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SDA Tranche 1 Transport Layer B

© SpaceX

All launches
SpaceX

SDA Tranche 1 Transport Layer B

Success

Falcon 9 Block 5
T-minus to liftoff

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00

HOURS

:

00

MINUTES

:

00

SECONDS

Sep 10, 14:12:11 UTC
StatusSuccess
VehicleFalcon 9 Block 5
OrbitPolar Orbit
PadSpace Launch Complex 4E
Loading map…

Mission

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.

Launch Timeline

Countdown

T-00:38:00

GO for Prop Load

T-00:35:00

Prop Load

T-00:35:00

Stage 1 LOX Load

T-00:16:00

Stage 2 LOX Load

T-00:07:00

Engine Chill

T-00:01:00

Startup

T-00:01:00

Tank Press

T-00:00:45

GO for Launch

T-00:00:03

Ignition

In-flight

T+00:00:00

Liftoff

T+00:01:12

Max-Q

T+00:02:30

MECO

T+00:02:34

Stage 2 Separation

T+00:02:42

SES-1

T+00:06:24

Entry Burn Startup

T+00:06:47

Entry Burn Shutdown

T+00:08:12

Stage 1 Landing Burn

T+00:08:36

Stage 1 Landing

T+00:08:38

SECO-1

T+00:56:43

SES-2

T+00:56:51

SECO-2

Quick facts

VehicleFalcon 9 Block 5
OrbitPolar Orbit
PadSpace Launch Complex 4E
SiteVandenberg SFB, CA, USA
WindowSep 10, 14:12:00 UTC→Sep 10, 14:27:00 UTC

Vehicle

FamilyFalcon
Height70 m
Diameter3.65 m
Stages2
ReusableYes
LEO capacity22,800 kg
Track record606/607 successful
Landings593/598
Acquiring satellite view…
Trajectory unknown
Space Launch Complex 4E
Vandenberg SFB, CA, USA
34.632, -120.611
Scrub riskLOW
Go90%
Q

Q's read

Weather & scrubLOW risk
Weather Go90%LL2 Go100%Wind4 ktGusts4 ktCloud10%Temp69°F

Limiting rule: No flight through cumulus cloud with top at or above the freezing level.

4000% cloud cover in layer above freezing (14878 ft) — approximated

Reusable Hardware

All boosters →
First Stage · Flight-provenB1093
active6th flight
Flights14
Landings14/14100%
Fastest turn21d 22h
Recovered · ASDS · OCISLY· 650 km downrange
27d 9h since last flight

Falcon 9 booster debuting on Starlink Group 11-11.

Previous flights · 14
  1. #15Starlink Group 15-14+28d 9hOCISLYJul 14, 2026
  2. #14Starlink Group 17-54+46d 12hOCISLYJun 15, 2026
  3. #13Starlink Group 17-36+30d 15hOCISLYApr 30, 2026
  4. #12Transporter 16 (Dedicated SSO Rideshare)+32d 20hOCISLYMar 30, 2026
  5. #11Starlink Group 17-26+34d 8hOCISLYFeb 25, 2026