NASA suspended the launch of its audacious solar probe, minutes before the car-sized rocket took off.
NASA announced that the launch was "scrubbed" to give engineers more time to investigate a red flag that was lifted at the last moment before takeoff.
The team was carrying out the final verifications of the $ 1.5 million unmanned probe when a problem was discovered.
The problem is related to the gaseous helium pressure alarm in the spacecraft, authorities said early Saturday.
The next start window opens at 3:31 (0731 GMT) on Sunday.