Falcon 9 Block 5 | SDA Tranche 1 Transport Layer B

Tranche 1 Transport Layer B is one of six missions by the United States Space Force Space Development Agency (SDA) for the Proliferated Warfighter Space Architecture (PWSA) Tranche 1 Transport Layer constellation, which will provide assured, resilient, low-latency military data and connectivity worldwide to the full range of warfighter platforms from Low Earth Orbit satellites. The constellation will be interconnected with Optical Inter-Satellite Links (OISLs) which have significantly increased performance over existing radio frequency crosslinks. It is expected to operate over Ka band, have stereo coverage and be dynamically networked for simpler hand-offs, greater bandwidth and fault tolerance. This launch carries 21 satellites manufactured by York Space Systems.

Government/Top Secret · Polar Orbit (PO)

• B1093 · flight 6 · Autonomous Spaceport Drone Ship @ Of Course I Still Love You · landed ✓ · last flew Falcon 9 Block 5 | Starlink Group 17-4 · zone record 209/217

• SpaceX SDA Tranche 1 Transport Layer B — The Space Devs
• SpaceX - Falcon 9 - Tranche 1 Layer B - SLC-4E - Vandenberg SFB, CA - September 10, 2025 — SPACE AFFAIRS
• Watch live: SpaceX launches SDA's first 21 Tranche 1 satellites from California on Falcon 9 rocket — Spaceflight Now
• Space Development Agency’s First Tranche 1 Mission — SpaceX

1. T−38MGO for Prop Load
2. T−35MStage 1 LOX Load
3. T−35MProp Load
4. T−16MStage 2 LOX Load
5. T−7MEngine Chill
6. T−1MStartup
7. T−1MTank Press
8. T−45SGO for Launch
9. T−3SIgnition
10. P0DLiftoff
11. T+1M12SMax-Q
12. T+2M30SMECO
13. T+2M34SStage 2 Separation
14. T+2M42SSES-1
15. T+6M24SEntry Burn Startup
16. T+6M47SEntry Burn Shutdown
17. T+8M12SStage 1 Landing Burn
18. T+8M36SStage 1 Landing
19. T+8M38SSECO-1
20. T+56M43SSES-2
21. T+56M51SSECO-2

• Launch success.

  Cosmic_Penguin · 9/10/2025 · source

• Liftoff.

  Cosmic_Penguin · 9/10/2025 · source

• Unofficial Re-stream by SPACE AFFAIRS has started

  LL2 · 9/10/2025 · source

• Now targeting Sep 10 at 14:12:11 UTC

  hitura-nobad · 9/10/2025 · source

• Tweaked T-0.

  Cosmic_Penguin · 9/9/2025 · source

• GO for launch.

  Cosmic_Penguin · 9/5/2025 · source

• Added launch window.

  Cosmic_Penguin · 9/3/2025 · source

• NET September 10.

  Cosmic_Penguin · 8/14/2025 · source

• NET July.

  Cosmic_Penguin · 7/15/2025 · source

• NET late summer. (order of launches per https://sam.gov/opp/7111789df59149cd81596402c35e33d3/view P.12)

  Cosmic_Penguin · 3/8/2025 · source