The foam on your morning latte would be that much more satisfying if you were drinking it in space. Meaning, it wouldn’t disappear so fast. Coffee aficionados everywhere know that froth on a cappuccino has more lasting power — but there's more to foam.
Foam lasts longer in space without the force of gravity to degrade it. The FOAM-C (Foam and Optics Mechanics–Coarsening) experiment, developed by Airbus for ESA, will soon be landing in the Fluid Science Laboratory of the ISS. FOAM-C is the next level of a previous experiment, and is meant to observe the life cycle of foam bubbles. This time, astronaut Jessica Meir will be activating the experiment to investigate the stability of foams in space.
Of course, this experiment isn’t flying to space just to make coffee on terra firma fancier and possibly freak out a barista or two. So many manufacturing processes that involve foam, from building materials to pharmaceuticals, can benefit. There will be no rush to study foams that have sort of been frozen in time by the absence of gravity. What results from FOAM-C could be used for such processes on Earth — and eventually off.
What scientists really want to find out from FOAM-C is how foams behave in microgravity. Individual cells will hold liquids that need to be shaken and then subjected to laser optic and hi-res camera analysis. There is particular interest in foam coarsening, or the enlargement and bursting of bubbles during the transition of a foam from a mass of bubbles to a liquid. Since this happens too fast on Earth, it can only be studied in zero-G.
Foam is made of gas and a liquid with a surfactant, or a substance that reduces surface tension on that liquid. Thank surfactants for those fabulous mounds of shampoo bubbles when you lather up. When the liquid in a foam is pulled downwards by gravity, and pulls those bubbles with it, larger bubbles keep growing while smaller ones keep shrinking. This enlarging of the bubbles until they finally burst is called coarsening. Along with drainage, it explains the collapse of a foam back into liquid form.
There is no drainage to destabilize a foam in space because there is no gravity. Foam formation and coarsening will happen in slow motion, so scientists will be able to study the transition from a foam to a liquid as bubbles enlarge and eventually burst. Even a single bubble, like the one in the NASA video above, lasts in space like it never would on Earth. Longer bubble endurance means highly stable foams that could mean amazing advances in the manufacturing if we figure out how to stabilize them on Earth. In the future, maybe the solution will be to just manufacture certain items (or at least carry out the processes that involve foam) in space.
Unfortunately for your coffee that de-foams and gets cold way too fast, it’s probably going to stay that way unless you decide you want to be a space tourist.