Robust satellite communications are key to achieving decision superiority for U.S. forces, but the U.S. military’s SATCOM enterprise has not kept pace with the capabilities China, Russia, and others are developing to degrade or disable U.S. communications in space. Further, U.S. SATCOM were not designed to support the speed, scale, and complexity needed for military operations in the information age.
Consolidating military SATCOM capabilities under a single military service—the new U.S. Space Force—presents a once-in-a-generation opportunity to rethink the enterprise and chart a new path to achieve the assured connectivity necessary to defeat peer powers. DOD’s future SATCOM enterprise must enable command and control as well as information sharing around the globe, and must leverage both mature and emerging space technologies, such as laser communications and constellations of small satellites, to overcome today’s dependence on resource-intensive, limited range, and increasingly vulnerable line-of-sight radio communications.
Small constellations of large satellites make U.S. communications links vulnerable to enemy attack.
Since first proven in combat during Operation Desert Storm in 1991, DOD’s satellite communication networks have only grown in importance over the past 30 years. Yet because those capabilities developed largely in the absence of credible threats, the military came to take for granted the expectation of instant, always available SATCOM links. Because DOD added incrementally to its networks, generally procuring improved versions of the same kinds of systems acquired in the past, the Pentagon failed to keep pace with strategic competitors, who increasingly exploited more cutting-edge technologies. Today, U.S. satellite capacity and capability are largely indefensible and there are too few satellites to provide resilience in case of attack.
Most U.S. military communications satellites are in geostationary orbits high above the Earth’s equator. This ensures continuous coverage over most of the planet, an extremely efficient and flexible approach that can enable three evenly distributed satellites to provide continuous worldwide communications coverage over almost the entire Earth, excluding only polar regions and areas obscured by mountains, canyons, or other terrain features. Because geostationary satellites appear to be in fixed overhead locations, maintaining their orbits is simplified, precluding the need for complex and expensive satellite tracking equipment. On the downside, however, geostationary satellite signals are comparatively slow, imposing significant latency as signals traverse tens of thousands of kilometers from Earth to the satellites and then back down to Earth. This latency is incompatible, however, with modern applications that must operate at machine speeds.
Over time, as the size, capability, and complexity of DOD’s communications satellites grew, so did cost and acquisition cycles. Predictably, greater cost meant fewer satellites, which in turn drove evermore aggressive requirements. Today, acquisition cycles stretch out over a decade or more, leading to obsolescence in the midst of production, which often means costly retrofits. “All these dynamics tend to reinforce one another,” creating what a former vice commander of Air Force Space Command called the “vicious cycle of space acquisition.” With just 36 core military communications satellites today, the loss of even just a few platforms could lead to critical failure of the system.
Given that today multiple countries have proven anti-satellite capabilities, the U.S. is at serious risk in the event of conflict.
Military planners are wary of concentrating too much critical capability into too few platforms, concerned about reduced wartime effectiveness. But DOD developed its space networks during the Cold War at a time when the risk of counterspace attacks seemed minimal. More recently, as China, India, and Russia demonstrated anti-satellite capabilities, the U.S. was engaged with less capable adversaries, perpetuating the notion that space is benign.
At the same time, U.S. SATCOM systems evolved as a byproduct of technological advances and to meet specific user needs rather than in response to a unified enterprise strategy. With numerous authorities spread across the combatant commands, the military services, DOD agencies and multiple acquisition organizations, little consideration was given to enterprise-level requirements. Proprietary vendor equities and overclassification only make matters more difficult.
The Need for a New Approach
With China and Russia undertaking massive buildups of their respective militaries, the United States cannot expect to regain competitive advantage simply through like-for-like replacements of legacy communications systems. Instead, DOD must develop new capabilities and force designs capable of supporting highly dispersed, all-domain operations in every theater. Rapid and seamless data-sharing will enable faster decisions and better integrate the actions of all available forces. The U.S. strategy seeks both physical and psychological advantages by enabling friendly forces to operate inside its adversaries’ decision cycles, where it can impose multiple, simultaneous dilemmas to confound and even paralyze the enemy’s ability to respond. To achieve this, DOD must ensure its communications systems can operate under attack, negating adversaries’ efforts to degrade or negate them. DOD’s existing SATCOM systems are not up to this challenge and must be replaced with new command, control, and communications systems that can provide both the speed and resiliency needed to support operations in the information age.
DOD’s Joint All-Domain Command and Control (JADC2) strategy aims to achieve that operational advantage by leveraging artificial intelligence and cloud computing to accelerate data-sharing and analysis across every domain in near-real time. Space-based communications will be the backbone of that initiative, theoretically enabling any sensor—air, land, sea, undersea, in space, or cyberspace—to instantly connect to the shooters best equipped for any given target at any given location.
Terrestrial communications links can pass targeting data over short line-of-sight distances, only satellites can efficiently cover the range envisioned by DOD’s emerging warfighting concepts. At the same time, DOD needs more bandwidth, less latency, and interoperability that today’s SATCOM enterprise cannot support.
- Bandwidth poses a persistent challenge. New weapon systems are reliant on external sources of information to complete their missions. New applications that use high-definition imagery and video, support remote piloting of unmanned systems, or employ artificial intelligence also require greater bandwidth to operate smoothly.
- Latency poses an issue for many systems. While latency times of one or two seconds may not be a problem for short text messages, for example, it’s not an option for applications and decisions requiring precise timing, such as targeting using real-time video, or trying to intercept an incoming missile. The only way to reduce SATCOM latency is to reduce the physical distance data needs to travel by leveraging satellite orbits satellites closer to Earth.
- Interoperability is critical to enable disparate systems to interact. Improving joint, interagency, and coalition data-sharing is a longstanding issue. Unlike cell phones, which seamlessly switch from one cell tower or network to another, SATCOM systems are purpose-built, proprietary systems; they don’t allow users to roam freely from one network to another.
Meanwhile, both China and Russia seek to hold U.S. satellites at risk. The two believe U.S. dependence on vulnerable space systems can be exploited, and they have developed military doctrine, organizations, and capabilities with that in mind. Both prioritize information superiority as their main line of effort in future conflicts, believing that will provide a decisive warfighting advantage. China’s and Russia’s counterspace weapons now include direct-ascent missiles, co-orbital weapons, ground-based lasers, high power microwaves, cyber tools to compromise information networks, and electronic warfare capabilities to jam or otherwise interfere with satellite communications. These weapons are supported by robust networks of space surveillance capabilities that can locate, characterize, track, and otherwise facilitate counterspace targeting.
A New SATCOM Strategy
The standup of the U.S. Space Force presents a unique opportunity to chart a new path forward for DOD’s SATCOM enterprise. The future architecture must have greater bandwidth, higher speeds, improved interoperability, and the ability to counter and survive emerging threats. To build it, DOD must leverage advancements in space technologies that to date have been driven largely by the commercial sector: smallsats, optical communications, and their associated manufacturing, assembly, and testing.
Proliferating smallsats in low- and medium-Earth orbit (LEO and MEO) will reduce latency by reducing the distance data must travel. It will also improve capacity and resiliency against some forms of counterspace attacks. Satellite miniaturization and reduced launch costs, also driven by the commercial sector, have significantly improved the cost-effectiveness of LEO and MEO constellations. DOD’s efforts in this arena are led by the Defense Advanced Research Projects Agency (DARPA), through its Blackjack program, and the Space Development Agency (SDA), which is developing a “Transport Layer” to serve as the communications backbone for its National Defense Space Architecture.
One of the most promising aspects of satellites in LEO is reduced latency. Compared to the latency for returning signals from satellites in GEO, which is around 600 milliseconds, LEO SATCOM services could have latencies as little as 50 milliseconds or less. That allows data to travel from sensors to “shooters” in real-time. In fact, at longer distances an LEO SATCOM constellation could offer lower latency than even the fastest currently available terrestrial networks. For a hypersonic missile traveling at Mach 5—covering a kilometer in 600 milliseconds—that can be the difference between a successful intercept and a mission failure.
Instead of just a few satellites, as in GEO, a LEO satellite constellation would have to number in the tens or even hundreds to provide continuous coverage of a given geographic area. Where once this made LEO constellations seem infeasible and not cost effective, today the cost of building and launching smallsats is such that LEO satellites now can be economically deployed to provide global coverage. Using a combination of orbital inclinations, proliferated LEO constellations will offer better global coverage for the U.S. military than GEO, which lacks coverage in some critical areas, including the Arctic.
The larger numbers of LEO satellites makes the network more resilient and provides greater overall bandwidth. Even though large GEO satellites have greater bandwidth on a per-satellite basis, the large number of small satellites within a LEO constellation generally has more capacity. Finally, the proximity of LEO satellites to Earth means it takes less power to transmit a signal to Earth. This means smaller antennas and power amplifiers, easing integration.
LEO constellations that consist of large numbers of highly dispersed smaller satellites will make it more difficult for an enemy to degrade their operations. Where the loss of a few monolithic satellites in GEO orbit would result in a catastrophic failure of the entire system, a proliferated LEO constellation could withstand the loss of a relatively large number of satellites. Plus, satellites in LEO can be reconstituted more rapidly and far less expensively than larger satellites.
The linchpin to realizing the full potential of future SATCOM constellations is optical communications. Satellites today use radiofrequency (RF) communications to transmit and receive data. Inherent performance limitations are often a bottleneck and RF communications can be disrupted and denied by means of jamming electromagnetic signals.
Optical communications, by contrast, can modulate data onto a low-power laser beam that transmits its signal through free space to a receiver. Using lasers operating in much shorter wavelengths, data transfer rates are at least an order of magnitude greater compared to RF communications, and require lower power levels. Using highly directional, narrow laser beams minimizes the potential for interference from adjacent satellites and enhances the security of transmissions by reducing the area within which signals can be detected and intercepted. Even if detected and located, optical communications are incredibly difficult to disrupt, improving resiliency. Together, LEO satellite constellations and laser technologies form the basis for far more secure, resilient, and high-bandwidth communication networks.
A good initial application for optical communications is for satellite crosslinks—known as optical intersatellite links (OISLs)—to enable satellites to pass data directly between each other instead of routing their signals through a ground station. In the vacuum of space, these links could exceed rates of 10 gigabits per second—enough to transmit an entire high-definition movie in about three seconds. Data in such a network would travel from satellite to satellite until it reaches one within line-of-sight of the intended user, making it possible to deliver collected sensor data to warfighters in near-real time without ever touching terrestrial networks in non-secure locations.
Equipping each satellite with several OISLs will allow them to communicate with multiple adjacent satellites simultaneously, forming redundant satellite “mesh” networks. Mesh networks with an autonomous mission management system onboard each satellite is the basis for a “self-healing” network that can reroute traffic in the most efficient way possible if a node suffers either a temporary or permanent failure. If compatible, OISLs could connect disparate satellite constellations, potentially allowing other military and commercial intelligence and SATCOM providers to plug directly into the network.
Satellites equipped with optical communications could also connect with aircraft and other terrestrial systems, providing a high bandwidth, covert communication link that is incredibly difficult to jam. In practical terms, this would support far more information-sharing at faster speeds than is otherwise possible.
Improved terrestrial infrastructure
Realizing advances in orbit will require corresponding investments in terrestrial infrastructure, beginning with more widely deploying phased-array antennas for ground control stations and user terminals that can simultaneously track and contact multiple satellites across different frequencies and orbits. Because non-GEO constellations include scores of satellites rapidly moving across each receiver’s field of view, these systems require sophisticated tracking to manage up to dozens of satellite beam handovers per hour. Traditional parabolic-dish antennas are poorly suited for this task because they require mechanical steering mechanisms and only communicate with one satellite at a time. Likewise, the single contact parabolic antennas used in most ground stations have limited capacity to transmit and receive telemetry, tracking, and control (TT&C) data.
Instead, DOD should field flexible terminals that can roam between different satellite networks operating in different orbits and frequency bands. Flexibility at the terminal should be combined with enterprise management and control to autonomously determine why, when, and how communications move on one or another network. This would enable changing based on mission needs, threats, and operational status. The first step to this dynamic ground architecture is replacing existing analog Intermediate Frequency (IF) interfaces with an open, interoperable Digital standard that essentially turns the flow of data into an Internet Protocol (IP) network. This would follow best practices for network design.
The ability to securely command, control, and communicate with highly distributed forces in the Indo-Pacific and other theaters is critical to successful combat operations. For America’s military to achieve the necessary information and decision advantage, the Department of Defense should take the following steps:
- DOD should distribute, disaggregate, diversify, and expand its SATCOM options by deploying constellations of LEO and MEO communication satellites to augment existing systems that primarily reside in GEO orbits. Proliferating satellites in multiple orbits will increase communications capacity and coverage, reduce latency, improve resilience against attacks, and create more options to meet mission-specific requirements.
- DOD should aggressively develop and deploy optical inter-satellite links to connect its satellites while also selectively integrating optical communications terminals for terrestrial systems and users. Laser communications are key to forming space mesh networks that provide diversified connectivity paths to route information to, from, and through space at the speed, scale, and level of security needed for all-domain operations and to counter adversaries that threaten DOD’s communications networks.
- DOD should develop a terrestrial segment that allows it to fully realize the advantages of these new satellite networks and laser communications. This infrastructure will require phased array antennas capable of handling the rapid and continuous satellite beam handovers inherent to the operation of LEO and MEO constellations as well as terminals that can roam across different networks spanning multiple orbital regimes and operating over different frequency bands, waveforms, and security levels.
Collectively, these initiatives would establish a new U.S. SATCOM backbone that ties together all of DOD’s networks and supports service-led JADC2 initiatives that enable all-domain operations. Updated SATCOM architectures enabled and boosted by laser communication will form the connective tissue that empowers U.S. global distributed operations in real-time.
Maj. Gen. Lawrence A. Stutzriem, USAF (Ret.), is the Director of Research for the Mitchell Institute for Aerospace Studies.