NASA on Monday (Tuesday in Manila) was conducting critical final tests ahead of setting a launch date for its first crewed flyby mission to the Moon in more than half a century.

At approximately 11:25 a.m. EST (1625 GMT), the launch director of the Artemis 2 mission gave the green light to begin loading cryogenic liquid propellant into the giant rocket at the Cape Canaveral launch pad in Florida as part of the “wet dress” rehearsal.

The exercise, which includes leak checks, is the last major test before NASA aims to launch the mission around the Moon.

The US space agency had intended to begin the tests over the weekend, but postponed plans due to forecasts of freezing temperatures at the launch site as much of the nation experienced a cold snap.

In addition to demonstrating the ability to load more than 700,000 gallons of cryogenic propellants into the 322-foot (98-meter) rocket, teams on Monday will simulate a launch countdown, and practice safely removing the propellant.

The simulated launch is scheduled for 9 p.m. EST (0200 GMT), but could come as late as 1 a.m. EST (0600 GMT).

If everything goes well, NASA would send their Artemis 2 team of four astronauts on the Moon flyby as soon as 8 February.

Crew leads will make final determinations as to when to attempt the launch depending on the results of Monday’s rehearsal.

The astronauts remain in quarantine in Houston.