Let’s say you backup your computer to an external hard drive. Your computer works fine — better than fine, actually. Let’s say it’s the best computer in the world. But there’s a tiny chance that, for whatever reason, some or all of the data on that computer could be lost. Even if that doesn’t come to pass, your computer doesn’t have infinite storage space. Having a repository for excess data would be convenient, if nothing else.

Over seven billion people live on Earth. That number is expected to exceed eleven billion by 2100. Our planet is supporting a growing population with a shrinking number of natural resources. Meanwhile, at present rates of global climate change, the next century will see a rise in temperature of somewhere between 2.5 and 10 degrees Fahrenheit. In many parts of the world, this will precede rising sea levels, more powerful storms, droughts, heat waves, crop failures as well as greater poverty and famine. The relatively stable climate Earth has enjoyed over the last ten thousand years may not survive the next hundred years.

Anyway, out of an abundance of caution and a desire for convenience, you go to the store to buy this hard drive. By coincidence, there’s only one left in stock. It doesn’t come cheap, but it’s a prudent investment, and you’re glad you got to it before someone else did.

Last week, President Obama declared in an op-ed for CNN that the United States would send humans to Mars by the 2030s “with the ultimate ambition to one day remain there for an extended time.” He highlighted the role that the commercial space industry would play in this effort. Two weeks before that, SpaceX CEO Elon Musk said he wants to send people to Mars by 2022 and build a city-sized colony of as many as one million people there in the next 40 to 100 years. The CEO of Boeing said he would beat Musk to it.

The goal, in short, is to make human beings an interplanetary species. The commercial space industry will play an essential role in that process. But we have to make sure they don’t own Mars, and that means confronting the question of who, if anyone, can own the Red Planet, and more broadly, who can own outer space.

The SPACE Act of 2015 allows US citizens to explore and exploit resources on celestial bodies, providing a framework for private property in outer space. But according to the Outer Space Treaty, effective since 1967, “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 SPACE Act insists that allowing Americans to claim private property does not amount to a claim of sovereignty. But it’s not clear.

We didn’t buy Mars like you buy a hard drive. But having purchased this hard drive, you would be troubled to learn that you didn’t own it and didn’t have a right to the storage space it provides. Should a day come when Mars can support human life, every human being should have a right to live there, just as we all have the right to live on Earth and just as you have a right to that hard drive. After all, Earth may be the most hospitable planet for life in our galaxy today. But things could go wrong, and someday we all might need our next-door neighbor.

Groves is a government sophomore from Dallas. Follow him on Twitter @samgroves.