CAPE CANAVERAL, Fla. (AP) – After weeks of fuel leaks and other issues, NASA faced a trouble-free countdown Tuesday on the eve of astronauts' first trip to the moon in more than half a century.

Officials reported the moon rocket was doing well on the pad, and the weather looked promising. Forecasters put the odds of favorable conditions at 80%.

"Everybody's pretty excited and understands the significance of this launch," said senior test director Jeff Spaulding.

Four people in blue jumpsuits standing in front of rocket on conreted launch pad.
NASA astronauts (left to right) Reid Wiseman, Victor Glover, Christina Koch, and CSA (Canadian Space Agency) astronaut Jeremy Hansen, pictured at NASA's Kennedy Space Center in Florida ahead of the launch. (NASA/Bill Ingalls via AP)

The four astronauts assigned to the Artemis II mission will become the first lunar visitors since Apollo 17 in 1972. They'll zip around the moon without landing or even orbiting, and come straight back.

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It's the closest NASA has come to launching Artemis II. Hydrogen fuel leaks bumped the flight from February to March, then clogged helium lines pushed it to April. The space agency has only a handful of days every month to send the three Americans and one Canadian to the moon.

Related: NASA's Giant Moon Rocket Has a New Problem

Confident that all of these problems are fixed, the launch team plans to begin fueling the 32-story Space Launch System rocket on Wednesday morning for an evening send-off.