Photos: SpaceX Starship prototype explodes on landing in test flight

The self-guided, 16-story-tall rocket initially soared into the clear, blue South Texas sky from its Gulf Coast launch pad on what appeared from SpaceX's livestream coverage to be a flawless liftoff.

A SpaceX commentator for Tuesday's launch webcast said the rocket's flight to its test altitude, along with most of its subsonic re-entry, "looked very good and stable, like we saw last December."

"We just have to work on that landing a little bit," the commentator said, adding, "This is a test flight, the second time we've flown Starship in this configuration."

Reaching its peak altitude of about 10 km (6 miles), the spacecraft then hovered momentarily in midair, shut off its engines and executed a planned "belly-flop" maneuver to descend nose-down under aerodynamic control back toward Earth.

The trouble came when the Starship, after flipping its nose upward again to begin its landing sequence, tried to reactivate two of its three Raptor thrusters, but one failed to ignite. The rocket then fell rapidly to the ground, exploding in a roaring ball of flames, smoke and debris - 6 minutes and 26 seconds after launch.

A prototype of SpaceX's Starship rocket exploded during a landing attempt minutes after a high-altitude experimental launch from Boca Chica, Texas in a repeat of an accident that destroyed a previous test rocket.

The Starship SN9 that blew up on its final descent, like the SN8 before it, was a test model of the heavy-lift rocket being developed by billionaire entrepreneur Elon Musk's private space company to carry humans and 100 tons of cargo on future missions to the moon and Mars.

The SpaceX Starship SN9 prototype rocket explodes after descending from a test flight.

The SpaceX Starship SN9 explodes into a fireball after its high altitude test flight.

The SpaceX Starship SN9 explodes into a fireball after its high altitude test flight from test facilities in Boca Chica, Texas.