SpaceX
In an extended talk Saturday night, SpaceX founder Elon Musk discussed the debut launch of the Starship rocket on April 20. The bottom line, he says, is that the flight of the vehicle slightly exceeded his expectations and that the launch site was damaged. not all that extensive. He expects Starship to be able to fly again within two or three months.
“Essentially, the result was about what I expected and maybe a little above my expectations,” he said. “And I’m happy to report that the damage to the brake pads is actually quite minor, and it looks like it can be fixed pretty quickly. It was actually just good to get this vehicle off the ground because we’ve made so many improvements in Booster 9 and beyond.”
Musk spoke at a Twitter Spaces event for about an hour, answering questions from several journalists and spaceflight enthusiasts. For those who can’t listen, what follows is a summary of what Musk said.
On the run
When the rocket lifted off, there were three engines that had their ignition terminated because the flight software deemed them not “healthy enough” to reach full power. This left 30 of the Super Heavy first stage’s 33 engines in good condition, which is the minimum allowed for launch. Musk said he did not believe these three engines were damaged by the gravel and concrete thrown up by the massive thrust created by the rocket as it slowly lifted off the platform.
“Oddly enough, we saw no evidence that the rock tornado actually damaged engines or heat shields in any material way,” he said. “Maybe, but we haven’t seen any evidence of that yet.”
27 seconds into the flight, engine 19 lost communication during some sort of “energetic event,” Musk said. This also freed the outer heat shield from four nearby engines. SpaceX engineers are still assessing exactly what this energetic event was.
“So something bad happened at T-plus 27 seconds because the engine 19 lost all communication, and some sort of explosion knocked out the heat shields on engines 17, 18, 19 and 20,” Musk said. “There were visible fires seen from the rear of the vehicle for the remainder of the flight, but the missile continued. At T-plus 62 seconds, we see additional damage to the rear heat shield near engine 30; however, the engine continues to run. And then T-plus 85 seconds is where things really hit the fan.”
At that point, the rocket began to lose thrust control, or the ability to steer itself. This led to the start of the flight termination system.
Flight termination system
Just before a minute and a half into its mission, the missile’s flight termination system activated to break up the vehicle before it drifted too far off course. Essentially, the ammunition on board the rocket explodes to rupture the fuel tanks, leading to a rupture. In this case, however, there was a delay of about 40 seconds in system startup and missile breakup.
This delay did not pose any safety issues with the missile safely offshore, but it is an unacceptable delay for a system that is supposed to end the flight almost immediately.
Musk said the problem could be solved with a “longer detonator cord” to ensure the propellant tanks are fully unzipped quickly. However, he acknowledged that it may take some time to resolve this issue with the Federal Aviation Administration.
“The longest lead is probably the requalification of the flight termination system,” Musk said. “Obviously that’s something we want to make sure of before moving on to the next flight.”
