HomeTechnologyNASA's Artemis Moon Rocket Passes Critical Fuel Test Despite Hydrogen Leak

NASA’s Artemis Moon Rocket Passes Critical Fuel Test Despite Hydrogen Leak

NASA’s Space Launch System lunar rocket, plagued by leaks, had initially worrying problems during a fuel test on Wednesday, but engineers “handled” a new leak in a fitting that derailed a September 3 launch attempt and they were able to fill the massive propellant with a full 750,000 gallon charge of super-cold propellants.

They also carried out two other critical tests, verifying their ability to adequately cool the rocket’s four hydrogen-fueled engines as required for flight and successfully pressurizing the core-stage hydrogen tank to flight levels.

Launch director Charlie Blackwell-Thompson did not speculate on whether NASA could move toward a September 27 launch date as previously discussed, saying she wanted her team to review the test data before drawing any conclusions. But she said she was “extremely encouraged by today’s test.”

NASA’s Space Launch System megarocket on pad 39B at the Kennedy Space Center on Wednesday. Engineers carried out a full-scale fueling test to verify repairs to fix a hydrogen leak that derailed a launch attempt on September 3, and another leak arose in the same system. This time, the engineers were able to use different flow rates and pressures to fully fuel the giant rocket.


“I don’t like to get ahead of the data, so I’d like the team to have a chance to go through it to see if there are any changes we need to make to our loading procedures, our schedules, or if it’s fine the way it is,” he said.

The discussion could prove challenging given that the label blamed for delaying the previous release has been replaced and the same system, at least initially, was leaked again on Wednesday.

But even if the team concludes that September 27 is a viable target for the rocket’s maiden flight, it might not be enough. The Eastern Range Space Force, which oversees all military and civilian launches from Florida, has yet to comment on a request from NASA to waive a requirement to inspect batteries in the rocket’s self-destruct system.

Batteries are not accessible on the launch pad, and without a waiver, NASA will be forced to transport the 332-foot-tall SLS rocket back to Kennedy Space Center’s iconic Vehicle Assembly Building, delaying the launch. for a month or more.

The long-awaited Artemis 1 mission is designed to send an unmanned Orion capsule on a 40-day journey around the moon and back to pave the way for the first piloted Artemis mission in 2024. If all goes well, NASA plans land two astronauts near the south pole of the moon in the period 2025-26, the first in a sustained series of missions.

But engineers have been beset by elusive hydrogen leaks and other problems in the run-up to the rocket’s launch. Already years behind schedule and billions over budget, the SLS rocket was first transported to launch pad 39B on March 17 for a fuel test to clear the way for launch. But back-to-back scrubs were ordered on April 3 and 4 due to multiple unrelated issues.

Liquid oxygen and hydrogen propellants flow into the Space Launch System’s massive core stage through 8-inch-wide retractable lines that extend from two tail service mast umbilicals (at left) to the tailpipe fittings. quick disconnects attached to the side of the drive. A leak in the hydrogen fitting caused teething problems during a fueling test Wednesday, but engineers were able to reseat a suspect seal and successfully load the rocket with propellants.


A third test on 14 April was canceled due to a hydrogen leak near the core stage fuel line quick disconnect, and the rocket was returned to the VAB for repair. It returned to the launch pad in early June only to suffer further problems during a fueling test on June 20, when engineers were unable to cool the rocket’s motors due to a stuck valve in a different system.

The rocket was returned to the VAB for repairs in early July and transported back to the pad in mid-August for what NASA hoped would be its maiden flight. But a launch attempt on August 29 was canceled due to more hydrogen problems and again on September 3 when the 8-inch quick-disconnect fitting leaked.

Following the second launch cleanup, NASA managers opted to disassemble the accessory on the launch pad, replace an internal seal, reassemble hardware, and perform a fuel test to verify seal integrity. Hydrogen leaks usually appear only when the pipe is exposed to cryogenic temperature, minus 423 degrees Fahrenheit in this case.

Oxygen vapor exits from vents on the side of the Space Launch System rocket as the propellants in the upper booster stage are loaded.


Repair work was completed last week and testing began normally on Wednesday, with oxygen and hydrogen flowing into separate core stage tanks at low rates. In an effort to alleviate thermal shock during the transition to “fast fill” mode, the charging sequence was slowed down and flow rates were reduced to relieve stresses on the hardware.

But when flow and pressures increased, sensors detected an immediate buildup of hydrogen gas in a containment casing around the newly repaired quick-disconnect fitting, indicating a leak. Sensors detected concentrations as high as 7%, well above the 4% safety limit.

Engineers then opted to heat the fittings before restarting the flow of hydrogen in hopes of coaxing the inner seal to “reseat”. When flow resumed, there was still a leak, but it was well below the 4% threshold and engineers were able to move on, eventually filling the hydrogen tank to a full 730,000 gallon charge.

Close examination of the sensor data showed that, contrary to initially observed behavior, the leak rate decreased as pressure increased. This is how the fitting is designed to work, suggesting that efforts to reseat the seal were at least partially successful.

With the core stage’s hydrogen and oxygen tanks full, engineers went ahead with loading the upper stage of the SLS rocket, while conducting engine pressurization and cooling tests.

Another hydrogen leak was reported near a 4-inch quick disconnect fitting used for cooling testing. While engineers had already agreed to go ahead with the observed rally, it would have stopped an actual launch countdown. It’s not yet known what impact, if any, that issue might have on launch planning.

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