Astronauts use a special no-rinse soap to stay clean without ever taking a shower.

Maintaining hygiene on the International Space Station (ISS) requires innovative solutions because liquid water behaves unpredictably in microgravity. Surface tension causes water to form floating spheres that can easily drift into sensitive equipment or be inhaled by the crew. To prevent these hazards, NASA and other space agencies provide astronauts with specialized no-rinse body bath and shampoo products.The process involves applying a small amount of water from a pouch onto the skin or hair, followed by the no-rinse soap. Astronauts then use a towel to scrub away dirt and oils. Because there is no drain, the moisture from the wet towels and the astronaut's skin evaporates into the cabin air. This is where the Environmental Control and Life Support System (ECLSS) takes over.The ECLSS uses a sophisticated Water Recovery System (WRS) to capture humidity from the air, including sweat and breath. This moisture is processed through a series of filters and a high-temperature catalytic reactor to ensure it meets stringent safety standards. According to NASA, this system is so efficient that it recovers about 98% of all water used on the station, including urine and wash water, turning it back into potable drinking water for the crew.