Let's assume that I have all the resources to be able to travel to Mars or any other celestial body and colonize it. It is legal to colonize celestials bodies in space?

I think I read once that by international law, no country can colonize space. Is this true? If it is, will it apply to me as citizen of United States?

  • 1
    You need to be say more precisely what you mean by "colonize".
    – user6726
    Commented Aug 26, 2016 at 22:35
  • Basically establish society on another celestial body other than Earth.
    – scubaFun
    Commented Aug 27, 2016 at 16:23
  • Under that interpretation, establishing a society in space is completely legal, since it has nothing to do with countries of Earth.
    – user6726
    Commented Aug 27, 2016 at 17:44
  • 1
    @Nij Because of Outer Space Treaty a Sovereign nation is responsible for and required to supervise the actions of related organisations. An organisation can consist of 1 person. As a US citizen the questioner is subject to USA oversight in space.
    – LOIS 16192
    Commented Feb 6, 2017 at 4:42
  • 1
    @phoog you might pick and choose which nation will be supervising these actions, if multiple nations would agree to do so. Elon Musk is potentially a good example, holding multiple citizenships. However, it's reasonable to assume that some of them, e.g. the smaller nations, will handle the supervision and responsibility issues by a blanket policy that they disallow any operations, instead of by creating an expensive gov't agency to handle this and by assuming the financial liabilities if your launches damage something as en.wikipedia.org/wiki/Kosmos_954 did.
    – Peteris
    Commented Feb 17, 2019 at 14:46

3 Answers 3


The main treaty here is the Outer Space Treaty and its implementation in US law. For your purposes, the relevant sections of the treaty are Article II:

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.

Article VI:

States Parties to the Treaty shall bear international responsibility for national activities in outer space, including the Moon and other celestial bodies, whether such activities are carried on by governmental agencies or by non-governmental entities...The activities of non-governmental entities in outer space, including the Moon and other celestial bodies, shall require authorization and continuing supervision by the appropriate State Party to the Treaty...

and Article VIII:

A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such an object, and over any personnel thereof...

Article II means that setting up your colony doesn't give you ownership over the land it sits on (and Article XII permits anyone to stop by for a visit at any time), but it doesn't outlaw setting up a permanent base.

And I hope your "all the resources" includes a small army of lawyers. Between them, Article VI and Article VIII make the United States government responsible for anything you do in space, so there's a lot of paperwork involved in getting permission to do anything above the Karman line.


I don't think it's entirely regulated yet.

The Article II of the Outer Space Treaty states that "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." And the article VII says that the only ownership that a state can have is on the artifacts used to get there or constructed there.

In theory, you can build your personal dome on Mars and live there, but you can't appropiate a single molecule, so extracting water or stone for personal use could be legally troublesome.

There is, however, the Commercial Space Launch Competitiveness Act of 2015 (complete text here), that allows US citizens to "engage in the commercial exploration and exploitation of 'space resources'". This may be a US' step toward colonization, but it obviously violates the Outer Space Treaty, and both may be overriden soon by a future act, written to suit corporative interests rather than political ones, judging by the commercial twist space exploration is taking.

  • Can you elaborate why "it obviously violates the Outer Space Treaty" ? As far as I see, the outer space treaty doesn't explicitly prohibit commercial exploitation of space resources, it prohibits nations from claims of sovereignty and, essentially, assigning exclusive rights to some space resource. In essence, USA can allow Bob to mine asteroid #1234, but (because of OST) USA isn't allowed to declare that Jacques from France can't mine asteroid #1234 because of what USA told Bob.
    – Peteris
    Commented Feb 17, 2019 at 14:35
  • So, extracting water or stone for personal use is not an issue, what's legally troublesome is extracting water or stone for local resale - the other colonists can reasonably claim that the water isn't your property, you can't have exclusive rights to it, and you can't prevent them from using it. If you envision a local market for resources between colonies/colonists, then that isn't compatible with OST and lack of ownership distinctions.
    – Peteris
    Commented Feb 17, 2019 at 14:39
  • @Peteris If you extract a resource from x place... are you the owner of such resource?? If not, what gives you the right to sell it?? And who gave you the authorization to mine a land that doesn't belong to you?? Under which autority, are they the owners of the land or are they claiming sovereignty over it??? Since Article VI demands that non-governmental entities require authorization and supervision by their nation, authorizing mining means appropiation by a country, which contradicts Article II.
    – user24358
    Commented Feb 18, 2019 at 17:13
  • "who gave you the authorization to mine a land that doesn't belong to you" is actually very simple - as the default legal principle is "Everything which is not forbidden is allowed", by default, you don't need authorization. You need authorization to mine land that belongs to someone else, and that need is caused by property rights. Absence of property rights, in general, means that you can't have exclusive claims, that you can't prevent others to mine "your" (i.e. not your) resource, but you certainly can mine unowned land if there aren't any other regulations explicitly prohibiting that.
    – Peteris
    Commented Feb 18, 2019 at 17:22
  • "Claiming sovereignty over it" would be if you'd argue that you starting mining some place gave you some exclusivity rights for others not to mine that place, and OST prohibits that. However, you certainly can use a resource that's not owned by you assuming that it's also not owned by someone else, who's rights could be violated. I don't need any authorization to take water from the middle of the ocean and use it, or import it to my home. I don't own water in the middle of ocean, but neither does anyone else; and I would have ownership of the water that I brought home.
    – Peteris
    Commented Feb 18, 2019 at 17:27

This is my interpretation of Space law based on conversations with people who have studied space law, law of the sea, property law, international law, and contract law in a number of countries and my own research.

The Outer Space Treaty is the main basis, and it requires a treaty state to be responsible for the actions of any non-government or other entity.

  1. The natural resources of space should benefit everyone.
  2. Anything constructed belongs to the constructor.
  3. The constructor is governed by the laws of their nation.
  4. As a USA Citizen you are free to give up your citizenship and thus your future rights and obligations to the USA.

So assuming you offered to compensate or benefit "Everyone" fair value for what you used and some rent for the space you occupied, and you did so compliant to USA law the answer is you could go to Mars, or anywhere else extra-planetary construct what ever was necessary to function as a productive USA citizen, pay taxes and expect reasonable support from the Federal Government. Eventually a sufficiently large number of people would be able to apply for state hood.

If you choose to exercise your right to terminate your citizenship, then you need to join another sovereign treaty nation or be recognized as a sovereign nation and sign the treaty.

To pay to "Everyone" you would probably be covered if you paid some "reasonable" amount into a trust used for general benefit. I would suggest 10% of costs would be sufficient.

I am not a Judge (potentially able to set precedent) or even a lawyer.

I am involved in a project to simulate 1 billion plus people living in space.

  • I can't tell if this means "Yes you can" or "No you can't". I also don't understand how your reply related to the OST, e.g. the "need" to join another treaty signatory nation or to become a nation of your own. Where did that come from?
    – user6726
    Commented Feb 6, 2017 at 6:10
  • What if a citizen or organization from a nonsignatory nation colonizes Mars?
    – phoog
    Commented Feb 6, 2017 at 6:13
  • @phoog Anyone who wants to do it will need more than one trip and and lot of resources, including the tecnological solution to counter Mars' extremely harsh environment. There's not a chance that a "rogue colony" will be completed before the rest of Earth's nations intervene.
    – user24358
    Commented Feb 16, 2019 at 0:29
  • @LudovicoN on what basis would they intervene? What form would the intervention take?
    – phoog
    Commented Feb 16, 2019 at 6:26
  • @phoog depending on the political context of the time there will always be a 'reason' to intervene, either by economic or military means, because... that's what we do. Nations getting in the way of other nations is, after all, what history is mainly about.
    – user24358
    Commented Feb 17, 2019 at 7:13

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