Photo-Frenzy on the International Space Station. Check out how we take photographs in the Cupola module.

5/3/2016
The crema; it does not float to the top of your espresso when in weightlessness. The signature trait of an espresso is the layer of crema. It consists of stabilized foam created from a complex array of organic surfactants liberated in the brewing process. Carbon dioxide, liberated from the coffee grounds when subjected to hot water, fills the bubbles, which is perhaps one acceptable use for this greenhouse gas. The brewing takes place under pressure, up to 8 atmospheres (over 100 PSI), and when released into your cup, the sudden drop in pressure coupled with all the organic complexities creates this wonderful foam. The crema has a lower density than coffee so it floats on the surface as a cohesive mass. The bubbles slowly pop, releasing olfactory essence that greets our nose and contributes to the whole culinary effect.

In space the olfactory sensations will be different. If sipped through a straw from a bag (the normal engineered way to drink in space), none of the aromatics will find passage to your nose and the coffee will taste, well, like coffee would if you had a clothespin on your nose. If sipped from the space cup, your nose will find its way below the curvilinear entrance where the aromatics can tickle your olfactory sensation while sipping this orbital delight.

So what will happen to the fate of the crema in weightlessness? Before Samantha Cristoforetti did the experiment, the answer seemed obvious: the crema will not form a top layer but instead will remain mixed, forming a turbid brew of coffee and bubbles. Quite unexpectedly, something new was observed. A spontaneous structure formed throughout the espresso-crema mixture where larger bubbles formed centers surrounded by circular clouds of finer ones. When I saw the downlinked photo I couldn’t help but think of a Hubble photo of a nebular cloud forming solar systems, all in your space cup of coffee.

photo captions:
Crema on Earth (left) forms a floating foam layer consisting of mostly fine bubbles with a few larger ones. Notice how capillary forces driven by the two-angled walls are attempting to lift the crema “up”. Crema in space (right) remains suspended within the bulk espresso forming a turbid suspension that climbs the angled walls via capillary forces parking itself at the winged-lip ready to be sipped. An unexpected structure formed where larger bubbles become surrounded by a circular cloud of finer ones. 

4/11/2016
A siphon in space; siphons conger the image of some hapless person who has run out of gas sucking on a short chunk of hose attempting to transfer gasoline from a donor tank. Siphons require gravity and one volume of liquid to be lower than the other. Without both of these conditions there will be no flow. In the weightlessness of space, the concept of a siphon was simply not possible. Using two space cups during the Capillary Beverage experiment, space station crew (Scott Kelly, Kimiya Yui, Kjell Lindgren) guided by Mark Weislogel and Drew Wollman through the space to ground radio link discovered how to make a siphon in space. The process of starting a siphon is just like that on Earth; the transfer hose must be completely filled and to do that you place one end into the donor container and suck on the other end until you get a mouthful. Then you quickly place that end into the receiving container and either spit out or swallow, depending on what the fluid happens to be. The secret to the space siphon is where the ends of the open hose are placed within the cups. In the donor space cup, the hose end must be placed near a wall with a large radius of curvature. In the receiving space cup, the hose end must be placed near the angled walls that give a small radius of curvature. The hose now connects the capillary gradient between these two surfaces and thus the fluid flows from the large radius of curvature to the small. Move either hose to a different location within the space cup and the flow stops. What an eureka moment! This is science at its best.

photo: Siphon in space; the coffee is flowing from the left space cup to the right space cup under capillary forces. 

4/1/2016
The capillary beverage experiment measures via video the fluid interface during space cup filling and draining. Fluids vary from water, coffee, tea, and particle-laden suspensions from our galley such as peach smoothie. By knowing the space cup geometry, the fluid density, viscosity, surface tension, and wetting angle in these simple experiments, the videos give data that is used to calibrate computer models so that new systems involving gas-liquid free surfaces can be designed. These observations with the space cup can thus be applied to designing the system of screens and vanes inside rocket fuel tanks, humidity control equipment for spacecraft atmosphere recycling, and of course, separating urine from the entrained airstream in the space toilet. I will drink to that!

Photos: Capillary Beverage experiment in progress on Space Station. The space cup being filled showing capillary channel flow directing the water to the lip-cusp (L) and taking a sip, showing how capillary flow replenishes the supply of water to the lip-cusp and the effectiveness of the “cup-wings” in preventing dribbles (R).

3/12/2016  
I made a bet with Mark Weislogel about the necessity of having “wings” on the space cup.  The first generation cup did not have these and seemed to work just fine so why did the second generation cup need them?  Since I was one of the few who had ever sipped from such a cup I was poised to make this proclamation from my orbital throne.  Mark insisted that the wings would add an essential feature to the space cup based on his mathematical intuition.  He was right and I was wrong.  The wings added an essential aspect that keeps one from doing the orbital equivalent of dribbling.  

Don’t be a space goop; drink from a cup that has wings.  And students don’t try this at home.  

3/8/2016
The second generation space cup, invented in 2014, is based on the same fundamental principles of the first generation but adds significant new invention into the design. The inventive genius behind this cup was Ryan Jenson, Andrew Wollman, and Mark Weislogel working at their small techno-company, IRPI LLC, a company spawned from Mark’s research at Portland State University. The unique shape of this cup is defined by the mathematics of fluid physics applied to a microgravity environment. Very little artistic license was used. A trait of good engineering is when mathematical based designs can serve a useful function and have a high aesthetic measure.

Schematic and model of the second generation space cup designed by IRPI LLC. Good engineering; when mathematical based designs can serve a useful function and have a high aesthetic measure. This is a 3D printed space cup is made from food grade clear plastic that remains food-safe at temperatures over 100 C. 

5/6/2016
Lawyers in space: in the course of human exploration of space, lawyers will be needed. What happens when invention occurs? Who and what country can claim legal due process for the intellectual rights? Sounds far out but this has already happened with the space cup; it is the first example of something invented in space and patented (e.g. not invented on Earth and subsequently flown into space which is the case for Space Station related patents to date). Like so many techno-aspects of space, the folks at NASA lead the way. Kurt Hammerle and Ted Ro, NASA patent attorneys, wrote a seminal paper on this subject on 2008. To summarize this 34-page paper, they proposed an extension of well established maritime law for invention in space. If a person on a ship in international waters creates an invention, it follows the due process under the country of ship registry. So likewise follows invention in the galactic waters of space.

The International Space Station is a spacecraft designed as a scientific laboratory where invention is bound to take place. It seems reasonable that the country of registry for a particular international module suffices to be like the registry of a ship in international waters. So during the docked phase to the International Space Station of Space Shuttle Endeavor, STS 126, when the space cup was invented, I happened to be in Node 2 (and also the Lab to get some Kapton tape). Both of these modules are USA NASA controlled entities. So it was only fitting that we applied for the space cup patent through the US Patent office. If I had been 15 feet to port, in the Japanese JAXA module, or 15 feet to starboard, in the European ESA module, the legal aspects would probably still be under debate.

figure caption:
Hammerle, K.G., Ro, T.U., “Extra-Territorial Reach of US Patent Law on Space Related Activities”, Jour. Space Law, vol. 34, no. 2, 2008, pp. 241-275.


4/26/2016
To conduct an experiment using the space cup requires a setup with carefully chosen camera angles so that useful measurements can be digitally obtained from the video frames. These measurements are used to calculate the fluid dynamic parameters needed for modeling capillary flow in weightlessness. Once the model works for the experiment, then the model can be used to design an entirely new fluid system such as capillary driven flow in a urine collection-processor.

video caption:
Kjell Lindgren conducts an experiment with the second generation space cup on the Space Station.  

4/3/2016
The unappreciated value of smell; it is intrinsically known that smell is important to the overall quality of food enjoyment however we do not give it much thought until this ability is no longer possible. We heap near super powers onto our taste buds giving them credit for presenting us with this sense of gourmet delight. Even our choice of words when discussing these sensations is filled with idiomatic expressions describing the palette. Our proboscis is rarely credited and when so it is often in jesting reference to Cyrano de Bergerac. For the nose to take in culinary aromas, your food and beverage must first be on a plate or in an open container. Equally important, and neglected by most, is the role of gravity driven convection from warm food sending buoyant billows of tantalizing vapors upwards to where our nose just happens to be.

When in space, we dig our food out from deep pouches and sip our beverages through straws from bags thus neither can directly release their culinary vapors. And even if they could, in weightlessness the normal buoyancy driven convection that we take for granted on Earth simple does not work. In space, there is no expedient way for such vapors to travel the distance from our spoon to our nose. Our nose may as well be on another planet. Thus our culinary sensations in space are reduced to something more aligned with hastily imbibing the contents of pouches and bags to simply stay alive and squelch the sensations in a hungry gut.

The space cup changed this and for the first time allows beverages to be sipped from an open container with a geometry that places your nose inside the cup surrounded by aromas where once again they can be sensed by our olfactory process. When we find ourselves in the frontier, abstract from normal civilized life, simple pleasures from home take on significance difficult to explain to those who have never ventured away.

photos: Smell; the prime value of drinking coffee from an open container. The space cup geometry places one’s nose in the prime spot for taking in the aroma, something that sucking your fluids through a straw from a bag does not allow. Samantha Cristoforetti sips espresso coffee (L) from a room with a view enjoying both java taste and smell. With each sip, the geometry of all versions of the space cup place your nose inside the entrance and in direct contact with the aromas (R); the first generation made on orbit from plastic film, the second generation 3D laser printed, and the slip cast porcelain version. 

3/31/2016
Space cups in space; we now have six of the second generation space cups on the International Space Station. They are part of a NASA fluid physics experiment called “Capillary Beverage” used for both experimentation and for crew to have the pleasures of sipping coffee or tea from an open container instead of sucking through a straw from a bag.



3/9/2016
Form makes function; to function the space cup must have form. The evolution of this cup’s form begins on the backside with a circular cross section. That shape will stabilize the fluid and keep it in the cup but will not move it to the lip. The circular cross section blends into a gentle obtuse angle, the beginning of the necessary angled walls required for capillary driven channel flow. Moving along the channel, the obtuse angle decreases past 90 degrees thus becoming acute as two intersecting walls define the front cup edge. This channel culminates with a cusp at the lip. Technically speaking, a true cusp exists only in mathematical constructs, but in the real world of engineering, we can get close enough. This decreasing angle efficiently drives the fluid along the channel. After moving to the lip-cusp, the capillary channel flow becomes balance by surface tension forces thus the flow stops. The fluid simply sits at the lip-cusp waiting for a pair of lips to come take a sip. Fluid consumed at the lip-cusp disturbs this equilibrium driving more fluid along the channel to replace it. When sipping stops, so does the capillary flow and once again equilibrium is established at the lip-cusp. Nature coupled with human design can create elegant beauty.

The lip-cusp wings prevent errant drops from climbing onto your lips and chin, thus preventing the zero gravity equivalent of dribbling, which of course in space would not happen since the tea would just sit there as undulating hemispherical blobs. Chin dribbles leave the same sort of impression with your colleagues whether on Earth or in space.

Form makes function; the space cup backside has a circular cross section that blends into an obtuse angle (left). Form makes function; the space cup front side has two acute angled walls whose angle steadily decreases until it approaches a cusp at the lip. A pair of wings keeps the fluid from doing the space equivalent of dribbling (right). 

3/7/2016
The mathematics of capillary channel flow was first described by Paul Concus and Robert Finn in a paper published in June of 1969, one month before Apollo 11 landed on the Moon. At this time our experience in space was limited to days not months. It took 40 years of humans living in space before this cup was invented. Decade-length delays are not uncommon in the technical world; a theoretical advancement or raw scientific observation usually require years before practical applications emerge. The current scientific research on Space Station is now being published in technical journals for the world to have. It will be fascinating to see what practical constructs come from this in the decades to come. By the time the full utility of research in space is actually realized by those living on Earth, this Space Station will probably have been de-orbited.

The mathematical theory behind capillary channel flow was published in 1969.