Maxar Technologies said on July 24 that it has gone through a Critical Design Review (CDR) of the company’s Maxar 300 series bus for the L3Harris‘ [LHX] offering for the U.S. Space Force’s Space Development Agency (SDA) Tranche 1 Tracking Layer against ballistic and hypersonic missiles.

Maxar’s SSL subsidiary in Palo Alto, Calif., builds the Maxar 300. SSL was formerly Space Systems Loral.

The “inaugural Maxar 300 series bus is designed for eight or more space vehicles per launch while delivering the demanding low jitter and high power required for the missile defense mission,” Maxar said on July 24. The company said that the Maxar 300 series is its “smallest and most modular bus” and is designed for “high-rate production, rapid constellation deployment and mission-level reliability” for low Earth orbit (LEO) missile warning/missile tracking.

SpaceX and L3Harris are the contractors for the Tranche 0 Tracking Layer, while L3Harris and Northrop Grumman [NOC] are building satellites for the Tranche 1 Tracking Layer (Defense Daily, July 20).

In fiscal 2024, the Space Force is requesting a $1.1 billion increase over last year’s appropriated amount for LEO and medium Earth orbit (MEO) missile tracking systems.

The service’s request for the LEO portion of the architecture is nearly $1.3 billion–a $480 million increase over last year, while the Space Force’s ask for the MEO part is $538 million, about $130 million more than last year’s appropriation (Defense Daily, March 16).

The Space Force budget zeroes research and development funding for one of the GEO Next Generation Overhead Persistent Infrared (Next Gen OPIR) missile warning satellites by Lockheed Martin [LMT], as the Space Force posits that having a band of many, smaller satellites in the lower orbits of LEO and MEO will complicate an adversary’s anti-satellite targeting and improve deterrence against potential Russian and Chinese ballistic and hypersonic missile attacks.

Chris Johnson, Maxar’s senior vice president and general manager for space, said in a company statement on July 24 that the Maxar team “completed CDR just 10 months from award, and we’re on schedule to begin production of our platforms later this year with initial deliveries in early 2024.”

In January, SDA renamed the proliferated LEO constellation as the Proliferated Warfighter Space Architecture (PWSA).

Last month, the House Armed Services Committee (HASC) said that it has not received details from SDA on how the PWSA “contributions for missile warning will meet stated combatant commander resiliency requirements or be integrated into the overall Integrated Tactical Warning and Attack Assessment architecture” (Defense Daily, June 21).

Maxar said on July 24 that the CDR on the Maxar 300 “examined all the principal elements of the new system, including structural design, power, attitude control and command and data handling.”

“Maxar will build 16 platforms for the T1TRK program, each about the width of a conventional oven,” the company said. “Those dimensions help the SDA achieve its goals to significantly reduce size, weight, power and cost compared to traditional missile detection satellites. The SDA mission will also adapt and extend Maxar’s deep commercial communications satellite experience for new uses.

The Maxar 300 leverages “the company’s decades of experience building more than 90 spacecraft for low Earth orbit,” Maxar said. “Both the platform and Maxar’s production capacity are scalable, with the ability to address multiple missions with flexible production rates that meet delivery timelines.”