NASA began tanking testing of the Space Launch System core and upper stage today at Kennedy Space Center, which could pave the way for the launch of Artemis I to the Moon next week, but a new leak in a fuel line has again Gave NASA a headache.
Testing, which got to proceed at 7:30 a.m. on Launch Pad 39-B, seems to ensure that the fuel lines built since the Scrub on Sept. 3 are repaired with more than 730,000 gallons of cryogenic liquid hydrogen and liquid oxygen. can support. Needed to be flown in the main stage of the SLS as well as the upper interim cryogenic propulsion stage.
But a new leak in the same line that caused that scrub was detected as NASA stopped refueling liquid hydrogen shortly before 10 a.m.
“They had detected a hydrogen leak in the tail service mast umbilical cord,” NASA Communications commentator Darrol Nell said. “It’s at the bottom of the rocket. They have a 7% reading of hydrogen in a cavity where that quick disconnect line is. This is what was repaired.”
A quick disconnect is designed to cause the rocket to fall off and move away when it is launched.
NASA has a 7% leak above the 4% limit for cryogenic fuel limits. NASA had been loading liquid oxygen since 9 a.m. with no problems, but once again liquid hydrogen, which gave NASA issues during the first launch attempt in August as well as wet dress rehearsals in the spring, was loading. stopped the process.
NASA then moved to solve the problem using the same warmup process it had tried several times in the past leak detection. This process returns the lines’ temperatures to their super cold fill temperatures: minus 423 degrees Fahrenheit for liquid hydrogen and minus 294 degrees Fahrenheit for liquid oxygen.
The lines are then re-cooled in the hope that pressure and temperature changes can close off any spaces that may be the source of the leak.
Re-attempts to load liquid hydrogen began after 11:30 a.m., but with minor changes in operation.
“This is different from previous plans during the second launch attempt and is that they are going to reduce the pressure on the storage tank to less than 5% psi – leave it as too low pressure for this operation,” Keel said. Told. “And then as they fix the flow in the tank in the cryosphere, they’re becoming very, very slowly, kind and gentle enough to increase the pressure.”
Fix was somewhat up and running with operations on both cryogenic fuels so that by noon, liquid oxygen was reaching 100% of its 196,000-gallon capacity and liquid hydrogen, up to 25% on very-fast-flows. was not. , of its 538,263-gallon capacity.
After the restart, the leak topped out at just 3.4%, NASA officials said, and teams were able to complete another planned test called a kickstart bleed, during which liquid hydrogen is used to drain four RS of the core’s bottom. -25 is used to cool the engine. Forum. The process was among the issues that led to the first launch attempt in August being scrubbed because of a faulty sensor that said one of the engines was not as cool as it should be, a requirement NASA needs to provide for the engines. have to be thermally conditioned so that they can tolerate super-cold fuel as it flows into the engine.
As of 12:45 p.m., the liquid hydrogen filling process was 68%, but still under the normal fast-fill pressure flow normally used for tanking on launch day.
“The team discussed plans to move forward with the launch director, and here they are,” Nell said. “They want to gradually increase the pressure of the storage tank which will also increase the pressure at this quick disconnect. It also increases the flow as expected for the fast fill flow that would be nominal for a launch attempt. That’s the end goal.” Is.”
By 1 p.m. liquid hydrogen was more than 90% full, and soon after reaching the top the teams were in replenishment mode, during which only enough liquid hydrogen is pumped into the core phase to replenish the boiled amount.
“Some interesting data we just learned and that is that during the fast-fill operation, where the storage tank for loading the liquid hydrogen was at full pressure, the leak rate was less than half a percent,” Keel said. “Very manageable for the team here, but a lot of people are still scratching their heads over this at the moment.”
Today’s test also revealed a failed sensor that may have triggered a change from slow to rapid filling of liquid hydrogen. NASA teams halted liquid hydrogen loading as they sought to switch to a backup sensor, and that’s when the leak was detected.
“We’re getting some good news from the Liquid Hydrogen team regarding the leak,” Keel said. “meaning it reversed its trend where earlier when the pressure increased, the leakage increased, but now they are seeing a trend for this particular seal that when the pressure increases, it decreases. As the engineers say That is to say, the way it is designed and intended to work. … So now, both the tanks of the core stage are in refueling and are stable.”
Now that the main stage is full, the plan is to open the supply lines to the upper stage ICPS, which is the hardware with its own engine that will be used by SLS after the Orion spacecraft is sent out of Earth’s atmosphere.
The teams told to go for ICPS tanking just before 2 p.m. Its smaller tanks hold 19,250 gallons of liquid hydrogen and 5,700 gallons of liquid oxygen.
ICPS Orion will send it on its way for a multi-week mission, known as the Trans-Lunar Injection, that will see the unmanned spacecraft travel farther from the Moon than any other Will bring you back to Earth quickly. Human-rated spacecraft to ensure that it will be safe for astronauts on future Artemis missions.
Earlier, the tanking work was expected to be completed by 3 pm, but due to leakage, it may increase further.
After the most recent scrub, NASA made repairs on the launch pad, so that if today’s test is successful, there could be a possible launch attempt next Tuesday.
Go to Launch – Space News
Get your telescope fix on all the space-related news, from rocket launches to space-industry advancements.
The core stage’s engines, combined with two solid rocket boosters not being tested today, will provide 8.8 million pounds of thrust at liftoff, making the SLS the most powerful rocket ever since the Saturn V used in Apollo. To make the best of rockets are launched from Earth. Program.
The test already involved what NASA managers called a kind, courteous method of loading to avoid any temperature and pressure shocks that could have been the reason behind the Sept. 3 leak.
“It’s part of the new operation where they’re taking it very slowly with liquid hydrogen to cool the lines very slowly and then slow down a little bit slower than normal in the slow tank,” Keel said. he said.
NASA still needs an OK to go from the US Space Force, which controls the eastern range at which the rocket will launch. NASA is seeking the relaxation of a rule about testing batteries on rocket flight termination systems, which currently requires NASA to ensure that batteries are charged within 25 days, a process that requires large The scale would require a 5.75-million-pound, 322-ft. Long combination of rocket, launcher and spacecraft to roll back to vehicle assembly building.
The last time the self-destruct mechanism was tested was before August 16, when Artemis I last reached the launch pad from the VAB.
If NASA gets a waiver, it is pursuing two possible launch dates. The first is Tuesday, September 27, a 70-minute window that opens at 11:37 a.m. that will fly on a nearly 40-day mission that will return to Earth on November 5. The second is Sunday, October 2. , a window of 109 minutes that opens at 2:52 p.m. and takes off for the nearly 41-day mission and lands on Nov. 11.
Follow Orlando Sentinel Space Coverage Facebook.com/goforlaunchsentinel,