NASA has released a report containing detailed plans for a human mission to Mars. This has been a long-standing goal for NASA and their report outlines the challenges of Mars exploration in three stages. The first, ‘Earth Reliant’, stage focuses on research aboard the International Space Station. The ‘Proving Ground’ stage puts humans deeper into space for research, while remaining a few days from Earth. The ‘Earth Independent’ stage completes the plan by getting humans to the surface of Mars.

NASA is not the only organization preparing to send humans to the red planet. SpaceX, Dennis Tito’s Inspiration Mars Foundation, and Mars One have all expressed an aim to visit and in some cases even colonize Mars.

Before any nations or organizations begin exploring and establishing settlements, ambiguities in international law regarding space exploration and settlement should be clarified and resolved. The potential costs, financial and political, of ignoring this issue of sovereignty in space are too high to allow these mission plans to develop much further.

Current space exploration policy is largely defined by the Outer Space Treaty, written in 1967. This Treaty bars its signatories from installing weapons of mass destruction in space, limits the use of space to peaceful purposes, prohibits any nation from claiming land on any celestial bodies (known as the ‘non-appropriation principle’), and asserts that space is ‘the province of all mankind’.

The Outer Space Treaty was written before humans landed on the Moon, as Cold War tensions mounted, and so is poorly equipped to direct the course of space exploration. Many clauses of this Treaty are undoubtedly necessary, such as the prohibition of weapons of mass destruction, and the use of space for exclusively peaceful purposes. However, the absolute restriction on sovereign claims by the non-appropriation principle could lead to future conflict.

While complete details for any proposed human missions to Mars (whether public or private) are still under development, the basic premise of colonizing, as opposed to simply exploring, raises concern. The non-appropriation principle of the Outer Space Treaty prohibits ‘appropriation by claim of sovereignty, by means of use or occupation, or by any other means’. This suggests that the act of colonization itself is inconsistent with the Treaty. How these organizations intend to colonize without claiming sovereignty is an unresolved and vitally important issue to decide upon before landing on Mars.



One potential way of resolving this is by focusing on economic claims to the resources on Mars rather than the land itself. Public and private parties might land on Mars and establish a base in which their own country’s law will apply to all inhabitants and visitors—similar to existing legal provisions that govern the International Space Station. They could also establish a limited plot of land where they may claim exclusive economic rights and conduct science. However, such an ‘exclusive economic zone’ would lack any claims to sovereignty. A Mars resident from any colony may pass peacefully through these zones, and could even set up another base of their own. However, all extractable resources contained within the zone are the exclusive right of the original claimant. This proposal provides a way to satisfy the resource-gathering goals of many current Mars missions, permit plans for colonization to proceed, and fulfill the requirements of the Outer Space Treaty.

Many proponents of Mars colonization missions object that any such missions will irreversibly pollute the natural environment of Mars, harming scientific research as well as marring the natural beauty of the planet. To combat these worries, a planetary park system similar to Earth’s national park system could be established. Planetary parks would be identified and regulated according to the input of Earth scientists all over the world—following a consensus model along the lines of NASA’s decadal survey for selecting space missions. Some parks might be open only to science pursuits, while others might be a purely aesthetic designation to preserve Mars’ natural environment.

Agreeing upon a plan like this could provide a peaceful way forward. However, there will always be minor conflicts between colonists, especially if the non-appropriation principle is to hold along with colonization, as no nation or organization will be able to exercise complete control over their exclusive economic zone. A temporary tribunal system may be a good way of settling disputes between settlers on Mars without involving the International Court of Justice on Earth. When two colonies come into conflict with each other, their case may be heard and resolved by a tribunal consisting of representatives of the other colonies. This model allows for colonial interests to be preserved by resolving disputes exclusively among colonists.

The plan outlined above is one possible way forward. However, it is crucial for nations and organizations to enter into a dialogue about how to continue. Existing plans to colonize Mars have not addressed how they will deal with the issue of claiming sovereignty. But any organization under the jurisdiction of a nation party to the Outer Space Treaty will need to abide by the Treaty’s stipulations. Perhaps the solution is to re-examine the Treaty, especially the non-appropriation principle, and determine if this requirement is still relevant today. Or perhaps the solution is to amend the Treaty to explicitly decide upon a method of settlement. The current state of affairs is too ambiguous, and conflict seems unavoidable unless a colonization regime is decided upon before the first humans arrive on Mars.

Sara Bruhns studied physics and astronomy at the University of Virginia. She investigated the of sovereignty on Mars with Jacob Haqq-Misra (@haqqmisra) through the Young Scientist Program at the Blue Marble Space Institute of Science. The views here are the authors’ alone.

