On Thursday morning, NASA's Artemis I mega moon rocket underwent its third attempt at a final pre-launch trial. However, the test ran into some difficulties and ended abruptly at 5:10 p.m.

In an attempt to power the 98-meter-tall Artemis I rocket pile at Kennedy Space Center in Florida, which includes NASA's Space Launch System and Orion spacecraft, the operation team faced a number of setbacks.

As stated in a tweet from Jeremy Parsons, Deputy Leader of the Exploration Ground Systems Plan at Kennedy Space Center, "the team will not perform the end countdown activities today as scheduled and will evaluate the next steps after today's operations." 

Identified as a "wet dress rehearsal," this critical test allows engineers to visualize every stage of a launch without having to send the rocket off the ground.

In this process, the propellant is loaded into the rocket tanks, the rocket goes through a full countdown simulation, the countdown clock is reset and the rocket tanks are drained.

The process had already been tweaked in response to a problem that occurred over the weekend while preparing for this attempt, and this was the second time around.

According to Tom Whitmeyer, Deputy Associate Supervisor for Exploration Systems Improvement at NASA Headquarters, any launch system that comes forward in a new program goes through particular upgrades and the rocket is being tested to understand its operation.

The malfunctioning helium check valve that NASA engineers discovered over the weekend is the source of the problem.

During fueling, helium is used to cleanse the engine prior to loading the supercold propulsion system - the wet in the wet dress rehearsal - into the combustion chamber.

Check valves are devices that allow gas or liquid to circulate only in one direction in order to avoid backflow.

In this particular instance, the part that isn't working is approximately 3 inches long and prevents helium from escaping back into the atmosphere.

The revised version of the wet dress rehearsal is still required, however, in order to ensure the safety of the rocket's flight hardware during the launch.

After this test is completed, the Artemis I rocket will be pushed back into the Vehicle Assembly Building at the Kennedy Space Center for further processing.

While the specific problems that were discovered during the test attempts were not anticipated, they were unavoidable as part of the process of evaluating a new rocket.