The latest test of Space X's giant Starship rocket has failed, minutes after launch.
Officials at Elon Musk's company said the upper stage was lost after problems developed after lift-off from Texas on Thursday.
The mission came hours after the first flight of the Blue Origin New Glenn rocket system, backed by Amazon boss Jeff Bezos.
The two tech billionaires both want to dominate the space vehicle market.
"Starship experienced a rapid unscheduled disassembly during its ascent burn. Teams will continue to review data from today's flight test to better understand root cause," SpaceX posted on X.
"With a test like this, success comes from what we learn, and today's flight will help us improve Starship's reliability."
Unverified footage on social media shows what appears to be the rocket breaking up in flames.
"Success is uncertain, but entertainment is guaranteed!" Mr Musk posted on X, sharing footage of the launch's aftermath.
He also said "improved versions" of the ship and booster were "already waiting for launch".
Footage of the launch clocked up 7.2m views, according to a SpaceX livestream.
The Starship system had lifted off from Boca Chica, Texas, at 17:38 EST (22:38 GMT) in the company's seventh test mission.
The Starship upper stage separated from its Super Heavy booster nearly four minutes into flight as planned.
But then SpaceX Communications Manager Dan Huot reported on a live stream that mission teams had lost contact with the ship.
The Super Heavy booster managed to returned to its launchpad roughly seven minutes after lift-off as planned, prompting an eruption of applause from ground control teams.
It comes a day after a SpaceX rocket blasted off from Florida carrying two privately constructed lunar landers and a micro rover to the Moon.
The uncrewed Falcon 9 launched from the Kennedy Space Center on Wednesday.
And Bezos' Blue Origin company successfully launched a rocket into orbit for the first time.
It was a huge step forward for Bezos and his company that has spent years getting to the point of sending a rocket into orbit.
