NASA's SLS Booster rolls back to the Vehicle Assembly Building at the Kennedy Space Center, Florida on April 26. NASA plans to conduct repairs to the rocket and its mobile launch platform before returning to the pad for a wet dress rehearsal and tanking test in June. Photo by Joe Marino/UPI | License Photo
ORLANDO, Fla., May 5 (UPI) -- NASA is targeting early June for its next attempt of the Artemis 1 wet dress rehearsal, officials announced on Thursday.
The test aims to demonstrate that the rocket can be safely loaded with propellant and practice the launch day procedures, aside from actually launching, to identify concerns and potential issues.
Previous attempts at the wet dress, conducted in April, resulted in NASA having to stop the testing due to valve, fueling and leak issues that led to rolling the rocket back to the Vehicle Assembly Building for troubleshooting.
With June as the target for the next attempt at a wet dress rehearsal, the rocket's launch has likely also been pushed back. NASA officials said at a teleconference Thursday they will aim for later in the summer, likely in August, a delay from the original June launch window.
Crews have been inspecting the craft since April 26, when it got back to the VAB, to determine what the next steps are.
"[Rolling back] was absolutely the right thing to do to be able to work through the issues we found at the pad," Jim Free, NASA's associate administrator for the Exploration Systems Development Mission Directorate said during a news briefing on Thursday.
During the fueling process in April, engineers discovered a faulty check valve in the rocket's upper stage. NASA officials said the valve was in a location that was easier to access once the launcher was back inside its assembly building, as opposed to the launch pad.
"Over the weekend, our partners at ULA replaced the check valve cover," Free said. "There was a small piece of rubber that was preventing it from sealing correctly."
He said there were no obvious issues with the valve, but analysis is ongoing to determine where the rubber came from.
NASA made a total of three attempts to complete the wet dress rehearsal. But over the course of two weeks, officials said progress was plagued by some sort of glitch -- either with the rocket, the mobile launch platform or the ground system equipment that supplies the rocket with fuel.
Teams were able to complete some of the test objectives, including partially filling the liquid oxygen tanks.
The most dynamic portion of the test, however, pressurization and terminal countdown -- the moment before the rocket's engines would ignite in a real launch -- was not completed.
SLS requires more gaseous nitrogen, which is used to purge its fuel tanks, than most rockets because its size. NASA said an issue existed with its gaseous nitrogen supplier, Air Liquide, and that the supplier would need to upgrade its hardware at the launch pad.
Free noted that moving the SLS back to the VAB has allowed Air Liquide to "work through the upgrades at the launch pad," and that they are expected to be finished "around May 11."
Additionally, NASA also needed to repair a leak on the mobile launch tower's "tail service umbilical," which is a 10-meter-tall structure that supplies propellant and electricity to the rocket while it's on the launch pad.
"The hydrogen leak is coming from an umbilical [on the mobile launcher] connected to the core stage," Free said. "Leak checks have been completed on all fill lines and we found loose bolts that could be the cause of the leak."
To mitigate the leaks, crews have tried tightening the bolts that connect the lines in 30-hour increments and found it to be effective.
"We haven't found any more leaks," said Cliff Lanham, NASA's senior vehicle operations manager for the Exploration Ground Systems Program at Kennedy Space Center. "More leak checks will be conducted once we're back on the pad and can start cryogenic fueling."
He explained that it's common to see no leaks at air temperature, but then to see them at cryogenic temperatures.
Once NASA is able to prove that it can safely load the rocket with fuel, run through a simulated countdown, and then detank, agency officials can determine when the rocket might actually fly. Free said early- to mid-June is currently when they hope to get the rocket back out to the launch pad.
SLS was designed to be the driving force behind NASA's return to the moon. Part of the Artemis lunar program, the massive vehicle is preparing for its maiden voyage around the moon.
The mission will provide data on how the rocket performs in deep space and will ultimately pave the way for future crewed flights around the moon and to the lunar surface, NASA officials have said.
The rocket will be moved back to the Vehicle Assembly Building (VAB) after failing some of its prelaunch testing. Failing to make the June launch window, the date will be pushed back to late June or early July. Photo by Pat Benic/UPI | License Photo