Imagining safety zones: Implications and open questions

The scarcity of lunar resources like volatiles illustrates the need to deconflict activities on the Moon in a way that is acceptable by all participants. (credit: NASA)

In May, NASA announced its intent to “establish a common set of principles to govern the civil exploration and use of outer space” referred to as the Artemis Accords.[1,2] The Accords were released initially as draft principles, to be developed and implemented through a series of bilateral agreements with international partners.

The Accords offer the possibility to advance practical implementations of long-held principles in the Outer Space Treaty (OST). They raise a rich set of policy questions as we begin to take the law into new levels of resolution. This bold pursuit of uncharted territories is to be applauded, and yet, there is also the risk of diverging from 53 years of international law.

One the ten principles is focused on Deconfliction of Activities, with “safety zones” named as a specific mechanism of implementation:

“Avoiding harmful interference is an important principle of the Outer Space Treaty which is implemented by the Artemis Accords.

Specifically, via the Artemis Accords, NASA and partner nations will provide public information regarding the location and general nature of operations which will inform the scale and scope of ‘Safety Zones’.

Notification and coordination between partner nations to respect such safety zones will prevent harmful interference, implementing Article IX of the Outer Space Treaty and reinforcing the principle of due regard.”

The concept of safety zones are not a new consideration for NASA operations[3] nor for discussions of future space resource activities.[4] Nonetheless, the proposal has raised eyebrows in policy circles because of concerns that they may, whether overtly or inadvertently, erode the prohibition on national appropriation contained in Article II of the OST. While operational principles of due regard and prevention of harmful interference will undoubtedly be an important component of early lunar activity, safety zones are but one possible approach to implementation of Article IX. In this context, it is worth asking, what exactly do we mean by safety zones? Can safety zones be implemented without involving de facto appropriation? How large is it appropriate to make them? And if they are the right tool, what might be important characteristics of their implementation?

There are no precedents here. This article advocates a normative perspective, exploring different aspects of and approaches to safety zones. Operators, international partners, private actors, and regulators must consider the opportunities as well as practical implications and tradeoffs involved. “The law can take us so far; but beyond a certain point we are, as it were, on our own.”[5] The details are up to us: those who go, the policy community, and public.

Property rights associated with safety zones

A working definition of a safety zone, adapted from the Hague Space Resources Working Group Building Blocks, is an “area-based safety measure… necessary to assure safety and to avoid any harmful interference.”[6]

From terrestrial property law, the “bundles of rights” approach can help to structure a discussion of rights and obligations associated with safety zones on the lunar surface. In the lunar context, property rights derive from the object of a spacecraft itself (Article VIII), but they can also derive from shared stakeholdership of natural resources. Although the United States has been clear that it does not see space as a “global commons,”[7] the legal distinction does not invalidate best practices from the domain of natural resource management. Property management regimes for natural resources include the rights of access, withdrawal, management, exclusion, and alienation.[8]

Under Article II of the OST, it’s fair to assume that establishment of a safety zone as such would not convey the rights of sale or lease, known together as alienation. Prevailing interpretations of the requirements for free access (Article I) and visitation (Article XII) imply that the right of exclusion would also be seen as akin to appropriation.[9]

That said, there are still numerous possible approaches to rights in this context. The safety zone might allow an actor to occupy a site and withdraw resources, but not to manage it: for example, under Article VI of the OST, states bear responsibility for national activities in outer space. A commercial operator asserting a safety zone might have the right to occupy and withdraw, but management of that right might be left to the state party. Another approach might be for safety zones to convey the rights of occupation only, with the right to withdraw handled by a separate regime entirely (discussed below.) A more conservative approach, as discussed by Chris Johnson, is that safety zones should not convey “rights” at all, but rather act as a standard of information transfer that allows others to make informed decisions of their own accord.[10] Reporting this information in a precise, transparent, and timely manner could perhaps be correlated with a release of liability for associated damages, incentivizing participation.

Finally, on the topic of management: given the concerns of exclusion, the centrality of the access principle in the OST, and the proviso that exploration and use shall be “the province of all mankind,” a regime must invite all international actors to consent to the designation of specific safety zone areas before they are adopted. This is especially true when we consider just how scarce volatiles appear to be, and volatiles near high-value landing sites even more so. In Ostrom and Shlager’s property management framework, there is a distinction between the “constitutional” right to design the rules, and the right to execute and manage rules agreed upon by all stakeholders.[11] This distinction will be especially important as safety zones are implemented.

Scope of safety zones

The duration of safety zones is also important. There are terrestrial analogs like the International Seabed Authority that can provide references for thinking about appropriate duration, as well as cautionary tales and the lived experience of operators. The question of duration extends to whether and how far ahead of time safety zones can be asserted, what the requirements for approval are, and who has a say.

Safety zones, if that approach is pursued, will need to cover all the locations of a spacecraft’s activity. Although a landed asset may be static, in general a regime for safety zones will need to account for mobility. One approach to doing so is to declare the zone to be the superset of all the places a mobile asset intends to rove; alternatively, there might be a zone around the asset that itself moves. The latter would certainly be more minimal, but may also involve more complex implementation requirements and monitoring considerations. Regime designers might be well advised to consider strategies that balance any incentives to designate more area than one needs, or for longer than it is needed, lest the regime be weaponized between nascent actors or used in a competitive manner between states. As valuable resources begin to be identified, two or more spacecraft may want to operate against the same valuable deposit (supporting the development of private activity), or even to coordinate on some kind of service provision.

However, the area in which it is safe to operate might involve parameters that vary as a function of the location; for example, the particular terrain, the activity, or the instruments being used. A safe operating distance might also be a function of the specific entity or activity that’s close by. How sensitive are their instruments, and what is their intended activity? The technical determination of a safety zone therefore involves more than just mobility: it involves changing parameters, which are themselves not necessarily well known ahead of time. Thus, we might think of minimal safety zones as needing to be dynamically responsive to their environment, whether through human operators or automated operations.

An emphasis on minimal, mobile claims would be bolstered by a collective commitment to transparency and information sharing, especially if the parameters of the zone are themselves changing. Doing so provides an incentive for others to do the same, and in turn a basis for verification and enforcement, both of which are understood to be key to successful arrangements between self-managed actors.[12] While Artemis principles 2 (transparency) and 5 (registration) both speak to this need, it’s clear we will need more than a registry of objects for space if we are to capture this information—we will need a registry of activities.[13]

Practical policymakers tend to approach such complexities by striking a balance between the extremes of precision, ease, and values: an approach that is “good enough” for most situations, combined with designated procedures for extenuating circumstances. The balance between minimalism and ease should be held explicitly as part of the policy design and consultation process.

Codes of conduct

As we begin to think about the interaction between safety zones and other actors, it’s clear the safety zone concept would need to address both how far away others should stay to avoid negative impacts from this spacecraft, as well as the kinds of impacts from others that this spacecraft seeks to avoid. It might be difficult to delineate all of the possibilities ahead of time, but what might be possible is to assert or broadcast (whether through a beacon or a registration mechanism) a set of parameters and thresholds required for safe operations.

This abstraction from the direct assertion of an area-based zone begins to look more like a code of conduct. A code of conduct might be defined as a standard, with standard fields and formats that could be addressed computationally by autonomous spacecraft in the field or manually by operators communicating with each other. After all, the motivating principle in the Accords is deconfliction, and as we have seen here the potential for harmful interference can be much broader than a physical radius: for example, spectrum interference, exospheric dust contamination, or planetary protection.

Going back to the non-appropriation concept, we can see that there is an important difference between rules that consider elements of territory, and rules that have borders or boundaries. Safe zones of operation don’t come from static borders, but from an incorporation and consideration of environmental factors and circumstances. While some of these may derive from the physical environment, others will not at all.

Priority rights

If you can have a safety zone around an activity, can you also have one around, say, a heritage site or a radio quiet zone? A safety zone as a tool might not have to be about multiple actors at all. Although that’s not obviously part of the baseline intention, it brings up the question of whether one needs to be present on the surface to assert a safety zone. Information about planned safety zones might be communicated ahead of time, but any restrictions on access or movement would, it seems, need to follow from actual surface presence. If one communicates plans for future activity and associated safety zones in an area that another operator competes to land in first, are they obliged to honor your zone? That might seem reasonable on its face, but doing so would quickly escalate safety zones into priority rights, and open up the ability for vacuous claims.

Certainly, future actors investing billions of dollars into plans and hardware for a specific site and activity (whether human science activities or robotic mining) will rightly seek some mechanism to have confidence about access to intended landing sites and locations of operation. The international community may well want to implement a priority system for landing complex missions and/or speculative activity. But, importantly, such a priority right doesn’t have to be paired with a safety zone. They should be decoupled as mechanisms. The stakeholders for each might also be legitimately different: the community of stakeholders for making a decision about and approving a planned mining activity might be very different than those involved in operational deconfliction.

Open and participatory process

Though it goes beyond the deconfliction principle, the Artemis Accords’ emphasis on negotiation of bilateral agreements raises some questions as well. Does it make sense if the notion of safety zone only applies to those who have signed the Accords? Though agreements can only be binding on the parties of an agreement, well-designed protocols motivate voluntary participation through balancing incentives and self-interest. To achieve this requires a deep commitment to open development, consultative process, and international buy-in. Bilateral discussions might be an effective tool for identification of common ground, but a bilateral implementation would seem to actively undermine the purpose of the Accords. Developing the Accords in an open and transparent manner, with all actors—including major space powers and the private sector—courted to participate, is in the interest of protecting one’s own assets as well as loftier goal of cooperation.


The bundle of rights framework can help to have precise conversations about the implementation of deconfliction, and highlight the implications of specific proposals for operators and stakeholders alike. The interpretations might even seem obvious, but teasing out the specific rights makes clear the complex ways in which an overly simplistic interpretation of the concept might actually conflict with, or frustrate states’ obligations under, the OST.

Lunar deconfliction, however it is implemented, should be defined to incentivize minimalism and transparency, and may be more effectively framed as a code of conduct offering an interface, rather than a “zone.” A code of conduct would allow actors to assert specific deconfliction parameters and thresholds, with safe distances calculated and applied once the circumstantial details are known. Such information would also be well suited to the long-standing principles of transparency and registration also present in the Accords.

In sum, it’s not entirely clear that an area-based approach is the optimal solution to the motivating goal of deconfliction. This discussion also raises the question of whether such a strategy is compatible with the “minimalist” approach likely expected in the international community, and urges caution about conferring formal rights with any zone concept. Further, while tools for recognizing priority to a site will be valuable, any mechanism for implementing priority rights should be distinct and not conflated with safety zones themselves.


  1. Foust, J. “Bridenstine ties international cooperation on Artemis to norms of behavior in space”, SpaceNews, May 6, 2020.
  2. NASA. Principles for a Safe, Peaceful, and Prosperous Future
  3. The ISS has a widely reported 200-kilometer “keep-out sphere,” though official references are sparse. See for example, Koons, D.S. and Schreiber, C., 2010. Risk Mitigation Approach to Commercial Resupply to the International Space Station. On the lunar surface, dust mitigation guidelines suggest a 2km radius. See “NASA’s Recommendations to Space-Faring Entities: How to Protect and Preserve the Historic and Scientific Value of U.S. Government Lunar Artifacts,” NASA, July 2011.
  5. Vaughan Lowe, Hague Academy of International Law, The Limits of the Law, Recueil des Cours, Tome 379, 2016.
  7. “Executive Order on Encouraging International Support for the Recovery and Use of Space Resources,” United States Government, April 6, 2020.
  8. Schlager, E., & Ostrom, E. (1992). Property-Rights Regimes and Natural Resources: A Conceptual Analysis. Land Economics, 68(3), 249-262.
  9. “…space resource utilization activities may not be structured around rights in celestial bodies or their resources in place, since Article II of the Treaty prohibits the creation of any such rights.” From “The Next Fifty Years of the Outer Space Treaty,” Brian Egan, Galloway Symposium on Critical Issues in Space Law, December 7, 2016.
  10. Johnson, C. “Space Law Context of the Artemis Accords”, May 19, 2020.
  11. Page 3, Schlager, E., & Ostrom, E. (1992). Property-Rights Regimes and Natural Resources: A Conceptual Analysis. Land Economics, 68(3), 249-262.
  12. Ostrom E. Governing the commons: The evolution of institutions for collective action. Cambridge university press; 1990 Nov 30.
  13. Building Block 14, BUILDING BLOCKS FOR THE DEVELOPMENT OF AN INTERNATIONAL FRAMEWORK ON SPACE RESOURCE ACTIVITIES. November 2019; Moon Dialogs Research Salon #3: Safety Zones in Practice and Lessons from Earth, June 5, 2020; Jessy Kate Schingler and Michelle Hanlon, “The Lunar Registry: An Enhanced Registry of Space Objects and Activities,” forthcoming, IAC 2020.