'Welcome home, Artemis': Crew celebrates historic 10-day moon mission

NASA teams are troubleshooting an issue with the temperature of one of the batteries on the Launch Abort System.

NASA is reporting that the temperature is out of range for one of the two batteries. The agency says it is not a constraint for launch currently, but it will be if the issue continues when the temperature is checked during the final countdown minutes.

"Engineers investigated a sensor on the launch abort system’s attitude control motor controller battery that showed a higher temperature than would be expected. It is believed to be an instrumentation issue and will not affect today’s launch," the agency said in a statement.

-ABC News' Briana Alvarado

Transportation Secretary Sean Duffy said the Artemis II moon mission is "critically important" a few hours ahead of the scheduled launch.

"This is a moment that brings the country together," Duffy told Gio Benitez on ABC News Live.

"The technology, the time, the effort that has gone into making today possible is so cool," he added.

Duffy said the U.S. is in a race against China to get to the moon's South Pole. Currently, Artemis III is planned for 2028, while China’s space program is gearing up for a moon landing by 2030.

"There was a time that the adage was, ‘He who controls the seas controls the world.' Now it is, 'He who will control space will control the world,'" Duffy said. “We have to win. This is critically important."

NASA said it has resolved the Flight Termination System issue, adding it is "no longer a constraint" and is proceeding with countdown operations.

The issue affected the rocket, not the Orion spacecraft. The FTS is a signal to blow the rocket up if it starts heading in a direction that would endanger lives.

Orion would have separated from the rocket safely, and the rocket would be issued a command to self-destruct.

Additionally, the Launch Abort System hatch is now also closed. The closeout crew successfully closed both hatches on Orion, concluding the hatch preparation and closure phase of launch operations.

-ABC News' Briana Alvarado and Gio Benitez

President Donald Trump called NASA Administrator Jared Isaacman Wednesday afternoon to "wish everyone luck this evening" ahead of the Artemis II launch, according to a post by one of Trump's top advisers.

"We will all be watching, along with the rest of the world," Dan Scavino, an assistant to the president and one of Trump's top aides, added in the post on X.

-ABC News' Michelle Stoddart