the SLS validates a fundamental test for the return to the Moon

Despite a leak which raised fears of a new failure, the return of Man to the Moon is beginning to take shape.

Better late than never ! On Monday June 20, NASA’s Space Launch System (SLS), the huge launcher on which the next Artemis I lunar mission will be based, finally successfully passed its wet dress rehearsal (WDR). This is a decisive test for the continuation of operations, and the engineers can finally sleep on their two ears after several consecutive failures.

This is a test and training sequence for engineers and ground crews. The objective is to approach as much as possible the real conditions of the launch. Or, more precisely, the sequence of events that will lead to it.

The most important step in WDR is to test the filling of the tanks. This involves charging 2.6 million liters of very low temperature liquid hydrogen and oxygen. These two elements will be vaporized and then combined at launch and throughout the ascent to propel the craft. It is from the presence of these fluids that comes the term wet (“wet” in English) in the name.

Le wet dress rehearsal finally validated after three failures

NASA had made a first attempt on April 1 (see our article). But the agency failed to properly pressurize a connector that was supposed to connect to the tank. The teams were therefore unable to fill the tanks, nor go as far as the famous fictitious countdown which would have concluded the test.

This multi-billion dollar device and its creators therefore had to be patient. A delay that was not particularly surprising; since WDRs rarely go as planned on the first try. But there; Since then, NASA’s controversial mega-rocket has continued to make quirks.

The technicians experienced two additional failures in early April before deciding to repatriate the SLS to the workshop for further examination. For two months, NASA had therefore been busy solving all the problems encountered during these three attempts.

They thus repaired several critical elements, including the valve responsible for the first failure. They also had to update a significant part of the software side. Well it took them, since the machine came back in much better condition. “It was absolutely the best thing to do to solve the problems we had encountered on the launch pad”, asserts the NASA via the administrator Jim Free.

The Orion capsule perched on the SLS, itself perched on the huge transit platform. The set is so huge that it is difficult to photograph it entirely without encountering perspective problems, as can be seen in the corners! © NASA, Aubrey Gemignani

The SLS (almost) has its ticket to the Moon

But even with all these precautions, this 4th attempt by WDR almost came to an end following … another hydrogen leak. Luckily, this time it wasn’t a damaged item. The incident was simply due to an incorrectly locked connection where the two stages of the rocket must separate. The leak was quickly brought under control and the connection restored.

After this incident, the test could finally be completed; the launch was therefore successfully simulated in its entirety – that is, until the countdown reaches T-30 seconds. It is finally a first major victory for the controversial mega rocketplagued by delays, budget explosions and long mired in a difficult collaboration with Boeing (see our article).

“It’s a big day for our team,” says Charlie Blackwell-Thompson, program launch director. And the expression is well deserved. After pushing back the June launch for the last time since the failure in April, NASA has repeatedly reaffirmed its ambition to launch the Artemis 1 mission in August 2022.

© Boeing

A launch planned for the fall

And that launch window now seems very close. NASA will now scrupulously analyze the data collected during the WDR, and if everything is in line with its expectations, it can then officially lock in a launch date.

The next window will occur on August 23. In contrast, on NASA’s schedule, it is designated as a “short” mission window. It will therefore probably not be compatible with the mission. To have such a window, you will have to wait until August 29, otherwise until September 2.

On this date, the SLS will take off for the famous mission Artemis 1. This inaugural adventure will consist of carrying an Orion capsule into orbit around the Moon to test all the equipment in real conditions. It will thus be able to lay the foundations for the Artemis 2 mission. This will bring astronauts back to lunar orbit. We will then arrive at Artemis 3, planned around 2026; it was during this last mission of the Artemis program that the astronauts will land on our satellite for the first time since Apollo 17 in 1972.

The return to the Moon is becoming clearer, but the future of the SLS remains uncertain

A rendering of Base Camp Artemis as imagined by NASA. ©NASA

The SLS project will have been a long way of the cross, but it will finally be able to try to justify the billions of dollars swallowed up by the development. And this step promises to be even more complicated than the wet dress rehearsal.

As a reminder, the SLS is much talked about for the same reasons as our European Ariane 6; it’s a vehicle that has yet to take off once, but is already behind technologically, leading many observers to call it a “stillborn” (see our article).

Indeed, the SLS is a single-use launcher; the bulk of the structure will come crashing back in the middle of the ocean… a philosophy that raises many eyebrows at a time when SpaceX’s reusable launchers have completely redefined this industry to the point of changing everyone’s roadmap the major players in the sector.

There is therefore reason to be skeptical about the future of the SLS, especially since NASA’s current program plans to exploit this launcher, which was already retrograde even before its inauguration, until… 2030.

But anyway, the passage of the wet dress rehearsal remains an exciting step for all space lovers; the return to the Moon is now getting closer day by day, and with a bit of luck, this prospect will arouse a great collective thrill that will make people forget the galleys of the SLS for a while. We therefore give you an appointment in the fall for this mission not to be missed under any circumstances.

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