The U.S. Space Force ordered 36 additional missile-tracking satellites from L3Harris Technologies and Sierra Space in contracts worth $1.75 billion combined, announced by the Space Development Agency on July 14. The satellites are part of the Accelerated Missile Defense Tranche 3 program and will expand the SDA's Proliferated Warfighter Space Architecture Tracking Layer constellation, which detects and tracks incoming missiles from orbit using infrared sensors. All 36 spacecraft are expected to be ready for launch by the end of 2028.
L3Harris will provide 18 HBTSS-variant satellites and receive up to $955 million, while Sierra Space will supply 18 missile warning and tracking variants for up to $798 million. Both companies will equip their spacecraft with infrared sensors to integrate into the constellation's existing global network. The 36 satellites will be distributed across four orbital planes to provide what the agency calls "global stereo coverage" of next-generation missile threats.
These 36 satellites add to an earlier order of 72 Tranche 3 Tracking Layer spacecraft that the SDA announced in December 2025 for $3.5 billion, bringing the total Tranche 3 constellation to a planned 108 satellites worth approximately $5.25 billion. L3Harris noted it already has more than 70 missile tracking and defense satellites on order across multiple programs, with five currently in orbit. The earlier batch of 72 is expected to launch by the end of 2029, while the newly contracted 36 may reach orbit sooner, though no specific launch timeline has been announced.
Once operational, the Tracking Layer transfers real-time missile detection data through a low-latency communications network to military forces on the ground. The Space Force will assume operational control and integrate the new satellites to support joint force operations once they reach orbit.