WASHINGTON — The Pentagon’s Space Development Agency is planning a new procurement of satellites that will be part of a global constellation of missile-tracking space sensors. 

The agency is looking to buy 28 satellites for the constellation known as Tracking Layer Tranche 1, according to a Dec. 6 draft solicitation.

These 28 spacecraft, projected to start launching in late 2024, would expand the Tracking Layer Tranche 0, a batch of eight missile-detecting satellites currently being produced by L3Harris and SpaceX for launch in 2023.

The Tracking Layer is envisioned as a global network of eyes in the sky that would provide a defense shield against Russian and Chinese ballistic and hypersonic missiles. 

The data collected by missile-tracking satellites would be sent via optical links to the Transport Layer, a constellation of communications satellites that SDA also is building. That would ensure that if a missile threat is detected, its location and trajectory data can be transmitted securely through space and downlinked to military command centers. 

The Tracking Layer Tranche 1 satellites will be procured using Other Transaction Authority, or OTA, contracts. This is the same contracting method the agency is using to procure Transport Layer satellites. OTAs give government agencies more flexibility to set the rules for contractor proposals, and cannot be protested like traditional Federal Acquisition Regulation awards. 

Under OTA agreements, large Pentagon contractors have to team up with commercial firms and small businesses, or have to fund one-third of the cost of the project. 

Tracking Layer satellites must have infrared sensors and a minimum of three optical inter-satellite links for space-to-space, space-to-aircraft and space-to-ground communications. The 28 satellites will be deployed in four orbital planes at an altitude of about 1,200 kilometers above Earth. 

SDA plans to select multiple vendors. Companies will be asked to bid for two orbital planes, along with the ground support and operations and sustainment capability.

The draft solicitation asks companies to submit comments by Jan. 7. The final request for proposals is expected to be released in the first quarter of 2022. The Tracking Layer Tranche 1 has not yet been funded in the Pentagon’s budget. SDA plans to request funding in fiscal year 2023. 

In parallel to the procurement of satellites, SDA is working with the Missile Defense Agency (MDA) on infrared sensor technology for detection of missile threats in low Earth orbit. Being able to identify objects in LEO is important in order to detect low-flying hypersonic glide vehicles like those being developed by China and Russia.  

Both agencies collaborated on an experiment called infrared imaging payload, or PIRPL, that flew to the International Space Station in August on a Northrop Grumman cargo spacecraft. An SDA spokesperson said PIRPL departed the ISS on Nov. 20 aboard the Cygnus NG-16 resupply space vehicle and collected multispectral infrared imagery of terrestrial regions and images of IR stars.

“Cygnus was commanded to body point for these collections, the first time this has been done with a Cygnus space vehicle to such an extent,” the spokesperson said. Image collections will continue until Dec. 13. SDA and MDA will use the imagery to create a database of low Earth orbit infrared clutter backgrounds that will be used in the development and verification of algorithms for missile detection and tracking. 

Congressional concerns 

Congressional committees have warned DoD about unnecessary duplication of missile-defense satellite programs, and specifically raised concerns about overlap between SDA’s Tracking Layer and MDA’s Hypersonic and Ballistic Tracking Space Sensor program known as HBTSS.

MDA has selected two satellite designs made by L3Harris and Northrop Grumman and plans to launch both prototypes to orbit in 2023. These satellites are intended to operate in different orbits than SDA’s satellites. 

The Senate Appropriations Committee criticized MDA’s plan to launch HBTSS payloads on separate satellites instead of hosting them aboard SDA’s Tracking Layer Tranche 0 satellites. “MDA and SDA each launching their own satellites reveals a lack of coordination and cooperation between SDA and MDA, poor oversight on the part of the Department of Defense’s space acquisition enterprise, and waste of taxpayer dollars,” said the SAC in a report. 

The 2022 National Defense Authorization Act conference agreement released Dec. 7 allows MDA to field prototype satellites but warns the agency that HBTSS will be subject to increased oversight. “A misalignment of orbit requirements between those of the Space Development Agency and the Missile Defense Agency now requires the Missile Defense Agency to field two prototype satellites for hypersonic and ballistic missile tracking,” said a report accompanying the NDAA.

“The committee is acutely concerned that the Missile Defense Agency could be fielding a program of record of satellite constellations and ground systems. The reason why the Congress created the Space Force was explicitly to consolidate space functions of the Department of Defense into the Space Force.”

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...