SpaceX is set to launch another set of U.S. spy satellites tonight (June 28).

A Falcon 9 rocket carrying payloads for the National Reconnaissance Office (NRO) is scheduled to lift off from California’s Vandenberg Space Force Base during a two-hour window that opens at 11:14 p.m. EDT (8:14 p.m. local California time; 0314 GMT on June 29).

SpaceX will webcast the launch via its X account beginning about 10 minutes prior to liftoff. However, the company may end the stream relatively early at the request of the NRO, which builds and operates the United States’ fleet of spy satellites.

If all goes according to plan, the Falcon 9’s first stage will come back to Earth about 8 minutes after liftoff tonight, landing on the drone ship Of Course I Still Love You, which will be stationed in the Pacific Ocean. It will be the eighth launch and landing for this particular booster, according to a SpaceX mission description.

Tonight’s mission, which the NRO calls NROL-186, will be the second dedicated to building out the agency’s new “proliferated architecture.”

This network will consist of “numerous, smaller satellites designed for capability and resilience,” the NRO wrote in an NROL-186 mission description. That’s a departure from the traditional U.S. spysat strategy, which depends on big, highly capable spacecraft that are expensive and time-consuming to develop and build.

We don’t know exactly what the NROL-186 satellites will be doing, or what they’re capable of; the NRO releases few details about its spacecraft and their activities.

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SpaceX also launched the first “proliferated architecture” batch, on the NROL-146 mission, which lifted off atop a Falcon 9 from Vandenberg on May 22 of this year.

Tonight’s launch will be the 66th Falcon 9 mission of the year already. Forty-seven of the rocket’s 65 launches in 2024 have been dedicated to building out SpaceX’s Starlink broadband megaconstellation in low Earth orbit.