Elon Musk gives a detailed review of Starship’s first launch – and what’s next – by Ars Technica

In a wide-ranging talk Saturday night, SpaceX founder Elon Musk previewed the first launch of the Starship rocket on April 20. The bottom line, he said, was that the craft’s flight slightly exceeded his expectations and that the damage to the launch site was not all that widespread. He expects the Starship to fly again in two or three months.

“The result was basically kind of close to what I expected and maybe a little bit more than my expectations,” he said. “And I’m happy to report that the damage to the pillow is really very small, and it looks like it can be fixed very quickly. In fact, it was a good thing to launch this car because we’ve made many improvements in Booster 9 and beyond.”

Musk spoke for about an hour during a spaceflight event on Twitter, responding to questions from several journalists and spaceflight enthusiasts. Here is a summary of what Musk said to those unable to hear.

in flight

When the rocket lifted off, there were three engines that had been shut down because the flight program did not deem them “healthy enough” to achieve full thrust. That left 30 of the 33 Super Heavy engines in the first stage in working condition, the minimum allowed for takeoff. Musk said he doesn’t think those three engines were damaged by the gravel and concrete that were blown away by the tremendous thrust the rocket created as it slowly lifted off the platform.

“Weirdly, we haven’t seen evidence that the Shale Hurricane actually damaged engines or heat shields in a physical way,” he said. It may be so, but we have not yet seen evidence of that.”

Musk said that within 27 seconds of the flight taking off, Engine 19 had lost simultaneous communications with some sort of “energetic event.” This also freed the external heat shield from four nearby engines. SpaceX engineers are still evaluating exactly what this energetic event was.

“Something bad happened on the T-plus 27s because Engine 19 lost all connections, and there was some kind of explosion to take out the heat shields of Engines 17, 18, 19, and 20,” Musk said. Fires were seen from the rear of the vehicle for the remainder of the flight, but the missile continued. On the T-plus 62s, we see additional heat shield damage in the back near engine 30; However, the engine continues to run. Then the T-plus 85 seconds is where things really hit.”

At that point, the missile began to lose control of its vector, or its ability to orient itself. This triggered the flight termination system.

Trip termination system

A minute and a half before its mission, the missile’s flight termination system kicked in to dismantle the vehicle before it veered off course. Essentially, the ammunition on board the missile explodes to rupture the fuel tanks, causing the crash. However, in this case, there was a 40-second delay in starting the system and the missile exploding.

This time delay posed no safety issues with the missile safely offshore, but it is an unacceptable delay for a system that is supposed to terminate flight almost immediately.

Musk said the problem could be solved by using a “longer detonation cord” to make sure the fuel tanks are fully decompressed quickly. However, he acknowledged that working through this issue with the FAA could take some time.

“Probably the main longer component will be the rehabilitation of the flight termination system,” Musk said. “Obviously, that’s something we want to make sure of before we proceed on the next flight.”

Strengthening the launch site

Musk also addressed damage observed at the launch site, including a large crater dug by the missile’s thrust. The damage from what he described as “the world’s largest cutting torch” caused ruptures in a material called Fondag, one of the world’s strongest types of concrete.

“We’re going to put a lot of steel,” Musk said of the area at the base of the missile, which he described as “a huge pie of steel.” This would provide power under the rocket and a regenerative cooling system by pumping water up to dampen the exhaust from the rocket’s 33 engines.

“It’s basically a sandwich covered in water and it’s two layers of steel sheet also perforated on the top side,” Musk said. “This is basically a massive, super strong, upward-pointing steel shower head.”

This approach should minimize damage to the launch site and eliminate the scattering of concrete bits and dust observed during the initial test flight last month. “The debris is really just sand and rock, so it’s not toxic at all or anything,” he said. “It’s like a sandstorm, basically. A man-made sandstorm. But we don’t want to do that again.”

Payment vector control

Musk said that had the super-heavy booster not lost control of the thrust vector, the vehicle might have caused it to disengage. Ensuring the rocket can continue to orient itself, even with multiple engine failures, is key to attempting the next flight with Booster 9, the company’s next rocket in line.

“The Booster 9 is a lot easier because we use electric motors to power the motors instead of hydraulic motors, where you have a common manifold between the hydraulic motors,” Musk said. Electric motors will be more isolated.

It would be key to ensuring that any single-engine malfunctions are isolated, he said, and the company has made the rocket more powerful for this.

“If you have very good motor insulation and one motor fails, it won’t cause the adjacent motor or the same phase to fail,” Musk said. “Because if you lose one of the 33 motors, that’s a 3 percent loss of thrust. It’s not a big deal. If you don’t have good motor insulation, then motor failure can spill over into other motors or phase parts, and then you have an unreliable design.” Extremely. “

Next trip forecast

Because of the rocket and launch pad upgrades, Musk said he expects SpaceX to be ready to attempt a second spacecraft launch within six to eight weeks. However, he acknowledged that finalizing the work with the FAA on the flight termination system and taking other procedures necessary to obtain a launch permit could take longer.

He’s cautiously optimistic about the next launch attempt, which will repeat the same mission profile — Super Heavy launches and landings in the Gulf of Mexico; The spacecraft separates, almost reaches orbital velocity, and then returns to the Pacific Ocean north of Hawaii.

“I think this time, we have a better than 50 percent chance of getting into orbit,” he said. “I hope we can launch four flights this year, or maybe five flights.”

The goal of these initial flights is to continue to collect information on the performance of the Super Heavy and Starship. After the launch system can reliably reach orbit, the next phase of the program will involve demonstrating the transfer of fuel into space, initiating a descent, and reusing both the booster and upper stages.

“It will probably take us a few more years to achieve reusability on a regular basis, where we put the booster back and put the ship back,” he said. “It will take a few years to get to where it is today’s Falcon 9, where it’s very normal for a rocket to go down.”

Musk has estimated that SpaceX will spend about $2 billion on the Starship program in 2023, but he does not anticipate the need to raise additional capital this year.