The Space Reviewin association with SpaceNews

Starship launch
The first integrated Starship launch “was roughly sort of what I expected,” Elon Musk said, despite its early end and the mess it made of the pad and surrounding landscape. (credit: SpaceX)

Starship after the dust settles

Bookmark and Share

In the days after SpaceX’s Starship/Super Heavy vehicle finally took flight for the first time on an abbreviated launch (see “Grading on a suborbital curve”, The Space Review, April 24, 2023), there were celebrations by the company’s fans and debate among others about how successful this launch was. There was far less information, though, about exactly what happened on that April 20 launch from Boca Chica, Texas, including the issues that ultimately doomed the rocket.

“Overall, I actually feel like that was a great flight,” Musk said.

Most companies would release a statement or hold a press conference discussing the outcome of the launch and their future plans. SpaceX CEO Elon Musk, though, turned to Twitter: not in tweets but in an audio chat, open only to those paying a $4/month subscription to his account on the social network that Musk also owns. Musk said early last week he’d hold the conversation on Friday; like a launch, that slipped to Saturday night, when a little more than 4,000 subscribers tuned in, and a handful got to ask him questions.

So, what has his assessment of the launch? “The outcome was roughly sort of what I expected and maybe slightly exceeded my expectations,” he said during the nearly hour-long conversation. He wanted the rocket to clear the pad and collect “significant” data during the flight, which it did. “Overall, I actually feel like that was a great flight.”

It was not without problems, notably multiple failures of Raptor engines in the Super Heavy booster. Musk said that the rocket lifted off with only 30 of its 33 engines working; three either failed to start or were aborted during startup. That was the bare minimum needed to get the vehicle off the ground and accounted for a “lean” in the vehicle as it slowly rose from the pad.

More engines would fail during ascent, including one at T+27 seconds that coincided with “some kind of energetic event” that broke off shielding around that engine and three neighboring ones. Another Raptor suffered heat shield damage at T+62 seconds but continued to operate.

At T+85 seconds, “things really hit the fan,” he said. Communications were lost with another engine, taking with it the rocket’s thrust vector control system. “We lose steering at T+85 seconds,” he said.

He didn’t offer details on the timeline of events after that—he got distracted by questions by others in the chat—but without the ability to steer, the vehicle was unlikely to fly on course for much longer. Soon, the combined vehicle started to tumble, and controllers issued commands to activate the flight termination system (FTS) and destroy the vehicle.

That system did not work as fast as expected: Musk said it took about 40 seconds from the time the FTS command was issued to when the vehicle disintegrated. “We need more detonation cord” to break up the tanks of the rocket, particularly at high altitudes, he said.

There was no effort, he added, to try and separate the Starship upper stage from the Super Heavy booster. “The ship currently does not attempt to save itself. Arguably, maybe it should,” he mused.

“If we had expected to dig a hole, we would not have flown,” he said od damage to the pad.

He said the company didn’t know why the engines failed, or what caused the other problems like that “energetic event.” He suggested that it may simply have been the result of using older, less reliable Raptors. “The engines on Booster 7 were built over a long period of time. Each engine was a little bit of a unique item,” he said. Booster 7 was the Super Heavy vehicle used on the April 20 launch.

“The engines on Booster 9, which is next, are much newer and more consistent, and really with significant reliability improvements,” he said, along with improved shielding between the engines. “I think we’ll see a much more robust engine situation with Booster 9.”

Preventing another rock tornado

Perhaps a bit surprisingly, Musk appeared to rule out damage from the debris kicked up by the rocket itself. The thrust of the rocket tore apart much of the heavy-duty concrete material called Fondag around the pad, sending debris flying across the launch site and beyond, as well as creating a massive plume of dust and sand.

“Weirdly, we do not see evidence of the rock tornado actually damaging engines or heat shields in a material way,” he said. “It may have, but we have not yet seen evidence of that.”

That debris was not anticipated, Musk said. “If we had expected to dig a hole, we would not have flown,” he said. Data, such as from the February static-fire test of 31 engines of Booster 7, led the company to conclude that the pad might erode would not break apart in a launch. That earlier static-fire test, though, was done with the engines at 50% thrust.

SpaceX had already been working on a solution, which Musk described as a water-jacketed “steel sandwich” that will be placed under the launch mount and serve as a water deluge system. “You have what’s basically a massive super strong steel showerhead pointing up,” he said.

That system, though, was not going to be ready in time for an April launch, but SpaceX decided to proceed based on the earlier tests. “We thought it would be fine for one launch.”

Musk minimized the damage to the pad. While propellant tanks by the pad were damaged, he said those were already slated to be replaced by improved models. There was no significant damage to other elements of the pad, like the tower. The pad, he suggested, could be ready for another launch in six to eight weeks—at least on Musk time.

Environmental concerns

Musk also played down the environmental concerns that pad damage caused. “The debris was basically sand and rocks,” he said, “but we don’t want to do that again.”

“I think you can’t even see it at this point,” he said later in the conversation about damage around the launch site. “To the best of our knowledge, there has not been any meaningful damage to the environment that we’re aware of.”

Three days earlier, the US Fish and Wildlife Service released its assessment of the damage it saw after checking out the nearby Lower Rio Grande Valley National Wildlife Refuge that it is responsible for.

“Federal officials should defend vulnerable wildlife and frontline communities, not give a pass to corporate interests that want to use treasured coastal landscapes as a dumping ground for space waste,” said Jared Margolis.

“Impacts from the launch include numerous large concrete chunks, stainless steel sheets, metal and other objects hurled thousands of feet away” from the pad, the agency said in a statement to media. It also noted “a plume cloud of pulverized concrete that deposited material up to 6.5 miles [10.5 kilometers] northwest of the pad site.”

The agency said it found no debris on refuge property, but did find it scattered over 385 acres (155 hectares) of property belonging to SpaceX and neighboring Boca Chica State Park. There was also evidence of a 3.5-acre (1.4-hectare) brush fire by the site.

“At this time, no dead birds or wildlife have been found on refuge-owned or managed lands,” the Fish and Wildlife Service noted.

However, the debris created by the launch appeared likely to trigger a new round of debates about the environmental impacts of Starship launches from Boca Chica, and it has. On May 1, several environmental groups filed suit against the FAA in federal court, arguing that the agency failed to properly evaluate the environmental risks in its review of Starship launches from Boca Chica, allowing SpaceX to proceed provided it implemented more than 75 mitigations.

The organizations, in the complaint, described the April 20 launch as “spewing chunks of concrete and metal, as well as ash and sand, over a large area.” It was just the latest in a series of anomalies they cited in the suit, such as crashes of previous Starship prototypes and other explosions that generated debris.

The suit also says that the SpaceX has closed the road leading both to the Starbase site and the state park far more than allowed, violating state law that guarantees open public access to beaches. The FAA, it added, should have given more consideration to alternatives such as launches from Florida.

“Federal officials should defend vulnerable wildlife and frontline communities, not give a pass to corporate interests that want to use treasured coastal landscapes as a dumping ground for space waste,” said Jared Margolis, senior attorney at the Center for Biological Diversity, the lead plaintiff in the suit, in a statement.

Neither the FAA nor SpaceX, which was not named as a defendant in the suit, commented on it. The case could take months to work its way through federal court and, with no announced plans to seek an injunction, those launches could resume while federal courts consider the case. The groups are asking the court to revoke the launch license the FAA issued to SpaceX and order the agency to perform a more thorough environmental impact statement.

NASA administrator Bill Nelson downplayed the impact of the Starship test on the agency’s Artemis efforts to the House Science Committee April 27. (credit: NASA/Bill Ingalls)

“Not a big downer”

Many people and organizations weighed in on the Starship launch, but one of the most influential opinions belongs to NASA. It has issued $4 billion in awards to SpaceX for lunar lander variants of Starship the agency plans to use for the Artemis 3 and Artemis 4 missions.

NASA had provided only a tweet’s worth of congratulations to SpaceX immediately after the launch, with administrator Bill Nelson saying that every “great achievement throughout history has demanded some level of calculated risk, because with great risk comes great reward.”

Nelson, testifying before the House Science Committee a week after the launch, said he was not concerned about the fact that the rocket was destroyed four minutes into the planned 90-minute test flight. “The explosion, that’s not a big downer,” he told the committee. “That’s their modus operandi. They launch, and if something goes wrong, they figure out what it is, go back, and they launch it again.”

Nelson said he has been in regular contact with SpaceX. “As of today,” he said at the hearing, “SpaceX is still saying that they think it will take about at least two months to rebuild the launch pad and, concurrently, about two months to have their second vehicle ready to launch.”

That appeared to assuage most, but not all, members. After Nelson noted that NASA chose SpaceX for the lunar lander awards because it had a far lower bid than competitors, Rep. Zoe Lofgren (D-CA), ranking member of the committee, weighed in. “I must say, when I saw that rocket blow up, I thought, thank God there’s no people on board,” she said. “Sometimes the lowest bidder is not always the best choice.”

Next launch

Musk, in his Twitter chat, offered a similar timeline for getting ready for flight, with six to eight weeks to both fix the pad and get the next vehicle ready for launch. (Recertifying the FTS, he said, might take the longest time.) “Hopefully, we’ll be ready to fly again in a couple months.”

“That’s their modus operandi,” Nelson said of Space. “They launch, and if something goes wrong, they figure out what it is, go back, and they launch it again.”

He was more optimistic about the prospects of success on the second flight, giving SpaceX a better than 50% chance of reaching orbit, although the second flight will attempt the same trajectory as the first: a long suborbital flight, with Starship splashing down near Hawaii after less than one lap around the planet.

Musk estimated SpaceX will attempt four to five Starship launches this year. “I would be surprised if we exit this year without getting to orbit,” he said, giving the company an “80%-plus probability” of doing so, increasing to nearly 100% within 12 months.

“We do have a production line that, if it takes us ten flights, we’ll do it,” he added.

Money is not an issue, he claimed. The company expects to spend about $2 billion “all in” on Starship this year, he said, but he said he did not expect the company to have to raise outside funding, as it has done several times in recent years, to pay for Starship development.

Gwynne Shotwell, SpaceX president and chief operating officer, said at a February conference that money from Falcon launches and Dragon space station missions, along with its Starlink constellation, covered development work elsewhere. “So the cash flow from those operations basically pay for our development,” she said then.

Musk is known for his aggressive schedules, and that extended to the company's development of the lunar lander version of Starship. Getting that ready for Artemis 3 requires not only getting Starship into orbit but doing so repeatedly, demonstrating in-space cryogenic propellant transfer, and then sending the lunar lander version of Starship to the moon on an uncrewed test flight.

Asked in the Twitter chat of he felt getting the lunar lander version of Starship would be the long pole for Artemis 3, currently scheduled for late 2025, he disagreed. “I think we will be the first thing to really be ready,” he claimed, putting it ahead of the Space Launch System, Orion, and new lunar spacesuits. “We will not be a limiting factor at all.”

Note: we are using a new commenting system, which may require you to create a new account.