SpaceX Starship survives "toasty" fourth test flight – barely

BOCA CHICA, Texas - SpaceX launched the fourth flight of its massive Starship spacecraft atop the largest and most powerful rocket in the world on Thursday, successfully simulating a booster recovery and making it through the blistering heat of reentry.

Liftoff from the company's Texas launch site came just before 8 a.m. CT. The giant rocket blasted off amid an enormous plume of smoke and steam, and though one of the rocket's 33 engines quickly shut down, Starship safely reached orbit while, for the first time, the Super Heavy first stage successfully returned to a simulated landing – a "soft splashdown" – in the ocean.

An hour later, live views from Starship showed white-hot plasma engulfing the spacecraft as it reentered the atmosphere, burning off chunks of the aerodynamic control fins. But the ship hung on to complete its landing burn and splash down in the Indian Ocean as planned.

While SpaceX hopes to eventually use the craft to fly astronauts to the moon and even Mars, for this test flight, no humans were aboard.

What is Starship?

Starship is SpaceX’s reusable spacecraft, designed to carry over 100 tons of cargo – and, eventually, people – to space and then fly back to Earth to be launched again.

The Starship spacecraft is launched atop SpaceX’s new Super Heavy booster, a 33-engine monstrosity – also reusable – that is more powerful than even NASA’s Saturn moon rockets of the 1960s. Fully stacked, the Starship combination reaches 397 feet high.

The rocket is being developed to reduce the cost of launches and possibly take humans to the moon and Mars. NASA plans to use Starship as its lunar lander during the upcoming Artemis missions later this decade, landing astronauts on the moon and then carrying them back up to the Orion capsule.

What happened during the first three Starship launches?

The first Starship launch, back in April 2023, ended with an in-flight explosion just before stage separation. An investigation later determined that leaking fuel lines inside the booster had caught fire, which ultimately led to the loss of communication to the booster engines and control of the rocket.

Meanwhile, the launch blasted sand and debris from the launch pad, creating a technical and an environmental hazard. The company installed a water-deluge system for the second flight to keep that from happening.

(SpaceX image)

That second flight, though, also ended with an explosion, but later in the ascent. Unlike the first mission, all of the Raptor engines fire up and continued to burn through stage separation. Moments later, one engine "failed energetically" – likely due to a liquid oxygen filter blockage – leading to an explosion that destroyed the booster.

The Starship upper stage continued toward orbit until a leak during liquid oxygen venting led to a fire, cutting power to all six engines, which in turn activated the vehicle’s automatic self-destruct.

The third flight, in March, was much more successful. The first-stage booster made its first-ever landing burn attempt, but blockage in the liquid oxygen line led to "lower than expected landing burn thrust" and the soft splashdown attempt failed.

Starship, meanwhile, reached space, allowing engineers to test a variety of systems, including the craft's new payload door and demonstrate propellant transfer while the upper stage was coasting. But SpaceX says clogged valves sent Starship into an unplanned roll and the craft did not survive reentry.

Onboard video cameras provided stunning views of the fiery plasma building up around the reentering craft before it spun out of control and burned up.

Starship's fourth mission

The primary goal of this fourth test flight was gathering more information about reentry heating and the performance of the 18,000 hexagonal protective heat shield tiles. Engineers actually removed a few of the tiles and replaced them with heat sensors in hopes of learning more about the intense heating the craft experiences as it returned from space.

Live camera views, powered by SpaceX's Starlink internet satellites, again showed the colorful buildup of plasma, flames, and sparks during reentry. This time, the vehicle did not roll out of control, even as the white-hot plasma burned through part of the ship's flaps, sending chunks of the craft flying past the cameras.

"It's safe to say this ship is getting beat up," launch commentator Kate Tice offered as live views showed debris spraying from the burning vehicle. "This is a nail-biter."

Though the view was muddled by debris, it was clear enough to show Starship right itself as it approached the Indian Ocean, apparently executing its landing burn and splashing down as planned.

"From South Texas to the other side of the earth, Starship is in the water," commentator Dan Huot exclaimed.

The company plans to use the data gathered in Thursday's flight to push closer to operational missions – the test-until-you-fail philosophy SpaceX has been using for years.