“All of the objectives that we set out to do we were able to accomplish today,” said Charlie-Blackwell Thompson, launch director for NASA’s Exploration Ground Systems Program at Kennedy Space Center in Florida.
The Space Launch System rocket and Orion spacecraft are in a safe configuration and continue to sit on the launchpad at Kennedy Space Center.
NASA engineers detected a liquid hydrogen leak during Wednesday’s test that had “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. Afterward, they “did not see the same leak signature, which was wonderful,” Blackwell-Thompson said.
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.)
Then, the Artemis team fueled the rocket’s upper stage and conducted a pre-pressurization test, which went “very well” according to the engineers. It was scheduled to last for an hour, but only took 15 minutes.
The test was intended to “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 a Monday update from NASA officials. It would “enable teams to dial-in the necessary settings and validate timelines before launch day, reducing schedule risk during the launch countdown.”
A hydrogen leak detected on the 4-inch quick disconnect line for the engine bleed reached a little over 5%, which is above the 4% threshold, during the pressurization test. This quick disconnect line carries liquid hydrogen out of the engines after they have run through the engines and chilled them. But as the hydrogen continued to flow, the leak rate lowered on its own. The team will drain the tanks of all propellant and is looking forward to assessing the data from the test.
Raising pressure caused the leak to go down, which was encouraging to Blackwell-Thompson and her team, she said. They will evaluate the lessons learned from the test to see if any changes need to be made to loading procedures or timelines.
“I think we’ll take the data and we’ll go see what it tells us,” she said. “I am extremely encouraged by the test today. I couldn’t be more proud of the team today and the work that they did.”
The next launch attempt could take place on Tuesday, September 27, with a 70-minute window that opens at 11:37 am ET. The mission managers will meet to discuss the test results on Sunday, September 25, to assess the potential launch date.
Managing a hydrogen leak
The Artemis I cryogenic demonstration test began with fueling at 7:30 am ET Wednesday.
Artemis team members were slowly filling the core stage of the rocket with supercold liquid hydrogen, but they stopped shortly after 10 am 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 filling 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 tooth 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 remained 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.
Preparing for launch
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 at the Kennedy Space Center, 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.”
“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.”
CNN’s Jackie Wattles contributed to this story.