The Space Development Agency (SDA) has awarded up to $1.75 billion in contracts to L3Harris Technologies and Sierra Space to build 36 Accelerated Missile Defense Tranche 3 (AMDT3) satellites for the Trump administration's Golden Dome missile-defense initiative, bringing the planned Tranche 3 Tracking Layer to 108 low-orbit spacecraft.
18 Satellites Each, Ready For Launch By End Of 2028
Under the awards, L3Harris receives up to $955 million to deliver 18 “missile defense variant” spacecraft based on its Hypersonic and Ballistic Tracking Space Sensor (HBTSS) heritage, while Sierra Space will receive up to $798 million to deliver 18 “missile warning and missile tracking variant” vehicles built on the Horizon bus from its Eclipse satellite series. All 36 satellites are expected to be ready for launch by the end of 2028, distributed across four orbital planes to deliver global stereo coverage of next-generation missile threats.
The AMDT3 layer will use infrared imaging in low Earth orbit and a low-latency mesh communications network to detect, track and cue missiles for interceptors on the ground, at sea and — increasingly — in space.
Golden Dome's Tracking Layer Passes 108 Satellites
The new awards come on top of the 72 Tranche 3 tracking satellites SDA ordered in December 2025 for $3.5 billion from L3Harris, Lockheed Martin, Rocket Lab and Northrop Grumman. Combined, the Tranche 3 layer is now valued at about $5.25 billion.
Golden Dome's Expanding Contractor Footprint
The awards reinforce L3Harris — which already has more than 70 missile tracking and defense satellites on order — and mark Sierra Space's second consecutive Tranche win after the Tranche 2 Tracking Layer program. Related programs include our recent coverage of the Space Force's $17B NSSL Phase 3 Lane 1 launch pool, the Pentagon's FAMM cruise-missile multiyear, and Northrop Grumman's MRV-1 GEO servicing debut.
Reporting based on coverage from Space.com, Air & Space Forces Magazine, DefenseScoop and SDA.