NASA fuels up giant Artemis 2 moon rocket. Yes, it's a little leaky. So is it ready to fly?

NASA's big moon rocket leaks a little bit, but it just might be ready to carry astronauts beyond Earth.

The space agency conducted a crucial fueling test today (Feb. 2) with the Artemis 2 mission's Space Launch System (SLS) rocket, loading more than 700,000 gallons (2.65 million liters) of cryogenic liquid hydrogen (LH2) and liquid oxygen (LOX) into the two-stage vehicle on Pad 39B at Kennedy Space Center (KSC) in Florida.

Teams had to stop loading LH2 into the SLS core stage twice to deal with leaks, but they managed to troubleshoot the issue in relatively short order and top up the rocket's enormous tanks.

Today's tanking was the trickiest part of the Artemis 2 wet dress rehearsal, a two-day-long practice run through the operations that will precede an actual launch.

Currently, NASA is targeting Feb. 8 for the liftoff of Artemis 2, which will send NASA astronauts Reid Wiseman, Victor Glover and Christina Koch and Canada's Jeremy Hansen on a 10-day trip around the moon. But that's contingent upon a successful wet dress, as well as a number of other factors — good weather conditions, for example.

It's too soon to tell whether or not NASA considers the wet dress a complete success; the exercise is still going on, after all, and may not conclude until 1 a.m. EST (0600 GMT) on Tuesday (Feb. 3).

But we may get an answer on Tuesday at 12 p.m. EST (1700 GMT), when the agency holds a press conference about the wet dress. You can watch that briefing live here at Space.com when the time comes.

It wasn't surprising that leaks sprang up during LH2 loading today, given how small that molecule is; it can slip through the tiniest of cracks. And history is a guide here as well: The Artemis 1 launch campaign was delayed repeatedly by LH2 leaks and other issues.

That mission, the first of NASA's Artemis program of moon exploration, was originally scheduled to launch in the spring of 2022, but it didn't get off the ground until Nov. 16 of that year.

Things went well after liftoff, however: Artemis 1 successfully sent an uncrewed Orion capsule to lunar orbit and back to Earth, showing that Artemis hardware can handle a crewed mission to deep space.

NASA is taking many lessons learned from Artemis 1 to Artemis 2 and beyond — and some of those lessons apparently helped out today.

The LH2 leaks that plagued Artemis 1 centered on an interface with the tail service mast umbilical (TSMU), a line that carries propellant from the mobile launch tower to the rocket. The two leaks observed during today's wet dress also occurred at a TSMU interface, according to a NASA update. But the mission team quickly troubleshot the issue and moved on.