FOR THE next decade, a growing area of Sino-American competition will center on the establishment of permanent scientific and water mining sites on the polar regions of the Moon. Current data suggest that very large deposits of water can be found in those polar craters, whose floors have not been exposed to the sun for billions of years. Not unlike the Wild West in the United States during the nineteenth century, there could be a mad rush to stake out various water rights. The USSF could play the role of the 7th Cavalry in protecting those water rights. As noted above, the stage could be set for direct conflict between the United States with its Artemis Accord allies and a Sino-Russian alliance that make competing claims—with dubious legal precedence. Very quickly, various research and mining stations might have a military garrison occupied mostly with combat robots and defensive weapons.

What might combat on and around the Moon look like? What might be the forces deployed without constraint by the late 2030s? Several features of the lunar surface as a battlefield should be emphasized. First is the fact that the lunar gravity well is one-sixth of Earth’s, meaning that a discharged munition needs to reach only just over three and half thousand miles an hour to reach lunar orbital velocity. A mortar with a rocket-propelled shell could reach hundreds of kilometers downrange. These physics mean that combat as we know it must be rethought. Human and robot soldiers are likely to be equipped with zero recoil weapons, which may or may not include directed energy weapons such as high-power microwaves and lasers.

Precision-guided weapons will need reaction jets, since the lunar surface is without a meaningful atmosphere. Most ordinance may come in two forms. First are munitions that generate clouds of fragments, not unlike the late nineteenth-century Shrapnel artillery shells. Second are lunar-penetrating warheads designed to destroy lunar fortifications and/or underground sites. Another weapon concept much discussed by science fiction more than fifty years ago is the electromagnetic mass accelerator. It is possible that a commercial variant may be built to provide lunar building materials to one or more very large space stations under construction during the 2030s—the current dream of Jeff Bezos and others. On the other hand, a very large mass driver will be extremely vulnerable to destruction by a number of tactical weapons described.

Survival for human combat troops will be daunting, with or without actual combat. They will need vehicles that can operate during the roughly two-week periods of daylight and nighttime. During nighttime, the lunar soldiers and their fighting machines will have to have sufficient power reserves to operate without solar power. Actual combat may be quite brief, given the fragility of human soldiers and human infrastructure on the Moon. One side may win or lose very quickly. Naturally, the war might be continued by the losing side through the use of munitions launched from cislunar space or the Earth.

Given the fragility and overhead costs of human combat troops, it is highly likely that the major military players will rely heavily on robotic combat systems. These will range from swarming munitions launched from mortar launchers to large, centaur-type combat robots. The latter may use a combination of legs and wheels for surface locomotion. Many of these combat systems may have rocket propulsion to allow for short and long-distance hopping maneuvers. The concept of hopping vehicles will likely be fully developed to support diverse exploration activities during the first decade of the human return to the Moon. For example, the SpaceX HLS will have this capacity to conduct suborbital hops around the Moon.

What about combat in cislunar space? The battlefield will be enormous. Given the performance limits of current chemical and electric propulsion technology, engagements between hostile fighting vehicles might take days or weeks. Directed-energy weapons might be useful to provide close-in offense and defense options. Yet it is likely that all potential combatants will employ munitions that can create a high-velocity cloud of fragments. These munitions could be accelerated by rocket or electromagnetic propulsion. Once detonated, the cloud will overwhelm any plausible close-in defense weapon. As noted above, these spacecraft might be equipped with munitions to strike the lunar surface if only as part of an assured retaliation capability to deal with any military imbalance on the surface of the Moon. Not to be forgotten, one or more nations involved in this military competition might be prepared to launch nuclear weapons from the Earth as the ultimate assured retaliation capability.

To develop and deploy the types of combat capabilities described above will consume very large resources that could be more usefully put toward the more noble goal of establishing a productive long-term presence on the Moon—not to mention possibly on Mars and various asteroids with commercial mining potential. Given the mutual vulnerabilities and accessibility of multiple means to disrupt or destroy satellites and other space infrastructure, war in space is very likely to be very expensive and indecisive. The notion of space dominance falsely compared to the concepts of naval and air dominance is likely to prove a mirage.

OF ALL the unresolved questions about space activities, the most urgent need—and most promising for new cooperation—is removing or mitigating the threat from space debris. Nations cooperate, pooling risks and burdens when they perceive their interests intersect. The threat of space debris to all nations’ vital economic and national security assets in space—democracy-autocracy polarization notwithstanding—would, like climate change, seem such an instance.

The U.S. Department of Defense’s Space Surveillance Network is the premier mechanism for monitoring space junk. Russia has some orbital monitoring capacity, but few other states do. Moreover, in addition to its unrivaled space surveillance capacity to monitor debris, the United States already has Spacing Sharing Agreements with over 100 nations to provide data and notifications to avoid collisions. These are important global public goods that can provide diplomatic leverage for shaping space rules and standards on space debris. The United States had given a heads-up to China about such risks during the Obama administration, according to well-placed sources. 

In addition, private sector firms and startups in Japan, the United States, and Europe are devising ways to remove space debris, in what appears to be a coming sector of the space economy. The U.S. Space Force’s technology arm is already exploring the possibility of funding private firms to remove space debris. There are a range of methods of space junk removal being developed from satellite magnets, nets, harpoons, and even spider-like webs. These are all likely future contractors, bearing the risks of research and development.

All this points to possibilities for new collaboration on space junk, great power competition notwithstanding. No need for formal UN bureaucracies to begin. There are only a handful of high-performance space-faring states—the United States, Russia, China, the EU, Japan, and India. As discussed above, the United States is well-positioned as first among equals to launch an ad hoc public-private coalition of space powers—the Space Sextet, if you would—partnering with the private sector to pool resources and (non-national security-sensitive) capabilities to better monitor and clean up space debris and seek mutually acceptable codes of conduct and rules for such activities. It would be helpful if the five Permanent Members of the UN Security Council could give it a mandate with a UN Security Council resolution, or perhaps a G7 call to action. It should be an open architecture based on the principle of form follows function: open to emerging space powers—South Korea, Brazil, Israel, and others.

OVER THE coming decade, multifarious activities and presence in cislunar space and on the Moon will unfold. If left untended, the probability of conflicts over competing Moon presences, space mining, and military activities is significant, if not inevitable. Given the magnitude of the space debris problem—existential for all activities in space—a space debris-focused coalition would seem a strong opening gambit to begin to address the space governance deficit, and perhaps alter the tone and political climate, before space activities overwhelm the capacity to manage them. 

Creating an international consensus between great power rivals to redress the challenge of space debris may be the relatively easy part in any international agreements on the future conduct of space activities. The more daunting challenge is to try to build a framework for the exploration (and exploitation) of the Moon and the larger sphere of interest, cislunar space. A priority is to negotiate an agreement analogous to the Law of the Sea that defines property rights on the Moon, though such would likely be a protracted undertaking—the Law of the Sea negotiations began in 1973 and ended in 1982.

Negotiations between the alliance associated with the Artemis Accords and the likely coalition of states led by China are likely to be demanding and difficult. Yet the prospect of the lunar version of range wars over valuable real estate should give the international community pause. Unregulated resource exploitation on the Moon will likely lead to the competitive deployments of military forces on its surface and in the expanse of cislunar space. To avoid a full-blown military competition, it will be necessary to develop a number of confidence-building if not arms control measures. One possibility is to internationalize the demanding requirements for situation awareness in cislunar space. This might include the creation of one of more command centers or intelligence cooperative clearing-houses on the Earth and Moon that has access to a multinational fleet of surveillance spacecraft.