SpaceX is poised to launch a pioneering set of spy satellites for the U.S. government early Wednesday morning (May 22).

A Falcon 9 rocket is scheduled to loft the NROL-146 mission for the National Reconnaissance Office (NRO) from California’s Vandenberg Space Force Base Monday, during a 2.5-hour window that opens at 4 a.m. EDT (0800 GMT; 1 a.m. local California time).

SpaceX will webcast the launch via its X account, beginning about 10 minutes before the window opens.

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We don’t know much about the payloads going up on NROL-146, which isn’t surprising; the NRO typically reveals little about its satellites‘ activities and capabilities.

In a mission description, NRO states that NROL-146 will be “the first launch of NRO’s proliferated architecture.” The agency explains a bit more about that architecture when discussing the mission’s tagline, “Strength in Numbers.”

That motto “describes the NRO’s new strategy of a proliferated overhead architecture — numerous, smaller satellites designed for capability and resilience,” NRO officials wrote.

It’s therefore probably safe to assume that multiple small satellites are going up on NROL-146, rather than a single bulky spacecraft.

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The Falcon 9’s first stage will come safely back to Earth today, if all goes according to plan. It’s scheduled to land about 8 minutes after liftoff on the SpaceX droneship Of Course I Still Love You, which will be stationed in the Pacific Ocean. It will be the 16th launch and landing for this particular booster, according to a SpaceX mission description.

That description doesn’t say where the satellites are headed or give an expected time for their deployment, details that SpaceX usually includes for non-classified missions.

Wednesday morning’s launch will be the 52nd orbital liftoff for SpaceX already in 2024. Of this year’s 51 launches to date, 36 have been devoted to building out the company’s Starlink broadband constellation.