The situation seems much less worrying than during the first postponements of the launch, but we must remain cautious.
After weeks of logistical galleys and repeated leaks, NASA has finally succeeded in filling the tanks of the Space Launch System, the huge launcher which is to relaunch the great conquest of the Moon. But there is a catch: the machine still has sealing problems…
The test in question was a kind of lighter and more delicate version of the wet dress rehearsal. It is a process of checking the entire launch procedure step by step, including the fuel transfer, until the countdown begins. The objective is to allow the technical teams to validate the last technical details while repeating the launch procedure.
A wet dress rehearsal lightened that went well
The SLS first failed several times to validate this step before achieving it for the first time on June 21 (see our article). But here it is: in the meantime, the machine has collected technical problems, starting with a characterized incontinence. Operators spotted significant leaks in its hydrogen distribution circuit. Technicians have identified at least two. The first, and the most serious, was at the level of the main hydrogen column. The other, less significant, touched a connector which is used to fill the tanks.
This forced NASA to push back the launch first and then a second time within days. Result: while it was initially supposed to take off on August 29, the SLS has still not moved one iota. At the time of writing, the colossus is still comfortably perched on its launch pad, being pampered by engineers and technicians.
NASA is therefore doing everything possible to ensure that it is ready for the next launch, next September 27. She therefore has less than a week to complete the last (hopefully) preparations. And for the first time in some time, officials are finally starting to sound optimistic. “I am very encouraged by today’s test”, explained Charlie Blackwell-Thompson, launch director of the Artemis program.
That damn connector still leaks
On the other hand, she was careful not to confirm that the machine would take off on September 27. And for good reason: there are still a few unknowns, starting with… a leak that has still not been plugged.
Fortunately, this is the less important of the two, namely the one concerning the filler connector sometimes nicknamed “umbilical cord”. The good news is that this is not an active leak. The SLS therefore does not get rid of all this hydrogen over time; it simply loses some of its reserves the moment the connector is removed.
The liquid hydrogen leak remains manageable during the Artemis I cryogenic demonstration test. Teams warmed up the quick disconnect umbilical line and the leak then maxed out at 3.4%, which is within the acceptable range to continue.
— NASA’s Exploration Ground Systems (@NASAGroundSys) September 21, 2022
According to the agency’s measurements, this represented 3.4% of the total hydrogen volume. This figure does not exceed the safety threshold established by NASA. She was therefore able to continue the test to completion. In theory, therefore, there is nothing more to worry about; the SLS should no longer get stuck on the ground – or at least not because of a leak.
Too early to claim victory
But in any case, it is better to remain cautious, knowing that this metal monster has already made the engineers see all the colors. The data produced during the test is still being analyzed, and the technical teams are not not yet safe from a new unpleasant last-minute surprise.
Plus, NASA is still going to have to tick a few more boxes before proceeding with the launch. At the time these lines are written, the agency has still not indicated whether the US Space Force has responded to its request for an extension of the Flight Termination System. This emergency stop device must be checked and certified during an official procedure for a period of 25 days which is coming to an end, and must therefore be extended in order to be able to envisage a departure at the end of September or the beginning of October (see our post for more details).