Elon Musk’s giant Starship rocket rumbles into space once more

The commercial company SpaceX successfully conducted its fourth launch of the largest rocket ever made Thursday morning.

The mammoth "Starship" lifted off shortly before 8 a.m. CT from Boca Chica, Texas. One of the 33 engines on its "super heavy" booster failed seconds after liftoff , but the rocket still rumbled off the pad and made a smooth ascent to space.

After the booster separated from Starship, it turned around and used its engines to land gently in the Gulf of Mexico. The soft landing marks a major milestone for SpaceX, which hopes to be able to rapidly reuse both Starship and its booster on future missions.

The Starship spent about an hour cruising at the edge of space, all-the-while broadcasting views via SpaceX's Starlink satellite network. As it began its re-entry, a camera showed a bright purple plasma forming around one of the flaps used to control Starship's orientation.

The flap appeared to partially melt off in the intense heat of the upper atmosphere. Debris clouded the camera monitoring the spacecraft, and the lens eventually appeared to crack.

Nevertheless, the mammoth craft appeared to stay under control as it descended through the atmosphere. It's battered flaps shifted and put it into a vertical position. Cheers erupted from SpaceX headquarters at Hawthorne, Calif. as the craft appeared to touch down in the ocean as expected.

"From South Texas to the other side of the earth: Starship is in the water," said SpaceX communications manager Dan Huot.

Here’s what else you need to know about this latest test flight.

Starship is the largest rocket ever built

Standing nearly 400 feet tall when stacked on top of its “Super Heavy” booster, Starship is larger than even the Saturn V rockets that carried the Apollo astronauts to the moon. The spaceship is also unique in that it uses stainless steel instead of light-weight metals like aluminum and titanium.

SpaceX founder Elon Musk wants Starship to one day carry astronauts to Mars. NASA has also given the company billions to develop it into a lunar lander, as part of its Artemis program to return astronauts to the moon. Finally, Starship is expected to play a pivotal role in the expansion of SpaceX’s Starlink satellite network, by allowing the company to launch large numbers of internet-capable satellites all at once.

To achieve those lofty goals, Starship has to first prove it can work as intended. Its stainless steel body is supposed to make it rugged and rapidly reusable, and that is key to its many missions. The rocket's Raptor engines must also be able to fire and relight at different points in the flight.

Outside observers say that the fact both the spacecraft and its booster appeared to return to earth in one piece is a major milestone. This latest test flight puts the Starship program "over the hump" towards actually flying payloads to orbit around the earth, says Jonathan McDowell, a researcher at the Smithsonian Astrophysical Observatory who tracks spaceflight.

"It surpassed my expectations, it was amazing," says Laura Forczyk, the executive director of Astralytical, a space consulting firm.

SpaceX had made significant progress with its three previous tests

Starship’s first test launch in April of 2023 ended with the entire rocket exploding over the Gulf of Mexico. Its second test flight ended after the spacecraft triggered its self-destruct system before reaching orbit.

But by test flight three, Starship was behaving more like an actual spacecraft. It successfully reached its expected orbit, and cruised part way around the world.

There were still plenty of problems. A cargo door didn’t appear to open properly. And the Starship tumbled as it began to re-enter earth’s atmosphere. SpaceX believes clogged valves prevented the roll-control thrusters from working properly. The superheated gasses around the vehicle eventually caused it to disintegrate somewhere over the Indian Ocean.

Meanwhile the super-heavy booster also had issues. Its engines failed to re-light properly as it reentered the atmosphere and fell back towards earth. It broke apart above the Gulf of Mexico.

With this launch, the company went further than it ever has before

SpaceX made several modifications to the Starship in preparation for its fourth launch. Engineers added extra roll-control thrusters to keep it from tumbling. They also made modifications to help the super-heavy booster more reliably relight its engines.

The company also took care to make sure its heat shield remained in tact, minus a few tiles that were deliberately removed to test how the structure would respond to heating.

There were clear issues with the test, such as the failed engine, and the partial disintegration of at least one of Starship's fins.

However, experts agreed that this fourth flight was a major milestone for the program. SpaceX collected valuable data that will further allow development of the system.

"It was not flawless," Forczyk says. "But I don't think anyone believed it would be flawless."

McDowell says the Starship is probably still a few test flights from actually carrying cargo to orbit. Still he says, "they've successfully demonstrated some of the most difficult bits."

"I think they're legitimately pretty happy with this flight," he says.

As the company's webcast drew to a close, SpaceX engineers Kate Tice and Jessica Anderson celebrated the landing by roasting marshmallows—a nod to the searing heat of re-entry.

"Just like Starship, I like this toasty," Tice joked as she held her flaming treat. Then she promised: "We've got s'more test flights coming to you soon!"