An unpleasant reality of spacesuits used for extravehicular activities (EVAs) (commonly known as spacewalks) is that astronauts spend hours in the suits, during which time normal bodily functions like urinating and defecating continue. The current record for an EVA on the ISS is just under nine hours, making a new approach necessary. A team of researchers has developed an idea for an in-suit water recovery system, [Sofia Etlin] and colleagues Published in The forefront of space technology.
The current solution for the current Extravehicular Mobility Unit (EMU) EVA spacesuit is: Mug: Maximum Absorbency Garment. This is essentially a premium adult diaper with sodium polyacrylate absorbent that absorbs up to 2 L of liquid. It replaces the Urine Collection Devices (UCDs) used until the 1970s when female astronauts joined the astronaut corps. Typically, astronauts aim to not defecate until the end of the EVA, leaving them with the task of urination and subsequent hydration, as the spacesuit holds only 0.95 L of water during the EVA.
By filtering urine and reusing it as drinking water, all of the drawbacks of diapers could be avoided and astronauts could significantly increase the amount of water they drink during spacewalks. reference Still Suit Sand DunesThe device is fairly unadvanced, with the filtration unit being large enough to fit into a backpack, weighing around 8 kg. Wastewater is filtered using a dual forward osmosis reverse osmosis (FO-RO) system, with the FO used as a pre-filter to prevent membrane fouling, which is common with RO.
Urine collection is done by the UCD, reminiscent of pre-MAG systems, using a silicone cup that fits over the genitals of a male or female astronaut. When you urinate, the inner lining of the cup detects moisture and a vacuum pump is activated to remove the urine, sending it to the FO-RO system as quickly as possible. Salt is added to the filtered water before it is potable.
It’s worth noting that this is obviously still a prototype, but considering that similar technology is already being used on the ISS to filter wastewater, it’s likely only a matter of time before a miniature version is added to new spacesuits. Not only would this have obvious benefits for astronauts during spacewalks, but it would also make traveling while strapped into a space capsule for hours on end a much less uncomfortable experience.
