SpaceX has completed a mostly successful fourth test of its revolutionary new Starship rocket, a key step toward returning humans to the Moon and, maybe one day, landing on Mars.
The flight, integrated flight test 4, lifted off today from SpaceX’s Boca Chica test site in Texas at 7:50 am Central time. Standing 233 feet (71 meters) tall, the rocket and its 33 methane-fueled Raptor engines roared to life, raising Starship—the largest rocket in history—into the sky over the Gulf of Mexico from the test site, called Starbase.
“Today’s test was the clearest success to date,” says Abhi Tripathi, a former mission director at SpaceX and now an aerospace engineer at the Space Science Laboratory at UC Berkeley. “It was amazing.”
Although one of the engines failed (Starship is designed with redundancy in mind in case of engine failures), the rocket’s journey to space passed smoothly. This was the third time a Starship vehicle had reached space and the second time it had reached suborbit, the other being the last test flight, IFT-3, in March.
Starship is composed of two parts, a lower section known as the Super Heavy booster and the upper section, Starship itself, which will one day house as many as 100 humans on trips to the moon and Mars. Three minutes into today’s flight, at an altitude of about 48 miles (78 kilometers), the two sections separated as planned, with Super Heavy then beginning its journey back to Earth.
Once Starship is fully operational, the goal is for each Super Heavy booster (and Starship) to land back at the launch site, where they will be caught by giant “chopsticks” on the launch tower, ready for another flight. Before SpaceX is comfortable attempting this, however, it wants to prove Super Heavy can return to Earth safely. So one of the key goals of today’s test was for the booster to descend toward the Gulf of Mexico, relight 13 of its engines, and gently splash down.
That test was passed flawlessly for the first time, with the booster splashing down seven and a half minutes into the mission. “That booster landing on the ocean was phenomenal,” says Laura Forczyk, a space consultant and founder of the George-based firm Astralytical. “That gives us confidence that SpaceX can make Starship reusable.”
Starship’s journey into space continued, with the vehicle making its way over the Atlantic Ocean, southern Africa, and toward the Indian Ocean, reaching a peak altitude of 132 miles—half the orbital height of the International Space Station—about 24 minutes into the flight.
From here it then began its own journey back into Earth’s atmosphere, in an attempt to also perform a vertical test landing on the ocean. This task is much harder for Starship, however; traveling at some 17,000 miles per hour, the vehicle must contend with temperatures of 2,600 degrees Fahrenheit (1,400 degrees Celsius) when it hits the atmosphere.
The bottom of the spacecraft is coated in heat tiles to displace this heat, but on Starship’s last test flight in March the vehicle broke apart at an altitude of about 40 miles because of the intensity of reentry. This time SpaceX was hoping to make it all the way to the ocean, with two of the tiles also removed to see how the vehicle itself coped with the high temperatures.
The reentry was smooth until about 57 minutes into the flight, when one of the two flaps that Starship uses to orient itself in the atmosphere caught fire. Onboard camera footage showed the fin being ripped apart, cracking the camera in the process, as Starship plummeted to Earth. “We can see pieces of the vehicle flying off,” Kate Tice, senior quality engineering manager at SpaceX, said in a livestream of the launch.
Incredibly the vehicle survived and, about one hour and six minutes into the mission, Starship attempted its own vertical landing at sea. While the exact fate is unclear, the landing burn of Starship’s engines appeared to be mostly successful, and the vehicle gently impacted the ocean in an upright position. “It got a lot further than the previous flights,” says Tripathi. “It made it all the way to the ocean. That’s a great success.”
However, Tripathi says there is clearly still some work to do with Starship’s thermal protection system to ensure it can survive the heat of reentry. “We all saw there is still a ways to go there,” he says. “The flap was pretty damaged and battered.”
Starship’s next test flight, pending regulatory approval from the Federal Aviation Administration, could happen in a matter of weeks. SpaceX CEO Elon Musk said in an update from Starbase in April that the company may attempt landing Super Heavy back on the ground rather than at sea if Starship Flight 4 went smoothly, which it appears to have done so, with those two giant chopstick-like arms catching the booster in midair.
“If the landing on the ‘virtual tower’ with the booster works, we will actually try with flight five to come back and land on the tower,” Musk said. “It is in the realm of possibility.” That simulated landing successfully happened over the Gulf of Mexico today.
Next year, SpaceX then hopes to prove it can transfer fuel between two Starships in space, a key milestone to getting Starship ready to go to the moon. To reach the moon, a Starship will need to refuel in space, and placing a refueling depot in orbit and filling it with sufficient fuel could require more than a dozen Starship launches. NASA’s return to the moon—its Artemis III mission—aims to use Starship to take humans to the lunar surface in September 2026.
That might still be a longer way off. “I do not have confidence that Artemis III will launch in September 2026, for multiple reasons, not just Starship,” says Forczyk. But today’s test shows that Starship is at least heading in the right direction, and perhaps one day, might become the giant, rapidly reusable rocket that Musk envisions can make humans a multiplanetary species.
“From the beginning of the program we’ve designed Starship to land on Mars,” said Jessica Anderson, manufacturing engineering manager at SpaceX, in the livestream of the fourth test, “something we know will take launching millions of pounds of cargo and equipment into space spread across thousands of launches.” Starship Flight 4, it seems, is another step in that direction.
