of moon debris got knocked loose and landed in the Sahara Desert. If you wanted to buy a piece of moon rock that's currently up there orbiting Earth, you'd have to break international law.

Except, surely, for the complication that international law only binds states. This points us to one of the most frustrating things about space law: It's all very debatable. Big players make big claims about rules' core features, with mutually exclusive implications.

Take the 1967 Outer Space Treaty (OST). Still the vanguard of space regulation but written at the height of the space race, the OST's core goal is peace. It commands that astronauts "shall be regarded as the envoys of mankind," that stationing weapons of mass destruction in space isn't permitted, and that "national appropriation" is also forbidden. Unlike more minor space agreements, such as the Moon Treaty, the OST binds all the key spacefaring nations and many others besides: 112 countries are currently party to it. But the situation is complicated by questions of interpretation.

Consider that ban on "appropriation." What exactly does the treaty forbid, and to whom does this apply? Some have tried to argue that the OST's focus on the national level leaves space open for individuals to stake claims--although it's almost universally accepted that a prohibition on individual appropriation is baked into the national prohibition. More convincingly, while some interpret the treaty as outlawing the appropriation of anything at all, others claim that its nonappropriation principle pertains only to the "physical domain," meaning "void space" and "celestial bodies." Under this interpretation, the OST shouldn't be assumed to prohibit the extraction, or even ownership, of resources found "on or in" such bodies. But the prohibition of land ownership tends to have an impact on the use of land resources.

There are other features of the treaty--not least a requirement of free, equal access to "all areas of celestial bodies"--that further complicate matters for anyone trying to stake claims in space. And the treaty's repercussions for "space resource utilization" came long before options like space mining seemed a serious possibility.

As economist Branko Milanovic has pointed out, new technologies both create new needs and help us to satisfy those needs by letting us derive more from the resources around us. This also applies to wants: The vast opportunities of space ownership, newly possible, not only...