It was called off when the countdown clock reach T-7 seconds
The launch of a U.S. spy satellite built onto a powerful Delta IV Heavy rocket was cancelled for the second time on late September 30. It’s launch was cancelled last month as well.
The Delta IV Heavy, built by the United Launch Alliance (ULA) was set to loft the clandestine NROL-44 satellite at 11:54 pm EDT from Florida’s Cape Canaveral Air Force Station. It was called off when there were just seven seconds remaining.
Cause for cancellation
ULA CEO Tory Bruno tweeted out the cause shortly afterwards, saying, “We experienced an automated abort because a sensor reported a fault. Automated Safety System operated as intended. Bird and payload are safe and unharmed. Engine ROFI ignitors were not fired. Turbo pumps were not spun up. Mission safety first…”
ROFI is short for “radially outward firing initiators,” and Delta IV Heavy has two types of it. One is embedded in a rocket engine’s injector plate and ignites the engine by spraying hot gas. The other one is included in the pad infrastructure and is used to burn off excess hydrogen propellent.
The second one, also known as a hydrogen burn-off unit also serves as a visual treat for the Delta IV Heavy and causes the flames to reach all the way to the bottom of the 72 metre rocket.
The last launch attempt was on August 29 and at that time, it was called off when the countdown reached T-3 seconds. The cause was another anomaly that was detected and caused everything to shut down.
The launch team is currently reviewing the data and will be giving a statement on what they’re planning to do next.