6 ms·
NASA: Capillary Cup
- zackkatz 3y agoThe article doesn’t address the question of how the cup truly works. It relies on capillary action but, based on the article, I’m not sure how. https://en.m.wikipedia.org/wiki/Capillary_action https://en.m.wikipedia.org/wiki/Capillary_action
- mallomarmeasle 3y agoThey say in the article that capillary action draws the coffee along the narrow edge. This is aided by surface tension, just like how water is drawn into a capillary tube.
- keepamovin 3y agoHow gorgeous! It's hilarious how yonic it appears when looking down upon the brim. I think it works because the narrowing channel has increasing surface area to volume ratio, as you proceed toward the spout, so the capillary forces pull along a gradient toward the spout, gently tugging the liquid toward it. The bowl of the cup is lightly pinched around the brim to provide a kind of barrier to prevent the globule of zero-g liquid from just floatin' away! Hahaha :)
- sandworm101 3y agoFluid flows/sticks more easily along the sharp seam than the rounded corners. So there is always a little bit close to that sharp focus point near your lips. You slurp/sip from that sharp point, drawing more fluid along the seam. But, for exactly the same reasons, this thing is probably a pain to clean. Sharp corners and cleaning don't mix. That narrow seam will likely become caked in the dried residue of a hundred previous drinks. Even in an earth dishwasher, soap scum would be difficult to rinse out. I suspect these are not used many times.
- vanderZwan 3y ago> That narrow seam will likely become caked in the dried residue of a hundred previous drinks On the other hand, without gravity there is convection, which means those corners probably don't dry out as quickly. If I'm right about that then rinsing left-over residue out with plain water is easier if you don't wait too long.
- Terr_ 3y ago> But, for exactly the same reasons, this thing is probably a pain to clean. I dunno, given the size I imagine a regular toothbrush could dislodge anything dried, and small sponge-on-a-stick could get it acceptably dry. It's also worth asking what it might replace: On the ISS do they clean any drink-pouches, or are they all treated as disposable? I imagine that they become trash, since the next drink (or dehydrated drink-to-be) was probably already shipped in its own flattened pouch.
- ywnico 3y agoCorners are actually super effective at moving liquid using surface tension (assuming the contact angle is such that the surface is concave). The key is that at the front of the liquid, where it's very thin in the corner, the surface has a small radius of curvature => low pressure. If there's a lot of fluid filling up a corner, the radius of curvature is large => high pressure. So fluid naturally flows into the corner. This is used a lot in space applications, e.g., for propellant management devices [1]. The first analysis of the effect I know of is a paper by Concus and Finn (1969) [2], who realized that fluid can be carried arbitrarily high in a triangular groove, even against gravity, and proposed that trees may use this mechanism to carry water to their highest reaches. (The catch is that the fluid front becomes thinner and thinner as it gets higher. And it starts breaking down when it gets so thin that the continuum limit no longer applies). If you like math, I'd highly recommend checking out Mark Weislogel's research [3] which deals with the dynamics of viscous flow in triangular grooves. Shameless plug: chapter 4 of my Ph.D. thesis [4] gives an introduction to the subject. [1] http://www.pmdtechnology.com/PMD%20Physics.html http://www.pmdtechnology.com/PMD%20Physics.html [2] https://doi.org/10.1073/pnas.63.2.292 https://doi.org/10.1073/pnas.63.2.292 [3] https://scholar.google.com/citations?user=rNOJ49QAAAAJ https://scholar.google.com/citations?user=rNOJ49QAAAAJ [4] https://theses.hal.science/view/index/identifiant/tel-04015510 https://theses.hal.science/view/index/identifiant/tel-040155...
- gomox 3y agoHere's a video of the cup in action: https://twitter.com/ISS_Research/status/1631385518796849152 https://twitter.com/ISS_Research/status/1631385518796849152 Apparently the thinning spout shape sucks up the glob of liquid into it by way of capillary action, with the dual benefit of making the glob stay inside the cup despite it being open, while also making it available for slurping at the edge. Very cool.
- clarkdale 3y agoThis would make a great gift for a space lover!
- wmanley 3y agoIt looks like it would be a great space lover.
- dr_orpheus 3y agoThey sell them here, but appear to be sold out: https://spaceware.co/ https://spaceware.co/ Although you can by the NASA flight-certified version for the low low price of $650
- pierat 3y agoTo be fair, the lip of the object looks like a vagina. There's probably a reason they look functionally the same. (note: im referring to the physics of said 2 objects and how they keep liquids in. this isnt some bad sexual joke in jest.)
- itronitron 3y agoThey could call it the Cuppa-lingus
- queuebert 3y agoThe lip looks like labia -- the vagina is on the inside. But this being a nerd website, I can see how you wouldn't know ... ;-)
- pierat 3y agothat was a pre-coffee post. thats my only defense :/
- make3 3y agothis sounds like a joke of bad taste but I've seen a video of someone drinking from the cup in zero G and it looked so much like a vagina, even more with the added liquid for some reason, that the video looked like a parody skit
- helpfulContrib 3y agoStupid question: Is the math of the design of cup based on the math of the water? In other words, are the actual curves and angles of things derived from the surface tension properties of water in space? So, if one wanted to make a capillary cup for custard, it'd be different dimensions? Would love to see a parametric version of this (OpenSCAD?) somehow that can be generated for different liquids ...
- rtkwe 3y agoIt would need to be different for custard or it just may not work properly past a certain viscosity point where the resistance to flow in the matter overcomes the forces pulling it into the corner. Or it might just flow slowly enough it's not functional but still forms the same shapes eventually not sure. Zero-G fluid dynamics are difficult to work with intuitively.
- ywnico 3y agoTo expand on your point a bit, it depends on the type of fluid. Newtonian fluids [1] (a good approximation for water and many other "normal" fluids) will be pulled into the groove regardless of how viscous they are. E.g., the cup would probably work for treacle (syrup). Custard is non-Newtonian; more specifically, it's probably a Bingham fluid [2], meaning it acts like a solid until enough shear stress is applied, and then it acts like a liquid. The problem here is that even if there's enough shear stress for the custard far from the walls to move, the custard deep in the corner will likely remain a solid. So the corner capillary effect won't work. [1] https://en.wikipedia.org/wiki/Newtonian_fluid https://en.wikipedia.org/wiki/Newtonian_fluid [2] https://en.wikipedia.org/wiki/Bingham_plastic https://en.wikipedia.org/wiki/Bingham_plastic
- dr-detroit 3y ago[dead]
- DrThunder 3y agoI'm more interested in the astronaut wearing the Starfleet Deep Space Nine uniform.
- NoGravitas 3y agoThat is Italian astronaut Samantha Cristoforetti. She is known for installing the first microgravity espresso machine, and brewing the first cup of espresso in space (which depended on the cup shown in the article). The Star Trek uniform references Captain Janeway's love of coffee and willingness to go to extreme measures to ensure its availability.
- DrThunder 3y agoNiiiice. I forgot they had the same style uniform in Voyager too.
- moffkalast 3y ago"There's coffee in that nebula"
- rtkwe 3y agoThere's some neat video of Don Pettit who did the work on the prototype version made out of what looks like plastic sheets and Kapton tape. He's very happy to go on shows and talk about it so there's lots of video of him explaining the principals. This [0] is the original NASA recording of him explaining it. [0] https://www.youtube.com/watch?app=desktop&v=pct3JhVFSLo https://www.youtube.com/watch?app=desktop&v=pct3JhVFSLo [1] https://www.youtube.com/watch?v=ugQIivUuuXk https://www.youtube.com/watch?v=ugQIivUuuXk
- vidanay 3y agoHe is the most "uncomfortable" NASA astronaut I have ever seen. He seems to really not want to be on camera whereas every other one I've ever seen is fine with it.
- rtkwe 3y agoI'm not sure that might just be how he speaks, he seems to do a fair amount of non-mandatory PR engagements if he really didn't like doing them. I read his mood as more "excited energy" from an unpolished public speaker rather than distinctly unhappy to be performing, he came up from the scientist track rather than the pilot/military track for astronauts which can also explain it somewhat maybe.
- mkl 3y agoI've seen quite a few of his videos and never got that impression. He seems to love explaining stuff on camera.
- wyldfire 3y ago> “We take gravity for granted,” Pettit said. “Generally, we are unaware of the weight of our hands, or how easily we pour coffee into a cup. We don’t stop to think, ‘Will the coffee rise up and pour out?’ or ‘Can we pour the coffee?’ We just do it. Gravity handles this for us by applying force to the coffee, pulling downward." Donald Pettit is tugut mang fo wa Earther. Oye, Beltalowda!
- Maxion 3y agoOye, we all share da inyalowda space together, sasa ke?
- qrush 3y agoI rarely feel some RIT pride but for some reason, seeing this domain on HN sparks it. If you spent many a winter traversing windy long walks and tunnels in Rochester like I did - hoping you are doing well.
- c0unt 3y agoI opened the link in the middle of class at RIT and got so confused why I was seeing the RIT domain. Nice to see it on here!
- konstantinua00 3y agowhat is rit?
- singleshot_ 3y agoRochester Institute of Technology, an engineering school in New York.
- floren 3y agoStill fighting science with wood, buddy.
- deelowe 3y agoThis is a neat engineering achievement, but is it practical? What's the benefit of pouring the liquid out of a bag into this versus drinking out of the bag directly?
- sp332 3y agoYou can smell your drink this way.
- hetspookjee 3y agoMakes me wonder in how far you can actually. Wouldn’t the smell molecules also more or less stay roughly in the same space without convection and gravity playing their part?
- sp332 3y agoThey still have airflow on the space station. And since brownian motion does a fine job of spreading smells up against gravity on earth, I would guess that it works ok in space too.
- TeMPOraL 3y agoOn a space station this size, I'm not sure it's a feature - especially if it starts being used for a more varied selection of consumable liquids than just coffee. Speaking of, how do they manage smells up there? Is "ISS smell management" someone's job at NASA?
- dr_orpheus 3y agoThey have filters in the air cycling that I assume include some sort of carbon filter for smell. However, astronauts have definitely noted that the ISS has "a smell" https://www.space.com/international-space-station-smells-european-astronaut https://www.space.com/international-space-station-smells-eur...
- jjk166 3y agoWhat's the benefit of using a coffee mug on earth? We risk spilling hot coffee on ourselves and things that can stain, we allow heat to escape to the air, and there is potential for something to get into and contaminate our coffee. And yet most of us probably have a decent collection of coffee mugs. Ergonomics and aesthetics, while perhaps not the very highest priorities, are nevertheless important.
- Waterluvian 3y agoI’d love to read more about inventions astronauts developed as a side-effect of being in space. Ie. Not because it was a scheduled project but because they had a problem and hacked together a utility for the problem.
- kraig911 3y agoRandom question. Why haven't we made a spinning space station yet to simulate gravity? Would fluids still work? Does the spinning actually work?
- asperous 3y agohttps://www.popularmechanics.com/space/rockets/a8965/why-dont-we-have-artificial-gravity-15425569/ https://www.popularmechanics.com/space/rockets/a8965/why-don...
- jylam 3y agoNot a specialist, but that: 1/ is hard to build in space (big pieces that need to be assembled) 2/ needs to be big enough not to make everyone sick (the diameter must be quite large for the gradient of gravity not to be too noticeable) 3/ Not very useful when one of the main points of having a space station is to do ~zero g experiments
- SushiHippie 3y agoRelated submission from 9 days ago: One Revolution per Minute [video] (254 points, 155 comments) https://news.ycombinator.com/item?id=37736853 https://news.ycombinator.com/item?id=37736853
- jylam 3y agoThat's very neat, but it seems that if you handle it a bit to harshly the liquid will come out and make a mess, unlike the bag. If you are careful enough I guess that's a more flavorful and natural way to drink tho, I like this kind of stuff <3
- TeMPOraL 3y agoWonder if it would make sense to add a lid to this cup, such that when put on, the only open part would be the drinking "beak".
- r3trohack3r 3y ago> make a mess IIUC spilling liquid in zero-gravity is extremely dangerous. When you spill on earth, it falls to the floor. When you spill in space, it floats around and globs up. Then that glob is attracted to, and sticks to, anything that’s hydrophilic. Which happens to include you. More alarmingly, your face. If I remember correctly there was a recent incident where an astronaut’s dehumidifier in their suit gave out, and they almost drowned in the water being released from their own body (breath, sweat, etc)
- r3trohack3r 3y agoCapillary Action is my favorite Wikipedia article: https://en.wikipedia.org/wiki/Capillary_action https://en.wikipedia.org/wiki/Capillary_action Leonardo da Vinci observed Capillary Action making him remark that the paint brush was a gift from the gods. He rightfully observed paint brush has an unnatural, given our understanding at the time, attraction for paint. If you place the brush in a cup of paint, and come back some time later, the brush will have _pulled_ the paint into itself noticeably above the surface of the paint in the cup. It wasn't until the early 1800s that we had the early versions of the Young-Laplace equation which attempted to quantitatively explain the phenomenon. Fast forward to 1900, Albert Einstein's first paper was still exploring Leonardo's paint brush: https://web.archive.org/web/20171025203011/http://gallica.bnf.fr/ark:/12148/bpt6k15314w/f595.image.langFR https://web.archive.org/web/20171025203011/http://gallica.bn... The wikipedia entry reminds me that this world is full of magic and wonder, everywhere you look. Something as simple as a paintbrush can reveal something peculiar that takes generations of study by the brightest of human minds to try and explain. Go outside and turn over a rock, any rock, and there is a lifetime of wonder and mystery under it. And, just because we can explain it now, doesn't mean Leonardo's paint brush isn't magic. It just means that the magic is real.
- peheje 3y agobeautiful
- CamperBob2 3y agoArgues for a 'news.ycombinator.com/bestof' category.
- callalex 3y agohttps://news.ycombinator.com/highlights https://news.ycombinator.com/highlights
- JanSolo 3y agoDon Pettit is my favorite astronaut. I loved watching all his ISS videos where he did wacky experiments and nerded-out about capillary flows, static attraction and similar stuff. He's also a renowned photographer and has taken some of the coolest space pictures from the ISS. He actually refined the guidelines for shooting pictures thru the glass windows of the station. I hope that they fly him again soon; I can't wait to see what he'll come up with next!
- eh_why_not 3y agoHe's active as u/astro_pettit on reddit.
- luxuryballs 3y agoHow far are we from that whole spinning spaceship manufacturer gravity thing I wonder, if it’s even possible.
- xwdv 3y agoIf you do that coffee will still pour out of the spout quite weirdly, not like it does on Earth. Very annoying.
- aaron695 3y ago[dead]
- deleted 3y ago[deleted]