In Robert Heinlein's 1951 science fiction classic The Man Who Sold the Moon, the protagonist uses the legal principle Cuius est solum, eius est usque ad coelum et ad inferos ("Whoever owns the soil, it is theirs up to heaven and down to hell") as part of a plot to finagle the United Nations into ceding ownership of the moon to his company. World leaders must have taken notice. The U.N.'s 1967 Outer Space Treaty enshrines outer space as "a zone devoid of sovereign control," says Michael Dodge, a space law expert at the University of Mississippi. "Article II prohibits states on Earth from attempting to scoop up land for their future use, thereby avoiding colonialization of space," he says. A second United Nations treaty executed twelve years later declared the natural resources of the moon and other celestial bodies to be reserved for the "common heritage of mankind." (Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, Dec. 5, 1979, 1363 U.N.T.S. 3.) But the Moon Agreement hasn't stopped would-be entrepreneurs from preparing for business far beyond our planet. Bigelow Aerospace of North Las Vegas is seeking Federal Aviation Administration approval to launch inflatable modules to be stationed on the moon, and has recently petitioned the FAA to amend the 1967 space treaty so that anyone who makes it to the moon can have private property considerations. And last spring Planetary Resources Inc. of Redmond, Washington, announced plans to send robotic explorers to asteroids within the next two years, hoping to mine them for water and precious metals. Dodge emphasizes that the legal environment for the moon and other natural bodies in space is different from that aboard the orbiting International Space Station. "Ultimately, the differences stem from the entwined notions of jurisdiction and sovereignty," he says. "The real question is to what extent can states gather materials from the moon and other celestial bodies without appropriating the land to themselves, thereby de facto claiming parts of the moon under their sovereign control." The U.N. attempted to address that issue in its 1979 Moon Agreement, Dodge says. And although that treaty has never found favor among spacecraft-operating nations (the United States is not a signatory) because of mining provisions that call for equitable distribution of resources, its framework generally guides activities in space. As the prospect of actual lunar mining draws closer, he expects "a resurgence of attention to the Moon Agreement." Asteroid mining presents another issue, since according to Dodge there is no consensus yet on whether asteroids are 'celestial bodies,' like planets and moons. "If asteroids are not," he says, "then the rules that apply to mining them could be different in subtle, yet financially significant ways." In July, Reps. Bill Posey (R-Florida) and Derek Kilmer (D-Washington) introduced H.R. 5063, the American Space Technology for Exploring Resource Opportunities in Deep Space Act. ASTEROIDS, as it is known, would establish that resources obtained from asteroids are the property of the company that extracts them. The bill also provides "freedom from harmful interference" for any entities subject to U.S. law that are engaged in asteroid mining. "The legislation is woefully nonspecific, perhaps to avoid conflicting with U.S. international obligations under the Outer Space Treaty," Dodge says. "Hopefully, the House will attempt to iron out some of these quandaries." Difficult intellectual property issues confront companies wherever they mine in space. "If a corporation is acting independently, then the IP restrictions found in NASA agreements will not apply," Dodge says. "But if the corporation is acting with NASA or at its behest, then the same tricky, title-taking problems will apply." Despite the "common heritage of mankind" language in the Moon Agreement, space lawyers may yet find room in the treaty for private development in deep space. "You can't ask for property rights, because those are prohibited," says Mark Sundahl, associate dean and professor at the Cleveland-Marshall College of Law. "So instead, you might ask for the right of noninterference." But Sundahl adds, "At some point, we're going to have to address the ownership of natural resources. A company like Planetary Resources isn't going to invest billions of dollars prospecting for precious metals on an asteroid without clear legal title to ownership."