A SpaceX Falcon 9 rocket stands ready to launch two of SES’ O3b mPOWER satellites on July 21, 2025. SpaceX called that day’s attempt off.

SpaceX aborted the launch of two communications satellites just before liftoff on Monday evening (July 21).

A Falcon 9 rocket topped with two of SES’ O3b mPOWER internet spacecraft was set to launch from Florida’s Cape Canaveral Space Force Station at 5:27 p.m. EDT (2127 GMT) on Monday.

But it didn’t quite happen: SpaceX called an abort just 11 seconds before liftoff. The launch window extended for another 90 minutes or so, but the company soon decided to stand down for the day.

“Standing down from today’s launch of the @SES_Satellites O3b mPOWER mission and now targeting tomorrow, July 22 for liftoff. Vehicle and payload remain healthy,” SpaceX said via X on Monday evening.

At the time of this article’s publication, the company had not yet explained what caused the abort.

The two-hour launch window on Tuesday opens at 5:12 p.m. EDT (2112 GMT). SpaceX will stream the action live via its website and X account, beginning about 15 minutes before liftoff.

Luxembourg-based SES’ mPOWER constellation consists of eight satellites in medium-Earth orbit, all of which have been launched by SpaceX.

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The network is already operational, but it’s not complete; it will eventually feature 13 spacecraft.