WASHINGTON, United States (AFP)-Bad weather on Monday forced SpaceX to postpone the latest launch of its massive prototype Starship rocket, key to founder Elon Musk’s dreams of colonising Mars and NASA’s plans to return astronauts to the moon.

The tenth test flight, which could now happen as soon as Tuesday, comes at a time of heightened scrutiny for the world’s most powerful launch vehicle following a string of explosive failures that have begun raising doubts about its viability.

Standing 403 feet (123 meters) tall, the stainless steel behemoth was set to lift off from the company’s Starbase in southern Texas in a window that opened at 6:30 pm local time (2330 GMT).

It was the second delay in two days after a ground-system leak, a relatively routine issue in spaceflight, scuppered an attempt on Sunday.

The mission aims to put the upper stage — also known as “Starship” or simply “ship” and eventually intended to carry crew and cargo — through structural stress testing as it flies halfway around the world before splashing down in the Indian Ocean.

SpaceX will also try out new heat-shield materials and attempt to deploy mock Starlink satellites as cargo. Unlike recent attempts, the “Super Heavy” booster will not be caught by the launch tower’s giant “chopstick” arms but instead aim for a controlled splashdown in the Gulf of Mexico.

The company’s aggressive “fail fast, learn fast” approach has been credited with giving it a commanding lead in space launches through its Falcon rocket family.

Its Dragon capsules are the only American spacecraft ferrying astronauts to the International Space Station, while Starlink has become a geopolitical asset.

But concern is mounting over whether these successes will translate to Starship, a rocket unlike any before it. The upper stage has exploded in all three 2025 test flights.

Two scattered debris over Caribbean islands, while the third broke apart after reaching space. In June, another upper stage blew up during a ground “static fire” test.