Space is becoming more congested, contested and competitive. Since the Soviet Union put the first satellite, Sputnik I, into space in 1957, no nation has deliberately destroyed another's satellite in orbit. But there is a growing possibility that battles may soon be waged in space.

Although the militarization of space started long ago, a number of technological developments and tests over the past decade show that the race toward its weaponization is accelerating. Driven by Washington's dominance of and strategic dependence on space, U.S. rivals are working to develop and deploy anti-satellite weapons (widely known as ASATs). The technology, which began to be developed during the Cold War, has become an area of intense competition for the world's most capable militaries over the past decade.

For the United States, being the leader in military space technologies provides immense advantages. At the same time, its outsized reliance on those technologies entails risks. The current unequal dependence on space, the United States fears, could give adversaries incentive to attack its infrastructure in orbit. Washington is therefore pushing to bolster its capabilities and is preparing for the possibility that a future conflict could escalate into space. As the militarized space race continues, the United States will stay focused on deterrence. A war in space would be devastating to all, and preventing it, rather than finding ways to fight it, will likely remain the goal.

An Unequal Dependence:

Washington's dependence on space infrastructure reflects the United States' dominance in space. The tyranny of time and distance inherently hinders the United States' ability to deploy its military across the globe. But the space domain effectively helps the country to overcome the limitations, allowing for enhanced force projection. As a result, the U.S. military relies heavily on its orbital assets for navigation, intelligence collection, precision targeting, communication, early warning and several other crucial activities.

The great advantages that space assets afford the United States have not gone unnoticed by its potential rivals. Though China and Russia, for instance, also rely on space, they are less dependent on their space assets than the United States is. First, neither nation has as much in orbit. In addition, because both put greater focus on their immediate geographic regions, they can use more conventional tools to achieve their objectives. For instance, Beijing, by virtue of geographic proximity, could rely on its ground-based radars and sensors in a conflict in the Taiwan Strait. The United States, on the other hand, would have to lean on its satellites to support a response in the same area.

Despite the United States' superior ability to strike at enemy space constellations — groups of similar kinds of satellites — competitors may determine that the resulting loss of space access would be worthwhile if they could severely degrade U.S. space access. And while the United States is the most proficient nation in space-based warfare, there are limits to its abilities. Satellites in orbit follow predictable movements, have restricted maneuverability and are difficult to defend from an attack.

There is little doubt that a full kinetic strike on U.S. satellites, which would inflict physical damage, would invite a devastating response. But tactics designed to degrade the satellites' abilities, rather than to destroy their hardware, could be deemed less escalatory and therefore perhaps worth the risk. These include jamming signals, hacking operational software and dazzling (temporarily blinding) or permanently disabling sensors. Calculating the risk of nonkinetic strikes, which would create little physical damage and could even be reversed, a potential foe would take into account the United States' hesitance to escalate a conflict in space, given its heavy dependence on orbital technology.

Reinforcing Deterrence:

If the United States wants to preserve its primacy in the face of increasing threats to its strength in space, Washington will need to invest in strategies to deter attacks on its orbital assets. The first step in strengthening space deterrence is to ensure proper attribution: The United States cannot hold its enemies accountable for attacks if it does not know who initiated them. But the vastness of space, along with the difficulty of obtaining physical evidence from attacked satellites, can make responsibility hard to prove.

To that end, the United States is investing in a second-generation surveillance system, known as Space Fence, to track satellites and orbital debris. Slated to begin operating in 2018, Space Fence uses ground-based radars that give it 10 times the detection capability of its predecessor, the Air Force Space Surveillance System. In addition, the United States has been working with a classified satellite defense technology called the Self-Awareness Space Situational Awareness system, which reportedly will be able to pinpoint the source of a laser fired at a satellite.

Redundancy and shielding can also deter limited attacks against satellites. The innate redundancy of large satellite constellations could make attacking them too risky; such an assault would fail to significantly impair U.S. space control while still inviting retaliation. Meanwhile, more widespread use of resistant antenna designs, filters, surge arresters and fiber-optic components, which are less vulnerable to attack, is already being explored to further shield satellites from jamming, dazzling and blinding.

Finally, the United States can work alongside its global partners and allies to convey the idea that a full-blown battle that would destroy orbiting satellites would be bad for all of humanity. Reinforcing this message and openly tying it to a powerful U.S. response could further bolster deterrence.

Preventing a War in Space:

While the United States works to discourage hostilities in space, in no small part to ensure its enduring advantage there, Washington is also taking more steps to plan for the contingency of a war in space. The Department of Defense has nominated the secretary of the U.S. Air Force as the initiative's principal adviser, tasked with coordinating space-related efforts across the military. Late last year, the United States also established the Joint Interagency Combined Space Operations Center at Colorado's Schriever Air Force Base. The center facilitates information sharing across the national security space enterprise and has already run a number of wargame scenarios to simulate conflict in orbit.

Furthermore, the Pentagon has added $5 billion to its space programs budget in 2016, pushing the total to about $27 billion. The budget provides for spending on technologies and tactics that can help the United States mitigate and recover from a space attack. One effort, spearheaded by the Operationally Responsive Space Office, aims to develop small satellites and associated launch systems that can be built and deployed quickly and cheaply. (For the most part, the current U.S. fleet consists of large, sophisticated and expensive satellites, some of which cost billions of dollars and take years to construct.)

As part of this endeavor, the office has directed the development of a standardized but modular satellite chassis that allows for multiple payload variations. The result is increased flexibility, as well as lower costs and quicker turnaround in production. Developing a less expensive and more efficient way to launch replacements for destroyed or disabled systems is the next step. With that in mind, the Operationally Responsive Space Office is funding the development of the Spaceborne Payload Assist Rocket-Kauai (SPARK) launch system, designed to send miniaturized satellites into low-Earth and sun-synchronous orbits. In its efforts to rapidly launch swarms of miniaturized satellites on the cheap, the U.S. military is also looking to leverage the private sector. Companies such as Virgin Galactic (with the LauncherOne) and the Rocket Lab (with the Electron Vehicle) have expressed keen interest in the initiative.

The small satellite revolution promises the speedy replacement of disabled satellites in the event of attack — theoretically securing the U.S. military's use of space constellations in support of operations during a conflict. Small satellites are not a magic bullet, however; key satellite functions will still depend on bulkier and more complex systems, such as the large but critically important nuclear-hardened command-and-control mission satellites. Many of these systems involve hefty antennas and considerable power sources.

Given that access to orbit may not be guaranteed during a war in space, the United States has also been exploring alternative ways to perform some of the core functions that satellites now provide. At this stage, high-flying unmanned aerial vehicles with satellite-like payloads offer the most advanced alternative. But considering the vehicles' vulnerability to sophisticated air defenses, their lower altitude and endurance relative to orbital satellites, and their limited global reach, this remains a tentative solution at best.

Overall, the United States is getting far more serious about the threat of space warfare. Investment in new technologies is increasing, and the organizational architecture to deal with such a contingency is being put in place. In the race between shield and sword, however, there is no guarantee that offensive ASAT capabilities will not have the advantage, potentially denying critical access to space during a catastrophic celestial war.

The High Cost of a War in Space:

Increased competition in space is reviving fears of a war there, one with devastating consequences. Humanity depends on space systems for communication, exploration, navigation and a host of other functions integral to modern life. Moreover, future breakthroughs may await in space, including solar energy improvements, nuclear waste disposal and extraterrestrial mining.