On Wednesday, NASA's Artemis 1 moon rocket completed a crucial fuelling test, likely keeping it on schedule for a planned liftoff on Sept. 27.

"All of the objectives that we set out to do we were able to accomplish today," Artemis launch director Charlie Blackwell-Thompson said in brief remarks after Wednesday's test.

Artemis 1 will use a massive Space Launch System (SLS) rocket to launch an uncrewed Orion capsule into lunar orbit. NASA attempted to launch the mission on Sept. 3 but was delayed by a liquid hydrogen propellant leak at a "quick disconnect" on the SLS core stage, an interface that connects the rocket to a fuel line from its mobile launch tower.

On Sept. 9, the Artemis 1 team replaced two seals surrounding the quick disconnect, then arranged a fueling test to check if the correction was successful. That test took place on Launch Pad 39B at NASA's Kennedy Space Center (KSC) in Florida on Wednesday, and it offered excellent news for the mission.

Artemis 1's scheduled launch date is currently set for Sept. 27, with Oct. 2 as a potential backup. Despite Wednesday's success, Blackwell-Thompson said it is still too early to formally commit to either of those dates.

For Artemis 1 to start the mission in the upcoming two weeks, a few other things must also go in its favor. On Florida's Space Coast, the weather is never guaranteed to cooperate, for example. The flight termination system (FTS), which is intended to kill the SLS if it veers off course during launch, must also receive a waiver before the mission can proceed.

The U.S. Space Force, which monitors rocket launches in the Eastern Range, licensed Artemis 1's FTS for 25 days, which has now expired. If the waiver is not granted, the massive rocket will have to be wheeled from Pad 39B back to KSC's Vehicle Assembly Building, which is the only area where recertification can take place.

Artemis 1 has previously received one of these FTS waivers, which increased the certification period from 20 to 25 days.

In 2024, Artemis 2 will launch astronauts to orbit the moon, and Artemis 3 will land a year or two later close to the lunar south pole, assuming everything goes according to plan with Artemis 1. The ultimate goal of the Artemis program is to create a sustained human presence on and around the moon, with the intention of using the expertise and knowledge acquired there to send astronauts to Mars in the late 2030s or early 2040s.