Rush says the most applicable piece of law we have regarding real estate outside of Earth is the Outer Space Treaty, which has served as the basic framework for international space law since 1967. More specific, Article II of the treaty addresses claiming ownership of extraterrestrial property: 
 
 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 UN treaty does apply to governments and their private citizens, which invalidates Hope's claim to the moon and other celestial bodies, she said. These include, on the moon, the Apollo landing sites. It's the moon that's been his biggest seller to date. The main reason for its creation stemmed from fear that the United States would plant a flag on the moon and claim ownership. "It was addressed towards government bodies." "As far as we know, which is confirmed by our experts, it is not possible to claim ownership of Mars land. To illustrate his point, Lansdorp points to Dennis Hope, an entrepreneur who claimed ownership of the moon, then in 2009, maintained he had sold more than 2.5 million one-acre lunar plots for about $22 each. Hope, who heads the Lunar Embassy Corporation, then went on to establish his own Galactic Government, complete with a constitution, congress and its own currency. He fought to receive official recognition and argued that because the Galactic Government was not part of the UN, any agreements regarding the moon were irrelevant. He has issued a lunar currency and has made overtures for the moon to join the International Monetary Fund. Forty years later a Nevada entrepreneur says he owns the moon and that he's interim president of the first known galactic government. We just want recognition so we can work together," Hope told National Geographic in 2009. That agreement, however, has been ratified by just 13 countries, none of which are major spacefaring states. However, Tanja Masson-Zwaan, deputy director of International Institute of Air and Space Law and one of Mars One's legal experts, says the law won't bend, even for someone who does complete a successful Mars mission. A separate 1979 treaty known as the Moon Agreement sets up a framework for establishing clearer rules for managing the moon's natural resources, once the use of those resources becomes feasible. As the moon's representative, he says, he has established relations with some 30 earthly nations. In that case, we can only assume that territories of some kind will have to be established. You don't need to own a place to make money on it, Masson-Zwaan said.
– Calling it the biggest loophole in the world doesn't quite capture its reach: Dennis Hope claims that he owns the moon—and our solar system's planets—due to what the Outer Space Treaty doesn't say. Mashable reports the treaty has been the guiding document on space law since 1967, and while it bars any country on Earth from laying claim to a heavenly body, it makes no mention of private companies or individuals doing just that. So Hope formed Lunar Embassy Corp, snatched up the property rights to the moon and more, and has been selling off one-acre lots since. Though Yahoo shines a light on Hope's offerings (your own piece of the moon will cost just $19.99 an acre; Mars will run you slightly more at $22.49), it's far from the first time he's been in the news. He was featured in the documentary Lunarcy!, out last month on Epix, notes the Hollywood Reporter, and he's talked to media before. As National Geographic previously reported, Hope thinks he has solid ground to stand on: He registered his moon claim with the UN in 1980, and got no answer, which he thinks means it's a go. And while there's still plenty of real estate to be had, Hope has sold more than a nominal amount of each: 600 million moon acres (about 7.5% of it) and 325 million Mars acres. He says two former US presidents are landowners as well as 250 "very well known celebrities," as are two US hotel chains. But Hope does draw the line somewhere: The Apollo landing sites are off-limits.