The Next Challenge for Musk’s SpaceX? Explaining What Happened to Starship

A beautiful machine came to an ugly end on April 20 when SpaceX’s sleek, silvery, 40-story tall Starship rocket consumed itself in an orange and white fireball just four minutes after launch and 39 km (24 mi.) above the Gulf of Mexico off the coast of Texas. As maiden voyages go, it was not pretty.

In the days since, much virtual ink has been spilled, both applauding the launch and condemning its failure. “Congrats to @SpaceX on Starship’s first integrated flight test!” tweeted NASA Administrator Bill Nelson. “Every great achievement throughout history has demanded some level of calculated risk, because with great risk comes great reward. Looking forward to all that SpaceX learns, to the next flight test—and beyond.”

I also chimed in, calling the explosion “no big deal” in my analysis for TIME, pointing to serial crashes and explosions as an unavoidable part of the rocket design business. That fly-and-fail approach, I argued, helps identify problems well before a new rocket carries a payload or crew, making the vehicle more reliable and, much more important, safer.

The rest of the twitterverse wasn’t as sanguine. “This wasn’t calculated risk. This was rushed. This was careless,” countered Twitter user @iwriteforme.

“Absurdly misplaced ignorant jubilation,” tweeted @clarecastle in response to media outlets in the U.K. echoing Nelson’s positive spin.

But whether the Starship explosion was a “successful failure” as some have dubbed it or a failure, period, the causes of the incident still have to be determined. That question must be answered soon, if SpaceX hopes to launch another Starship in anywhere close to the “few months” SpaceX founder and boss Elon Musk promised in a tweet immediately after the aborted flight.

Read more: Inside SpaceX’s Starship, the Most Massive Rocket Ever Built

Musk’s tweet barely had time to go public before the Federal Aviation Administration (FAA) announced it was temporarily grounding the entire Starship fleet. “An anomaly occurred during the ascent and prior to stage separation resulting in a loss of the vehicle,” the statement read in part. “A return to flight of the Starship / Super Heavy vehicle is based on the FAA determining that any system, process, or procedure related to the mishap does not affect public safety.”

Clearing that FAA hurdle will require SpaceX to take a deep dive into the telemetry that streamed down from the Starship during its brief flight. This much is clear: of the 33 engines that power the rocket’s first stage, flight video reveals that at least eight failed to fire. In a Feb. 9 “static fire” test, during which the engines were ignited with the rocket anchored to the ground, 31 of the 33 worked as planned.

“Team turned off 1 engine just before start & 1 stopped itself, so 31 engines fired overall. But still enough engines to reach orbit!” Musk said via Twitter about the static fire test at the time.

That may be true when 31 engines are firing, but not a mere 25. Had the Starship’s engines worked as planned last week, the first stage would have separated and fallen back to earth at the three-minute point of the flight, leaving nine engines on the second stage to carry the rest of the spacecraft to space. Instead, it was at that point that the rocket went into an uncontrolled tumble that lasted for a full—and harrowing—minute. At the end of that minute the rocket blew up.

The explosion itself was no accident. In a post shortly after the flight ended, SpaceX announced that its “flight termination system” (FTS)—essentially a self-destruct mechanism to prevent danger to people or structures on the ground—destroyed both stages of the rocket. The company did not reveal whether the FTS was triggered automatically by the out-of-control tumbling or whether it was manually activated from the ground. Starship is not remotely alone in being equipped with an FTS. Indeed, the FAA requires the system in all rockets before it will allow them to fly.

The loss of the rocket itself was not the only harm done that day. The launch pad suffered serious damage as bowling-ball-sized chunks of concrete were broken loose and flung about from the force of the engines that did ignite. As The New York Times, Texas Public Radio, and others reported, in Port Isabel, Tex., a city six miles from SpaceX’s Boca Chica launch site, buildings shook, at least one window shattered, and a cloud of sandy debris rained down on the residents and their homes.

“It was truly terrifying,” Port Isabel resident Sharon Almaguer told the Times. Other SpaceX launches from Boca Chica have caused some rumbling in the town, but “this was on a completely different level,” Almaguer added.

Read more: Is Space Travel Good for the Environment? No

SpaceX is not pretending that solutions to all of the problems that arose on April 20 will come soon—and after-action reports and repairs like the one the company is faced with are typically slow, painstaking affairs. “I look forward to hearing the outcome of SpaceX’s Incident investigation, or at least what changes they’ll make for the next attempt,” says Scott Pace, a professor at George Washington University’s Space Policy Institute. “Why didn’t the Starship [second stage] separate as planned? Why did a few engines fail on the booster phase? What will be done to mitigate launch area damage on future missions?”

All good questions—and there are others too. The second stage of the rocket didn’t even get a chance to try flying, after all, so there is no way of knowing yet if there are design flaws buried within it that will be revealed only on subsequent tests after the problems in the first stage are worked out. And if 25 engines can do the kind of damage they did to Port Isabel, what will happen when the full complement of 33 do successfully light in tandem—especially since even with just a portion of its engines burning, Starship’s April 20 flight still made it the most powerful rocket ever launched?

For now, SpaceX is keeping its head down—trying to solve its problems, make its repairs, and satisfy the FAA, which holds the ultimate leash on future Starship flights. There are many who continue to believe the company has the wherewithal to do that—and that Starship has a bright future.

“This was a test flight,” says astrophysicist Pascal Ehrenfreund, a professor at the George Washington University Space Policy Institute. “During the development of a disruptive launcher, setbacks are anticipated. The investigations will reveal when a next test flight will be possible. There will certainly be a next test flight and hopefully Starship becomes a commercial reality.”