The question of whether astronauts drink recycled urine often sparks curiosity about life support in space. Water management aboard spacecraft like the International Space Station (ISS) involves sophisticated engineering and scientific processes. This is essential for human survival and exploration beyond Earth.
The Truth About Astronauts and Water
Astronauts do not consume raw urine. They drink highly purified water reclaimed from various sources within the spacecraft. These sources include astronaut urine, humidity from breath and sweat, and water used for hygiene. The water undergoes a rigorous purification process. The recycled water on the ISS often surpasses the purity standards of many municipal tap water systems on Earth.
How Water is Recycled in Space
The International Space Station employs a Water Recovery System (WRS), part of its Environmental Control and Life Support System (ECLSS). This system reclaims and purifies nearly all water used by the crew. The WRS collects wastewater from sources like moisture condensed from cabin air, hygiene water, and crew urine.
The Urine Processor Assembly (UPA) uses vacuum distillation to recover water from urine. The UPA heats the urine and applies a vacuum, causing water to evaporate at a lower temperature, separating it from impurities. The resulting water vapor, or distillate, is then sent for further processing. A Brine Processor Assembly (BPA) was recently introduced to extract more water from the concentrated brine left by the UPA, increasing the overall water recovery rate to about 98%.
Collected wastewater, including purified urine distillate and humidity condensate, flows into the Water Processor Assembly (WPA). The water undergoes multiple purification stages. These involve filtration to remove suspended particles, followed by multifiltration beds with adsorbent media and ion exchange resins to eliminate dissolved contaminants. A high-temperature catalytic reactor then breaks down remaining organic compounds and microorganisms. Iodine is added to the purified water to prevent microbial growth during storage.
Why Water Recycling is Crucial for Space Missions
Water recycling is essential for sustaining human presence in space, driven by economic and logistical considerations. Transporting water from Earth to orbit is exceptionally expensive; one gallon can cost around $83,000 to launch, while a single pound might cost $2,500. Historically, water constituted nearly half the payload mass for shuttles traveling to the ISS. This immense cost and limited cargo capacity make it impractical to continuously ship all water needed for long-duration spaceflights.
Beyond drinking, water is used for various daily activities aboard a spacecraft, including hygiene, food preparation, and generating oxygen through electrolysis. Developing efficient closed-loop life support systems, where resources like water are continuously recycled, is important. Such systems are cost-effective by reducing reliance on Earth-based resupply and enable extended missions to the Moon, Mars, or deeper in space, where resupply options are limited.