PHOTO/NASA - Joel Kowsky - Depending on how much or how little delay the management team assigns to the third take-off attempt, the SLS will or will not return to the Vehicle Assembly Building (VAB), where it will be thoroughly checked
It was not to be. A recurring liquid hydrogen leak has been to blame for the SLS launcher remaining on the ground instead of flying to the Moon.
As NASA engineers proceeded on the morning of 3 September to fill one of the two large propellant tanks on the main stage of the SLS rocket, a serious technical anomaly forced the launch director of the Artemis I lunar mission, Charlie Blackwell-Thompson, to give the order to abort the liftoff and stop the countdown.
This is the second attempt to lift off the SLS launcher from the Kennedy Space Center (Florida), which after the cancellation of the 29 August launch, had been rescheduled for Saturday, 3 September, at 20:17 Spanish time, 14:17 on the East Coast of the United States.
The cancellation of the second flight attempt of Artemis I occurred "at approximately 11:17 Eastern Standard Time", 17:17 Spanish peninsular time, according to a NASA communiqué released at 17:22 peninsular time (11:22 in Florida).
The Agency reports that ground control teams "found a liquid hydrogen leak while loading the SLS rocket's central stage booster".
However, despite "multiple efforts to troubleshoot the area of the leak, resealing the quick disconnect where the rocket is fed liquid hydrogen, they did not fix the problem". The NASA memo concludes that engineers "continue to collect additional data".
At 05:36 a.m. Florida time (11:36 a.m. Spanish time), Charlie Blackwell-Thompson gave the order for ground crews on launch pad 39B at Kennedy Space Center (Florida) to begin filling the cryogenic tanks with liquid hydrogen and liquid oxygen. Both feed the RS-25 engines of the first propulsion stage of the Space Launch System, or SLS.
Operations began with the cooling of the liquid oxygen and super-cold liquid hydrogen transfer line, which effectively started at 7:09 a.m. on the launch pad.
But at 7:24 a.m. at KSC, NASA reported that a "liquid hydrogen leak had been detected, and engineers were attempting to seal it". Meanwhile, the flow of liquid oxygen continued. The problem was resolved at 8:09.
The liquid oxygen tank in the central stage has filled up. NASA engineers and NASA ground crews have been battling for long hours to solve the source of the liquid hydrogen leak to no avail.
The Artemis I mission management team, a committee of key mission managers, is due to meet shortly and, with the engineers' reports in hand, plan the next step.
A new launch window opens on 5 September, next Monday, a date so close that it seems unlikely that NASA will take it up. The next launch window would be in the second half of this month, between 20 September and 4 October.
That means that the SLS launcher would have to return to the huge Vehicle Assembly Building (VAB), where the anomaly checkout operations would be carried out in more detail.
A few weeks ago, Cliff Lanham, NASA's manager for in-vehicle operations for the Exploration Ground Systems programme, said that returning SLS to the VAB "represents a real challenge for us".
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