Using Forward- And Reverse-Osmosis to let Astronaut EVA Suits Produce Fresh Water From Urine

Using Forward- And Reverse-Osmosis to let Astronaut EVA Suits Produce Fresh Water From Urine

An uncomfortable reality with the spacesuits used for extravehicular activities (EVA) – commonly referred to as spacewalks – is that the astronaut spends hours in them, during which normal bodily functions like urinating and defecating continue. The current EVA record at the ISS is currently a hair under nine hours, necessitating a new approach. A team of researchers have now pitched the idea of an in-suit water recovery system with an article by [Sofia Etlin] and colleagues as published in Frontiers in Space Technologies.


For the current Extravehicular Mobility Unit (EMU) EVA spacesuit the current solution is what is called the MAG: the Maximum Absorbency Garment, which is effectively a fancy adult diaper with sodium polyacrylate as absorbent for up to 2 L of fluids. It replaced the urine collection device (UCD) that was used until female astronauts joined the astronaut corps in the 1970s. Generally astronauts aim to not defecate until they finish their EVA, which leaves urinating and the related activity of rehydrating as the spacesuits only have 0.95 L of water that has to last the duration of the spacewalk.


Prototyping the system circuitry. (Credit: Sofia Etlin et al, 2024, Front. Space Technol.)

By filtering the urine and recycling it into potable water, this should both prevent all the disadvantages of diapers and give astronauts much more water to drink during EVAs.  Although the media reporting on this paper have often referenced the stillsuits of Dune, this device is significantly less advanced and quite bulky, ..

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