Coffee cups for cosmonauts: The difficulties of drinking in outer space and the cup created to circumvent this problem

by Ashini K Ekanayake

There are many activities we take for-granted, such as having a cup of coffee. Enjoying a caffeinated brew is often a crucial part of most people’s daily rituals start the day, where going through the motions of the preparation and consumption of the beverage is enough to get you in the correct frame of mind to begin the day’s work.   

However, this is something our compatriots in outer space cannot enjoy as much. Normal cups cannot work since there is the chance that small droplets of coffee would escape in the low gravity environment and potentially harm billions of dollars’ worth of equipment. One would come to the conclusion that straws would solve this seemingly simple problem. However, straws rely on air pressure, where lowering the pressure inside the straw forces the drink up it. In outer space there is no such pressure, hence straws do not work 1.

To overcome this hurdle, as trivial as it may sound to some, a team of researchers at Portland State University have come up with a design for a cup which directs fluids directly to the mouths of our caffeine craving cosmonauts.

Figure: Model of the cup

Figure: Model of the cup

The cup’s design is based on a Prototype first put forward by an astronaut while on board the International Space Station in 2008 by the name of Petit. Instead of utilizing gravity, the cup focuses on using surface tension, the geometry of the cup’s odd shape, and wetting, which is the study of how a liquid on a solid spreads out. One notable facet of the design is the point in the center of the cup. It uses surface tension to guide the liquid towards the mouth of the astronaut2.

Despite being an oddly specific problem, this development has many potential applications, both in outer space and on Terra Firma. Firstly, with the development of the cup, it can be easily 3D printed on board the ISS, and this will reduce the weight of the amount of drinking bags sent to space, in turn improving the fuel efficiency of rockets. On earth, this design is relevant to several such as in medical research and the delivery of drugs3. Hence the simple innovation of this small cup has resulted in the convergence of science, technology and design.