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SpaceXFalcon 9 Block 5Space Launch Complex 4E, Vandenberg SFB, CA, USA

SDA Tranche 1 Transport Layer B

Launched

September 10, 2025 · 14:12 UTC

Launch SuccessfulWeather 100% go
SDA-T1TL-B

Image: SpaceX

Summary

SDA Tranche 1 Transport Layer B launched on a SpaceX Falcon 9 Block 5 from Space Launch Complex 4E, Vandenberg SFB, CA, USA on September 10, 2025 at 14:12 UTC. The launch window ran from 14:12 to 14:27 UTC. It was SpaceX's 566th launch, 117th this year and humanity's 7,058th orbital launch attempt. It was the 474th Falcon 9 Block 5 flight and the 113th this year. Booster B1093 flew for the 6th time and landed at Of Course I Still Love You. The payload was bound for Polar Orbit (PO). The tracked orbit of Praetorian SDA-602, one of 21 catalogued objects, from September 23, 2025, was 950 × 959 km inclined 81.3°. 21 objects from this launch are catalogued, all of them payloads.

Watch
Vehicle
Falcon 9 Block 5 · SpaceX
Booster
  • B1093 · flight 6 · Autonomous Spaceport Drone Ship at Of Course I Still Love You · landed209/217 landed here · 27 days after its previous flight, Starlink Group 17-4 · 650 km downrange
Mission
Government/Top Secret · Polar Orbit (PO)for SDA
Milestone
474th Falcon 9 Block 5 flight · 113th this yearSpaceX's 566th launch117th this yearhumanity's 7,058th orbital launch attempt209th orbital launch attempt this year

Flight preview

Simulate in Flight Club

Orbit: as tracked

81.3°Inclination
950 × 959 kmPerigee × apogeefrom mean elements
104.0 minPeriodfrom mean elements
257.8°Ascending node
387 d agoElement epoch2025-09-23 14:00 UTC · stale

Praetorian SDA-602 · NORAD 65565 · 2025-203 · Space-Track · tracking 1 of 21 objects

Show the numbers for orbit elements
Object
PRAETORIAN SDA_601
Object ID
2025-203A
Epoch
2025-09-23 14:00:01 UTC
Mean motion
13.84632088 rev/day
Eccentricity
0.00059416
Inclination
81.2986°
Ascending node
257.7646°
Arg. of perigee
185.8389°
Mean anomaly
239.7801°
Element set
999
Rev at epoch
130
B*
-0.041438188

Perigee, apogee and period are Kepler figures from the catalogued mean elements, not a propagated state. Published orbit: PO.

Flight timeline

21 steps, T−38 min to T+56 min 51 s
  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. T−0Liftoff
  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

Catalogued objects

21 catalogued: 21 payloads; 21 still in orbit

  • Praetorian SDA-602 · NORAD 65565 · in orbit
  • Praetorian SDA-603 · NORAD 65566 · in orbit
  • Praetorian SDA-604 · NORAD 65567 · in orbit
  • Praetorian SDA-605 · NORAD 65568 · in orbit
  • Praetorian SDA-606 · NORAD 65569 · in orbit
  • Praetorian SDA-607 · NORAD 65570 · in orbit
  • Praetorian SDA-608 · NORAD 65571 · in orbit
  • Praetorian SDA-609 · NORAD 65572 · in orbit
  • Praetorian SDA-610 · NORAD 65573 · in orbit
  • Praetorian SDA-611 · NORAD 65574 · in orbit
  • Praetorian SDA-612 · NORAD 65575 · in orbit
  • Praetorian SDA-613 · NORAD 65576 · in orbit
Show 9 more payloads
  • Praetorian SDA-614 · NORAD 65577 · in orbit
  • Praetorian SDA-615 · NORAD 65578 · in orbit
  • Praetorian SDA-616 · NORAD 65579 · in orbit
  • Praetorian SDA-617 · NORAD 65580 · in orbit
  • Praetorian SDA-618 · NORAD 65581 · in orbit
  • Praetorian SDA-619 · NORAD 65582 · in orbit
  • Praetorian SDA-620 · NORAD 65583 · in orbit
  • Praetorian SDA-621 · NORAD 65584 · in orbit
  • Praetorian SDA-601 · NORAD 65585 · in orbit

Data from J. McDowell, planet4589.org

About this launch

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.

Official page: SpaceX

Pad

Map of Space Launch Complex 4E

Space Launch Complex 4E, Vandenberg SFB, CA, USA

215th launch from Space Launch Complex 4E, 41st this year · 829th from Vandenberg SFB, CA, USA

Local pad time at liftoff: Sep 10, 7:12 AM PDT, in daylight

303 launches from this pad · 919 from Vandenberg SFB, CA, USA

3 days 20 hours after the previous launch from this pad

All launches from Vandenberg SFB, CA, USAOpen in maps

Updates

Launch success.

Cosmic_Penguin · Sep 10, 2025 · source

Show 9 earlier updates

  • 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

Questions

When did SDA Tranche 1 Transport Layer B launch?

SDA Tranche 1 Transport Layer B launched on September 10, 2025 at 14:12 UTC. The launch window ran from 14:12 to 14:27 UTC.

Where can I watch SDA Tranche 1 Transport Layer B?

Coverage: SpaceX SDA Tranche 1 Transport Layer B; SpaceX - Falcon 9 - Tranche 1 Layer B - SLC-4E - Vandenberg SFB, CA - September 10, 2025; Watch live: SpaceX launches SDA's first 21 Tranche 1 satellites from California on Falcon 9 rocket. Watch the replay

What rocket launched SDA Tranche 1 Transport Layer B?

Falcon 9 Block 5, flown by SpaceX. Falcon 9 Block 5 spec sheet

Where did SDA Tranche 1 Transport Layer B launch from?

Space Launch Complex 4E, Vandenberg SFB, CA, USA. Liftoff was Sep 10, 7:12 AM PDT local time at the pad.

Did the booster land?

Booster B1093 flew for the 6th time and landed at Of Course I Still Love You.

What orbit did SDA Tranche 1 Transport Layer B reach?

The tracked orbit of Praetorian SDA-602, one of 21 catalogued objects, from September 23, 2025, was 950 × 959 km inclined 81.3°.

How many satellites did SDA Tranche 1 Transport Layer B launch?

21 payloads from this launch are catalogued, 21 of them still in orbit (Data from J. McDowell, planet4589.org).