The highly anticipated Delta IV Heavy rocket at Vandenberg Air Force Base will get another chance at liftoff Tuesday evening. The United Launch Alliance rocket blastoff is planned for 5:57 p.m. from Space Launch Complex-6 on South Base.
The team tried twice last week, but technical glitches foiled both attempts Friday and Saturday nights, leading to a delay of more than a week.
The rocket will carry a National Reconnaissance Office spacecraft into orbit for a mission dubbed NROL-71. Due to the top-secret payload, the launch window was not released, but lasts less than an hour. Equipped with three common booster cores strapped side by side, the Delta IV Heavy is designed to carry some of the county’s biggest national security payloads.
The rocket employs the launch pad initially built for the West Coast space shuttle program canceled before any liftoffs occurred. Launch spectators may get an extra gift from this mission since the Delta IV Heavy’s departure near sunset could create a twilight phenomenon if conditions are suitable.
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A twilight phenomenon occurs following rocket or missile launches 60 minutes before sunrise or after sunset when exhaust particles from propellant left in the contrail of a launch vehicle condenses, freezes and then expands in the less dense upper atmosphere.
The exhaust plume mixed with high sunlight can create a colorful contrail visible from miles away, and sometimes is mistaken for a failed launch. In some cases, the twilight effect is more dramatic for those several hundred miles away from Vandenberg
A Falcon 9 rocket launch last year generated the twilight phenomenon, leaving some Los Angeles area residents to think it was an unidentified flying object. For safety reasons, Jalama Beach County Park will be evacuated several hours ahead of the launch.
However, several locations around the Lompoc Valley offer views of the launch, including the western end of Ocean Avenue, the peak of Harris Grade Road, near the intersection of Moonglow and Stardust roads and other sites.