This is not an insignificant question, because at first blush the answer would appear to be a resounding “no.” And the neglect of this question in the current excitement over these ventures is a little puzzling, given that just a few weeks ago a legislative proposal to create a Wild West-style land rush in outer space received a lot of attention. The legal questions presented by both stories are the same. International law makes no distinction between extraterrestrial resources, whether they be on the Moon, Mars or other planets, or asteroids. And if these resources are really just there for the taking, there would be no need for a proposal such as the so-called “Space Settlement Prize Act.”
Our starting point is the Outer Space Treaty (OST) of 1967, which is established international law and has been ratified by 100 states parties, including all of the major spacefaring nations, and an additional 26 nations that have signed but not ratified the treaty.
On its face, the OST prohibits nations from asserting sovereignty over the Moon and other celestial bodies. In fact, Article II states that "Outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.” The OST’s ban on national appropriation is imputed to private citizens of the states parties. In other words, states parties have a legal obligation under international law to stop their citizens from doing what the national government itself cannot do under the OST. In fact, Article VI of the treaty requires states parties to supervise and regulate the spacefaring activities of private entities over which they have national jurisdiction.
Even more significantly, the OST declares the Moon, the planets and all celestial resources to be “the province of all mankind,” a frequently used concept in international law. In other words, these resources are part of the celestial commons that belong to all of humanity, to be held in trust for future generations. Article I of the treaty states that “The exploration and use of outer space, including the moon and other celestial bodies, shall be carried out for the benefit and in the interests of all countries, irrespective of their degree of economic or scientific development, and shall be the province of all mankind.”
That isn’t all the OST has to say on this point, however. Under Article VII, states parties are “internationally liable for damage to another State Party to the Treaty or to its natural or juridical persons by such object or its component parts on the Earth, in air or in outer space, including the moon and other celestial bodies.” Further, Article IX requires states parties to “conduct all their activities in outer space, including the moon and other celestial bodies, with due regard to the corresponding interests of all other States Parties to the Treaty.” The same article prohibits nations or entities under their control from doing anything resulting in "harmful contamination" of the Moon or other celestial bodies (begging the question of what constitutes harmful contamination, of course).
The thread of my argument here is obvious: if the celestial commons “belongs” to all nations and peoples of Earth, no one entity or government can unilaterally appropriate those resources for themselves, and national governments have an international obligation to stop such activity under their control. Especially if that appropriation consists of grabbing a 100-foot asteroid containing up to $25-50 billion in platinum, and keeping the proceeds for oneself and one’s investors.
Unfortunately, the OST is not self-enforcing. Article IX merely allows states parties that believe they will be harmed by the activity of another state party to request “consultation.” In the United States, at least, nothing would appear to stop anyone of any nationality from filing an action in U.S. federal court seeking a declaratory judgment that the U.S. federal government has an international legal obligation to stop such activity or to regulate it in some manner. Further, other states parties could seek enforcement against a government in an international legal forum with recognized jurisdiction.
Finally, another treaty, known as the Liability Convention, is generally regarded as fleshing out the bare-bones liability provisions in the OST mentioned above. However, with some creative lawyering, it may provide a cause of action for redress for those opposed to the unilateral appropriation of celestial resources. I’ll save that for another day.
All of the above is not intended to suggest that we should not eventually exploit the resources of outer space for the betterment of all of humanity. But such exploitation must occur under a recognized international regime, perhaps one modeled on the sea bed mining provisions of the Law of the Sea Treaty. Whatever the eventual legal regime, it must ensure that celestial resources are not merely exploited by those with the means to do so and for their benefit alone, but are indeed treated as the “province of all mankind.”