SpaceX has aborted an attempt to catch the first stage booster of its Starship mega rocket in the "chopstick" arms of its launch tower, instead guiding the rocket into an ocean splashdown.
The hitch came as President-elect Donald Trump joined SpaceX chief Elon Musk at the company's Starbase in Boca Chica, Texas, to watch the test flight.
It marks SpaceX's sixth Starship test flight to space, eyeing an array of improvements on the rocket.
Mr Musk gives a tour to Trump before the launch of the sixth test flight of the SpaceX Starship rocket. (AFP: Brandon Bell)
The roughly 122-metre-tall rocket system, designed to land astronauts on the Moon and ferry crews to Mars, lifted off at 4pm local time.
The first stage, called Super Heavy, unexpectedly made a splashdown in the Gulf of Mexico instead of attempting to return to its launch pad, indicating something went wrong.
Mr Musk has been a constant presence at Trump's side since the incoming president's election victory, joining him at a meeting with Argentina's President Javier Milei and even at a UFC bout.
Mr Musk has been outspoken about his support for President-elect Donald Trump. (AFP: Brandon Bell)
Company representatives cited unmet technical criteria, dampening the triumph of an event attended by several Trump-world figures, including Donald Trump Jr.
Trump's decision to travel to Mr Musk's home turf was the latest sign of the growing alliance between the billionaire duo.
The strengthening relationship has raised questions over possible conflicts of interests given SpaceX's lucrative contracts with NASA and the Pentagon.
Mr Musk aims to launch the first uncrewed missions to Mars as early as 2026.
ABC/wires