United Launch Alliance (ULA) has launched the dual-manifested SES-20 & 21 telecommunication satellites on the final Atlas V 531 rocket to a near-circular geosynchronous orbit (GSO). The Atlas V launched from Space Launch Complex-41 (SLC-41) at the Cape Canaveral Space Force Station (CCSFS) on Oct. 4 at the opening of the window at 5:36 PM EDT (21:36 UTC).
The 45th Weather Squadron first predicted an 80% chance of favorable weather, which improved to 90% just over five hours ahead of the opening of the window.