NASA Works Through New Leak for Artemis I Tanking Test Ahead of Potential Launch Next Week

Richard Tribou / Orlando Sentinel (TNS)

ORLANDO, Fla. — NASA began tank testing of the core and upper stage of the Space Launch System, which could pave the way for Artemis I’s launch to the Moon next week, at Kennedy Space Center on Wednesday, but again a new leak in one Fuel line gave NASA a headache.

The test, which was cleared at 7:30 a.m. Eastern Time on Launch Pad 39-B, is designed to ensure fuel line repairs made since a Sept. 3 clean support the more than 730,000 gallons of cryogenic liquid hydrogen and fluids oxygen, which must flow into both the core stage and the upper preliminary cryogenic propulsion stage of SLS.

But a new leak in the same line that caused this scrub was discovered when NASA halted liquid hydrogen refueling just before 10 a.m

“They have detected a hydrogen leak in the tailmast supply line,” commentator Derrol Nail of NASA Communications said. “It’s in the bottom part of the rocket. You have 7% hydrogen in a cavity where that quick disconnect line is. This is the one that was repaired.”

A quick disconnect is designed to fall off and move away from the rocket during launch.

The 7% leak is above the 4% threshold set by NASA for cryogenic refueling limits. NASA had been loading liquid oxygen since before 9 a.m. with no problems, but once again liquid hydrogen, which caused NASA problems on its first launch attempt in August and during the spring’s wet dress rehearsals, caused the loading process.

NASA then proceeded to troubleshoot, using the same warm-up procedure it had tried several times on previous leak locations. This process brings the temperatures of the lines back from their super cold fill temperatures: minus 423 degrees Fahrenheit for the liquid hydrogen and minus 294 degrees Fahrenheit for the liquid oxygen.

The lines are then re-cooled in hopes that pressure and temperature changes could shut down any spot that may have been the source of the leak.

The attempt to load liquid hydrogen again began after 11:30 a.m., but with a slight change in operation.

“It’s different from previous plans during the second launch attempt and that means they’re going to drop the pressure on the holding tank to less than 5% psi — that’s a very low pressure for that operation,” Nail said. “And then as they recover, they flow into the tank, into the cryosphere, and they go very slowly, as gently and gently as possible to build the pressure.”

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The solution worked to a degree, with both cryogenic fuels operating so that by midday the liquid oxygen was nearing 100% of its 196,000 gallon capacity and the liquid hydrogen was above 25% at not-quite-fast flow. , its capacity of 538,263 gallons.

NASA officials said the leak was down to 3.4% after the restart, and teams were able to conduct another planned test called kickstart bleed, which uses the liquid hydrogen to cool the four RS-25 engines under the core stage is used. That process was among the problems that led to the scrubbing of the first attempt at launch in August because a faulty sensor said one of the engines wasn’t as cold as it needed to be, a requirement NASA needs to have to keep the engines thermal to condition them so they can endure the super cold fuel that goes into the engines.

At 12:45, the liquid hydrogen fill process was at 68%, but still below the normal fast fill pressure flow normally used for launch day refueling.

“The team discussed the plan with the launch director to move from here, and this is where they settled,” Nail said. “They want to gradually increase the storage tank pressure, which also increases the pressure on that quick connector. It also increases flow, hopefully getting it up to the quick-fill flow that would be nominal for a launch attempt. That is the ultimate goal.”

At 1:00 p.m., the liquid hydrogen was over 90% full, and shortly after refilling, the teams were in resupply mode, during which only enough liquid hydrogen was pumped to compensate for the amount boiled off in the core phase.

“Some interesting data to share that we just learned is that during the fast-fill process where the storage tank for loading the liquid hydrogen was under full pressure, the leak rate was less than half a percent,” Nail said. “Very manageable for the team here, but a lot of people are scratching their heads about it at the moment.”

Wednesday’s test also uncovered a faulty sensor that would have triggered the switch from slow to fast filling of the liquid hydrogen. NASA teams halted the liquid hydrogen loading as they attempted to switch to a backup sensor, and then leak detection ensued.

“We’re getting some good news from the liquid hydrogen team regarding the leak,” Nail said. “That means it has reversed its trend where earlier as the pressure went up the leakage increased, but now you’re seeing a trend for this particular seal of it decreasing as the pressure goes up. This is, as engineers say, the way it works and is intended. … So now both core stage tanks are refilled and stable.”

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Now that the core stage is full, the plan is to open umbilicals into the upper stage ICPS, the self-powered hardware that will be used once SLS sends the Orion spacecraft out of Earth’s atmosphere.

Shortly before 2:00 p.m., the teams gave the go-ahead for the ICPS refueling. The smaller tanks hold 19,250 gallons of liquid hydrogen and 5,700 gallons of liquid oxygen.

The ICPS will propel Orion into what is known as trans-lunar injection, sending it on its way on a multi-week mission that will see the unmanned spacecraft travel further beyond the moon and return it to Earth faster than any human before it. evaluated spacecraft to ensure it is safe for astronauts on future Artemis missions.

After ICPS refueling, NASA plans what is known as a pre-pressurization test that will pressurize the core stage’s liquid hydrogen tank to the level of pressure that would be needed just before launch, allowing engineers to calibrate the appropriate engine conditioning at a higher flow rate of both propellants, which will be needed during of the final count would take place on the starting day.

The teams were allowed to go to the prepress test at 3:30 p.m

“This prepress test is crucial for the number of terminals,” said Nail. “During the final count at T-4 minutes and 40 seconds, the high-flow bleed begins for a start countdown. It runs for about 4 1/2 minutes and gets the engines up to just the right temperature to start. The launch team has not yet been able to validate this procedure. You have the opportunity now.”

The reason it has yet to be tested was that spring’s wet dress samples faced pressure and valving issues that didn’t allow operations leaders to achieve all of their goals. Despite this, they continued launch attempts. This pad test essentially acts as another wet dress rehearsal.

A new hydrogen leak on an engine bleed line surfaced during the prepress test but stabilized at around 4% and the mission managers had a launch contingency for it to exceed 4% but no longer than five minutes. Said Nagel. The leak on the earlier line had been shut off by the SLS during pre-press testing as no incoming propellants were involved at the time.

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“The start team has reached the desired pressure,” said Nail. “It’s a tight range but they have it in the spec. Great performance there. … the test is now complete.”

Now the teams are refilling the core stage with the liquid hydrogen that was expelled during the prepress test and putting the upper stage back into refill mode, essentially restoring a stable set of propellants in both the core stage and the ICPS.

Originally, the refueling process was supposed to be completed by 3:00 p.m., but delays due to the leak extended this schedule.

After the final scrub, NASA made repairs to the launch pad, so if Wednesday’s test works, a possible launch attempt could happen next Tuesday.

The core stage engines combined with two solid rocket boosters, which will not be tested on Wednesday, will combine to provide 8.8 million pounds of thrust at launch, which would make the SLS the most powerful rocket ever launched from Earth and the Saturn V rockets used in the Apollo defeated program.

The test already included what NASA executives called a gentler mode of loading to avoid temperature and pressure shocks that could have been the cause of the September 3 leak.

“This is part of the new operation where they are taking it very slowly as the liquid hydrogen allows the lines to cool very slowly and the slow fill of the tank to be a little slower than usual,” Nail said.

NASA still needs an OK from the US Space Force, which controls the Eastern Range over which the rocket would launch. NASA is seeking a waiver of a rule to check batteries in the rocket’s flight termination system, which currently requires NASA to ensure the batteries are charged within 25 days, a process that costs the massive 5.75 million pounds and 322 would have required foot-large combination of rocket, launch vehicle and spacecraft to return to the Vehicle Assembly Building.

The last time the self-destruct mechanism was checked was before August 16, when Artemis I last taxied from the VAB to the launch pad.

If NASA gets the waiver, it will be pursuing two possible launch dates. The first is Tuesday, September 27, a 70-minute window that opens at 11:37 a.m. and would fly on a nearly 40-day mission that would land back on Earth on November 5. The second is Sunday, October 2, a 109-minute window opening at 2:52 p.m., which would fly for an approximately 41-day mission and land on November 11.

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