For starters, there’s the feeling of weightlessness. (Technically, astronauts are subject to 90 percent of the gravity that we feel here on Earth, but the station’s brisk traveling speed of 17,500 miles per hour keeps everything on board in a constant free fall that resembles zero gravity.) The ISS is equipped with handrails and footrests so that astronauts can push themselves around the station or stay in one place while they’re working on something. Tools can drift away and out of reach.
So can water. Unleashed in weightlessness, water behaves like soap bubbles blown from a wand. Water molecules are more attracted to one another than molecules of another substance. They like sticking together. On the ISS, that means water molecules pull themselves together into a shape with the least amount of surface area: a sphere. But unlike its soapy counterpart on Earth, this kind of bubble doesn’t pop and vanish.
There is no photographic evidence of the leak, according to a NASA spokesperson. To imagine how it may have transpired, I reached out to Tom Jones, a former NASA astronaut and the author of Ask the Astronaut: A Galaxy of Astonishing Answers to Your Questions on Spaceflight. Jones flew on the Space Shuttle four times before the program ended in 2011, and spent a week helping assemble the station during his last mission in 2001. He has experienced firsthand the strange phenomena of water in microgravity.
“If it was a slow leak, it would have built up into a big, undulating blob that would have drifted off or crept along the wall with surface tension,” Jones says. “If it was under a higher pressure and it was coming out at a fast rate, it would spray and make droplets go flying across the cabin.”
Jones says the first scenario is preferable. It would be easier to chase after fat globs of water than tiny beads.
Water, like most earthly comforts, is a precious resource on the ISS. The loss of two and a half milk jugs’ worth of water seems concerning. But none of the liquid was actually wasted. The crew left the soaked towels out to dry, and the water eventually evaporated. The systems that control the station’s temperature and humidity sucked up the moisture and dumped it back into a mechanism that produces potable water.
It is thanks to water’s unpredictability in space that there are no faucets or showerheads on the ISS. Astronauts use squirt-gun–like hoses to dispense and carefully distribute water onto washcloths and toothbrushes. Showers are a distant daydream. There’s no toilet flushing, either. Contrary to some news reports about a leaky toilet, the toilet system on the ISS doesn’t use water.
Astronauts urinate into a hose with a special funnel on top. (Don’t worry, everyone gets a personal funnel.) They flip a switch to activate a fan in the tube, and the liquid is suctioned away. For solid waste, astronauts stick their feet into stirrups and sit down on a plastic seat, with a chute below. Urine is recycled in the station’s life-support systems and converted into drinkable water. The rest takes a rather dramatic journey: Solid waste is sealed in plastic bags or metal containers. Astronauts eventually transfer the waste, along with other trash, to departing cargo ships. The ships undock from the station and fall back to Earth, where they burn up in the atmosphere like a meteor shower.