# Tracking Layer by Space Development Agency

Canonical page: https://technooptimist.io/spaceflight/tracking-layer
Frontier: [Spaceflight](https://technooptimist.io/spaceflight.md) · Field: Military space · Company: [Space Development Agency](https://technooptimist.io/companies/space-development-agency.md)
Stage: Pilot (3 of 5: Research → Proto → Pilot → Deploy → Scaling)
Updated: last update 2025-12-19, facts checked 2026-10-11
Goal: Detect and follow every missile in flight, including hypersonic weapons that older warning satellites lose, with hundreds of cheap satellites renewed every two years so no single loss blinds the system.
Status: Tranche 1's 28 tracking satellites await launch, now listed for late 2026; Tranches 2 and 3 under contract.
Next milestone: First Tranche 1 tracking launch, target Q4 2026 (slipped 18 months; originally Apr 2025)

## Milestones

| Status | Milestone | Date | Slip |
| --- | --- | --- | --- |
| Done | Tranche 1: L3Harris and Northrop to build 28 satellites | 18 Jul 2022 |   |
| Done | Tranche 2: 54 satellites from L3Harris, Lockheed, Sierra Space | 16 Jan 2024 |   |
| Done | Tranche 3: 72 satellites, about $3.5B, four builders | 19 Dec 2025 |   |
| Current | First Tranche 1 tracking launch | Q4 2026 | +18 mo (originally Apr 2025) |
| Planned | Tranche 2 tracking satellites launch | Apr 2027 |   |
| Planned | Tranche 3 tracking satellites launch | 2029 |   |

## Upcoming events

- **Q4 2026**: First Tranche 1 tracking launch (slipped 18 mo)
- **Apr 2027**: Tranche 2 tracking satellites launch
- **2029**: Tranche 3 tracking satellites launch

## Most important updates

- **19 Dec 2025**: SDA awards $3.5B for 72 Tranche 3 tracking satellites to Lockheed, Rocket Lab, L3Harris and Northrop. SDA awarded four agreements for 18 satellites each: Lockheed Martin ($1.1B), Rocket Lab (up to $805M), L3Harris (up to $843M) and Northrop Grumman (about $764M). ([our story](https://technooptimist.io/stories/sda-awards-3-5b-for-72-tranche-3-tracking-satellites-to-lockheed-rocket-19531960.md) · [original source](https://breakingdefense.com/2025/12/space-development-agency-awards-four-contracts-worth-3-5b-for-next-gen-missile-tracking-satellites/))
- **16 Jan 2024**: SDA orders 54 Tranche 2 tracking satellites from L3Harris, Lockheed Martin and Sierra Space for $2.5B. SDA picked three companies from nine bidders for its Tranche 2 Tracking Layer: L3Harris ($919M), Lockheed Martin ($890M) and newcomer Sierra Space ($740M), 18 satellites each. ([our story](https://technooptimist.io/stories/sda-orders-54-tranche-2-tracking-satellites-from-l3harris-lockheed-a295c648.md) · [original source](https://www.defensenews.com/battlefield-tech/space/2024/01/16/space-development-agency-to-buy-54-missile-tracking-satellites/))
- **18 Jul 2022**: SDA awards L3Harris and Northrop Grumman about $1.3B for 28 Tranche 1 missile-tracking satellites. The Space Development Agency awarded Tranche 1 Tracking Layer contracts: 14 low-orbit infrared satellites each from L3Harris ($700M) and Northrop Grumman. ([our story](https://technooptimist.io/stories/sda-awards-l3harris-and-northrop-grumman-about-1-3b-for-28-tranche-1-42156892.md) · [original source](https://www.airandspaceforces.com/sda-awards-1-3b-to-l3harris-and-northrop-grumman-for-28-missile-tracking-satellites/))

## Current obstacles

- **Two years behind the first plan**: Tranche 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 quality**: Turning 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 patch**: From 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 stops**: A 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

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

Provenance: reported = stated by the company; estimated = our estimate; sample = a sample figure.

## About Space Development Agency

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.

- Founded: 2019
- Headquarters: US
- Status: government
- Website: https://www.sda.mil
- People: Gurpartap "GP" Sandhoo (Director, Space Development Agency)
- Partners, customers, investors: York Space Systems (supplier); Lockheed Martin (supplier); Northrop Grumman (supplier); L3Harris (supplier); Sierra Space (supplier); Rocket Lab (supplier)

Company page: https://technooptimist.io/companies/space-development-agency.md

## Related programs

More from Space Development Agency:

- [Proliferated Warfighter Space Architecture (Tranche 1)](https://technooptimist.io/spaceflight/proliferated-warfighter-space-architecture-tranche-1.md) (Deploy)

Everything in Spaceflight: https://technooptimist.io/spaceflight.md

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