In space, astronauts cannot simply flush away their waste like we can on Earth. On the International Space Station (ISS), astronauts have developed methods for collecting and recycling urine to conserve water and minimize waste.
How astronauts pee in space
Astronauts use special toilets that rely on air flow to collect urine for recycling. Here’s a quick overview of how the toilets work:
- Astronauts pee into a funnel attached to a hose that leads to a collection tank.
- Air flow pulls the urine away from the body and into the hose.
- Urine is deposited into a tank where it is temporarily stored.
Without gravity, urine doesn’t flow “down” like on Earth. The air flow allows astronauts to pee normally and collect their urine to be recycled.
What happens to the collected urine?
The urine collected in tanks is not discarded. It is fed into the ISS’s water processor where it goes through a recycling system that reclaims clean water for re-use:
- Urine goes through a filter to remove particles and debris.
- Chemicals are added to control pH and prevent bacteria growth.
- Distillation removes impurities and separates water from concentrated waste.
- The reclaimed water passes through filters to remove odors and taste.
After this recycling process, the reclaimed water from urine is clean and safe for astronauts to use for drinking, food preparation, oxygen generation, and hygiene needs.
Why recycle urine in space?
Recycling urine serves several important purposes on the ISS:
- Conserves water supplies – Water is heavy and expensive to transport to space, so recycling urine reduces the amount of water that needs to be supplied from Earth.
- Cuts waste – Storing urine and other waste on board takes up limited space. Recycling urine minimizes waste products that would otherwise accumulate.
- Provides clean water – The ISS water processor can turn astronauts’ urine into potable water meeting strict standards for drinking and use on board.
Urine recycling is a key sustainability practice that allows astronauts to live for months on the ISS without regular water resupply missions. Astronauts drink recycled urine along with water from other sources with no issues.
How much urine gets recycled?
The ISS urine processor can recycle about 6,000 L (1,585 gallons) of crew member urine per year. With an average crew of 6, that means over 90% of an astronaut’s urine can get recycled annually.
| ISS Crew Size | Average Urine Produced Per Crew Member Per Day | Total Urine Recycled Per Year |
|---|---|---|
| 3 | 1.2 L (0.3 gallons) | ~3,000 L (~792 gallons) |
| 6 | 1.2 L (0.3 gallons) | ~6,000 L (~1,585 gallons) |
These numbers illustrate how the urine processor can keep up with the urine output of a fully staffed 6-member crew on the ISS.
Interesting facts about astronaut pee
- Astronauts attach undergarments called “maxi pads” when using the toilet to keep urine from escaping in the microgravity environment.
- The first American woman in space, Sally Ride, helped design the first space toilet, which was installed on shuttle missions starting in 1983.
- Astronauts have to anchor themselves when peeing standing up, or the force of the urine could propel them backward!
- Space toilets have featured fun target stickers inside as “entertainment” for astronauts.
- Astronauts use wet wipes and rinseless soap to clean themselves due to limited water supplies for bathing.
Conclusion
From advanced toilets to intricate filtration systems, astronauts utilize special technologies to collect and recycle urine on the ISS. Recycling urine allows them to conserve water, minimize waste, and sustain life far from Earth’s resources. While peeing in space requires some new methods, astronauts can rest assured their urine will come back around as clean water instead of being flushed away uselessly like on Earth.