Hydration is essential for human survival, but in space, meeting this need presents distinct challenges. Astronauts on the International Space Station (ISS) navigate microgravity, where liquids behave differently than on Earth. This requires specialized drinking methods and innovative water supply systems.
Types of Beverages Consumed
Astronauts have a variety of beverage options beyond plain water. Most drinks are freeze-dried or powdered to minimize weight and maximize shelf-life. These rehydratable choices include coffee, tea, hot cocoa, and fruit juices like orange juice and lemonade. Specialized options such as breakfast drinks, smoothies, and sports drinks are also available, often for their nutritional content.
Astronauts add water to powdered mixes directly within vacuum-sealed pouches. The ISS also features an “ISSpresso” machine, allowing astronauts to brew fresh espresso, tea, or broth, which serves as an experiment in fluid dynamics in microgravity. Packaging and preparation methods are lightweight and compact, important due to strict mass limitations for anything launched into space.
The Act of Drinking in Microgravity
Drinking in a weightless environment differs significantly from Earth, as liquids do not simply pour. In microgravity, fluids form spherical blobs or cling to surfaces due to surface tension, rather than flowing freely. To manage this, astronauts primarily drink from specialized containers, most commonly vacuum-sealed pouches with straws. These pouches have a needle valve or low-pressure hose connection, allowing astronauts to add water and sip the rehydrated beverage without spillage.
A notable innovation is the “zero-G cup,” designed to allow astronauts to drink from an open container. Prototyped by astronaut Don Pettit, this cup utilizes capillary action and surface tension to guide the liquid. It features an angled channel that draws the liquid along its wall to the rim, enabling a sipping motion similar to how one drinks on Earth. This design prevents the liquid from floating away and offers a more conventional drinking experience, allowing astronauts to smell their drinks more fully.
Water Management in Space
The water astronauts drink primarily comes from highly efficient recycling systems onboard the International Space Station. Transporting water from Earth is expensive, costing approximately $83,000 per gallon, making recycling necessary for long-duration missions. The ISS employs a closed-loop system, the Environmental Control and Life Support System (ECLSS), which processes and purifies nearly all wastewater generated on the station.
This system collects moisture from sources including astronauts’ sweat, exhaled breath, urine, and hygiene water. Key components like the Urine Processor Assembly (UPA) and Water Processor Assembly (WPA) filter and treat this collected water. Recent advancements, including a Brine Processor Assembly (BPA), have enabled the ISS to achieve an impressive water recovery rate of up to 98%. The purified water is often cleaner than Earth’s tap water and is used for drinking, food preparation, and hygiene. While resupply missions bring some fresh water, the emphasis remains on self-sufficiency through advanced recycling technologies.