SpaceX is scheduled 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 set 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 on its X account, beginning about 10 minutes prior to liftoff. However, the stream may end 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 return to Earth about 8 minutes after liftoff, landing on the drone ship “Of Course I Still Love You” stationed in the Pacific Ocean. This will be the eighth launch and landing for this particular booster, according to a SpaceX mission description.

Tonight’s mission, designated NROL-186 by the NRO, is 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,” marking a departure from the traditional U.S. spy satellite strategy, which relies on large, highly capable spacecraft that are expensive and time-consuming to develop and build.

Details about the NROL-186 satellites, including their specific capabilities and missions, are classified, as the NRO releases limited information about its spacecraft.

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. So far, 47 of the rocket’s 65 launches in 2024 have been dedicated to building out SpaceX’s Starlink broadband megaconstellation in low Earth orbit.