A prototype of the SpaceX rocket exploded minutes after landing in Texas.
"A wonderful soft landing," SpaceX had just commented on video.
The flames erupted from the underside of the rocket, and were extinguished by the teams on the spot.
A few moments later, however, a huge explosion literally threw the aircraft into the air, which then fell to the ground and crashed.
At the moment no explanation has been provided.
This type of vehicle was chosen by Elon Musk, to go to Mars one day.
The prototype, named SN10, for "Serial Number 10", took off just before 11:20 GMT from Boca Chica, Texas, for a third test.
After the departure towards the sky, the progressive shutdown of the three engines, and the cruise, the rocket reached 10 kilometers of altitude, before starting its descent, and then landing exactly where expected before the explosion.
Two other prototypes (SN8 and SN9) crashed on landing in December 2020 and last February.
The tests are taking place in an almost deserted area leased by SpaceX, in the far south of Texas, near the border with Mexico and on the edge of the Gulf of Mexico.
Elon Musk plans to launch several of these rockets to conquer Mars.
But initially the spacecraft could prove useful for closer trips, especially to the moon.