WASHINGTON — Millennium Space Systems announced Nov. 23 its proposed satellite design for a U.S. Space Force missile-warning constellation passed a critical review.

The company, a subsidiary of the Boeing Co., is developing a sensor satellite for a constellation that the Space Force plans to field in medium Earth orbit (MEO) to detect and track hypersonic missiles. Millennium Space and Raytheon in May 2021 were selected to design separate MEO satellite concepts. 

Passing a critical design review allows Millennium Space to move forward to the next phase of the program. The Space Force next year plans to seek industry bids for as many as four MEO satellites for a projected multi-orbit architecture of overhead persistent infrared (OPIR) sensors. 

“This initial CDR process marks 18 months of hard design work that is necessary to build the next generation of affordable OPIR sensors that can detect and maintain custody of emerging missile threats,” Lt. Col. Gary Goff, a program official at the U.S. Space Systems Command’s space sensing directorate, said in a statement. 

Jason Kim, CEO of Millennium Space, said the company developed a “digital model that gives our customer the ability to accurately track hypersonic glide vehicles and modern threats.”

“Millennium will transition into space and ground segment development for a projected launch in 2026,” he said. 

Following the design review, the Space Systems Command exercised the next contract option for the first space vehicle to be delivered in August 2026, a Millennium Space spokesperson said. There are contract options for a second and third vehicle.

MEO satellites would add a new layer to the Pentagon’s missile-defense architecture to provide extra eyes on enemy hypersonic missiles. The Pentagon is requesting funding for as many as four MEO satellites to be launched from 2026 to 2028. 

Compared to current sensors in geostationary satellites, sensors in medium orbits closer to Earth would see and track a wider area than satellites in low Earth orbit. The Space Force plans to deploy a constellation of 135 missile-warning and missile-tracking satellites in LEO and 16 in MEO.

The Space Development Agency will develop the LEO layer. The Space Systems Command is responsible for the MEO layer and serves as the total system integrator. 

The Aerospace Corp. in a recent report said a MEO constellation could provide additional resiliency to the U.S. missile-warning network due in part to being in a different orbit than other missile warning assets.

“If the eventual constellation is to consist of purely LEO and MEO capabilities, the MEO systems would offer wider field of view and longer pass times over target areas than the LEO systems and add angular diversity to the broader architecture for tracking missile threats,” said the report.

The Pentagon requested $139 million for MEO missile-warning satellites in the 2023 budget. Congressional committees in markups proposed increases of anywhere from $100 million to $300 million above the Pentagon’s request to speed up the deployment of the MEO constellation. The Aerospace report noted that Senate appropriators, particularly, “seem to want to accelerate this transition, cutting some of the funding for next-generation GEO and polar-orbiting systems and nearly doubling the funding for LEO and MEO.”

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...