Editor’s Note: This story has been corrected to clarify available information about the planned launch date.
HUNTSVILLE, Ala. — The additional missile tracking satellites the U.S. Space Development Agency put on contract July are meant to accelerate use of a technology expected to play a major role in tracking advanced threats from space: infrared sensor payloads.
The SDA in July awarded contracts worth up to a combined $1.75 billion to L3Harris Technologies and Sierra Space Corp. for the Accelerated Missile Defense Tranche 3, or AMDT3. The tranche is to comprise 36 satellites, expanding SDA’s planned Proliferated Space Warfighter Architecture constellation.
L3Harris will build its infrared payloads in-house and rely on Lanteris Space Systems for the satellite buses, the same arrangement for all its SDA contracts. Alternatively, Sierra Space is building the buses and turning to Leidos for its infrared sensor payloads.
A Sierra Space spokesperson told me, “We’re excited to integrate their flight-proven sensing technology into our satellite architecture.”
Earlier versions of the L3Harris and Leidos payloads are already on orbit, aboard Tranche 0 satellites launched to demonstrate technologies for SDA’s planned Proliferated Warfighter Space Architecture constellation. This effort was closely linked to the U.S. Missile Defense Agency’s Hypersonic and Ballistic Tracking Space Sensor program.
SDA Director GP Sandhoo referenced the Tranche 0 demonstration at a July media roundtable, saying “we have shown multiple times at this point that this design that we are trying to proliferate can detect and track these advanced threats from low orbit.”
L3Harris and Leidos executives told me their focus now is maturing that infrared sensor technology, refining the data algorithms involved and delivering on their SDA contracts.
“Think of infrared as the ability to see heat,” said Rob Mitrevski, president of Golden Dome strategy and integration for L3Harris, on the sidelines of the Space and Missile Defense Symposium here in August, “and what you want in your ability to track missiles is to be able to see a heat signature.”
That’s fairly straightforward when tracking intercontinental ballistic missiles (ICBMs), he said, because these designs “travel through their engine power” along predictable trajectories.
Tracking hypersonic glide vehicles is more complex, Mitrevski continued, because those designs “actually turn their engines off” during the glide phase, resulting in dimmer heat signatures. At that point, infrared sensors are “really tracking the friction of the overheated surface of that gliding object against the atmosphere,” which is “really challenging.”
Like other hypersonic threats, hypersonic glide vehicles can also travel at lower altitudes than ICBMs, staying within the atmosphere on maneuverable trajectories. This creates additional difficulties when trying to track their flight paths from orbit.
“When you’re looking from space, there’s cloud cover,” Larry Barisciano, chief operations officer for Leidos Defense, said separately on the sidelines of the same conference. “There’s junk. There’re other things that are lit up [on the sensor] when you’re looking at the Earth.”
Volcanoes, cities, lightning, even sunlight reflecting off the ocean surface — lots of activities on Earth generate heat and can therefore be detected by orbiting infrared sensors. The challenge is “you have to be able to detect [a threat] from a very complex image and be able to pick that out, strip out all the clutter and then be able to zero in on it,” Barisciano said.
As a result, “part of the trick of missile defense from space isn’t just the sensing,” Mitrevski said. “It’s the work of the sensor and the data processor and its algorithms in working together to create a scene, a target, a track that is accurate.”
With additional tracking satellites, he added, “the more data sources you have, and the more fusing you can do, the more accurate you’re going to be in creating the three-dimensional tracks that you’re going to need for an interceptor.”
With AMDT3, SDA’s plans for the Proliferated Warfighter Space Architecture expand to 190 operational satellites. So far, it has delivered 63 satellites since the first launch last September.
The SDA said in its announcement of the July contracts that AMDT3 satellites “are expected to be available for launch by the end of 2028.” However, Sandhoo, who also serves as the Space Force’s portfolio acquisition executive for missile tracking and warning, told reporters later that month that the launch schedule will be based on whichever contractor is ready first.
Asked about the timeline for the first AMDT3 launch, Mitrevski said that “at the end of the year, [SDA has] got a launch that they’re shooting for” but declined to provide additional information.
Facts Only
* The U.S. Space Development Agency awarded contracts up to $1.75 billion for the Accelerated Missile Defense Tranche 3 (AMDT3) to L3Harris Technologies and Sierra Space Corp.
* AMDT3 will comprise 36 satellites, expanding SDA’s Proliferated Space Warfighter Architecture constellation.
* L3Harris will build infrared payloads in-house and use Lanteris Space Systems for satellite buses.
* Alternatively, Sierra Space is building the buses and using Leidos for infrared sensor payloads.
* Earlier versions of L3Harris and Leidos payloads are already on orbit from Tranche 0 satellites.
* SDA demonstrated that the design can detect and track advanced threats from low orbit.
* Infrared sensing is key to missile defense; tracking ICBMs is straightforward due to predictable trajectories.
* Tracking hypersonic glide vehicles is complex because they turn engines off during the glide phase, creating dimmer heat signatures.
* Tracking hypersonic objects faces challenges from atmospheric phenomena and thermal noise from other Earth activities (volcanoes, cities).
* Accurate tracking requires the integration of sensor data with algorithms to filter out clutter.
* AMDT3 plans expand SDA’s Proliferated Warfighter Space Architecture to 190 operational satellites.
* Launch schedules for AMDT3 satellites will be based on contractor readiness.
Executive Summary
Full Take
The narrative surrounding missile defense from space pivots on the tension between technological capability and environmental complexity. The shift from tracking predictable ICBMs to highly dynamic hypersonic glide vehicles highlights a fundamental challenge in sensor fusion: moving from simple detection to high-fidelity, real-time scene reconstruction amidst significant thermal noise. The core difficulty is not just detecting heat, but successfully isolating a threat signature from the pervasive background of terrestrial heat, which introduces systemic uncertainty into tracking algorithms.
The focus on data processing—the necessity for sensors, processors, and algorithms to work together—suggests that physical hardware alone is insufficient; true defense lies in the complexity of information management. This raises questions about the governance and validation of these fusion processes. If the efficacy hinges on filtering out complex, real-world clutter (cloud cover, city heat), then the vulnerability shifts from external threats to the internal integrity of the data pipeline itself. The timeline uncertainty regarding launch schedules, tied to contractor readiness, introduces a layer of operational fragility that exists independent of technological success.
The pattern observed is a dependency chain where advanced defense capability relies equally on sophisticated sensor physics and robust computational integration. The challenge for future development, therefore, extends beyond developing better infrared sensors; it involves establishing universal standards for correlating disparate data streams under variable atmospheric conditions. What assumptions about the predictability of terrestrial thermal signatures are built into the current tracking models? How does the necessity of operational speed influence the rigor applied to the complex data fusion processes described?