The crucial test, known as the wet dress rehearsal, simulates each step of the launch without the rocket leaving the launch pad. This process includes refueling, reviewing a full countdown, firing simulation, resetting the countdown timer, and draining the rocket tanks.
The team was able to let super-cold propellant into the SLS rocket’s core stage tanks, but “encountered a liquid hydrogen leak on the tail service mast’s umbilical cord that prevented the team from conducting the test,” according to the agency.
“After troubleshooting, the team decided to turn it off for the day because when you have hydrogen leaks and you have ambient oxygen out there, you only need an ignition source to close the fire triangle. So it was a fire hazard,” he says. Mike Sarafin, Artemis mission leader at NASA headquarters, said during a Friday news release conference.
Technicians collected data, emptied tanks and ensured that the rocket remained safe and stable. Despite the leak, the team has was able to work through a number of critical test topics during the third experiment.
“The Mega Moon rocket is fine,” Sarafin said. “All the problems we encounter are procedural and experiential.”
Now the test team continues to assess how to solve the leak. Troubleshooting began Friday morning.
The team “will look at these particular areas that we think may be the problem, how we access them” and determine a way forward, said Charlie Blackwell-Thompson, Artemis’ launch director for NASA’s Exploration Ground Systems program, during a Friday news conference.
Meanwhile, the team is getting ready for the next potential opportunity at another wet dress rehearsal on April 21, the earliest time the team is familiar with, Sarafin said. The Artemis team is working closely with SpaceX because the Crew-4 launch is expected to take place at a nearby launch pad on April 23rd.
Sarafin did not reveal the exact plan to keep the passage on track, as only 24 hours have passed since the leak, but he said the team is investigating options that are “readily available.”
“We hope this is something that is fairly straightforward and needs to be adjusted or easily resolved, and we can do it by the pillow and do it in a pretty short amount of time, “Sarafin said.” And then there are a few more invasive options, and we have to weigh them up against a wide range of considerations that include putting further stress on the vehicle. “
The longer the rocket stays on the launch pad, the more it is exposed to wind and other stressors while being exposed to the elements – not to mention the load induced by repeated tests. It can determine when the stack will be rolled back into the Vehicle Assembly Building in the space center.
Test ambitious missions
When the team was asked if it is possible for Artemis I to launch without conducting certain aspects of a full test, the team said it would have to reach an acceptable level of risk. But the ground and float test programs are not finished, so the team has not reached that consideration yet, Sarafin said.
The point of the wet dress rehearsal is to learn about problems that can be fixed before they are forced to interrupt a launch attempt, and that is something that the Apollo and shuttle programs also faced, Blackwell-Thompson said.
There were about five or six refuelings, or wet rehearsals, of the first shuttle before launch, she said. And the space shuttle had only a single stage, whereas the SLS rocket has a core and an upper stage that must be supplied with super-cold propellant, making the process even more complex.
Sarafin said the team occasionally talks to staff working on the previous programs, comparing the challenges to physics, fluid dynamics, thermodynamics, super-cold temperatures, structural stresses and fire hazards.
“History has shown that it has been a challenge for pretty much everyone who has done something of this magnitude,” Sarafin said.
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.
“But there is no doubt in my mind that we will end the test campaign and we will be ready to fly,” Blackwell-Thompson added.