SpaceX launches a batch of Tranche 1 Transport Layer satellites for SDA on Oct. 15. Photo: SpaceX

The second batch of U.S. Space Force Space Development Agency (SDA) Tranche 1, Transport Layer communications satellites launched on Wednesday from Vandenberg Space Force Base, California.

A SpaceX Falcon 9 rocket carried the 21 Lockheed Martin satellites. Last month, a Falcon 9 launched the first Tranche 1, Transport Layer satellites — 21 by York Space Systems – from Vandenberg.

Space Force and SDA public affairs offices have been on a shoestring since the Oct. 1 federal shutdown, and neither office put out statements on Wednesday’s launch. SpaceX did, however, stating that the launch occurred at 4:06 p.m. Pacific time.

Tranche 1, Transport Layer satellites are to be the first to provide utility to military forces in the field through high-speed space to Earth Link 16 communications links.

The satellites are part of SDA’s envisioned Proliferated Warfighter Space Architecture (PWSA), which also includes a Tracking Layer to counter advanced missiles, such as hypersonic ones. SDA expects to have all 154 Tranche 1 satellites — 128 for the Transport Layer and 26 for the Tracking Layer–in orbit in the next nine months, as the agency plans to launch once per month until the constellation is up.

SpaceX said that it will launch 10 Tranche 1 missions.

SDA Space Operations Centers at Grand Forks Air Force Base, North Dakota, and Redstone Arsenal, Alabama, are to manage the Tranche 1 satellites.

“Beginning in 2027, T1 [Tranche 1] will provide an initial warfighting capability through the PWSA to deliver regional persistence for tactical military data channels like Link 16, along with advanced missile tracking and missile warning, and beyond-line-of-sight targeting plus demonstration of UHF and S-band tactical satellite communications,” Space Force has said. “This timeline supports warfighter needs communicated to SDA by U.S. combatant commands through the agency’s Warfighter Council.”

SDA has used Tranche 0, Transport Layer satellites, launched in April 2023, to test Link 16 over allied airspace, as the agency awaits Federal Aviation Administration approval for testing over U.S. airspace.

This story was first published by Defense Daily