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A crucial fueling test for the Artemis I mega moon rocket has experienced some ups and downs Wednesday, which could determine when the mission launches on a journey around the moon and back.
NASA is providing live coverage of the test on its website.
NASA engineers detected a liquid hydrogen leak during Wednesday’s test that has “the same signature” as a leak that prevented the September 3 launch attempt. However, their troubleshooting efforts appeared to allow the team to manage the leak.
The team was able to completely fill the core stage with liquid oxygen and liquid hydrogen. They also completed an engine bleed test, which conditions the four engines and brings their temperature down prior to launch. The mission team scrubbed the first Artemis I launch attempt on August 29 largely due to an issue with a faulty sensor that occurred during the bleed.
The Artemis team then fueled the rocket’s upper stage and conducted a pre-pressurization test.
“The test will bring the liquid hydrogen tank up to the pressure level it will experience just before launch while engineers calibrate the settings for conditioning the engines at a higher flow rate, as will be done during the terminal count,” according to an update from NASA officials on Monday. “Performing the pressurization test during the demonstration will enable teams to dial-in the necessary settings and validate timelines before launch day, reducing schedule risk during the launch countdown.”
The hydrogen leak remained stable at 4%, which is right on the threshold, during the pressurization test.
The Artemis I cryogenic demonstration test began with fueling at 7:30 a.m. ET Wednesday. The Space Launch System rocket and Orion spacecraft continue to sit on the launchpad at Kennedy Space Center in Florida.
Artemis team members were slowly filling the core stage of the rocket with supercold liquid hydrogen, but they stopped shortly after 10 a.m. ET due to the detection of the hydrogen leak. The leak is in the same area as a recently repaired quick disconnect line, and it occurred at the same moment when the team encountered issues before – as the liquid hydrogen was transitioning from slowly filling the rocket to a faster fill.
As soon as the team stopped the flow of liquid hydrogen, the 7% leak rate came down. The launch team let the line warm up in the hopes that when they resumed the flow of liquid hydrogen, it would restore the connection and cure the leak.
The team reduced the pressure in the storage tank and as they began flowing liquid hydrogen again, they very slowly increased the pressure.
Engineers resumed fast fill of liquid hydrogen into the rocket’s core stage. While a small hydrogen leak remained, it was below the threshold for concern. Engineers increased the pressure and monitored the rate of the leak. They wanted to gather data to see at which point the leak shifted in response to the pressure change.
Since the second scrubbed launch attempt of the uncrewed Artemis I mission on September 3, engineers have replaced two seals on an interface for the liquid hydrogen fuel line between the rocket and mobile launcher, according to NASA officials. These seals were associated with a large hydrogen leak that led to the scrub of the launch attempt.
Engineers found an indentation on the seal on an 8-inch (20-centimeter) quick disconnect line for hydrogen, said Mike Sarafin, Artemis mission manager, at a Monday NASA press conference.
The indentation on the seal was under 0.01 inch (0.3 millimeter), but it allowed pressurized gas to leak through, something that can be very dangerous given the flammability of hydrogen when it meets air. The team believes the dent was associated with the leak, but the results of the test could confirm it. They have since replaced the seal.
The purpose of the cryogenic demonstration is to test the seals and use updated, “kinder and gentler” loading procedures of the supercold propellant, which is what the rocket would experience on launch day.
The Orion spacecraft and rocket boosters remain unpowered during the test, and the team does not intend to go into terminal count, or the final 10 minutes that occur in the countdown before launch, said Jeremy Parsons, deputy manager for NASA’s Exploration Ground Systems Program at Kennedy Space Center.
The kinder and gentler loading procedure is to minimize pressure spikes and thermal spikes witnessed during prior launch attempts.
If the cryo test goes well, the next launch attempt could take place on Tuesday, September 27, with a 70-minute window that opens at 11:37 a.m. ET. The mission managers will meet to discuss the test results on September 25 to assess the potential launch date.
The Artemis team is receiving daily briefings about Hurricane Fiona in case it has any impact on whether or not the rocket stack needs to be rolled back into the Vehicle Assembly Building, a process that can take three days.
If Artemis I launches on September 27, it would go on a 39-day mission and return to Earth on November 5. Another backup launch date is possible on October 2. While these launch dates are recommended by NASA, the team ultimately depends on a decision by the US Space Force, which would need to issue a waiver for the launch.
The US Space Force, an arm of the military, still oversees all rocket launches from the United States’ East Coast, including NASA’s Florida launch site, and that area is known as the Eastern Range.
The officials at the range are tasked with making sure there’s no risk to people or property with any launch attempt.
The Artemis team continues to have “productive and collaborative” discussions with the Eastern Range, NASA officials said, and NASA is sharing additional detailed information requested by the Space Force for review.
“We’re going to go when we’re ready,” Sarafin said. “But in terms of the reward of flying this flight, we have said from the outset that this is the first in an increasingly complex series of missions, and it is a purposeful stress test of the rocket.”
The inaugural mission of the Artemis program will kick off a phase of NASA space exploration that intends to land diverse astronaut crews at previously unexplored regions of the moon – on the Artemis II and Artemis III missions, slated for 2024 and 2025, respectively – and eventually deliver crewed missions to Mars.
The agency released on Tuesday an updated version of its “Moon to Mars” objectives, which lays out a blueprint for solar system exploration.
“We’re helping to steward humanity’s global movement to deep space,” said Jim Free, NASA’s associate administrator for the Exploration Systems Development Mission Directorate, in a statement.
“The objectives will help ensure a long-term strategy for solar system exploration can retain constancy of purpose and weather political and funding changes.”