SpaceX launches missile tracking satellites for MDA and SDA

by Danny Lentz

SpaceX launched the USSF-124 mission carrying six prototype missile tracking satellites for the Missile Defense Agency (MDA) and Space Development Agency (SDA) into a 1000 kilometer altitude, 40 degree inclination orbit on Wednesday, Feb. 14 at 5:30 PM EST (22:30 UTC). The mission took off from SLC-40 at Cape Canaveral Space Force Station (CCSFS) in Florida. After stage separation, the Falcon 9 booster returned to landing pad LZ-2 at CCSFS.  Space Systems Command (SSC) confirmed successful deployment of the satellites into their intended orbit.

The forecast from the 45th Weather Squadron showed very good weather at the scheduled liftoff time with a greater than 95 percent chance of favorable conditions.

This was the first of three launches scheduled within eight hours for SpaceX from its three active launch pads for Falcon rockets, along with the Intuitive Machines IM-1 moon lander and Starlink 7-14 flights. Depending on the order they eventually take off, one of these missions will be the 300th Falcon 9 flight, coming little more than a year after the 200th Falcon 9.

This was the seventh flight for booster B1078. It had previously flown the Crew-6 Dragon mission to the International Space Station, a pair of satellites for the SES O3B mPOWER constellation, and four batches of Starlink satellites. The two payload fairings will be recovered downrange by SpaceX’s multi-purpose recovery vessel Doug. SpaceX VP of Falcon launch recently noted on X that a single fairing half has now flown 15 times, with its 16th flight upcoming.

For this flight the second stage of the launch vehicle is sporting a gray stripe that is used to help control propellant temperatures during missions with an extended coast period. In a teleconference on Tuesday, Feb. 13, a senior SDA official described the orbit for these payloads as “near equatorial.” The satellites will be deployed into a single orbital plane.

USSF-124 is the 11th National Security Space Launch (NSSL) mission for SpaceX, and the second under the NSSL Phase 2 contract.

Dr. Walt Lauderdale, AATS mission director at SSC, said of the Space Force’s partnership with SpaceX: “As we move forward together with SpaceX, we’re methodically expanding reuse to leverage the benefits for the USSF and our space vehicle teammates. The mission team was able to add the Tranche 0 satellites to USSF-124 in under 30 days, less than six months from the then scheduled launch date. This unprecedented responsiveness is a needed capability for the Space Force to confront today’s threat environment.”

B1078 rolling past the Vehicle Assembly Building to SLC-40 to launch USSF-124. (Credit: Max Evans for NSF)

The flight carries two Hypersonic and Ballistic Tracking Space Sensor (HBTSS) satellites for MDA. Northrop Grumman and L3 Harris each built one of these prototype Medium-Field-of-View (MFOV) missile tracking spacecraft. They are designed to be able to track dim targets such as hypersonic glide vehicles as they maneuver in flight, with sufficient accuracy to provide targeting data for missile defense systems.

Also on board are four Wide-Field-of-View (WFOV) missile tracking satellites built by L3 Harris for the Tracking Layer of SDA’s Tranche 0 constellation, the demonstration phase of the new Proliferated Warfighter Space Architecture (PWSA). This is the third and final launch for Tranche 0.

Continuing to expand the supplier base for PWSA, the L3 Harris satellites are using optical communications terminals (OCT) made by CACI, as opposed to the TESAT developed OCTs used on the rest of the Tranche 0 spacecraft.

PWSA is focused on providing beyond line of sight targeting and advanced missile detection and tracking using satellites in low-Earth orbit. The overall constellation has two main components, the Transport Layer for communications and the Tracking Layer hosting the missile tracking payloads.

These satellites were originally intended to operate in the near polar orbit used by the rest of Tranche 0. When the completion of these spacecraft fell behind schedule, SDA took advantage of an opportunity to move them to the USSF-124 launch, minimizing delays for other Tranche 0 satellites flown in September 2023.

Launching these two groups of satellites into the same orbital plane will allow comparison of the different sensor types with the same targets, as well as the opportunity to demonstrate using data from the WFOV sensors to cue the more precise MFOV payloads. In the future, the HBTSS capability will be rolled into PWSA. There are HBTSS payloads on some Tranche 1 Tracking Layer spacecraft, with similar capabilities planned for inclusion on the Tranche 2 Tracking Layer.

Some milestones completed so far for Tranche 0 include: getting first light from the payloads on the SpaceX built Tracking Layer satellites approximately 60 days into their mission; demonstrating the use of Link 16 communications from space for the first time in late November of last year; and closing links between OCTs in orbit. SDA will work with MDA and other agencies to identify opportunities to demonstrate the capabilities of these satellites throughout the coming year.

The next phase of PWSA, Tranche 1, will begin launching with Transport Layer satellites in late 2024. Tranche 1 Tracking Layer satellites will follow in spring 2025.

(Lead image: Falcon 9 launching the USSF-124 mission from SLC-40. Credit: Julia Bergeron for NSF)

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