Live coverage: Atlas 5 countdown and launch journal

A little more than a year after the Falcon Heavy rocket’s first test flight, SpaceX teams on Florida’s Space Coast are readying the world’s most powerful operational launcher for its second mission Thursday with a commercial communications satellite.

A $1.8 billion U.S. Air Force communications satellite rode a United Launch Alliance Atlas 5 rocket into orbit Wednesday from Cape Canaveral, joining three similar craft perched more than 22,000 miles above Earth to ensure government leaders can remain in contact with military commanders in the worst-case scenario of nuclear war.

NASA, United Launch Alliance and Air Force officials hold the pre-launch news conference for the Delta 2 rocket with the agency’s SMAP environmental satellite from Vandenberg Air Force Base on Jan. 27.