The Mobile Assembly Shelter (MAS) is retracted from its position at Space Launch Complex-6 at Vandenberg Space Force Base
The Mobile Assembly Shelter is retracted from its position at Space Launch Complex-6 at Vandenberg Space Force Base. The MAS protects the rocket and payload during processing ahead of the United Launch Alliance Delta IV Heavy rocket carrying the National Reconnaissance Office NROL-91 mission. (United Launch Alliance photo)

Another era will close at Vandenberg Space Force Base with the departure of the final Delta IV Heavy rocket from a launch pad with a storied, and seemingly jinxed, history.

Liftoff of the United Launch Alliance Delta IV Heavy rocket is planned for 2:53 p.m. Saturday from Space Launch Complex-6 on the South Base.

Since the rocket will lift a top-secret payload into orbit, the actual launch window remains classified, but it would not extend after 4:15 p.m., officials have said. The launch opportunity is likely to be much shorter, however, based on past missions.

“We’re really excited to be here to launch that last Delta IV Heavy from out here at Vandenberg,” said Col. Chad Davis, from the National Reconnaissance Office’s space launch office. “It’s going to be a fantastic experience, I think, so I’m really looking forward to it.”

The team has spent this week completing last-minute reviews and other chores ahead of the countdown for the mission labeled NROL-91.

“We’re in great condition,” said Gary Wentz, ULA’s vice president of government and commercial programs. “We’re not working any issues for Saturday’s launch.”

He offered advice for those hoping to view the massive rocket as it climbs away from Vandenberg and makes history.

“What I would tell you is, don’t look at this launch through a camera,” Wentz said, adding that there will be plenty of images and video available on the Internet afterward. “Just savor that launch because it’s a great opportunity to see it.”

Weather remains ready to accommodate the NRO mission with just a 10% likelihood that conditions — identified as liftoff winds — would prevent the launch Saturday or, if it slips 24 hours, on Sunday.

SLC-6 sits in a valley near the most southern end of the base and is not visible from around the Lompoc Valley, unlike other launch sites. Popular viewing sites remain the western end of Ocean Avenue, around Vandenberg Village, the peak of Harris Grade Road and other locations.

Jalama Beach County Park just south of Vandenberg reportedly will not be evacuated for this launch.

The Delta IV Heavy, standing 233 feet tall, employs three Common Booster Cores strapped side by side to carry some of the nation’s heftiest payloads.

Saturday’s departure will mark the final Delta rocket launch from Vandenberg as ULA gets set to retire the family of boosters as a step toward developments of the Vulcan Centaur rocket.

This mission marks the fifth Delta IV Heavy launch from Vandenberg, and the 95th and final launch of a Delta rocket from Vandenberg where earlier versions were dubbed Delta II and III. 

“For us, seeing the Delta launch from Vandenberg is bittersweet for sure,” said Col. Bryan Titus, a vice commander for Vandenberg’s Space Launch Delta 30. “We’re sorry to it go. We’re excited to support the mission.”

The Air Force first eyed SLC-6 — pronounced Slick-Six— as the home for the Manned Orbiting Lab, essentially a military space station, in the 1960s. But the program ended before any launches occurred.

A new chapter came with the West Coast Space Shuttle Program, also ended before any liftoffs took place. That cancellation followed the loss of the Challenge shuttle.

A much smaller rocket actually holds the title of being the first launch from SLC-6. But the many-named program — Lockheed Launch Vehicle, then Lockheed Martin Launch Vehicle and then Athena — ended. The program experienced doomed missions, some blamed on the rocket and at least one pinpointed as a satellite problem.

Looking for a home for the Delta IV family of rockets led to yet another use for the SLC-6 keeping the site active for two decades and home to nine previous Delta IV launches of the medium and heavy versions. 

“SLC-6 is iconic here. It’s legendary. It’s kind of what people think about when they think about Vandenberg. It’s had many lives,” Titus said. “I think that everyone here at Vandenberg has a warm spot in their heart for that place, and we’re going to make sure that it’s continued to be utilized, but we don’t know exactly what it’s going to look like.”

A new tenant could find a use for SLC-6 as other launch service providers have eyed the facility, Titus said.

“There’s a lot of infrastracture there. I’m fairly confident that it will be utilized. We just don’t know exactly how yet,” he added.

Live updates of launch countdown milestones will be available at Additionally, the webcast can be found at and is scheduled to start at 2:33 p.m. on launch day.

Noozhawk North County editor Janene Scully can be reached at Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.

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Janene Scully | Noozhawk North County Editor

Noozhawk North County editor Janene Scully can be reached at