NASA had to abort its second attempt to launch the Artemis 1 mission after a liquid hydrogen leak while the core stage was being fuelled. Mission engineers made three attempts at troubleshooting the issue but after all attempts failed, launch director Charlie Blackwell-Thompson officialy scrubbed the launch attempt.
“We saw a large leak in the 8-inch disconnect. It started when we went from slow-fill to fast-fill. This disconnect did not have such a problem on Monday. There was a small leak but not so large. The team tried to resolve three times and we had a large leak all three times. Sometimes the leak can heal itself if there is no differential temperature. The teams tried that but it was not successful,” said Michael Sarafin, Artemis mission manager, during a post-scrub conference.
According to Sarafin, mission engineers detected a hydrogen leak that was three times the maximum acceptable safe amount, creating a flammability risk. This is what led to the decision to scrub the launch.
After the scrub, the launch team had three options: The first option was to disconnect and then reconnect the “umbilical cord.” Sometimes, this could lead to the leak resolving itself if there is no temperature difference across the connection. But since a similar technique failed during the troubleshooting attempts, engineers believe this is unlikely to be a solution. This leads to two probable options, both of which include the removal and replacement of the “soft goods” in the 8-inch disconnect.
Soft goods refer to the “gasket” or other replaceable material that surrounds the disconnect. When replacing the soft goods, NASA has the option to either do it on the launchpad itself or do it after rolling back the launch vehicle to the Vehicle Assembly Building (VAB). If the replacement has to happen at launch pad where the launch vehicle is subject to environmental conditions, engineers will have to build protections around the disconnect. This is not a problem at the VAB since the building itself acts as protection.
Both of these options would take “several weeks,” according to Sarafin. But according to James Free, associate administrator for Exploration Systems Development at the space agency, the rollback of the vehicle to the VAB is inevitable since the Flight Termination System (FTS) batteries on the board will likely have to be tested and recharged. Both Sarafin and Free concluded that the decision depends on the Range Flight Safety team at the space agency, which addresses spaceflight operation hazards.
With all that taken into account, it seems unlikely that the next attempt would happen in September, with NASA administrator hinting at a launch in “the latter part” of October. It would not be possible to launch in the first week of SpaceX’s Crew-5 mission is scheduled for the first week of the month.
But even this delay of “several weeks” is working under the assumption that the underlying issue is because of soft goods on board, which doesn’t necessarily have to be the case.
“The quick disconnect is a metal device that has a gasket around it. If we were to see damage on the quick disconnect, we will need to replace the hardware. If we see foreign object debris, that would tell us that we got something else going on. If we saw simple damage on the gasket, we can quickly replace that. Our testing history tells us that a leak of this magnitude is typically solved by the removal and replacement of the soft goods, the seal. But first, we need to see what the hardware tells us,” said Sarafin to reporters during the press conference.
In case there is a need to replace the hardware, it is possible that the launch could be pushed back even further. NASA administrator Bill Nelson added that these delays will have no effect on the rest of the Artemis missions, with Artemis 2 scheduled for 2024 and Artemis 3 scheduled for 2025.
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