It’s a noble idea, says Hertzfeld, but there’s one glaring problem. “If the bill were to become law,” he says, “it would be very easy for other nations to say the U.S. is aggressively declaring sovereignty over parts the Moon”—something explicitly prohibited by the U.N.-sponsored Outer Space Treaty created in 1967. Indeed, the new American law would violate not merely the spirit of that 46-year international one, but the letter of it too since all national parks fall under the jurisdiction of the National Park Service, whose charter is to manage its assets “for the benefit and inspiration of all the people of the United States.”

That sounds an awful lot like a declaration of sovereignty, worries Hertzfeld. It might be possible instead to have the Apollo sites and other places with remnants of unmanned landers declared UNESCO World Heritage Sites—but again, says Hertzfeld, “all of those sites are on sovereign territory,” raising that tricky question again.

A better route, he and Pace argue, might be to create a new international treaty through the U.N. That, however, could take many years to push through, and with a new Moon rush about to begin, the diplomatic pace might not keep up with the exploratory one, leaving the historic sites vulnerable to damage. “The lunar regolith is dusty,” says Pace, “and if you kick up a lot of dust, you can inadvertently cause a lot of damage.” If lunar tourism ever begins in earnest—even if it’s virtual tourism, with a rover taking customers on a video ride-through of Apollo landing sites—the danger of flinging dust and, worse yet, obliterating astronaut footprints, would be even greater.