SpaceX rocket successfully launches, then explodes

The flight test was the first for Starship mounted atop the company's new Super Heavy rocket, and the first launch ever for that lower-stage booster, touted by SpaceX as the most powerful launch vehicle on earth.

The two-stage rocket ship made it less than halfway to the edge of space, climbing to almost 40 kilometres, but the flight achieved a primary objective of getting the new vehicle off the ground at lift-off despite some of its engines failing.

While SpaceX officials were heartened by the outcome, the mission fell short of reaching several objectives.

The plan was for Starship to soar into space at least 150km above earth before it would re-enter the atmosphere and plunge into the Pacific near Hawaii.

SpaceX said in a statement the spacecraft "experienced multiple engines out" during its ascent, then "lost altitude and began to tumble" before the "flight termination system was commanded on both the booster and the ship".

Musk, SpaceX's founder, chief executive and chief engineer, had appeared eager to temper expectations on Sunday when he downplayed the odds of a successful first flight.

SpaceX President Gwynne Shotwell told a conference in February "the real goal is to not blow up the launch pad".

By that measure, the debut flight of Starship with its booster rocket represented a milestone in SpaceX's ambition of sending astronauts back to the moon and ultimately to Mars, as a major partner in Artemis, NASA's newly inaugurated human spaceflight program.

NASA chief Bill Nelson congratulated SpaceX on Twitter.

"Every great achievement throughout history has demanded some level of calculated risk because with great risk comes great reward," he said.

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The two-stage rocket ship, standing taller than the Statue of Liberty at 120 metres, blasted off from the company's Starbase spaceport on the southern tip of Texas along the Gulf Coast east of Brownsville.

SpaceX hoped, at best, to pull off a 90-minute debut flight into space but just shy of earth orbit.

A live SpaceX webcast showed the rocket ship rising from the launch tower into the morning sky as the Super Heavy's Raptor engines roared to life in a ball of flame and billowing clouds of exhaust and water vapour.

But less than four minutes into the flight, the upper-stage Starship failed to separate as designed from the lower-stage Super Heavy, and the combined vehicle was seen tumbling end over end before blowing apart.

The pad and surrounding area were cordoned off well in advance of the test, SpaceX said.

Any debris from the explosion should have landed over the water in areas placed off-limits by the US Coast Guard.

The spacecraft reached a peak altitude of about 39km before its fiery disintegration, SpaceX said.

The company also noted the rocket reached the critical launch point of maximum aerodynamic pressure before appearing to lose control.

SpaceX officials on the webcast hailed the lift-off as a welcome accomplishment.

Musk, shown seated in the Starbase mission control room in Boca Chica, Texas, wearing a headset, said on Twitter afterward the next Starship test launch would be in a few months.

"Congrats @SpaceX team on an exciting test launch of Starship! Learned a lot for next test launch," he tweeted.

SpaceX principal integration engineer John Insprucker, one of the webcast commentators, said the experience would provide a wealth of data to inform further flight tests.

Australian Associated Press