Northrop Grumman’s rendering of the Space Development Agency’s (SDA) Tracking Layer. Photo: Northrop Grumman

The U.S. Space Force’s Space Development Agency (SDA) has issued a solicitation for Tranche 2 (T2) of the SDA Tracking Layer for first launch by April 30, 2027.

“The T2 Tracking scope includes the procurement and deployment of 54 – and potentially more – space vehicles (SVs) with infrared (IR) sensors in six orbital planes,” SDA said in a business notice.  “The fully deployed Tracking Layer is estimated to include more than 100 SVs in Low-Earth Orbit (LEO) across multiple planes.”

In January, SDA renamed its planned proliferated LEO constellation as the Proliferated Warfighter Space Architecture (PWSA).

“SDA has determined that the proliferation of various mission functions across the PWSA using commodity SVs is the most efficient and cost-effective means of evolving the architecture,” SDA said in the Tranche 2 Tracking Layer solicitation. “The objective is to establish and demonstrate the ability to rapidly evolve development processes and field capability on a significantly faster timeline than historical space systems acquisition. In pursuit of this objective, SDA requires each PWSA performer’s SVs and communications systems to be interoperable with the SVs and systems developed by all other PWSA performers as well as those to be deployed in Tranche 1. Additionally, all SVs must operate in an integrated fashion through a common ground system.”

SDA said that it plans to award more than one company contracts under the Tranche 2 Tracking Layer. The agency established several conditions to qualify for an award, including having “one nontraditional defense contractor or nonprofit research institution” on a contractor team or having “at least one-third of the total cost of the prototype project paid out of funds provided by sources other than the federal government.”

SDA plans to begin fielding the Tranche 1 satellites — the first for military operations — late next year. Tranche 1 is to include about 150 Transport Layer and Tracking Layer satellites.

The SDA Transport Layer satellites are to provide rapid sensor to shooter data, while the Tracking Layer satellites are to provide a significant leap in the detection and tracking of hypersonic and ballistic missiles.

SpaceX and L3Harris are the contractors for the Tranche 0 Tracking Layer, while L3Harris and Northrop Grumman are building 28 satellites for the Tranche 1 Tracking Layer.

“Each SV is equipped with an IR mission payload, Optical Communications Terminals (OCTs), and Ka-band and S-band communications payloads,” SDA said in the Tranche 2 Tracking Layer solicitation. “Select SVs will be equipped with a directed energy sensor.”

The latter is to provide satellite defense against directed energy attacks. The solicitation said that bidders “shall implement some additional methods for enhancing resiliency of selected mission payloads against threats such as directed energy effects.”

“The government is interested in mature elements or components that enhance Tracking constellation resiliency, particularly the IR payload sensor,” per the solicitation. “The offeror shall provide a directed energy resiliency system that at minimum includes a directed energy threat warning sensor. The offeror shall provide a feasible SV CONOPs that could be implemented to enhance survivability, thus providing the capability to continue IR mission operations during directed energy illumination.”

A version of this article was first published by Defense Daily