SpaceX launches 1st 21 satellites for advanced new US military constellation

SpaceX sent 21 satellites to orbit from California today (Sept. 10), beginning the buildout of an advanced new constellation for the U.S. military.

A Falcon 9 rocket launched from Vandenberg Space Force Base today at 10:12 a.m. EDT (1412 GMT; 7:12 a.m. local California time), kicking off the Space Development Agency's (SDA) first "Tranche 1 Transport Layer" (T1TL) mission.

The T1TL network will eventually consist of 126 satellites in low Earth orbit (LEO), which "will provide global communications access and deliver persistent regional encrypted connectivity in support of warfighter missions around the globe," according to an SDA explainer.

The SDA was established in March 2019, tasked with helping the U.S. military field highly capable and cost-effective space assets on rapid timelines.

"Recognized as the Department of Defense's constructive disruptor for space acquisition, the Space Development Agency (SDA) will quickly deliver needed space-based capabilities to the joint warfighter to support terrestrial missions through development, fielding, and operation of the Proliferated Warfighter Space Architecture," the SDA's website reads.

The Proliferated Warfighter Space Architecture (PWSA) is an envisioned LEO constellation of hundreds of small satellites, which will be linked via optical communications. This constellation will consist of seven "layers" — battle management, custody, deterrence, navigation, (missile) tracking, transport and support.

If all goes to plan, the PWSA will be refreshed and updated every two years, via the launch of a new "tranche" of satellites.

With today's launch, assembly of the transport layer's first tranche is underway. The 21 satellites that went up today were built by Denver-built York Space Systems. The SDA has contracted York, Northrop Grumman and Lockheed Martin to build 42 spacecraft apiece for this layer's first tranche.

The Falcon 9's first stage came back to Earth as planned today, landing at sea on the SpaceX drone ship "Of Course I Still Love You" about 8.5 minutes after liftoff. It was the sixth launch and landing for this particular booster, B1093, according to SpaceX.

The rocket's upper stage, meanwhile, continued carrying the 21 satellites to LEO. It's unclear exactly when and where they're scheduled to be deployed. SpaceX's mission description doesn't provide that information, and the SDA opted not to permit SpaceX to broadcast views of the payload or the Falcon 9 second stage during flight.