ULA Atlas V rolls out to Cape Canaveral pad ahead of late-night launch

A United Launch Alliance Atlas V rocket set to its most powerful configuration rolled out to its Cape Canaveral Air Force Station pad Monday, setting the stage for a late-night blastoff with a spacecraft destined to join a military constellation.

The 197-foot-tall rocket equipped with five strap-on solid rocket motors rolled out to Launch Complex 41 just before noon and is expected to take flight during a two-hour window that opens at 12:15 a.m. Wednesday.

“Unlike some of the other launch vehicles that you see, including ours, that kind of lumber off the pad, this one will jump off the pad and clear the tower really quick,” Gary Wentz, a vice president at ULA, said during a pre-launch briefing Monday. “So if you blink, you’ll miss it.”

On board: The Air Force‘s Advanced Extremely High Frequency 4 communications satellite, part of a $15 billion constellation designed to improve communications for military forces of the U.S., Canada, the Netherlands and the United Kingdom. The AEHF system was developed by Lockheed Martin and is expected to eventually feature six satellites.

Atlas V will be tasked with delivering AEHF-4 to geosynchronous transfer orbit.

Weather, meanwhile, looks solidly favorable with 45th Weather Squadron forecasters anticipating 80 percent “go” conditions during the window. The presence of cumulus cloud cover was noted as the primary concern.

Wednesday’s mission marks the final 2018 launch for ULA’s operations at the Eastern Range. Out west at Vandenberg Air Force Base in California, however, ULA teams in December are scheduled to launch a three-core Delta IV Heavy with a National Reconnaissance Office mission known as NROL-71.

Join floridatoday.com/space/ for countdown updates and chat at 11:30 p.m. Tuesday, including streaming of ULA’s launch webcast starting about 20 minutes before liftoff. The augmented reality-powered 321 LAUNCH app will also include live coverage of the mission.