By Dan Lewis
This is the last post in our series, Now I Know – Liquid Edition by Dan Lewis, author of Now I Know, a popular online newsletter.
You’re thirsty, so you grab a drink – water, Molokai Coconut, etc. Lift whatever the liquid is in, tilt it back a bit, and congrats: you’re on your way to quenching that thirst. It’s pretty easy and by age two or so, most of us have mastered it (with the occasional spill, as your nicest shirt can undoubtedly attest to). But all that works because of gravity. That force moves the liquid from the tilted cup into our mouths, making it relatively easy to get a sip. But in space – say, above the International Space Station (ISS) – there isn’t all that much gravity. So: how do astronauts drink.
There are a few ways.
The most boring? With a straw. Suction still works and even in low gravity environments, human mouths can provide plenty of that to get the drink out of its container – typically a pouch – and into the astronaut. Easy, but not a lot of fun. And when you’re in space for a few months, it’s not like you can alleviate boredom by going for a walk outside or many of the other activities we Earth-bound folks take for granted. Besides, drinking everything through a straw is just a bad culinary experience. So they’ve come up with alternatives. The first one, as seen in the video below, is reminiscent of a five-year-old’s birthday party when the bubble wands come out. The man in the video – Greg Olsen, a private citizen who took a self-funded trip to ISS in 2005 – takes the water spout aboard the ISS and releases spheres of water into the air around them. The water sticks together due to the property of cohesion, but because of the microgravity environment, the spheres don’t fall to the ground. Instead, the small amount of force which expelled the water from the spout in the first place remains as the dominant force, pushing the spheres toward the astronaut where he can gobble them up, Pac-Man style.
That’s not a very good idea, though. Any spheres of water which escape the astronaut’s gaze will float around effectively forever, wasted at best, and potentially interfering with the space station’s equipment at worse. And for anything other than water, the dangers posed by rogue liquids may be even worse. Take coffee, for example – you probably don’t want to shoot it out of a spout like Olsen did above. You probably don’t want to drink it through a straw, either. The good news: there’s a space-friendly alternative, colloquially called a Space-Cup.
The cup, as seen in the video above, uses the same principles as NASA and other space agencies use for fuel tanks designed to re-ignite in space. The cup, if you were to look at it from its opening on down, is shaped like a teardrop, coming to a sharp angle on one side. The liquid — coffee, in the video above – adheres to the pinched end of the cup and climbs up it. As the astronaut sips his coffee from the opening in the cup, the coffee at the bottom of the cup climbs up, and ultimately, into the astronaut’s mouth. The whole process is slow, for sure, but it comes with a fantastic upside – it’s spill-proof. Drop your coffee here on Earth, and be prepared for a mess and maybe even a scalding. Drop it on the ISS? It’ll just float there, in the cup, waiting for you to drink it. Bonus fact: One thing microgravity doesn’t mess with when it comes to eating? Swallowing. Even though it’s best to stay upright when eating or drinking (on Earth, at least, where gravity matters), it’s not necessary. Our bodies move food and drinks from our mouths to our stomachs via a contracting of muscles called peristalsis – no gravity required.