ELON Musk's Starship booster exploded and contact was lost today - but SpaceX claimed the launch was still "incredibly successful".
The two-stage rocket ship blasted off from the Musk-owned company's Starbase launch site near Boca Chica in Texas.
It soared roughly 55 miles (90km) above the ground on a planned 90-minute flight into space.
But the rocket's Super Heavy first stage booster exploded over the Gulf of Mexico shortly after detaching.
Meanwhile, the core Starship booster carried further toward space, but roughly 10 minutes into the flight a company broadcaster said that SpaceX mission control suddenly lost contact with the vehicle.
"We have lost the data from the second stage... we think we may have lost the second stage," SpaceX's livestream host John Insprucker said.
Read more Tech News
"Such an incredibly successful day," an announcer added. "Even though we did have a... rapid unscheduled disassembly of both the super heavy booster and the ship."
The launch was the second attempt to fly Starship mounted atop its towering Super Heavy rocket booster, following an April attempt that ended in failure about four minutes after lift-off.
A live SpaceX webcast of Saturday's launch showed the rocket ship rising from the launch tower into the morning sky as the Super Heavy's cluster of powerful Raptor engines thundered to life.
The test flight's principal objective was to get Starship off the ground and into space just shy of Earth's orbit.
Most read in Tech
Doing so would have marked a key step toward achieving SpaceX's ambition of producing a large, multi-purpose, spacecraft capable of sending people and cargo back to the moon later this decade for NASA, and ultimately to Mars.
Musk - SpaceX's founder, chief executive and chief engineer - also sees Starship as eventually replacing the company's workhorse Falcon 9 rocket as the centerpiece of its launch business that already lofts most of the world's satellites and other commercial payloads into space.
NASA, SpaceX's primary customer, has a considerable stake in the success of Starship, which the US space agency is counting on to play a central role in its human spaceflight program, Artemis, successor to the Apollo missions of more than a half century ago that put astronauts on the moon for the first time.
The mission's objective was to get Starship off the ground in Texas and into space just shy of reaching orbit, then plunge through Earth's atmosphere for a splashdown off Hawaii's coast.
The launch had been scheduled for Friday but was pushed back by a day for a last-minute swap of flight-control hardware.
During its April 20 test flight, the spacecraft blew itself to bits less than four minutes into a planned 90-minute flight that went awry from the start.
SpaceX has acknowledged that some of the Super Heavy's 33 Raptor engines malfunctioned on ascent, and that the lower-stage booster rocket failed to separate as designed from the upper-stage Starship before the flight was terminated.