SpaceX’s first Super Heavy booster lifted off on April 20 with three engines down, leaving 30 Raptor engines—the minimum needed to put a Starship upper stage into space for what the company had hoped would be a 90-min. flight test around the planet.
But 27 sec. into the flight an “energetic event” caused a communications breakdown with another engine, No. 19, and four other nearby engines lost their outer heat shielding, SpaceX CEO and chief engineer Elon Musk said.
“There were visible fires seen from the aft end of the vehicle for the remainder of the flight, but the rocket kept going,” Musk said during a Twitter Spaces talk on April 29.
“At T-plus 62 sec., we see additional aft heat shield damage near engine 30. However, the engine continues to run. And then at T-plus 85 sec. is where things really hit the fan,” he said.
The vehicle lost its thrust vector control system, spurring the automated flight termination system (AFTS) to trigger about 90 sec. after liftoff. The AFTS response was delayed about 40 sec., Musk said, leaving the 400-ft.-tall Starship/Super Heavy slowly tumbling 24 mi. above the Gulf of Mexico before the ordnance ruptured the vehicle’s fuel tanks and ended the flight.
The time lag did not pose a safety issue, but the system, which is supposed to terminate flight nearly instantaneously, will need to be requalified before another Starship/Super Heavy is launched.
“The longest lead item is probably requalification of the flight termination system,” Musk said. “That’s obviously something that we want to make sure of before proceeding with the next flight.”
The April 20 launch also damaged the rocket’s launchpad at Boca Chica Beach, Texas, but Musk said it should be repaired quickly. The Super Heavy booster, which can generate more than 16 million lb. of force—twice the power of a Saturn V or Space Launch System rocket—sat on its concrete launchpad for about 5 sec. before lifting off. The result was a “rock tornado” that spewed debris far from the intended fallout zone and left a 25-ft. hole in the ground.
On May 1, a group of environmental organizations sued the FAA, which oversees commercial U.S. spaceflight, over its decision to grant SpaceX permission to launch the Starship/Super Heavy flight test from Boca Chica Beach without a more in-depth study of the rocket’s potential environment impacts, Reuters reported. SpaceX’s South Texas spaceport is adjacent to a national wildlife refuge.
SpaceX’s next Super Heavy booster, which includes many upgrades, will lift off the pad faster, Musk said. The company also plans to add a steel underlay and regenerative water cooling system beneath the concrete to dampen the rocket’s exhaust.
“That is basically a water-jacketed sandwich that’s two layers of plate steel that are also perforated on the upper side,” Musk said. “So that is basically a massive, super-strong steel showerhead pointing upward.”
The work should take six to eight weeks, Musk said.
Debris from the launch rained down on Port Isabel, located about 6 mi. from the launch site, but Musk said the fallout was primarily just sand and rock. “It’s not toxic at all or anything,” he added. “It’s just basically a human-made sandstorm, but we don’t want to do that again.”
Overall, Musk said the outcome of the first Starship/Super Heavy flight test was “roughly what I expected … which is that we would get clear of the pad.
“We really just needed to fly this vehicle and then move on to the much-improved booster,” he added.
