How Do Astronauts Poop and Pee in Space? This NASA Astronaut Explains.

Ever wondered how astronauts use the bathroom in space? This new video tutorial gets into all the details.

NASA astronaut and United States Navy SEAL Christopher Cassidy said this is by far the most common question astronauts get. So, in a 7-minute video posted on social media, Cassidy, who has been an astronaut since 2004, takes viewers through the process.

Apparently, the urge to go to the bathroom isn’t much different when you’re in space.

“The desire to go is very similar as on earth. You just know you have to go,” Cassidy said.

He shows off a tiny stall called the Waste and Hygiene Compartment (WHC) which appears to be sandwiched between a treadmill and weight machine. Inside is the toilet, which consists of a seat and a metal bucket right below it. According to Cassidy, it holds about “30 deposits.”

Before using the WHC, astronauts first need to check the primary control panels. To pee, they make sure the lights on the panel form a V-shape, which means pee is set to go through the Urine Processor Assembly (UPA). When nature calls, astronauts urinate directly into a funnel attached to a hose that has airflow that sucks liquids in.

“So, we say ‘check that it’s V to pee’,” Cassidy said.

The pee may also go into a bucket instead, but Cassidy said the WHC is usually configured to the UPA so that crew members don’t have to go through the trouble of switching out the buckets.

Going number two is a bit more complicated. The toilet seat opening is only about five to six inches in diameter and lined with a plastic bag. With a packet of green beans and mushrooms, Cassidy demonstrates how poop goes into the toilet and directly into the plastic bag. He throws toilet paper into the toilet, closes the plastic bag, and uses a metal stick to push it down the metal bucket. After that, he lines the opening with a new plastic bag for the next user and closes the lid.

It could get confusing, so there is an instruction sheet on board for anyone who isn’t familiar with the WHC.

How astronauts pee and poop in space continues to fascinate many earth-bound humans. In June, NASA called upon the global community to submit designs for compact toilets that can be used in both microgravity and lunar gravity. The Lunar Loo Challenge began in June and winning designs to be determined on Oct. 21 may be used in NASA’s program to land the first woman and next man on the moon by 2024.