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Arthur T Knackerbracket has processed the following story:

NASA officials say they’re ready to try a new approach to fueling the Space Launch System to prevent the return of leaks that scrubbed an earlier launch attempt even though they are not certain what caused that leak.

Preparations are underway for the Sept. 21 tanking test of the SLS at Launch Complex 39B, with loading of liquid hydrogen and liquid oxygen propellants into the core stage beginning at around 7 a.m. Eastern. After filling the tanks of the core stage and upper stage, controllers will conduct tests of a “kickstart bleed” of hydrogen into the core stage engines and a pre-pressurization test before wrapping up at about 3 p.m. Eastern.

The main objective of the test is to confirm that repairs to seals in liquid hydrogen lines into the core stage, as well as other changes in procedures, eliminate a significant leak seen in the second attempt to launch the rocket on the Artemis 1 mission Sept. 3. Controllers saw concentrations of hydrogen in the enclosure around the connection at least two times a limit of 4%.

Workers replaced the seals for two liquid hydrogen quick-disconnect fittings. The larger one, 20 centimeters in diameter, has a “witness mark” or indentation associated with foreign object debris, said Mike Sarafin, NASA Artemis mission manager. The size of the indentation was about 0.25 millimeters. “An indentation of that size does provide an opportunity for a pressurized gas to leak through that,” especially hydrogen, he said.

However, later in the call agency officials backed away from the hypothesis that the foreign object debris caused the indentation, noting that no debris was recovered. They even hesitated to conclude the indentation was the source of the leak.

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