Sometimes to go to the moon, you first have to go underwater.

NASA is currently developing the training program for NASA's Artemis astronauts, some of whom could set foot on the moon during the agency's planned Artemis IV mission. As part of that development, two agency scientists recently donned Artemis moonsuits and took to NASA's underwater training facility.

What is it?

These photos show two NASA exploration geologists and Artemis science officers practicing using the same types of geology tools that astronauts might use when they explore the moon.

The scientists also "deployed a mock lunar payload under low-angle lighting conditions," according to a NASA statement accompanying the photo. NASA is currently aiming to place astronauts at the lunar south pole, where many areas remain in permanent shadow. As such, future lunar explorers may have to operate in near-total darkness and learn how to carry out their missions with very little light.

Why is it incredible?

The fact that NASA is preparing to send humans back to the moon is incredible in itself. Humanity hasn't set foot on our natural satellite since 1972. While NASA still has many technical hurdles to cross when it comes to developing and selecting a moon lander, the agency is pushing ahead with developing the training it will use to prepare its astronauts to explore the lunar surface.

For this particular part of Artemis training development, NASA placed two scientists in its Neutral Buoyancy Laboratory (NBL), a 40-foot-deep (12-meter) pool at NASA's Johnson Space Center in Houston. The particular test in these photos was "the first time that two geologists were suited up simultaneously for lunar geology training in the NBL," according to NASA's statement.

For these tests, a portion of the underwater laboratory was outfitted with soil and rocks that simulate the surface of the moon. The buoyancy of the pool can be manipulated in order to simulate different levels of gravity, helping astronauts train for spacewalks or for exploring other worlds like the moon.