The mission team plans to start fuel for the 322-foot (98-meter-high) Artemis I rocket stack, including NASA’s Space Launch System and the Orion spacecraft, Thursday.
The test, known as the wet dress rehearsal, has been adjusted in response to a problem encountered during the third attempt that took place over the weekend. Engineers identified a helium check valve that did not work. The valve is difficult to reach while the rocket is on the launch pad, but it can be replaced or repaired later. The modified version of the wet swatch is required to ensure the safety of the rocket’s flight equipment.
Helium is used to clean the engine before refilling super-cold propellant – the wet in a wet general sample – during refueling. Check valves allow gas or liquid to flow in one direction to prevent backflow. In this case, the part that does not work is about 3 inches long and prevents helium from flowing back out of the rocket.
When refueling of the rocket’s core stage starts on Thursday, the modified test will remove the load on the valve and the upper rocket stage with minimal propellant operations. Formerly the team had planned to burn the core and the upper stages of the rocket fully, but the valve problem prevents it steps from taking place during this test.
The results of this test will determine if there are more testing must take place before launch.
“I’m very confident we’ll have a good test on Thursday with the changed procedures,” John Blevins, SLS chief engineer at NASA’s Marshall Space Flight Center in Huntsville, Alabama, said during a Monday news conference. “I can not say that I’m glad we have a broken part, but I’m glad we caught it when we did before we embarked on operations that would be compromised by having a broken part. That’s why we’re doing these thorough tests. “
The wet dress rehearsal simulates each step of the launch without the rocket actually leaving the launch pad. This includes igniting the SLS rocket and Orion spacecraft, loading super-cold propellant into the rocket’s tanks, reviewing a full countdown simulating launch, resetting the countdown timer, and draining the rocket tanks.
It begins Tuesday around noon. 17 ET with the call to stations, which is a check-in with each team associated with a launch, to say that the test has begun.
Once this test is complete, the Artemis I rocket will be rolled back into the Vehicle Assembly Building at the Kennedy Space Center in Florida, where teams can analyze the valve and replace it if necessary.
The previous three attempts at the wet dress rehearsal have already provided valuable insight for the team, officials said, though they have worked through various issues.
“We’ve completed a lot of the test requirements we needed to get out of wetsuit activity,” Tom Whitmeyer, deputy associate administrator for exploration systems development at NASA headquarters, said during a news conference Monday. “We have a few more that we will get to on Thursday. The Mega Moon rocket is in good shape and we are treating it very carefully.”
Although the exact problems identified during the test trials were not foreseen, it is part of the process when testing a new rocket.
“Every new rocket that comes out in a new program like this kind of goes through these updates and understands how the rocket is performing,” Whitmeyer said. “And that’s the kind of thing we’re going through right now.”
“I can say that these will probably not be the last challenges we will encounter,” Mike Sarafin, Artemis’s Head of Mission at NASA Headquarters, said during the conference. “But I am convinced that we have the right team in place, and the ability to gather around these issues and overcome them is something we are proud of.”
The results of the wet dress rehearsal will determine when the unmanned Artemis I will launch on a mission that goes beyond the moon and returns to Earth. This mission will launch NASA’s Artemis program, which is expected to return humans to the moon and land the first woman and first colored person on the moon’s surface in 2025.
Current launch options include June 6 to June 16, June 29 to July 17 and July 26 to August 9, Sarafin said.