Watch the Falcon Heavy fire up its engines

The Starlink 17-12 mission will send the two dozen broadband internet satellites into a polar, low Earth orbit. SpaceX is targeting liftoff from pad 4E at Vandenberg Space Force Base no earlier than Friday, Sept. 19, at 9:31 a.m. PDT (12:31 p.m. EDT / 1631 UTC).

The U.S. Air Force’s fourth new-generation SBIRS missile warning satellite is headed for geosynchronous orbit after lifting off from Cape Canaveral at 7:48 p.m. EST Friday (0048 GMT Saturday), after a one-day delay caused by a troublesome fill-and-drain valve.

SpaceX hoisted its Falcon 9 rocket upright Sunday evening, hours before launching on a commercial resupply mission to the International Space Station. Technicians installed time-sensitive supplies into the Dragon cargo capsule earlier in the day.