Delta IV Heavy Rocket Launch From Vandenberg AFB Scrubbed, Pushed To Thursday

GettyImages-1015503676 (1) — The Delta IV Heavy rocket launch has been postponed to Thursday. Pictured: In this handout provided by NASA, The United Launch Alliance Delta IV Heavy rocket launches NASA's Parker Solar Probe to touch the Sun from Launch Complex 37 at Cape Canaveral Air Force Station on August 12, 2018 in Cape Canaveral, Florida. Parker Solar Probe is humanity's first-ever mission into a part of the Suns atmosphere called the corona. The probe will directly explore solar processes that are key to understanding and forecasting space weather events that can impact life on Earth. Getty Images/Bill Ingalls

The Delta IV Heavy rocket launch from Vanderberg Air Force Base that was scheduled for Wednesday evening has been moved to a later date for the fourth time. The launch has now been postponed three times due to weather and mechanical problems.

United Launch Alliance announced today that the Delta IV Heavy rocket launch has been scrubbed and pushed to Thursday, Dec. 20, at 5:31 p.m. EST. The launch was initially scheduled for Wednesday during a window that opened starting 5:44 p.m. from VAFB's Space Launch Complex-6.

But ULA wrote on Twitter hours later that it had been pushed back a few minutes to 5:49 p.m. Now they are setting up for a 24-hour recycle and will attempt another launch on Thursday.

Launch Alert: we have declared a scrub for today's launch of the #DeltaIVHeavy. We will set up for a 24 hour recycle and the next launch attempt will be 12/20 at 5:31pm PST.
— ULA (@ulalaunch) December 20, 2018

The launch time has been adjusted slightly to 5:49pm PST (8:49 p.m. EST; 0149 UTC) that takes into account the earlier brief hold in the countdown. #NROL71 #DeltaIVHeavy
— ULA (@ulalaunch) December 20, 2018

One step closer to launch of the #NROL71 #DeltaIVHeavy. The MST is parked and processing continues as we work towards a 5:44pm PST launch tonight. Follow our live launch blog for updates at https://t.co/wLoggekye0 pic.twitter.com/qu9W55maOe
— ULA (@ulalaunch) December 19, 2018

This is not the first time that the Delta IV Heavy launch has been postponed. It was first planned for Dec. 7, but ULA decided to postpone it due to a problem with a redundant communication link between the control center and the launch site.

After the first delay, the Delta IV Heavy rocket was then rescheduled to launch on Dec. 8. However, it was not meant to be and the launch was scrubbed just 7 seconds before take-off because of an issue detected by the Terminal Countdown Sequencer Rack.

Wednesday should have been a good time to launch, as ULA officials said there was an 80 percent chance of favorable weather conditions during the scheduled time. However, they decided to scrub the launch yet again due to high ground winds. There was apparently also a hydrogen leak, KSBY reported.

Delta IV Heavy is set to be part of a mission called NROL-71 and deliver a satellite for the National Reconnaissance Office into orbit. The rocket's payload has not been made public.

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