Don’t Delay Getting Serious About Cislunar Security

cislunar CAPSTONE

Recently, analysts predicted that a rocket stage from a Chinese space mission would crash into the moon. The impact was predicted to happen in March 2022. Did it? The world didn’t know until late June — almost four months later.

More and more space activities are being planned for the moon and the space near it, commonly known as cislunar space. This expansion is being driven by several factors, including the miniaturization of computing technology, decreasing costs of launch and manufacturing, growing maturity of the commercial sector, and renewed geopolitical rivalries motivating the exploitation of space for strategic purposes. But our thinking has not caught up to this changing reality. We lack situational awareness and effective frameworks for reasoning about this domain. We need new tools to help us understand this emerging landscape, lest perceptions become distorted, increasing the risk of conflict.



Another case in point: in the fall of 2021, a different Chinese mission, Chang’e 5, had been in a parking orbit near the sun for almost two years, studying the environment and performing tests after dropping off its primary payload for a lunar sample return mission in 2019. But that September, it slowly began to reposition itself into a new orbit around a Lagrange point near the moon. Lagrange points are special locations in space where the gravitational forces of two nearby bodies balance out, making them valuable for several use cases. The orbits around these points are of interest for upcoming lunar missions, and though their existence has been predicted theoretically, it is only recently that we have begun to test them operationally. The maneuver in question took several months and was not announced publicly. Almost no one noticed it was happening except a small band of amateur trackers using equipment in their backyards.

This event was notable for several reasons. The first is our general lack of situational awareness in cislunar space. Existing space situational awareness assets are designed and operated to watch what’s happening in orbit around the Earth, not the moon. Up until very recently, keeping tabs on cislunar space has not been a pressing need outside of a few national space agencies operating spacecraft there. Second, there is no clarity regarding who, when, and what to notify about activities of objects in cislunar space. Article XI of the Outer Space Treaty provides for best-effort information sharing, but the associated Registration Convention only requires registering the launch of space objects, not notifications of activities in orbit. And while articles VI and IX of the treaty ostensibly provide for ongoing national supervision, and an expectation of due regard with the ability to request consultations, no country has ever proactively undertaken or requested such “consultations” and supervision requirements are not well defined. A recent complaint filed by China regarding the perceived risk from nearby Starlink satellites was the first to reference this obligation directly since the treaty was adopted in 1967. Finally, our limited experience operating in and reasoning about this domain means that we lack the intuition and mental models for interpreting when an action is indeed at risk of such harmful interference in the first place.

The Chang’e 5 maneuver was eventually brought to the public’s attention by amateur space-watchers monitoring the region, not through any official organization or channels. Although it’s possible that it was also seen by classified systems, the fact that it didn’t become well-known until the amateurs raised the issue highlights a gap in public coordination and awareness in this region, as generally called for in the Outer Space Treaty (Article XI). It should also raise questions about how stakeholders will reconcile input from diverse information sources, and how to establish trust regarding shared information.

The expected growth in lunar activity will only exacerbate this issue. The days when a single mission was correlated with a single operator or even a single country are gone: Today, thanks to hosted payloads which allow for a satellite to carry sensors or instruments from organizations that are not the satellite operator, there can be dozens of different operators, nationalities, and interests associated with a single commercial mission. This growing activity, much of it by relatively new, non-governmental actors who often lack familiarity with the intricacies of the outer space legal regime, may lead to unintended provocations. Growing activity also makes it easier to obfuscate payloads or intentions, and can lead to blurred lines between commercial, defense, and civil activities. For example, the recently launched CAPSTONE mission was built by a U.S. company, paid for by NASA, and launched from New Zealand. While its primary mission is to study the orbit being planned for NASA’s Lunar Gateway, the operator Advanced Space also signed a data sharing agreement with the U.S. Air Force. In this environment, a lack of coordination and transparency provides ever-more opportunities to project our greatest fears into the void.

The world has yet to define the norms and coordination mechanisms that will eventually be necessary to address these potential slippery slopes and ensure a secure, sustained presence in this region. The Outer Space Treaty’s Article IV is clear on certain aspects of military activities in space: it prevents the placement of weapons of mass destruction in space and bans military installations on the moon and other celestial bodies. However, the placement of conventional weapons or transit of weapons in orbit was not included in these prohibitions, and the legality of specific activities conducted for national security interests (such as surveillance, or control or patrol of transit corridors in orbit or on the surface) was not directly addressed. The Moon Agreement , negotiated in subsequent years, contained a prohibition on the “threat or use of force or any other hostile act on the moon.” However, only the 19 signatories to the treaty are bound to uphold these commitments, so it can be argued that it has not achieved customary international law status. The Artemis Accords is a set of principles agreed to by partners of NASA’s Artemis program, but it was not designed to address military activities and only restates the commitment to peaceful purposes contained in the Outer Space Treaty. As a partnership agreement between space agencies, it also does not carry the same weight or international obligations as a treaty. Military activities remain something of a lacuna and the extent of their legality have yet to be determined by practice. Postures could end up more aggressive than necessary if we don’t invest in transparency and coordination early on.

In the United States, the Space Force, Air Force, and DARPA are already emphasizing the importance of this new domain. U.S. Space Command has defined its area of responsibility starting at 100 kilometers out to “infinity.” There is a small but vocal contingent in U.S. national security circles arguing that the U.S. Space Force should have some sort of cislunar military presence, if only to protect commercial interests. The Cislunar Highway Patrol System is a concept developed at the Air Force Research Lab which would deploy a spacecraft to cislunar space for space situational awareness. The system is described as “providing critical national defense for the moon and beyond.”

Air Force Research Lab has another project called the Deep Space Defense Sentinel, which is an effort to develop “foundational technologies” for “highly mobile” spacecraft in lunar orbit, including imaging capabilities. The goal is “to demonstrate extreme orbit mobility,” such as the ability to transit from geostationary orbit to different lunar orbits (Lagrange points, lunar orbit) efficiently. It is unclear if the Deep Space Defense Sentinel or Cislunar Highway Patrol System concepts are funded beyond initial research.

A company called Rhea Space is being contracted by the U.S. Air Force to develop a “lunar intelligence dashboard” to track and visualize objects in cislunar space. Recently, DARPA’s NOM4D program made some waves when some suggested they intend to bring a military presence to the moon through prototyping in-space manufacturing capabilities relevant for use there. Additionally, the Defense Innovation Unit has been considering an increased military presence through developing the logistics and capabilities needed to enhance mobility. DARPA is looking into nuclear-powered engines for cislunar monitoring.

China is also increasingly emphasizing the importance of lunar activity in its efforts to become a dominant space power, but is rather opaque about its goals and plans for the moon. As has often been discussed, Beijing does not make a clear distinction between military and civilian space activities, further obfuscating the matter. Experts have also noted that much of China’s discussion of space in defense white papers is limited to vague challenges. This lack of clarity regarding objectives in cislunar space leaves room for further miscommunications and misconceptions by rival states. It may also mean that China has not yet made up its mind and could still be influenced by our actions.

Although budgets are still relatively small, these efforts suggest governments are beginning to think not solely about building up situational awareness — a capability which is needed to improve coordination and spaceflight safety for the increasing number of activities in cislunar space and the moon — but also of how they can defend military and commercial interests.

Against this backdrop, rhetoric is heating up. Cislunar orbital space has already been referred to as “contested” and a “new high ground” that must be “controlled.” Lagrange points have been characterized as “critical choke points” with strategic importance analogous to islands in the South China Sea. Infrastructure, it is suggested, can help to exercise control of cislunar space. This narrative is being matched with small contracts to study ideas such as logistics stations and refueling depots. This discourse also contemplates the possibility that cislunar orbits could be used to station spacecraft that would surprise, approach, and/or surveil critical national assets in geosynchronous orbit without easily being detected. While these statements do not reflect official government policy, they nonetheless carry some weight as they are made by individuals with official positions and are likely to be followed closely by international colleagues.

Distinguishing between rhetoric and reality will require us to deepen our understanding and mental models of this new region. The moon is 10 times the distance of geostationary orbit from Earth, and direct analogies to Earth orbits are surprisingly few. Except for a few so-called ‘frozen’ orbits, most lunar orbits are unstable. There is also no equivalent to geostationary orbit around the moon, because the distance at which it would exist is already under the influence of Earth’s gravitational pull.

Many of the orbits around Lagrange points do have distinct advantages, such as visibility considerations from both Earth and the moon, fuel efficiency for access between Earth and the moon, and overall station keeping. Most significantly, the Lagrange “points” are theoretical ideals; they are not physical “points” in space but rather regions where the gravitational force between two bodies cancel out. Spacecraft do not occupy the points themselves,  nor  do they “hover” there, but rather select from special stable solutions of Lagrange-centered orbit families (so-called “halo,” Lissajous, and Lyapunov orbits are just some examples). These orbits are numerically derived, and most are as-yet experimentally untested. They are for the most part highly elliptical, with spatial orientations that can cross multiple planes, have periods measured in weeks, not hours, and are positioned tens of thousands of kilometers from the moon.

To give a sense of scale, geostationary orbit exists at 36,000km above the Earth’s equator. The L2 Lagrange point of the Earth and the moon is 1.6 times that same distance from the moon. Although both are described as being “at L2,” the Queqiao relay satellite is in a 14-day halo orbit that is 47,000 kilometers from the moon at its closest and 79,000 kilometers at its furthest, whereas the orbit planned for Gateway (and the aforementioned CAPSTONE mission) is a significantly smaller 7-day, 3,000 kilometers by 70,000 kilometers orbit. Putting a single satellite (or even multiple satellites) in these orbits isn’t going to “control” or block anyone from accessing them. But it seems this is not widely understood or accounted for. Conversely, there may be legitimate risks of contention that are poorly understood, and our intuition can be misled by imprecise terminology and selective analogies. Terms like “point” imply a risk of contention that isn’t matched by the physical conditions.

Orbits around the Earth are simple because their characteristics are dominated by a single gravitational source— the Earth. Lagrange points by their nature are influenced by two different sources, for example the sun and the Earth or the Earth and the moon. This means that many of the orbits around Lagrange points don’t lie in a plane the way they do around the Earth, but behave in seemingly unintuitive ways: some have components in three dimensions and even “wobble” around a well-defined point (referred to as “quasi-periodic”) but never actually come back to the same spot. These features can and should inform proper assessments of risks— including frequency interference, hiding, and orbital congestion— but first we have to understand the different characteristics of this new environment.

Just after the Chang’e 5 incident, the upper stage of another Chinese rocket was observed to be on a crash course with the far side of the moon — again by an amateur. At first, it was unclear as to what it was or who was responsible for it. The object was initially identified as a Starlink-related upper stage, then later as a Chinese object. It was eventually determined to be from the (confusingly named) 2014 Chang’e 5-T1 lunar mission, although the Chinese government never did acknowledge this, perhaps because of a sensitivity to being perceived as being an irresponsible actor when it comes to its Earth-bound space debris.

As mentioned in the introduction, this booster was predicted to have crashed into the Moon on March 4, 2022. However, because there were no satellites positioned to observe it at the time, no one knew for sure. The impact was only able to be observed several months later. Although the incident was not a security or flight safety threat, it underscores the point about a lack of situational awareness and tracking for this region. In the absence of information volunteered by an informal community in their spare time, a 4-ton on the lunar surface might have gone unnoticed.

Existing space situational awareness systems developed to monitor objects in Earth orbit came out of the Cold War. They were military in origin, and to this day, this information is still separated into classified and unclassified data sets. With the advent of a strong commercial space situational awareness sector and burgeoning non-U.S. government space situational networks, there are more options for space actors to get actionable data, but information sharing is still complicated by questions of interoperability and IP concerns.

As new systems to govern and monitor cislunar space are developed, there is a chance to reset how we approach topics of domain awareness and to acknowledge the need for openness and transparency. Sharing situational awareness data for the Moon could help to ensure that this increasingly complicated domain will continue to be used in a peaceful manner, allowing information to be freely shared with other operators from the outset. Funding could be pooled, sharing costs and diffusing tensions that might otherwise arise from individual military or national missions. Situational awareness will also be critical to establishing norms regarding notification and coordination as lunar activity increases.

Finally, there is a need to develop new spatial tools and lexicon for discussing and reasoning about activity in cislunar space. Euclidean diagrams and gravity maps do not reflect the emerging human geography of the cislunar region. There is an opportunity for trusted bodies such as the U.S. Geological Survey or international groups such as the International Cartographic Association to invest in developing new cartographic products that accurately reflect both the physical qualities and functional utilities of cislunar orbital space. Such maps could help to underpin shared mental models and cultivate improved intuition about the region. We also need to update our language to counteract the mental model seeded by phrases like “choke points” which use incorrect physical metaphors to militarize cislunar space and presuppose that these environments will become places of contention and conflict.  Public commentators, especially mission operators and government representatives, can replace references to Lagrange “points” with the term “Lagrange region” or “volume” when discussing satellite activity around them. This would help to emphasize the practical uses that need to be contemplated, as opposed to abstract mathematics.

As the use of space evolves and becomes more complicated, we are at a turning point where we can attune our terminology, perceptions, and processes to reflect the new reality and complexity arising from multi-national (and multi-sectoral) efforts in space. While there are security implications of geopolitical rivals extending their activities to the Moon and beyond, it helps no one to replicate military tensions and suspicions from terrestrial politics. By improving language and coordination amongst various space actors, we can ensure that this new use of space is done in a manner that is sustainable and stable for all.



Jessy Kate Schingler is director of strategy at the Open Lunar Foundation, which is focused on positive precedent setting in the lunar domain. 

Victoria Samson is the Washington office director for Secure World Foundation, a non-governmental organization that promotes the long-term sustainable use of outer space. She has nearly 25 years of experience in military space and security issues.

Nivedita Raju is a researcher at Stockholm International Peace Research Institute. She conducts research on space security and gender issues at the Weapons of Mass Destruction Programme.

Image: NASA