A Falcon 9 rocket carrying 21 military satellites stayed on the ground early Thursday. SpaceX had aimed to launch at 12:54 a.m. PT, or 3:54 a.m. ET, from Vandenberg Space Force Base in California.

The launch now sits at no earlier than Saturday, Oct. 10, at 7:29 UTC, according to the trackers Space Launch Schedule and Space Launch Live. That is 12:29 a.m. PT, or 3:29 a.m. ET. Their logs show two new one-day delays posted Wednesday: first to Friday, then to Saturday. No reason for the delays was given in either listing.

This mission has slipped many times. On Monday, Oct. 5, the countdown was put on hold and the launch was scrubbed for the day, Space Launch Schedule's log shows. The launch then moved to Tuesday, then to Thursday, and now to Saturday.

The satellites belong to the Space Development Agency, part of the U.S. Space Force. They will form the fourth orbital plane of a network called the Proliferated Warfighter Space Architecture, Edhat reported. It is a mesh of satellites in low orbit linked by laser beams. The goal is fast, secure military communications around the world, along with missile warning and tracking. Northrop Grumman built the 21 satellites.

This is the fourth of nine Tranche 1 missions that Falcon 9 will fly for the agency.

The booster, B1103, is set for its sixth flight, according to Space Launch Live. It last flew Aug. 12. About eight to 10 minutes after liftoff, it should land back at Vandenberg's Landing Zone 4.

That landing can be loud. People in Santa Barbara, San Luis Obispo and Ventura counties may hear one or more sonic booms, depending on weather, Edhat reported.

SpaceX streams its launches live on its website and on X, starting about 10 minutes before liftoff. Weather at the pad looked fine for Saturday, with overcast skies and no rain in the forecast, Space Launch Schedule said.

What we know: The launch did not happen Thursday and is now set for early Saturday.
What we don't: Why SpaceX keeps moving the date.