Space Force Plans To Place New Early Warning Satellites Into Non-Traditional Orbits Closer To Earth

The Space and Missile Systems Center is looking to Medium Earth Orbit for a new layer of missile detection satellites planned for 2022.

byBrett Tingley|
Orbital Systems photo


U.S. Space Force is considering tests of Next-Generation Overhead Persistent Infrared System early-warning satellites in Medium Earth Orbit, or MEO, as early as 2022. Placing the satellites in these non-traditional orbits would allow them to observe potential missile launch sites for longer periods of time than would be possible from Low Earth Orbit, or LEO. In addition, placing early warning and other missile defense satellites in MEO could ensure the service's ability to detect and track threats with a smaller number of satellites than would be needed if a constellation was placed in LEO. At the same time, they could provide much-needed increased flexibility and fidelity over their forbearers that remain in geostationary orbit. 

Breaking Defense

was first to report that officials at the Space and Missile Systems Center (SMC) had stated they could start building “real flight hardware” for MEO missile defense missions after contractors deliver digital models of prototype satellites in November 2022. Medium Earth Orbits (MEO) fall between traditional Low Earth Orbits (LEO) and Geostationary Orbits (GEO), in the range of around 3,100 miles to 12,400 miles. The focus on MEO shows Space Force’s growing commitment to utilizing a wider range of orbits for space-based missions, a goal Space Force Lieutenant General John Thompson, head of SMC, emphasized last year when he said that “all orbital regimes are on the table” when it comes to the Next Generation Overhead Persistent Infrared System, or Next-Gen OPIR.

Concept art from Raytheon, Raytheon via YouTube

“The ability to combat future threats that span from cruise and ballistic to fast-flying hypersonics requires a diverse, resilient missile warning/track custody architecture,” Paul Meyer, vice president of Space & C2 Systems for Raytheon Intelligence & Space, also said in a press release announcing Raytheon's prototype agreement with Space Force. “And operating in Medium Earth Orbit is a critical layer in that architecture.”

As part of this effort to develop a missile tracking layer in MEO, SMC awarded contracts in May 2021 to Raytheon and Millennium Space Systems for digital models of Missile Track Custody Prototype (MTCP) designs. These models will be used to test Next-Gen OPIR sensor designs in a digital environment before any real satellites are built.

Next-Gen OPIR sensors are designed to detect the bright infrared plumes generated by missile launches and pinpoint their locations, passing that data on to other satellites and ground-based sensors for continuous tracking. SMC will be reviewing those designs to determine which, if any, could satisfy the requirements for an MEO Missile Track Custody Prototype. Space Force Colonel Brian Denaro, Division Chief for the Strategic Systems Division at SMC’s Space Development Corps, said that the center could, at that point, “theoretically pivot to building real flight hardware, because we’ll have the maturity of that design that we’re confident … can be launched into orbit.”

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Space Force Colonel Timothy Sejba, SMC’s program executive officer for space development, said in May that these digital prototypes are “a key component of SMC’s Digital Engineering strategy, enabling the government to incorporate and connect multiple contractor models in an automated digital environment.” Using digital prototypes offers SMC what Sejba calls a “digital ‘try it before you buy it’ approach” allowing Space Force to estimate costs, schedule, and performance variables with precise computer modeling.

The Department of the Air Force designated its first block of Next-Gen OPIR satellites as a “Go Fast” acquisition program in 2018. As part of that program, Lockheed Martin was awarded $2.9 billion to develop three of these satellites intended for GEO, while Northrop Grumman is building an additional two intended for polar orbits. SMC plans to launch the first of the GEO satellites in 2025 or 2026, and to have the entire constellation in orbit by 2029.

Documentation from Space Force's FY 2022 budget requests show the service requested $2.45 billion for the Next-Gen OPIR program next fiscal year:


The mainstays of the United States’ existing space-based early-warning capabilities are relatively small number of large GEO satellites known as the Space-Based Infrared System (SBIRS), which you can read about in more detail here. SBIRS sensors are sensitive enough to detect events ranging from ballistic missile launches, to even artillery fire or aircraft exploding in the sky. In addition, the Air Force has operated Defense Support Program (DSP) infrared early-warning satellites. which orbit the Earth 22,000 miles away in GEO. 

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Still, there are some emerging threats, such as highly maneuverable hypersonic boost-glide vehicles, which these existing GEO satellites are not designed to detect and track. "Hypersonic targets are 10 to 20 times dimmer than what the U.S. normally tracks by satellites in geostationary orbit," former Under Secretary of Defense for Research and Engineering Mike Griffin had stated in the past, according to the Congressional Research Service.

Thus, aside from the existing GEO SBIRS satellites, the Space Development Agency (SDA) awarded close to $350 million in 2020 to develop an LEO Tracking Layer that consists of constellations of small satellites capable of wide field of view (WFOV) OPIR detection. These LEO satellites could be used to provide fire control tracking data for interceptors launched to neutralize hypersonic glide vehicles, a planned capability you can read more about here

Each satellite in LEO passes overhead very quickly, however, meaning a large number of satellites are needed for wide-area coverage. Maintaining these large, distributed constellations during a time of war could require rapid space launch capabilities, which Space Force has been developing at a break-neck pace

An illustration of the planned National Defense Space Architecture featuring satellites and assets in a range of orbits., DOD

Space Force’s recent focus on missions in non-traditional orbits, including some at the farthest reaches of orbital space, underscores the increasingly vital role that space assets will play in a wide range of operations moving forward. The many different layers of space-based sensors and satellites continue to be a critical enabler of America’s missile defenses. 

Existing early warning satellite systems are primarily designed to remain stationary to stare at large swathes of the globe for infrared plumes generated by ballistic missile launches, but even these satellites have difficulty tracking ballistic missiles once they detach from their boosters and go "cold" during the midcourse phase of their flight. The U.S. military is developing a Midcourse Tracking Sensor system to help address this problem, but it remains unknown when that system could be deployed operationally.

The longer dwell times of MEO satellites across broader areas could offer improved persistence and tracking potential compared to LEO systems, while their closer proximity to the planet could help better enable them to detect and track dimmer objects, such as hypersonic boost-glide vehicles, which are difficult to impossible to track post-boost phase for existing GEO satellites. This could give a missile defense architecture that includes an MEO satellite layer the capability to track threats beyond ballistic missiles and hypersonic boost-glide vehicles, potentially including hypersonic cruise missiles. Even if this is a secondary capability beyond their primary early warning function that overlaps with an LEO tracking constellation. MEO also adds a layer of survivability to satellites compared to LEO or even GEO. Of course, large constellations of small satellites in LEO also have their advantages in terms of resiliency and survivability. 

Matters of persistence and total coverage, as well as tracking capabilities and survivability, are key considerations for any missile defense-related satellite layer, and different orbits enable their own unique capabilities. Ultimately, no one layer or constellation is going to be optimized to detect and track every type of threat. For that reason, it’s increasingly looking like missile defense duties will rely less on the small numbers of GEO satellites that make up existing systems like SBIRS and fall instead to a layered network of satellites in LEO, MEO, and GEO, offering a wide range of capabilities and coverage, some of which may overlap, from multiple levels of space. 

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