Astronauts are testing NASA's new spacesuits underwater as the agency pushes toward the next moon landing

• NASA is developing new spacesuits for its planned missions to the moon.
• Astronauts are testing the spacesuits in a giant pool: the Neutral Buoyancy Lab in Houston, Texas.
• The pool mimics the feeling of microgravity and serves as a training ground for astronauts learning how to do spacewalks.

NASA is racing to get astronauts back to the moon in 2024. But before that can happen, the agency needs to perfect its spacesuits.

NASA has already designed the new suits that astronauts will wear on its Artemis moon missions. Now it's testing the suits to make sure people can actually walk in them and perform complex tasks, like handling tools and checking equipment.

Many of those tests happen underwater. At NASA's Neutral Buoyancy Lab in Houston, Texas, astronauts-in-training wear spacesuits in a giant pool to simulate what they'll feel like in microgravity.

The pool is 202 feet long, 102 feet wide, and 40.5 feet deep. It contains 6.2 million gallons of water — more than enough to fill nine Olympic-sized swimming pools.

According to astronauts, the pool does a surprisingly good job of preparing them for space.

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"When I did my first spacewalk, shortly after we went out the hatch, the sun set and it got dark, and it felt exactly like I was in the pool," astronaut Nick Hague said on an episode of NASA's "Curious Universe" podcast in April.

An astronaut's training ground

The Neutral Buoyancy Lab is designed to mimic microgravity, rather than zero gravity, because that's what astronauts on the space station experience. The weightlessness they feel comes from being in constant free-fall — the station is essentially falling perpetually in a circle around the Earth. The pool even contains full-scale mockups of space-station components and the cargo-carrying spacecraft used for resupply missions, like SpaceX's Dragon capsule and the Japan Aerospace Exploration Agency's H-II Transfer Vehicle.

"We have experience with [the] space station, but we need to determine how we're going to train the crew for surface operations during these specific missions," Daren Welsh, who's leading the tests, said in a NASA blog.

When training for space-station spacewalks, astronauts typically float around the pool, engaging with the models of different parts of the station. Their suits are weighted to be neutrally buoyant so that they neither sink nor float.

But the moon is different: Unlike the space station, it has a small gravitational pull that's about 1/6 of Earth's. So in exercises and tests related to moon missions, the spacesuits are weighted to make them sink. Astronauts then practice walking across the pool's bottom, which NASA staff cover in rocks and sand to simulate lunar ground.

Underwater, the astronauts practice planting a flag, picking up rocks, and examining a lunar lander spacecraft.

NASA hasn't officially selected the astronauts for its Artemis missions yet, but this kind of practice is essential both for testing the spacesuits and training the people who may eventually walk on the moon. Traversing the rocky, uneven lunar surface in low gravity is tricky. Apollo 17 astronaut Jack Schmitt learned that the hard way in 1972, when he took a few tumbles during a moonwalk.

Going forward, astronauts will also need to learn how to swing a chisel safely in lunar gravity to make sure it doesn't hit someone or fly away. They will also need to prepare for the light conditions on the moon's South Pole, where crews might conduct moon-walks. The lighting there is more extreme than at the sites where Apollo missions landed – some areas are almost permanently bright, whereas others are nearly always in shadow. In addition to the Neutral Buoyancy Lab, NASA staff are also developing moon-walk trainings in the Johnson Space Center's rock yard, a large outdoor area that mimics the moon's rocky, sloping terrain.

The Artemis program still needs $28 billion

The Artemis program consists of three proposed missions to start: First, an Orion spaceship would orbit the moon without any passengers, then it would carry an astronaut crew into lunar orbit on a flyby mission. After that, astronauts would land on the moon.

This all hinges, however, on funding. NASA has asked Congress for a total of $28 billion over the next four years. Most immediately, NASA is asking Congress for $3.2 billion for its Human Landing System, which would ferry humans from the Orion spacecraft to the moon's surface and back.

So far, the House of Representatives has only approved about $630 million in additional funds. However, NASA Administrator Jim Bridenstine said he hopes the agency can secure the full total after the November election.

"If we can have that done before Christmas, we're still on track for a 2024 moon landing," he said earlier this week.