Moving Up to MEO

Over the last several years, satellites in low-Earth orbit (LEO) have rapidly proliferated, with the private sector and the military launching constellations of hundreds of smaller satellites up to 2,000 kilometers above Earth.

Now, with adversarial threats evolving, to include hypersonic missiles and hypersonic glide vehicles, the U.S. military is expanding missile defense and space communications to medium-Earth orbit (MEO), reported Col. Michael Rupp, U.S. Space Force.

“Since we’ve got those [LEO satellites] on orbit, the threat has changed,” Rupp said. “Hypersonic glide vehicles have the ability to maneuver post-boost phase. These are uprising trajectories—and we do not know where they are going to land. The current system just cannot keep up with that evolving threat.”

Rupp is the system program director for Resilient Missile Warning and Tracking Systems (MWT) at Delta 84, Space Systems Command (SSC), Los Angeles Air Force Base.

The colonel spoke about the service’s planned space infrastructure at an AFCEA Los Angeles chapter event on June 16 at the Los Angeles Air Force Base.

Because hypersonic vehicles will be harder to detect—with those unpredictable trajectories and immense speed, not to mention the deadly ability to strike globally from space—the Space Force made the pivot to a multi-orbit architecture to enable the military to identify, track and defeat adversarial hypersonic threats.

A new class of threats requires a new class of architecture, Rupp stressed.

The missile warning and tracking capabilities that MWT is advancing will support U.S. combatant command operations and help defend the homeland. The solutions will also be a part of the greater missile defense kill chain, such as the Space Development Agency’s Proliferated Warfighter Space Architecture and the Missile Defense Agency’s efforts, Rupp noted.

The MWT is currently working on how the MEO mission warning and tracking segment will integrate with the military’s broader resilient mission warning and tracking architecture, which includes MEO communications, GEO/Polar-orbiting and the LEO transport layer.

“We meet on a recurring basis and have quarterly summits,” Rupp said. “We are starting to standardize message formats, data rates, requirements and methodologies for data processing. We are starting to work together instead of having three stovepipes acquiring three different cohort versions and requirements.”

Higher than LEO, the MEO layer includes altitudes between 2,000 km and 20,000 km, and fewer satellites are needed at these altitudes to provide wider coverage.

“MEO was chosen for a few different reasons,” he explained. “It’s kind of the Goldilocks zone, if you will. We are high enough to be fairly hard to get after, even though, yes, you can attack that layer, but it is distributed enough to where it makes it hard to get more than one satellite in one shot. And at MEO, we are looking at 25 to 36 satellites we can proliferate. As you push that down to LEO, you are in the hundreds of satellites, so MEO is really that sweet spot.”

Another feature of their approach is to address installation of the common ground systems first.

“One of the things that was big for us is ‘ground before launch,’” Rupp shared. “Too many times the satellite programs were really focused on the big, important part of the satellites, and we hand-wave the ground, saying it’ll be there. Trust me, we are really focused on delivering our ground segments before launch. Right now, we are about a year out [from launch] in the schedule. We have already got our mission operations center built out, and we are starting to do connectivity. Our ground entry points are starting to be constructed, so making good progress.”

The ground systems will take in data from MEO and process and operationalize it. Dedicated antenna sites for the MEO data downlink are under construction at the Boulder Ground Innovation Facility in Colorado. With the mission operations center, these will tie into an existing site at Pituffik Space Base in Greenland, a site in the United Kingdom and a fifth still-to-be-determined site in the Indo-Pacific region, Rupp said.

The MWT expects to begin delivering initial ground-enabled capability by 2028 or 2029, as part of the common ground system’s initial warfighter capability. Full warfighter capability is expected as early as 2031.

The colonel also noted that the approach to the integrated multilayer architecture includes a frequent constellation refresh approach under stage innovations called epochs. Gone are the days of 15-year cycles, he said.

Currently, the MEO mission warning and tracking effort is in the Epoch 1 stage, or the first series of capabilities that will set the foundation of the MEO constellation and provide initial tracking, Rupp shared.

Under Epoch 1, the SSC is procuring 12 space vehicles from Millennium Space Systems with Boeing as the payload provider. Those will be designed to operate in two planes, or areas, with agile pointing of satellites, the colonel said. They are planning two launches per Epoch stage. Epoch I launches are planned for late 2027 and nine months later, the second launch.

Notably, the MWT did not dictate the number of satellites needed per plane.

“They have 12 satellites on contract with two orbital planes, and it’s a different way of thinking as we build this program,” Rupp clarified. “We in the program office are not asking for a certain number of satellites; we are asking for a plane of capabilities. However, many satellites that takes the vendor to achieve, that’s up to them. That’s why you will start to see differences across the different Epochs between the number of satellites.”
 

This way, the MWT can analyze each of the proposals across the epochs with respect to the capabilities and what resiliency is provided across a plane.

“We are actually getting ready to run source selection now for a third plane satellite with a separate vendor for Epoch II, and it can be anywhere from three to six satellites,” the colonel offered. “It is really vendor-dependent and solution-dependent from a bus perspective. It is thinking a little bit differently. It’s really that plane of capability that we are trying to acquire as we march forward.”

Epoch I will provide regional coverage of missile threat tracking under regional task access operations, where the Space Force must be tasked to track a certain area.

The concept of operations for the first phase is for the satellites to be government-owned, contractor-operated through Mission Delta 4 at Buckley Space Force Base.

Epoch II will expand the MEO missile warning and tracking capacity and data delivery to provide global tracking access, albeit with a noncontinuous global reach—or intermittent persistence.

Epoch II will feature 13 to 16 satellite vehicles positioned in up to three planes, again with agile pointing sensor capability, also under a government-owned, contractor-operated approach with Mission Delta 4. Adding more satellite vehicles and planes scales the resilience and coverage of the MEO constellation against adversarial threats to satellites, Rupp explained.

The first assets for Epoch II should fly in early 2029, followed by the second launch six months later.

“By fourth quarter 2029 we are scheduled to have the first four planes and capability element up,” Rupp reported.

At the completion of Epoch I and II, the MEO missile warning and tracking will reach initial warfighter capacity.

And as part of the approach to bring in innovation and frequent capability refresh, Epoch II will bring in additional vendors. “This will expand the industrial base and design solutions to burn down risk going into full warfighting capability,” he said.

In addition, Epoch 2 will provide a common ground system to share data with the joint force as part of the military’s end-to-end missile warning and tracking system.

Future series of the MEO capability, in Epochs 3 and 4, will represent full warfighter capability, with satellites positioned in four planes and sensors providing wide-area coverage.

This continuous global stereo coverage will provide persistent tracking, Rupp said, a much-needed element against the threats.