Posted Jan 27, 2012 10:20am EST

On Tuesday, former Speaker of the House Newt Gingrich said if elected president he would encourage Americans to reach for the stars — literally — and that by the end of his second term there would be a permanent outpost on the moon "and it would be American."

But while his fellow GOP candidates panned the plan on the grounds that it would cost too much. Gingrich's proposal for stellar statehood faces another obstacle: It could violate space law.

"Statehood for a colony on the moon is going too far and would violate the [Outer Space Treaty of 1967] since it would involve rights to land on the moon and also require some type of territorial border," said Henry Hertzfeld, a research professor at the Elliott School of International Affairs Space Policy Institute, told BuzzFeed.

Gingrich introduced a bill in Congress in 1981 that would offer a path to statehood for a lunar colony with at least half a million residents. (Gingrich has mischaracterized the bill he introduced, saying it would grant statehood at 13,000 residents. In fact, the bill only provides for self-governance at 20,000 residents.)

At issue is the 1967 treaty, which the United States ratified, that prohibits any earth-based country from claiming sovereignty over moon or other space territory.

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.

Hertzfeld said that can legally use the moon and put people, structures and property there — and they own those items, but not the land they're on — so Gingrich can have his space base, but it can't "be American."