NASA's third attempt at crucial moon mission test delayed to Tuesday due to malfunctioning valve

In this photo provided by NASA, the Space Launch System rocket with the Orion spacecraft stands on a mobile launcher at Launch Complex 39B, Monday, April 4, 2022, as the Artemis I launch team conducts the wet dress rehearsal test at NASA's Kennedy Space Center in Florida. (Joel Kowsky/NASA via AP)

NASA announced Saturday that a crucial moon mission test has again been delayed and is now scheduled to begin on Tuesday.

The space agency was scheduled to begin a prelaunch test for NASA's Artemis I mission to the moon. The Artemis program is NASA's first mission to the moon since 1972.

On the NASA blog, the agency said the test was pushed due to a malfunctioning valve.

"Engineers have identified a helium check valve that is not functioning as expected, requiring these changes to ensure safety of the flight hardware," the agency said. Engineers at the Kennedy Space Center will evaluate the valve and replace it if needed, the agency added.

The critical prelaunch test is known as a "wet dress rehearsal" and simulates every stage of launch without the rocket actually leaving the launchpad. The Space Launch System (SLS) rocket and Orion spacecraft will be powered on, supercold propellant will be loaded into the rocket's tanks (the "wet" in wet dress rehearsal), and NASA's team will go through a full countdown simulating the launch.

This is the third time the wet dress rehearsal has been delayed. Originally scheduled for February, the rehearsal was delayed once for further testing and then again for issues involving propellant loading. The test is essential to determining when exactly NASA will conduct its Artemis I mission, in which an uncrewed spacecraft will reach the moon and then travel thousands of miles beyond it.

NASA has said that it plans to launch the mission in June or July, depending on the results of the wet dress rehearsal. The first step will be an uncrewed mission -- Artemis I. Then, Artemis II will take astronauts on a crewed flyby of the moon, and Artemis III will bring NASA astronauts to land on the lunar surface for the first time in fifty years.

The agency hopes to land the first woman and the first person of colour on the lunar surface by 2025.