NASA announces successful SLS tank test – SpaceNews

NASA said it completed all Space Launch System tank test targets on September 21 despite repeated liquid hydrogen leaks.

The one-day test at launch complex 39B of the Kennedy Space Center included filling the SLS core stage and upper stage with liquid hydrogen and liquid oxygen thrusters, implementing a “start-bleed” of liquid hydrogen in the core stage engines and a “pre-pressure” test of a liquid hydrogen tank. The test was designed to confirm that changes such as replacing the seals and making a new loading would prevent the hydrogen leak seen in the previous launch attempt on 3 September.

Early in testing, though, controllers reported a liquid hydrogen leak in the umbilical tail service mast, as liquid hydrogen is transferred from ground systems to the primary stage, which crossed the limits and paused loading. Heating and then cooling the navel connection to the primary phase appears to work, with leakage dropping below the 4% hydrogen concentration limit but not completely disappearing.

Another hydrogen leak occurred during pre-press testing of a second, smaller line of liquid hydrogen at concentrations up to 5%. Engineers continued testing and the leak diminished over time.

At the conclusion of the test, NASA said they had achieved all of their goals but stopped short of declaring that they were ready to proceed with the launch at the next opportunity, September 27.

“I think the test went really well,” said Charlie Blackwell Thompson, NASA’s Artemis 1 launch manager, during a televised interview with NASA shortly after testing of the tank ended. “All the goals we set to achieve we were able to achieve them today.”

She said, though, it was too early to say the car was ready for another launch attempt. “I think we’ll take the data and see what it tells us,” she said. “I don’t want to pre-empt the data, and so I would like the team to have the opportunity to look at it to see if there are changes we need to make to our loading routines, our schedules, or we’re good as it is.”

Tank testing is not the only factor affecting the launch decision. NASA is still working with Eastern Range to secure a waiver of the SLS flight termination system, whose certificate expired at the end of the previous launch period in early September. The US Space Force, which administers the range, was not expected to make a decision on the waiver until after the tank had been tested.

Tropical weather can also play a factor. A system called Invest 98L is currently shaping the Caribbean which is expected to become a tropical storm within the next few days and could head toward Florida, based on current long-range weather models. That would require NASA to at least consider returning the SLS to the Vehicle Assembly Building.

It will take about three days to return the vehicle to VAB, Jeremy Parsons, deputy director of NASA’s Earth Exploration Systems Program, said in a September 19 briefing.

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