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Yesterday we wrote that today there would be the cryogenic test of the big rocket NASA SLS for the Artemis I mission. The purpose was to verify that the loss of liquid hydrogen from one of the quick disconnect connectors that had blocked the launch on September 3 had actually been repaired (after the works of the past few days).
As stated in the past it was not a real one Wet Dress Reharsal (since the latter had been completed in many aspects in recent months). Instead we focused on the system itself quick disconnect repaired and in general on the new procedure for filling the tanks of the main stage of the Space Launch System and of the ICPS (the upper stage) as well as on the conditioning of the four RS-25 engines. The cryogenic test was carried out, not without some unforeseen event that made us fear for a postponement.
The NASA SLS cryogenic test for the Artemis I mission
Around 1pm today here in Italy, the launch director Charlie Blackwell-Thompson gave the command to start filling the tanks of the big space rocket. Particular attention should be paid to filling the tank of the main stage with theliquid hydrogen which has a temperature of -253C and one “insidious molecule” as it manages to insinuate itself into the materials and is easily flammable.
The operations began with the cooling of the lines for liquid oxygen and the subsequent slow filling of the tank of the central stage NASA SLS (around 15:00 we were at 5% of the tank). At that moment the cooling of the lines for liquid hydrogen was also started and in the meantime the loading of liquid hydrogen began.
When it was around 16:00 (Italian time) the liquid oxygen tank was at 32% and the rapid filling was about to begin. Shortly after 4:00 pm she was for identified a loss of liquid hydrogen in the area where it had been identified during the launch attempt on 3 September and thus blocked the loading of the propellant.
A solution to the NASA SLS loss
The procedure involved reheating the lines and retrying the loading to see if the seals could return and thus block the leak. After some tests, the loading of liquid hydrogen was resumed inside the tank of the central stage NASA SLS reducing for pressure. Also started the conditioning of the RS-25 engines.
Just before 18:00 the liquid oxygen tank was 92% full while the liquid hydrogen tank was 24%. Shortly after 6pm the NASA reported that the loss of hydrogen was lower than that of 3 September and was initially estimated to be below 1% and then rose to around 3.4% when the pressure increased (operations would have been stopped at 4%).
At 7:11 pm, however, the maximum loading level of liquid hydrogen was reached, never reached during previous launch attempts (around 6:50 pm, however, the filling of liquid oxygen was completed). The loss settled at values around 0.5%.
All NASA SLS tanks have been filled
Shortly before 7:40 pm, however, it was reported that both tanks in the central stadium were stable and the leak was manageable. The team thus aimed to begin the procedures for the filling of the upper stadium (ICPS). At 9:08 pm the upper stage liquid oxygen tank was 50% full. It must be remembered that in the past theICPS it never gave any problems.
At 9.47 pm the tanks of NASA SLS (both middle and upper stage) were completely full and the flow of liquid hydrogen to the engines was also correct despite a leak (which reached 5%) encountered during the pre-pressurization test. The problem remained linked to the loss from the central stage which increased (to 4%) with the pressure to the levels of that which will be experienced during the launch. The pre-pressurization test was then successfully completed (around 21:55) reaching the desired pressures and temperatures despite the two leaks detected.
At about 10:30 pm the end of cryogenic test of the Space Launch System for Artemis I with the team that started emptying the tanks. Now we need to have a complete review of the data and understand if theEastern Range will agree to extend the duration of the FTS certification for the September 27 or October 2 launch windows.
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