The launch from Cape Canaveral of a top secret spy satellite for the U.S. government was aborted at the last moment early Saturday as its United Launch Alliance Delta 4-Heavy rocket ignited three main engines, a dramatic cutoff of the countdown that will delay the mission by at least one week.
The 235-foot-tall (71.6-meter) Delta 4-Heavy rocket was three seconds from liftoff at 3:28 a.m. EDT (0728 GMT) when a computer detected a problem and automatically called the abort.
The abort occurred as the Delta 4-Heavy’s three Aerojet Rocketdyne RS-68A main engines were igniting, but before the hydrogen-fueled engines reached full power and hold-down restraints disengaged to permit the rocket to climb away from pad 37B at Cape Canaveral Air Force Station.
“Three, two, one and liftoff!” said Dillon Rice, the commentator on ULA’s launch broadcast.
Fire rose around the Delta 4-Heavy’s three first stage booster cores as the main engines began to ignite. The fireball is typically seen during normal Delta 4-Heavy launches.
But the heavy-lifter remained on the ground, and the orange glow dissipated as a member of ULA’s launch team confirmed the engines had shut down.
“Stand by,” Rice said. “We’ve obviously had a hotfire abort.”
The Delta 4 launch team soon confirmed the launch attempt was scrubbed and began procedures to drain the rocket’s propellant tanks of super-cold liquid hydrogen and liquid oxygen propellants.
In a statement, ULA said the countdown as halted “due to an unexpected condition during terminal count at approximately three seconds before liftoff.”
The launch operator — a 50-50 joint venture between Boeing and Lockheed Martin — said the mission would be delayed at least one week as teams review data and “determine the path forward.”
Tory Bruno, ULA’s president and CEO, tweeted that the Delta 4-Heavy was in “good shape” after the fiery abort.
“This was an automatic abort during the ignition sequence,” Bruno tweeted. “Cause appears to have been in the ground system. System functioned as intended to protect the vehicle and payload.”
A ULA spokesperson said later Saturday one of the Delta 4-Heavy’s three RS-68A engines — mounted under the rocket’s starboard booster — had already ignited when the abort was triggered three seconds before liftoff. The starboard engine ignites first in the Delta 4-Heavy’s staggered engine startup sequence.
The Delta 4-Heavy rocket is the most powerful vehicle in ULA’s fleet, and the largest rocket in the world currently flying. There have been 40 launches of Delta 4 rockets to date, and 11 flights using the triple-body Delta 4-Heavy variant.
The abort Saturday marked the first time a Delta 4 launch was aborted during its engine startup sequence.
The cargo mounted on top of the Delta 4-Heavy is a classified payload for the National Reconnaissance Office, which owns the U.S. government’s spy satellites.
The NRO has not disclosed the satellite’s purpose or design, but analysts believe the Delta 4-Heavy is launching a large intelligence-gathering satellite to an orbit more than 22,000 miles (nearly 36,000 kilometers) above Earth. In that orbit, the spacecraft is expected to unfurl a huge antenna the size of a football field to intercept telephone calls, data transmissions and other communications traffic from U.S. adversaries.
ULA planned to launch the Delta 4-Heavy rocket early Thursday, but managers called off that attempt to allow more time to evaluate an issue with a ground pneumatics system at the launch pad.
There was an automatic abort at T-minus 3 seconds, moments after the command to ignite the Delta 4-Heavy’s three main engines.
— Spaceflight Now (@SpaceflightNow) August 29, 2020
The launch abort early Saturday thwarted plans for up to three launches this weekend from Florida’s Space Coast.
SpaceX is readying two Falcon 9 rockets for takeoffs Sunday from separate launch pads a few miles north of the Delta 4 launch facility at pad 37B, but it was not immediately clear early Saturday whether the Delta 4-Heavy’s delay might affect SpaceX’s plans.
One of the Falcon 9 rockets is scheduled for launch from pad 39A at NASA’s Kennedy Space Center at 10:12 a.m. EDT (1412 GMT) Sunday with SpaceX’s next group of approximately 60 Starlink broadband satellites.
SpaceX is preparing another Falcon 9 for launch from pad 40 on Cape Canaveral Air Force Station at 7:18 p.m. EDT (2318 GMT) Sunday with Argentina’s SAOCOM 1B radar observation satellite.
The launch of SAOCOM 1B has been delayed a month due to range safety concerns associated with the Falcon 9 rocket’s planned southerly trajectory to place the satellite into a north-south polar-type orbit. Before reaching the Atlantic Ocean, the track will take the Falcon 9 nearly directly over pad 37B, where the National Reconnaissance Office’s high-priority — and very expensive — spy satellite sits on top of the Delta 4-Heavy rocket.
Most U.S. launches into polar orbit take off from Vandenberg Air Force Base in California, which overlooks the Pacific Ocean. But SpaceX moved the launch of SAOCOM 1B to Cape Canaveral to allow the company to reduce staffing levels at Vandenberg during a period with few launches there, Gwynne Shotwell, company’s president and chief operating officer, told reporters last year.
SAOCOM 1B was previously scheduled for launch in March, but Argentine officials called off the mission due to concerns about the coronavirus pandemic. Engineers placed SAOCOM 1B in storage at Cape Canaveral until early July, when engineers returned to Florida from Argentina to finish readying the spacecraft for liftoff.
The launch date ultimately was delayed again in a ripple effect from schedule slips suffered by other Falcon 9 missions. By the time SpaceX could have been ready to launch SAOCOM 1B, the NRO spy payload had been mounted on top of the Delta 4-Heavy rocket.
The SAOCOM 1B mission was then grounded, and has remained on hold until the Delta 4-Heavy rocket takes off. Sources said the delay was related to concerns that a Falcon 9 in-flight failure could drop debris on the Delta 4 launch pad and put its national security payload at risk.
SpaceX said Friday the plan for dual Falcon 9 launches Sunday — which would set a record for the shortest period between two SpaceX missions — was contingent upon the availability of the Eastern Range at Cape Canaveral to support the back-to-back liftoffs.
Email the author.
Follow Stephen Clark on Twitter: @StephenClark1.