A SpaceX Starship prototype roared into the skies over south Texas last week, hoping to do something its predecessors could not: stick a landing. That dream was short-lived, however, as the prototype briefly stood on solid ground, tilted at a slight angle, before suddenly exploding.
The retro-looking, silvery craft, designated serial number 10 (SN10), was the third full-scale prototype of the vehicle SpaceX hopes will eventually carry people to the moon and Mars. Fashioned from rolls of thin stainless steel, the Starship is only part of the overall launch system. The 165-foot-tall vehicle eventually will ride atop a larger first-stage booster known as the Super Heavy. Both elements are designed to be fully reusable. Until recently, the Super Heavy existed only on paper, but is now starting to take shape inside the company’s Boca Chica facility on the Texas-Mexico border.
For Wednesday’s test, SN10 rose off its launch pad and climbed to an altitude of roughly 10 kilometers, where it briefly hovered. Then it began its descent, belly-flopping through the atmosphere—horizontal to the ground to slow its momentum—before reorienting itself to make a controlled, nose-up landing.
By design, each of the vehicle’s Raptor engines shut down one-by-one as the rocket approached its peak altitude. During the descent, control fins went through a programmed sequence to steer the re-entry. Finally, right on cue, all three Raptors relit to flip and slow the vehicle before relying on just a single engine to land. These maneuvers were key parts of the test flight, designed to show that SpaceX engineers could throttle the Starship’s power.
It all seemed to go smoothly. But eight minutes after the soft touchdown, and shortly after SpaceX turned off its webcast and company head Elon Musk tweeted out that the test was a success, SN10 shot into the air again and erupted in a massive fireball. No immediate cause for the explosion has been identified, but the vehicle was a total loss.
Despite losing a third prototype, Musk seemed pleased, although he avoided any mention of the explosion. “The SpaceX team is doing great work,” he tweeted. “One day, the true measure of success will be that Starship flights are commonplace.”
After three explosions on three test flights, can we say SpaceX is making progress?
Musk first announced plans for the massive rocket in 2016, at a talk in Guadalajara, Mexico. Five years later, an assembly line of several Starship prototypes stands in a high bay at Boca Chica, awaiting test flights. By Thursday, crews were busy clearing the wreckage from the SN10 explosion in preparation for the next test, which SpaceX webcast commentator John Insprucker said would be “soon.” The next prototype, SN11, was rolled out to the launch pad on Monday. Judging by the recent pace of testing, the next launch could come later this month (SN8 was in December, followed by SN9 in February and SN10 in early March.)
Starship has enough power to lift off from the surface of the moon and Mars—where the pull of gravity is relatively weak—but it needs help from the Super Heavy to leave Earth. Both stages use the company’s next-generation Raptor engine. Six of these methane-fueled engines power Starship, while an estimated 30 engines will be needed for the Super Heavy to launch and return to the pad, just as the company’s Falcon 9 rockets do now.
Musk is convinced that Starship’s combination of rapid reusability and power will enable humans to start visiting other worlds in the very near future. According to the Starship website, the vehicle will be able to deliver 100 metric tons to low-Earth orbit, about four times what Falcon 9 can lift. Ever optimistic, Musk continues to state that the rocket could be carrying people to Mars in the mid-2020s.
He’s not the only one counting on Starship. NASA is considering the megarocket as one option for ferrying astronauts to the moon in the same time frame.
Although rockets exploding right after landing might seem like a failure, SpaceX doesn’t necessarily see it that way. Over the weekend, Musk tweeted that engine thrust on the descent was lower than expected, and the vehicle landed much faster than anticipated, resulting in a hard touchdown. This put too much pressure on the craft's stubby landing legs, causing them to buckle. It’s also possible that the legs didn't deploy correctly. Coupled with the too-fast landing, that would have spelled certain doom.
The company’s relatively rapid test cycle produces a lot of fireworks upfront, but by having a stable of Starships at their disposal, engineers can try, fail, and try again until they succeed. Each setback provides the company with a wealth of data on what to improve next time.
Since the first large-scale Starship test last August, each new prototype has been more complex. The first ones, resembling water towers or spray cans, lacked a nose cone and flaps and didn't look like traditional rockets. They were powered by a single Raptor engine and only flew several hundred feet in the air before landing—proof that the core of the craft could actually fly.
Engineers have worked through a variety of propellant and engines issues to date, and SpaceX is hoping that Starship will be ready for an orbital flight by the end of this year.
Before Wednesday’s test flight, Japanese billionaire Yusaka Maezawa announced he is going to take eight members of the public with him on a Starship for a six-day flight around the moon in 2023—a date Musk confirmed. The timetable is characteristically bold, perhaps unrealistically so. And we can expect that the lunar tourists will want to see SpaceX demonstrate more than a few non-explosive landings before they climb aboard.