SDA T1TL-C: SpaceX Launches 21 US Military Communication Satellites

A SpaceX Falcon 9 rocket launched at 2306 UTC on Oct. 15, from Space Launch Complex 4E at Vandenberg Vandenberg Space Force Base in California, deploying 21 satellites for the U.S. Space Force’s Space Development Agency (SDA) Tranche 1 Transport Layer (T1TL) constellation. This T1TL-C mission marked the second deployment of the T1TL network, with the satellites built by Lockheed Martin and designed to provide global, low-latency military data connectivity through optical inter-satellite links.

The Falcon 9 first stage booster B1093, which completed its seventh flight, successfully landed on the drone ship "Of Course I Still Love You" positioned in the Pacific Ocean, about 8 minutes after liftoff. B1093 also launched SpaceX's first T1TL mission on Sept. 10, as well as five flights carrying the company's Starlink broadband satellites.

The rocket's second stage meanwhile, flying on a southerly trajectory, placed the 21 satellites into a polar low Earth orbit less than an hour after launch.

The 21 satellites are part of the SDA’s Proliferated Warfighter Space Architecture (PWSA), designed to enable beyond-line-of-sight, secure, real-time communication for military forces worldwide by relaying data through a mesh network. The Transport Layer is intended to expand the range of the U.S. military’s Link 16 tactical data network to virtually any location on Earth.

The satellites were manufactured by Lockheed Martin, which secured a $700 million contract in 2022 to produce 42 satellites for Tranche 1. The spacecraft buses were supplied by Terran Orbital, a Lockheed Martin subsidiary  This mission was the second of six planned T1TL launches for Tranche 1, which will eventually include 126 Transport Layer satellites and 28 Tracking Layer satellites.

The first T1TL mission launched on September 10, 2025, carrying 21 satellites built by York Space Systems. The SDA, established in 2019, aims to reduce reliance on large geostationary satellites by deploying smaller, commercially built spacecraft in low Earth orbit using rapid acquisition methods and mostly Elon Musk SpaceX's efficient rocket and satellite capabilities.