Elon Musk's SpaceX Starship survives re-entry into Earth's ...

SpaceX's giant Starship rocket has survived re-entry through Earth's atmosphere on Thursday and splashed down in the Indian Ocean as planned during its fourth test mission after launching from south Texas.

The two-stage spacecraft, consisting of the Starship cruise vessel mounted atop its towering Super Heavy rocket booster, broke apart during its last attempt in March to survive a blazingly hot re-entry through Earth's atmosphere.

But the craft survived its re-entry on Thursday, a SpaceX live stream showed.

"Despite loss of many tiles and a damaged flap, Starship made it all the way to a soft landing in the ocean!" SpaceX CEO Elon Musk posted on social media after the splashdown.

The world's largest and most powerful rocket — at 121 metres tall — was empty as it soared above the Gulf of Mexico and headed east. 

The spacecraft on top was aiming for a half-lap around the planet with a splashdown in the Indian Ocean, once it ditched the first-stage booster in the gulf.

This time, SpaceX was looking to avoid explosions by controlling the descents.

SpaceX came close in March, but lost contact with the spacecraft as it careened out of space and blew up short of its goal. 

The booster also ruptured in flight, about 400 metres above the gulf.

Last year's two test flights ended in explosions shortly after blasting off from the southern tip of Texas near the Mexican border. 

The first one cratered the pad at Boca Chica Beach and hurled debris for thousands of metres.

SpaceX upgraded the software and made some rocket-flyback changes to improve the odds.

The Federal Aviation Administration signed off Tuesday local time on this fourth demo, saying all safety requirements had been met.

Starship is designed to be fully reusable.

That is why SpaceX wants to control the booster's entry into the gulf and the spacecraft's descent into the Indian Ocean — it is intended as practice for planned future landings. 

Nothing will be recovered from Thursday's flight.

NASA has ordered a pair of Starships for two Moon landing missions by astronauts, on tap for later this decade. 

Each Moon crew will rely on NASA's own rocket and capsule to leave Earth, but meet up with Starship in lunar orbit for the ride down to the surface.

SpaceX already is selling tourist trips around the Moon. 

The first private lunar customer, a Japanese tycoon, pulled out of the trip with his entourage last week, citing the oft-delayed schedule.

SpaceX's founder and CEO also has grander plans: Mr Musk envisions fleets of Starships launching people and the infrastructure necessary to build a city on Mars.

AP/Reuters