Why Beidou Could Help Protect GPS

Since the mid 2000s, China's anti-satellite (ASAT) capabilities have improved markedly. In 2007, China drew international condemnation when it destroyed a defunct weather satellite with a direct-ascent kinetic kill vehicle (KKV), creating a massive cloud of supersonic space debris.¹ Since 2010, the People's Liberation Army (PLA) has conducted several tests in which co-orbital satellites approached one another and even made contact.² China again tested missile technology capable of destroying satellites in 2010, 2013, 2014, and 2015.³ Such tests demonstrate China's ability to hold the US-controlled Global Positioning System (GPS, America's satellite navigation system) is at risk.⁴

Authoritative PLA texts such as Study of Space Strategy and The Science of Military Strategy assert that whichever side can control space will control the earth, and recommend that China launch early strikes on enemy military satellites.⁵ These texts call for the PLA to seek "space superiority," or the ability to make full use of space while restricting its adversaries' use of space.⁶ This requires both attack and defense, though PLA military sources on space tend to focus on offense and assert that without its satellites, the US military would cease to function.⁷ Naturally, such rhetoric and capabilities have the US worried. These worries are exacerbated by the fact that satellites are very difficult to defend from determined attack once an adversary has the capability to reach them.⁸ Recent disruption of GPS receivers and Chinese ASAT tests in high orbits suggest that GPS satellites could well be on China's target list.⁹

GPS is a global navigational satellite system (GNSS) comprising twenty-four satellites, positioned such that there are at least three of them visible from any point on earth at any given time.¹⁰ These satellites emit a signal that contains their location and the time at which the signal was transmitted. Receivers can use the difference between time of transmission to time of reception to identify distance and triangulate current position by finding the distance to and position of three satellites. Other GNSS constellations, including Russia's GLONASS (achieved global 24/7 coverage in 2018), the EU's Galileo, and China's Beidou (both slated to achieve global 24/7 coverage in 2020) operate on the same principles. Each emits two signals, one lower accuracy, public civilian signal and one encrypted, higher-accuracy military signal.¹¹ These systems help guide smart munitions, coordinate military operations, and orient soldiers. Any sudden loss of access to these signals can seriously impair military operations.¹²

Given the difficulties of defending satellites against a determined ASAT attack, the best way to protect GPS is probably to deter such attacks in the first place.¹³ At its heart, deterrence is about manipulating an opponent's cost-benefit analysis in such a way that they come to believe that the costs of taking action outweigh the benefits.¹⁴ One way to achieve this is through denial—that is, building defenses that make it likely that an opponent's attack would fail to achieve the benefit sought.¹⁵ Another is to increase the cost of such action, usually through threats of retaliation.¹⁶ To improve deterrence, the US should thus make it less likely for attacks against GPS to succeed, and increase the costs of those attacks.

Regarding ASAT attacks, two of the primary costs any would-be aggressor would face are the diplomatic/political costs of destroying and threatening fragile space architecture on which many nations depend economically, and the military/strategic costs incurred as states launch retaliatory attacks on the aggressor's own space assets.¹⁷ Fortunately, not only does the construction of Beidou and Galileo make global GNSS architecture much more difficult to critically damage, but it also significantly increases both the political and the military costs of attacking GPS or other GNSS constellations.

Deterrence by Denial

Making systems more robust and convincing adversaries that attacks on them will fail to bring any benefit is one way to deter attacks.¹⁸ While the proliferation of GNSS systems does not make strikes against GNSS satellites impossible, it does...