Posted BY: Trevor Mogg

NASA has completed what may have been the final ground test of its next-generation Space Launch System (SLS) rocket before its much-anticipated maiden mission to the moon.

It comes after a failed attempt at the same so-called “wet dress rehearsal” in April, when a number of issues caused the test to be called off.

Monday’s crucial test took place at Launch Pad 39B at the Kennedy Space Center in Florida, starting in the morning and concluding at 7:37 p.m. ET.

The entire procedure took about 12 hours and marked the first time for the SLS rocket’s propellant tanks to be fully loaded with fuel. The test ended with a mock countdown, a critical period of any rocket launch when many activities take place in rapid succession.

As the test has only just finished, information on how it went is scarce. Indeed, NASA is now analyzing the data gathered during the test to determine if it can launch the rocket and Orion spacecraft toward the moon in late August, or if more work needs to be carried out on the vehicle.

An initial NASA report released about an hour after the test finished suggested that overall it went well, though it wasn’t all smooth sailing.

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The agency said that during propellant loading operations early on Monday, engineers spotted a hydrogen leak in a component that attaches an umbilical from the tail service mast on the mobile launcher to the SLS rocket’s core stage. April’s test also featured a hydrogen leak though it’s not yet clear if the two issues are linked.

NASA said it tried to repair Monday’s leak using a warming and chilling process to realign the seals, but the effort failed. Determined to proceed with the test, engineers found a way to mask the leak-related data that in a real launch situation would have prompted the computer to pause the countdown.

The engineers’ actions enabled the team to “resume with the final 10 minutes of the countdown, called terminal count. During the terminal count, the teams performed several critical operations that must be accomplished for launch including switching control from the ground launch sequencer to the automated launch sequencer controlled by the rocket’s flight software, an important step that the team wanted to accomplish.”

The test clearly went better than the effort in April, but NASA will have to address the valve problem, among other issues that may have surfaced during Monday’s procedure.

NASA will provide a full account of the test at a media teleconference at 11 a.m. ET on Tuesday, June 21. You can watch the broadcast on the video player below or via NASA’s website.

The space agency will use the SLS rocket to power the Orion spacecraft on an uncrewed flyby of the moon in the Artemis I mission, which could launch in late August. Artemis II will send a crew on the same flight path, while Artemis III will put the first woman and first person of color on the lunar surface in a mission that will herald a new era of human space exploration.