SpaceX F9 : SDA T1TL-E : VSFB SLC-4E : Q1 2026

[AndrewM]

Discussion thread for the US Space Development Agency’s fourth(?) Tranche 1 Transport Layer mission.

SDA LEO Constellations Discussion Thread

Awarded on June 8, 2023 under NSSL Phase 2 with a target launch date in FY25. This is the fourth of 6 Tranche 1 Transport Layer missions launching on a Falcon 9 from Vandenberg. The mission will carry 21 satellites likely from York Space Systems.

Space Systems Command (SSC) recently assigned twelve FY23 National Security Space (NSS) launch service missions under the National Security Space Launch (NSSL) Phase 2 Launch Service Procurement contract. Six missions were awarded to Space Exploration Technologies Corp. (SpaceX) for the Space Development Agency (SDA) Tranche 1 Tracking Layer (T1TL)-B, SDA T1TL-C, SDA T1TL-D, SDA T1TL-E, SDA T1TR-C, and the U.S. Space Force (USSF)-31. Six other missions were awarded to United Launch Alliance (ULA) for the National Reconnaissance Office (NRO)L-64 and NROL-83, the Global Positioning Systems (GPS) III-08, SDA T1TR-B, SDA T1TR-D, and USSF-114.

There are four SDA Tranche 1 Transport Layer launches. SDA’s Transport Layer will provide assured, resilient, low-latency military data and connectivity worldwide to the full range of warfighter platforms. These are the second through fifth launches planned for the Tranche 1 Transport Layer. They will launch using Falcon 9 rockets from the Western range into polar orbit.

ULA and SpaceX continue to provide outstanding launch services with their reliable and innovative launch systems, and we are confident in their ability to maintain the unprecedented 100 percent program success for the NSSL missions assigned for launch in FY25.

[AndrewM]

SDA is aiming for monthly Tranche 1 launches starting with the 1st batch of York satellites (T1TL-B) which launched on September 10th. The 1st batch of Lockheed sats is the second launch which should be T1TL-A in mid-October. The 1st batch of Northrop Grumman sats should follow in November as T1TL-C. If this pattern repeats, the 2nd batch of York satellites should be T1TL-E in December.

Space Development Agency, SpaceX to launch next-gen national security satellites
September 10, 2025

[...]

There are 10 launches planned for Tranche 1, which include six within the Transport Layer and four within the Tracking Layer. Sandhoo said SDA is aiming for a launch cadence of roughly once per month with the next flight expected during the second week of October, this time featuring T1TL satellites from Lockheed Martin.

In August, York confirmed the 2nd batch should launch by the end of the year.

In June, its experimental Dragoon spacecraft flew for SDA, followed in July by a communications satellite called BARD that it built for NASA. Also on deck is a classified project called Tyndal and another SDA transport launch at the end of this year.

https://www.defensenews.com/space/2025/08/25/york-delivers-21-satellites-for-space-development-agency-launch/ [Aug. 25]

[AndrewM]

York confirmed they are still planning on launching their second batch before the end of the year following launch of their 1st batch.

https://www.businesswire.com/news/home/20250912492841/en/York-Space-Systems-Establishes-First-Contact-and-Confirms-Health-of-All-21-Satellites-Launched-for-SDAs-Tranche-1-Transport-Layer-Mission [Sep. 12]

York is the first of the prime contractors selected for the T1TL mission to launch and deploy. York will complete its T1TL contract launch and deployment campaign with an additional 21 satellites later this year. York is proud to continue to support SDA as it fields this critical capability for national security space.

[AndrewM]

Cross-posting as T1TL-E should be the 2nd batch of York satellites.

SES-STA-20251117-00943 [Nov 18]

180-day STA for Fairbanks, AK Earth Station for LEOPs for York-supplied USPWSA-T1TL Satellites

SES-STA-20251117-00661 [Nov 18]

2nd 30-day STA for Fairbanks, AK Earth Station for LEOPs for York-supplied USPWSA-T1TL Satellites

Requires an FCC account to view narrative.

[AndrewM]

With a monthly launch cadence and the 1st Northrop Grumman batch (T1TL-A) scheduled to launch ahead of this mission, this is now NET Q1 2026.