A United Launch Alliance Delta 4 Heavy rocket carrying a classified National Reconnaissance Office spy satellite suffered a dramatic "hot-fire abort" early Saturday, starting and then shutting down the first stage engine ignition sequence just three seconds before the planned liftoff.
A rush of flame at the base of the rocket misled ULA's launch commentator who, like many observers, initially thought the heavy-lift booster was taking off.
"Three, two, one and liftoff!" Dillon Rice said on the company's launch webcast as fire erupted from the base of the rocket. But the Delta 4 Heavy did not lift off. "Stand by," he quickly said as the flames died away. "We've obviously had a hot-fire abort."
A few minutes later, after a quick assessment of the rocket and ground systems, launch conductor Scott Barney told Lou Mangieri, the veteran ULA launch director, "we had a hot-fire abort at T-minus 3 seconds. We have performed our abort sequence securing, we are ready to proceed into detanking operations."
ULA CEO Tory Bruno tweeted "the bird is in good shape."
"This was an automatic abort during the ignition sequence," he said. "Cause appears to have been in the ground system. System functioned as intended to protect the vehicle and payload."
Originally scheduled for liftoff last Wednesday, the Delta 4 Heavy's launch was delayed to Thursday at the request of the NRO and then to Saturday after technical snags derailed the launch attempt Thursday.
The brief engine start and shutdown will keep the rocket on the ground for at least seven more days, ULA said in a statement, while engineers carry out detailed inspections, re-torque engine components and prepare the booster for another launch try.
In the meantime, the abort threw a wrench into plans for what could have been three launches in less than two days from Florida's Space Coast.
SpaceX plans two Falcon 9 launches Sunday, one from the Kennedy Space Center carrying another batch of Starlink internet relay stations and one from the nearby Cape Canaveral Air Force Station carrying an Argentine remote sensing satellite known as SAOCOM 1B.
The Delta 4 Heavy's abort was not expected to impact the Starlink launch. But the second flight, SpaceX's 101st orbital mission, could be delayed. The SAOCOM 1B satellite is headed for a polar orbit requiring the Falcon 9 to follow a southerly trajectory that will pass near the Delta 4 pad.
Officials said earlier the SAOCOM 1B mission would not be cleared for flight until after the NRO payload was safely out of harm's way. But there was no official word early Saturday on how the schedule might play out.