Another fuel leak forced NASA to cancel a second attempt to launch its massive Moon rocket.
On Saturday, almost three hours before the scheduled liftoff time of 2:17pm EDT (18:17 GMT), mission controllers suspended preflight operations.
The previous attempt on Monday was also hampered by hydrogen leaks, but those were on different parts of the 98-meter (322-foot) rocket, the most potent NASA has ever created.
The most recent setback may cause NASA's Moon-to-Mars Artemis program's initial mission to be postponed for several weeks or even months.
According to officials, the leak proved too difficult and time-consuming to diagnose and repair on the launch pad before the mission's current launch window closes on Tuesday.
Spectators jammed the Florida coast to see the SLS take off. A large number of people were anticipated by local authorities due to the lengthy Labor Day weekend.
At this point, the spacecraft will be rolled back into its assembly facility.