NASA began testing its Space Launch System primary and upper stage tanks today at the Kennedy Space Center that could pave the way for the launch of Artemis I to the Moon next week, but a new fuel line leak is once again causing NASA concern.
Testing that got to go ahead at 7:30 a.m. at Launch Pad 39-B looks to make sure repairs to the fuel lines made since the Scrub on September 3 can support the more than 730,000 gallons of cryogenic liquid hydrogen and liquid oxygen it needs. to flow into the primary stage as well as the upper temporary cryogenic thrust stage of the SLS system.
But a new leak was discovered in the same line that caused this scrub when NASA stopped supplying liquid hydrogen shortly before 10 a.m.
“They detected a hydrogen leak in the umbilical tail service mast,” said commentator Derrol Nail of NASA Communications. It is located at the bottom of the rocket. They have a 7% reading of hydrogen in the cavity there where the quick separation line is. This is what has been fixed.”
The quick disconnect is designed to fall and move away from the missile when launched.
The leak is 7% above the 4% threshold set by NASA for coolant fuel limits. NASA had been loading liquid oxygen without a problem since 9 a.m., but again, liquid hydrogen, which also caused NASA problems during the first launch attempt in August as well as during wet-clothes drills in the spring, brought the loading to a halt.
NASA then moved on to fixing the problems using the same warm-up procedure it had tried several times in previous leak finds. This process returns line temperatures back from ultra-cool filling temperatures: minus 423 degrees Fahrenheit for liquid hydrogen and 294 degrees Fahrenheit for liquid oxygen.
The lines are then refilled with the hope that changes in pressure and temperature will seal off wherever the leak may be.
Reloading the liquid hydrogen started after 11:30 AM, but with little change in the process.
“It’s different from previous plans during the second launch attempt, and that means they’re going to lower the pressure on the storage tank to less than 5% psi — and that lowers the pressure that’s too low for the process,” Neal said. “And then, as they recover from the flow into the reservoir, into the cryosphere, they go very slowly, as gently and gently as possible to intensify the pressure.”
The repair was so successful with operations on both the cryogenic fuel and its operation that by noon, liquid oxygen approached 100% of its 196,000 gallon capacity and liquid hydrogen, at a not quite fast flow, was above 25%, of its 538,263 gallon capacity.
After the restart, the leak only accounted for 3.4%, NASA officials said, and the teams were able to complete another planned test called Kickstart Blaze, in which liquid hydrogen is used to cool the four RS-25 engines below the core. The theater. This process was among the issues that led to the first launch attempt in August due to a faulty sensor that said one of the engines was not as cold as it should have been, a requirement that NASA has to thermally condition the engines to be able to withstand. The fuel is too cold as it flows into the engines.
By 12:45 p.m. the liquid hydrogen filling process was at 68%, but it was still under the normal fast-fill flow pressure normally used in the tank on launch day.
“The team discussed with the launch manager the plan to move forward from here and here where they settled,” Neil said. “They want to gradually increase the pressure of the storage tank which will increase the pressure on this fast separation as well. It also increases the flow and hopefully to the fast fill flow which will be symbolic of the launch attempt. That is the ultimate goal.”
By 1 p.m., the liquid hydrogen was over 90% full, and soon after it was occupied, the difference was in regeneration mode, where enough liquid hydrogen was pumped in to make up for the amount being boiled off into the base stage.
“Some of the interesting data we just learned is that during the rapid filling process, where the storage tank was under full pressure to load liquid hydrogen, the leak rate was less than half a percent,” Neil said. “It’s very manageable for the team here, but at the moment also there are a lot of people scratching their heads at this.”
Today’s test also revealed a failed sensor that would have triggered the switch from slow filling to fast filling of liquid hydrogen. NASA teams stopped loading liquid hydrogen as they sought to switch to a backup sensor, when the leak was detected.
“We’re getting some good news from the liquid hydrogen team regarding the leak,” Neil said. “This is the opposite of where previously when the pressure increased, the leak increased, but now they see a trend for this particular seal that when the pressure increases, it decreases. This, the engineers say, is how it was designed and intended to work. … Now, no The two core stage reservoirs are in a state of regeneration and stable.”
Now that the basic stage is complete, the plan is to open the supply lines to the upper stage of the ICPS, the hardware with its own engine that will be used once the SLS sends the Orion spacecraft out of Earth’s atmosphere.
She gave the teams to go to the ICPS tanks just before 2 p.m. Their smaller tanks hold 19,250 gallons of liquid hydrogen and 5,700 gallons of liquid oxygen.
ICPS will push Orion into what’s known as a translunar injection, sending it on its way on a multi-week mission that will see the unmanned spacecraft travel away from the moon and back to Earth faster than any other precedent. A human graded spacecraft to ensure it will be safe for astronauts on future Artemis missions.
After the ICPS tank, NASA plans to do what’s called a pre-pressure test, which will raise the liquid hydrogen tank in the primary stage to the pressure level that would be required just before launch, which would allow engineers to calibrate the engine conditioning that would be needed for what would be the flow rate Higher for propellant, something that can be done during the final count on launch day.
Tank operations were originally expected to be completed by 3 p.m., but delays due to a leak have extended this schedule.
After the latest scrubbing, NASA has made repairs to the launch pad so that if today’s test is successful, a possible launch attempt could occur next Tuesday.
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Combining the primary stage engines along with two solid rocket boosters not tested today will provide 8.8 million pounds of thrust on takeoff, making the SLS the most powerful rocket ever launched from Earth, superior to the Saturn V rockets used in the Apollo program.
The test already included what NASA administrators described as a gentler, more gentle method of loading to avoid any temperature and pressure shocks that might have caused the Sept. 3 leak.
“This is part of the new process where they take it very slowly with liquid hydrogen which allows the lines to cool very slowly and then the slow fill gets a little slower than normal in the tank,” said Neal.
NASA still needs approval to go from the US Space Force, which controls how far east the rocket will be launched. NASA is seeking a waiver of a rule around battery screening in the rocket’s flight termination system, which currently requires NASA to ensure batteries are charged within 25 days, a process that would have required 5.75 million pounds, 322 feet. – Complete set of missiles, launcher and spacecraft to return to the vehicle assembly building.
The last time the self-destruction mechanism was checked was before August 16, when Artemis I moved to the launch pad from the VAB.
If NASA obtains this 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 in on a nearly 40-day mission and land on Earth on November 5. The second is Sunday, October 2. , a 109-minute window that opens at 2:52 p.m., flies on a nearly 41-day mission and lands on November 11.
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