Engineers are set to reload NASA’s Artemis moon rocket with supercold fuel on Wednesday to ensure a repaired liquid hydrogen quick-disconnect fitting is leak-free, one of two requirements that must be met before the agency can make a third attempt at the booster. huge September launch. 27 on a morning moon.
The other is a required waiver from the Space Force Eastern Range, which oversees all military and civilian launches from Florida, allowing the unmanned launch to proceed without inspection and servicing of batteries in the booster’s self-destruct system .
The batteries were initially certified for 20 days, a limit that was extended five days later to give NASA three launch opportunities between August 29 and September 5.due to hydrogen leakage during fueling.
The batteries in question cannot be accessed at the launch pad, and without another extension from the East Range, the Space Launch System rocket would have to be towed back to NASA’s Vehicle Assembly Building, ultimately delaying the Artemis 1 mission October or early November.
“They are responsible for public safety, so they asked for additional information (about the batteries),” said John Blevins, chief engineer of the Space Launch System rocket.
The fueling test does not require a waiver and “we haven’t really focused, other than answering their questions, on any kind of deadline to get that news back,” Blevins said of the waiver request. “And so we’ll let them do what they do and see if the data we’ve provided answers their questions.”
NASA conducted four fueling tests between April 3 and June 20, encountering a variety of problems that prompted repeated interruptions and modifications. The first actual launch attempt on August 29 was canceled mainly due to difficulty cooling the rocket’s engines.
That problem was the result of a faulty sensor and NASA pushed ahead for a second launch attempt. But during fueling on Sept. 3, a high concentration of gaseous hydrogen was detected in a housing around an 8-inch quick-disconnect fitting at the bottom of the SLS core stage where liquid hydrogen, at minus 423 degrees Fahrenheit, flows into the rocket.
Sensors detected hydrogen concentrations of up to 8%, twice the allowable level, rising each time flow rates and pressure were increased. With clear signs of a leak, the launch was terminated.
After the second scrub, NASA instructed engineers to disconnect the quick-disconnect fitting at the launch pad and replace the internal seals. That work was completed last week, paving the way for Wednesday’s fueling test.
During a teleconference with reporters on Monday, managers said the seal taken out of the quick-disconnect fitting showed signs of deformation suggesting an impact from some sort of “foreign object debris.” The indentation only measured about .01 inch across, but that might be enough to explain the leak.
“We found a witness mark, or indentation, on the soft goods associated with foreign object debris,” said Mike Sarafin, Artemis 1 mission manager. “We didn’t recover a piece of foreign object debris, but there was clearly an indentation in the seal that indicated to us that there was a problem … that contributed to the hydrogen leak.”
Hydrogen leaks are extremely difficult to short out and fix because they usually only show up when the hardware is exposed to super cold or cryogenic temperatures. That’s why NASA managers chose to try to repair the launch pad, enabling a “cryo test” to verify that the seal is leak-free.
The allowable hydrogen concentration in the housing around the quick-disconnect fitting is 4%, the level at which the gas can spontaneously combust when mixed with oxygen. During the SLS rocket’s second launch attempt on September 3, sensors detected concentrations rising to 8% when flow rates and pressure were increased.
For Wednesday’s tanker test, engineers are using a “smaller and sharper” approach, filling the core stage tank a little more slowly and pushing a little lower to soften the shock as they transition from “filling” operations. slow” to “fast network”.
Countdown to the “cryo test” was expected to begin at 5:30 pm on Monday and end at 3 pm on Wednesday at the T-minus 10-minute mark.
Assuming Wednesday’s test goes well — and assuming clearance to proceed from the East Range — NASA plans to resume a fresh countdown at 1:27 p.m. EDT Sunday, establishing sent at 11:37 am on Tuesday.
The main goals of the Artemis 1 mission are to use an SLS rocket to launch the unmanned Orion crew capsule into a distant orbit around the moon before it returns to Earth on November 5, concluding a 39-day mission with a high-speed reentry. entry to a splash pad in the Pacific Ocean west of San Diego.
NASA hopes to follow up the Artemis 1 mission by sending four astronauts atop a second SLS rocket in late 2024 on a shakedown flight around the moon. And that will set the stage for two astronauts to land on the moon in the 2025-26 time frame.
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