Picture: AFP/VNA/CVN

    The final two-day rehearsal began Friday, April 1, in Florida for NASA's new SLS rocket, which is scheduled to blast off later this year toward the Moon.
 

Depending on how well the operation goes, it will determine the launch date of the Artemis 1 mission, the first in the American moon return program (but which will not yet have an astronaut onboard).

The last test started on Friday, April 1st at about 5 pm local time, and should end on Sunday afternoon. For two weeks, the 98-meter high rocket has been sitting on launchpad 39B of the Kennedy Space Center, with the Orion capsule perched at its top, where astronauts will settle in the future.

On April 1, immediately after the "call to stations", a countdown of more than 45 hours started. The rocket and the capsule must first be powered up, the communication systems checked, and a whole series of preparations made.

Then, about 8 hours before the fictitious takeoff, the rocket's tanks will be filled with more than three million liter of fuel - liquid hydrogen and oxygen, respectively at temperatures of -267°C and -170°C.

It is expected that the countdown will finally be stopped at T-9 seconds, just before the ignition of the engines. The idea is to simulate a forced abandonment procedure, for example, because of the weather or a technical problem. Afterwards, the vehicle's tanks will be emptied.



NASA plans to keep the general public informed of the different steps taken via its blog throughout the weekend. A live video is also available on Youtube - but without sound. The reason given: some information may be sensitive.

Spacecraft like the SLS "is very similar to ballistic capabilities, which other countries may be interested in," Tom Whitmeyer, NASA's exploration systems development manager, said at a press conference this week. It will deliver the first results of this dress rehearsal on Monday, April 4.

But "it will take several days to really assess not only the success of the test but also whether we observed anything unusual that we need to correct," Whitmeyer cautioned.

He is hopeful that he will announce a launch date for Artemis 1 in the next few days. The May launch window will most likely be missed, but others are possible in early June or early July.

After the dress rehearsal, the rocket will be brought back to its hangar for a final series of checks, then taken out for liftoff.

Artemis 1 will mark the first flight of the SLS, whose development has been years behind schedule. The Orion capsule will be propelled to the Moon, where it will be placed in orbit before returning to Earth.

Humans will not land on the Moon before Artemis 3, for the moment in 2025 at the earliest.