The facility known as LUNA, which was officially inaugurated on Wednesday, is the world's most faithful recreation of the lunar surface, according to the European Space Agency (ESA).

European astronauts will train inside the unique simulator and test equipment that will one day travel to the moon—including potentially on NASA's upcoming Artemis program, which plans to send humans there on a mission in a few years.

From the outside, it looks like a huge white hangar in a corner of the German Aerospace Center on the outskirts of Cologne.

But inside the nine-meter (30 feet) high facility, below the ink-black ceiling and walls, is a replica of the soil that covers the lunar surface.

Craters and lumps ripple in and out of darkness under the stark light of a sole lamp at one end of the 700-square-meter area—the equivalent of more than three tennis courts.

The terrain is strewn with rocks and smothered in a strange pale-gray dust.

ESA astronaut Matthias Maurer described walking through the environment wearing a space suit.

"When you're entering the black area and you have the sunlight in front of you," it can be difficult to find your way around, Maurer told journalists during a recent tour of the facility.