Countdown is underway! Delta IV rocket launch set to go at Vandenberg

Countdown is underway! Delta IV rocket launch set to go at Vandenberg

The leak prompted ULA to postpone the launch again for approximately 24 hours.

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"Launch Alert: we have declared a scrub for today's launch of the #DeltaIVHeavy".

The launch of a giant Delta IV Heavy from California was scrubbed for a fourth time Wednesday evening, with the clock reset for 5:31 p.m. on Thursday.

It was pure coincidence that the fireball flashed at 5:34 p.m. PT, just before United Launch Alliance called off the launch of a classified spy satellite known as NROL-71 for the National Reconnaissance Office, due to elevated hydrogen levels that were detected during the countdown.

Previous launches were also canceled seconds before liftoff due to technical issues.

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"The team is evaluating all the data, and we'll update about a launch date when we can", according to ULA.

December 30 will be the earliest possible date for the sixth attempting at launching the 233-foot-tall rocket, which is set to deploy a classified satellite for the U.S. National Reconnaissance Office.

In a statement released prior to the postponement of the launch, ULA vice president of government and commercial programs Gary Wentz said they are working as hard as they can to see the mission become a success.

ULA has carried out 27 launches for the National Reconnaissance Office over the past 12 years.

The three-booster Delta IV Heavy rocket that will carry the satellite was built by United Launch Alliance, a conglomerate of Lockheed Martin and Boeing.