Delta IV Heavy rocket
A Delta IV Heavy rocket sits in its mobile service tower at Space Launch Complex-6 on south Vandenberg Air Force Base. The next liftoff attempt will occur at 11:05 a.m. Saturday, United Launch Alliance representatives said. (United Launch Alliance photo)

A Delta IV Heavy rocket received the green light to begin counting down for a Saturday morning launch from Vandenberg Air Force Base.

Liftoff of the massive booster built by United Launch Alliance is planned for 11:05 a.m. from Space Launch Complex-6 on South Base. The launch window remains top secret but is expected to last less than an hour. 

“The Launch Readiness Review at Vandenberg Air Force Base in California today culminated with officials giving a unanimous ‘go’ for liftoff of the United Launch Alliance Delta IV Heavy rocket on the NROL-71 mission for the National Reconnaissance Office on Saturday,” ULA representatives said Friday.

“The LRR, led by Lou Mangieri, ULA’s NROL-71 launch director, assessed all aspects of mission readiness, discussed the status of pre-flight processing work, heard technical overviews of the countdown and flight, and previewed the weather forecast.”

Weather has improved slightly from forecasts provided earlier in the week, with just a 30-percent likelihood conditions will prevent blastoff, ULA representatives said.

Ground-level winds exceeding limits are the concern.

If the launch countdown Saturday is canceled, weather conditions worsen for a Sunday attempt with a 60-percent likelihood of a delay, again due to ground-level winds. 

SLC-6, once planned for the West Coast space shuttle program, sits in a valley at the southern end of Vandenberg and is not visible like other launch pads.

However, several sites around the Lompoc Valley will provide views of the booster once its climbs above the mountains. 

The Hawks Nest viewing site, off Highway 1 near Azalea Lane, for members of the public will be open to the public at 10 a.m. Saturday. 

People with regular base access can view the launch at 35th Street and New Beach Road.

Other popular viewing sites include the peak of Harris Grade Road, western end of Ocean Avenue and an area near Moonglow and Stardust roads. 

For safety reasons related to the launch, Jalama Beach County Park, just south of Vandenberg, will be evacuated from 6 a.m. to 12:15 p.m. 

This launch first aimed for blastoff Dec. 7 but has been delayed by technical troubles and unfavorable weather. 

Live launch updates and a webcast can be found by clicking here.

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