A hydrogen leak at the base of NASA's Artemis II moon rocket threw a wrench into a carefully planned countdown "wet dress" rehearsal, interrupting a test intended to help clear the way toward a possible weekend launch for four astronauts on a flight around the moon.

NASA ran into a leak while fuelling its new moon rocket Monday in one final make-or-break test that will determine when astronauts can launch on a lunar fly-around.

NASA conducted a critical test of its Artemis II moon rocket Monday night at Kennedy Space Center, briefly pausing the countdown after a minor equipment issue during the wet dress rehearsal, a key milestone ahead of the mission’s first crewed flight.

NASA begins Artemis II wet dress rehearsal, fueling the SLS and Orion ahead of a possible Feb. 8 launch window.

Preparations are underway to begin critical testing of NASA spacecraft for the Artemis II mission that will send four astronauts around the moon. Fuel testing is set to begin Monday, NASA says. The fueling phase of prelaunch testing known as a "wet dress rehearsal" was delayed because of freezing temperatures at the launch pad located at NASA's Kennedy Space Center in Florida.

NASA’s wet dress rehearsal—a crucial test of the agency’s Artemis II mission to the moon—hit a snag on Monday. Engineers had been fueling the mission’s Space Launch System (SLS) rocket up with liquid hydrogen and liquid oxygen propellant and planned to initiate a countdown sequence to simulate the launch.

NASA muscled through familiar headaches Monday at Kennedy Space Center during a critical tanking test dealing with liquid hydrogen leaks at the launch pad for the Artemis II moon mission that could fly as soon as this Sunday.

NASA teams worked through technical issues Monday as they conducted a high-stakes dress rehearsal for the Artemis II mission at Kennedy Space Center, a critical test ahead of the planned crewed flight around the moon.