The third time appeared to be the charm for Elon Musk's Starship rocket - until it wasn't.

The latest heavy-duty launch vehicle prototype from SpaceX soared flawlessly into the sky in a high-altitude test blast-off on Wednesday from Boca Chica, Texas, then flew itself back to Earth to achieve the first upright landing for a Starship model.

But the triumph was short-lived. Listing slightly to one side as an automated fire-suppression system trained a stream of water on flames still burning at the base of the rocket, the spacecraft blew itself to pieces about eight minutes after touchdown.

It was the third such landing attempt to end in a fireball after an otherwise successful test flight for the Starship, being developed by SpaceX to carry humans and 100 tons of cargo on future missions to the moon and Mars.

For Musk, the billionaire SpaceX founder who also heads the electric carmaker Tesla Inc, the outcome was mixed news.