Tracking Layer by Space Development Agency: status and timeline

Milestones

Next · First Tranche 1 tracking launch

Tranche 1: L3Harris and Northrop to build 28 satellites18 Jul 2022Complete.
Tranche 2: 54 satellites from L3Harris, Lockheed, Sierra Space16 Jan 2024Complete.
Tranche 3: 72 satellites, about $3.5B, four builders19 Dec 2025Complete.
First Tranche 1 tracking launchTarget Q4 2026+18 mo~~originally Apr 2025~~Current milestone.
Tranche 2 tracking satellites launchTarget Apr 2027Not yet reached.
Tranche 3 tracking satellites launchTarget 2029Not yet reached.

Most important updates

Upcoming

Q4 2026First Tranche 1 tracking launch+18 mo~~originally Apr 2025~~ (next)
Apr 2027Tranche 2 tracking satellites launch
2029Tranche 3 tracking satellites launch

Current obstacles

Two years behind the first planTranche 1 tracking launches were to start in April 2025; as of October 2026 none had flown, with listings pointing to late 2026.
Proving fire-control qualityTurning infrared dots into tracks precise enough to steer interceptors is new; Tranche 2 flies only six such satellites.

Physics limits

Each satellite sees a small patchFrom a few hundred to about 1,000 km up, one satellite's view covers only part of the Earth and sweeps past in minutes, so global watch needs dozens to hundreds of them.
A missile cools after its engine stopsA rocket plume is bright in infrared, but a warhead or glider coasting afterward is far dimmer, so following the whole flight needs sensitive, well-cooled detectors.

How it works

4 parts

Heat seeking

Infrared cameras watch for rocket plumes

Wide-view infrared cameras pick up the heat of a missile's engine against the cooler Earth below, from launch onward.

Low and many

Close to Earth, hard to kill

Flying in low orbit brings dim targets like gliding hypersonic weapons into view; with dozens per tranche, losing a few leaves no gap.

Fire control

Tracks good enough to aim by

Some satellites carry narrower, sharper cameras that measure a missile's path precisely enough to guide an interceptor to it.

Data relay

Handing tracks to the network

Tracking satellites pass what they see through SDA's Transport Layer relay satellites to commanders and missile-defence systems on the ground.

Spec sheet

Spec	Tracking Layer
Tranche 1 satellites	28 (4 planes of 7)^R (reported)
Tranche 1 cost per satellite	About $44M–$50M^R (reported)
Tranche 2 satellites	54 (6 with fire-control sensors)^R (reported)
Tranche 2 contracts	About $2.5B^R (reported)
Tranche 3 satellites	72^R (reported)
Tranche 3 contracts	About $3.5B^R (reported)
Design life	About 5 years, new tranche every 2^R (reported)

^R reported by the company

Update log

3 updates

About Space Development Agency

The team behind Tracking Layer

Space Development Agency

Pentagon satellite constellation, missile tracking, LEO

U.S. Department of Defense agency building satellite constellations for military communications, missile detection and data relay. PWSA deploys hundreds of small satellites in LEO for rapid refresh and resilience to attack.

SDA builds PWSA, a constellation of hundreds of small satellites for missile warning, communications and data relay.
Tranche 1 has 154 satellites from York, Lockheed and Northrop; launches resumed July 2026 after a technical pause.
Using many cheap satellites reduces cost and improves resilience: loss of one satellite has minimal impact.

sda.mil (opens sda.mil)Company profile →

Founded: 20197 yrs
Headquarters: United States
Status: Government
Valuation: government
Works in: SpaceflightMilitary space
Coverage: 2 programs · 5 updateslatest 1 Jul 2026checked 11 Oct
Suppliers: York Space Systems (opens yorkspacesystems.com)Lockheed Martin (opens lockheedmartin.com)Northrop Grumman (opens northropgrumman.com)L3HarrisSierra SpaceRocket Lab
People: Gurpartap "GP" Sandhoo (opens sda.mil)Director, Space Development Agency

Tracking Layer

Milestones

Most important updates

Upcoming

Current obstacles

Physics limits

How it works

Infrared cameras watch for rocket plumes

Close to Earth, hard to kill

Tracks good enough to aim by

Handing tracks to the network

Spec sheet

Update log

Fri 19 Dec 2025

Tue 16 Jan 2024

Mon 18 Jul 2022

About Space Development Agency

Current obstacles

Physics limits

How it works

Infrared cameras watch for rocket plumes

Close to Earth, hard to kill

Tracks good enough to aim by

Handing tracks to the network

Spec sheet

Update log

Fri 19 Dec 2025

Tue 16 Jan 2024

Mon 18 Jul 2022

About Space Development Agency