June 16, 2019

Delta 4-Heavy launch postponed by unspecified payload issue


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NROL-37 mission poster. Credit: United Launch Alliance
NROL-37 mission poster. Credit: United Launch Alliance

CAPE CANAVERAL — Payload readiness has delayed next weekend’s planned Delta 4-Heavy rocket launch for the U.S. National Reconnaissance Office.

Liftoff had been targeted for the afternoon of June 4. A new launch date has not yet been established.

The NRO is the secretive government agency responsible for the design and operation of the country’s fleet of spy satellites. The identity of the payload launching aboard the Heavy is classified.

The launch is known as NROL-37.

“The NROL-37 spacecraft and launch vehicle are secure on Space Launch Complex 37,” officials said in a statement.

The United Launch Alliance Delta 4-Heavy rocket is America’s largest operational booster flying today. It carries critical payloads for the U.S. government.

The vehicle is created by taking three Common Booster Cores — the liquid hydrogen-fueled motor that forms a Delta 4-Medium’s first stage — and strapping them together to form a triple-barrel rocket, and then adding a cryogenic upper stage.

The vehicle stands 235 feet tall, weighs 1.6 million pounds fully fueled and will unleash 2.1 million pounds of thrust from the three RS-68A main engines at launch.

Here’s a look at some stats about the mission. This will be:


  • The 374th Delta rocket launch since 1960
  • The 32nd Delta 4 rocket mission since 2002
  • The 9th Heavy configuration to fly
  • The 48-49-50th main engine from RS-68 family used
  • The 6-7-8th RS-68A main engine flown
  • The 468th production RL10 engine to be launched
  • The 35th RL10B-2 engine launched
  • The 26th Delta 4 rocket launch from Cape Canaveral
  • The 7th Heavy launch from Cape Canaveral
  • The 10th classified Delta 4 for the NRO
  • The 6th Heavy for the NRO
  • The 94th Evolved Expendable Launch Vehicle flight
  • The 107th United Launch Alliance mission since 2006
  • The 25th Delta 4 under the ULA banner
  • The 4th ULA launch this year
  • The 2nd launch of the Delta family in 2016

See earlier Delta 374 coverage.

Our Delta archive.


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