A Toilet on the Moon

It’s been almost 50 years since humans walked on the moon. But soon—perhaps as soon as three years from now—we will be going back. NASA is preparing to send astronauts to the moon as part of its Artemis program. The astronauts will conduct experiments and research that will help us better understand our universe—and pave the way for expeditions to Mars and beyond.

Sound exciting? Definitely.

But the mission won’t be without challenges. Any time humans go to space, there are significant dangers. There is no air, no food, no water. And it’s really cold: -455 degrees. Without protective suits, astronauts would turn into human Popsicles—after they lost consciousness and their eyeballs and blood boiled due to the low pressure.

To make the mission safe and successful, NASA has developed some incredible gear. This includes high-tech spacesuits to shield astronauts from the harsh environment of space. There will also be a new lander to carry astronauts down to the surface of the moon from their spacecraft, which will remain in lunar orbit.

But there is one problem NASA still needs to figure out: How will the astronauts poop?

When you think about everything involved in sending humans to the moon, toilets might seem like a minor detail. But going to the bathroom anywhere that isn’t Earth is pretty complicated. Here on Earth, gravity pulls our waste away from us. But out in space, where the force of gravity is less strong, waste doesn’t conveniently fall into a toilet. If you tried to use an Earth toilet on the way to the moon, droplets of urine and pieces of poop would float around—which wouldn’t be too pleasant for astronauts stuck together on a tiny spacecraft.

On the International Space Station (ISS), astronauts have a high-tech toilet that prevents this sort of appalling thing from happening. The toilet, which cost $23 million to create, uses a vacuum to suction waste (and smells) away. Urine is then recycled into clean water astronauts can drink. Toilet paper and solid waste are placed into canisters and shot toward Earth.

Now, don’t be alarmed. Astronaut poop won’t fall out of the sky and land on your head. The canisters are placed on a spacecraft with other items that are no longer needed. As the spacecraft falls toward Earth, it gets incinerated in the atmosphere. (Ever look up at the night sky and see a shooting star? It could be a meteorite—or burning space poop!)

So why can’t the ISS toilet work on the moon? The problem is that it’s designed for microgravity: the weightlessness that astronauts experience on the ISS. If you’ve been on a roller coaster, think about that feeling during a big drop when you seem to float for just a moment. That’s how astronauts feel in microgravity—all the time.

Astronauts on the way to the moon will also experience microgravity. But when they arrive, they won’t feel weightless anymore. The force of gravity on the lunar surface is about one-sixth that of Earth’s. That’s strong enough to keep astronauts—and their waste—from floating off into space.

For the Artemis program, NASA wants a space toilet that can work both on the way to the moon and down on the surface.

So what do you do when you’re looking for creative solutions? Ask for help ! In June 2020, NASA launched its Lunar Loo Challenge. (Loo is a British term for toilet.) Anyone could submit an idea for a space toilet; the toilet just had to be light, compact, and efficient.

By the time the challenge ended, some 3,000 ideas had been submitted from around the world. There was the Flushing Flushinator 600, the Artemis Easy Loo, and the SCET, which stands for Super Cool and Effective Toilet.

Last fall, NASA selected three winners in the adult category and 10 in the kids’ categories. NASA says it may use elements from a number of the winning entries in the final toilet design.

Whatever that design ends up being, the astronauts will surely appreciate their new space toilet. After all, there’s nothing that can ruin a trip to the moon like bumping into a piece of floating poop.