Starship, the most powerful rocket ever built, exploded during its first flight on Thursday, but Elon Musk congratulated his SpaceX team on an "exciting" test of the spacecraft designed to send astronauts to the Moon, Mars and beyond.
The uncrewed rocket disintegrated minutes after successfully blasting off at 8:33 am Central Time (1333 GMT) from Starbase, the SpaceX spaceport in Boca Chica, Texas.
The Starship spacecraft that will eventually carry crew and cargo had been scheduled to separate from the first-stage rocket booster three minutes into the flight, but separation failed to occur and the rocket blew up in a ball of fire over the Gulf of Mexico.
Despite the failure to complete the full 90-minute flight test and reach orbit, SpaceX and Musk, the founder and CEO of the private space company, declared it a success.
"Congrats SpaceX team on an exciting test launch of Starship!" Musk tweeted. "Learned a lot for the next test launch in a few months."
SpaceX said that "with a test like this, success comes from what we learn, and today's test will help us improve Starship's reliability as SpaceX seeks to make life multi-planetary."
"We cleared the tower which was our only hope," said Kate Tice, a SpaceX quality systems engineer.
The US space agency NASA has picked the Starship spacecraft to ferry astronauts to the Moon in late 2025 -- a mission known as Artemis III -- for the first time since the Apollo program ended in 1972.
NASA chief Bill Nelson congratulated SpaceX, saying "Every great achievement throughout history has demanded some level of calculated risk because with great risk comes great reward."
Starship consists of a 164-foot (50-meter) tall spacecraft designed to carry crew and cargo that sits atop a 230-foot tall first-stage Super Heavy booster rocket.
SpaceX conducted a successful test-firing of the 33 massive Raptor engines on the first-stage booster in February but the Starship spacecraft and the Super Heavy rocket were being flown together for the first time.
The integrated test flight was intended to assess their performance in combination.
Musk had warned ahead of the test that technical issues were likely and sought to play down expectations for the inaugural flight.
"It's the first launch of a very complicated, gigantic rocket. There are a million ways this rocket could fail," he said.
NASA will take astronauts to lunar orbit itself in November 2024 using its own heavy rocket called the Space Launch System (SLS), which has been in development for more than a decade.
Starship is both bigger and more powerful than SLS and capable of lifting a payload of more than 100 metric tonnes into orbit.
It generates 17 million pounds of thrust, more than twice that of the Saturn V rockets used to send Apollo astronauts to the Moon.
The plan for the integrated test flight was for the Super Heavy booster to separate from Starship after launch and splash down in the Gulf of Mexico.
They failed to separate however and the booster rocket and Starship spacecraft began spinning out of control, exploding four minutes into the test flight in what SpaceX euphemistically called a "rapid unscheduled disassembly."
"If we get far enough away from the launchpad before something goes wrong then I think I would consider that to be a success," Musk said prior to the test. "Just don't blow up the launchpad."
SpaceX foresees eventually putting a Starship into orbit, and then refueling it with another Starship so it can continue on a journey to Mars or beyond.
The eventual objective is to establish bases on the Moon and Mars and put humans on the "path to being a multi-planet civilization," according to Musk.
"We are at this brief moment in civilization where it is possible to become a multi-planet species," he said. "That's our goal. I think we've got a chance."