The Sea Launch vessels have departed Sea Launch Home Port in Long Beach, Calif., for the equator, in preparation for the launch of the Intelsat 21 satellite. Liftoff is planned for 23:56 Pacific Daylight Time (PDT) on Thursday, August 16 (06:56 UTC/GMT on August 17), at the opening of a 58-minute launch window.

Upon their arrival at the launch site at 154 degrees West longitude, the Sea Launch team will initiate a 72-hour countdown. After ballasting the launch platform Odyssey to launch depth, the team will roll out and erect a Zenit-3SL rocket on the launch pad, execute final tests and proceed with fueling operations and launch.

Prior to fueling, all personnel on the launch platform will transfer to the Sea Launch Commander for the duration of the mission. The team monitors both marine and launch operations remotely from the ship, positioned about four miles up range of the platform.

On launch day, the Zenit-3SL vehicle will lift the 5,984 kilogram (13,192 lb.) Intelsat 21 spacecraft into a defined high-perigee geosynchronous transfer orbit. Based on the BSSI 702MP platform, Intelsat 21 will refresh capacity for one of Latin America's most popular media distribution neighborhoods, serving direct-to-home (DTH) and cable programmers.

The satellite is designed to provide 18 or more years of service and features C-band services for North America, South America and Europe, and Ku-band services for North America, the Caribbean, Brazil and Europe.

Replacing Intelsat 9, Intelsat 21 also features a Ku-band mobility beam, providing coverage across the South Atlantic to Intelsat's maritime and aeronautical customers. Intelsat's global mobility platform is scheduled for completion in early 2013. The satellite's final orbital location will be 302 degrees East longitude.