A nifty bit of engineering on the ISS

May 23, 2015 • 3:00 pm

Destin from SmarterEveryDay analyzes a cool bit of engineering on the International Space Station: the system whereby the cupola windows, through which everything is photographed and filmed, are opened and closed. It turns out that the shutters are actually activated through two holes in the shuttle skin itself, sealed only with two small rubber-O rings! What would happen if one of them failed? The question is answered in the following video. Note that 6 minutes in, our Official Website Astronaut™, Samantha Cristoforetti, demonstrates the windows on the Station, and gives Destin’s site a plug.

I’m sure we’ll all miss AstroSam when she returns to Earth in early June (she was supposed to be back May 13, but a transport vehicle crash delayed her return).

h/t: David

28 thoughts on “A nifty bit of engineering on the ISS”

      1. Yes, he’s talked about it openly. He does great work on his channel, but he has some serious cognitive dissonance going on when it comes to religion. Reminds me of Francis Collins.

        1. I kind of wish I didn’t know that now, I do enjoy the series and his enthusiasm for learning is infectious. The one with the reverse bike was particularly good and funny.

          1. I feel your pain. It’s like not being able to “un-see” something horrible.

    2. I am an antitheist but I don’t care if Destin’s a believer. His faith is unscientific hokum but his science and engineering videos are grounded in reality, not faith.

      BTW, Jerry might enjoy Destin’s video analysing how cats fall on their legs (psalms 111:2 fyi). It’s on his youtube channel.

  3. I can see how the small O-rings might deteriorate due to time & the steep temperature gradient that they are exposed to. Personally I think they should be replaced before a problem occurs.

    1. While I would like to think that NASA has a pretty good idea of the expected service life of such parts and a proactive replacement schedule based on it…

      …I really wouldn’t worry at all in this case.

      From the geometry, it would take multiple o-rings to fail before you’d get an air leak, and a single failure would likely jam (or at least hinder) the mechanism. And even if you lost all the o-rings at once…it’s such a small surface area that there’d be no danger. You could put a metal cup (or the like) of suitable size on top of the handle and run a quick bead of caulking around it to stop the leak and then, if you really felt like it, fix it from the outside without having to depressurize the whole thing.

      Remember that Hollywood goes to great lengths to overly dramatize these sorts of things. You could remove the entire mechanism, leaving what looks like it’d be about a 1″ hole in its place, and the only reason you’d want to deal with it sooner rather than later is it’s going to eat into your reserve air tank kinda quickly. You’d get a nasty hickey if you covered it with your hand and held it there, but you’d have no trouble pulling your hand away. But Hollywood visions of it inexorably drawing you to and through it from the other side of the station, turning you inside-out in the process? Not even vaguely remotely realistic.

      b&

      1. If the hole is an inch square, then at full atmospheric pressure that’s just 15 pounds.

        The one thing I found really hard to accept in Alien Resurrection was that Junior could be sucked through a small hole in the side of the spaceship. All the other scientific ‘impossibilities’ didn’t even make me blink, but that one just lost me completely. Odd that.

        1. Yup. It’s worth noting that 15 pounds is a bit substantial, especially in such a small area…imagine supergluing, say, a ten-pound sack of flour to a quarter, and then supergluing the other side of the quarter to your body, and then lifting it. Won’t be a pleasant experience by any stretch of the imagination…but you’re staying inside the cabin, and you’ll have no trouble pulling away.

          …and, yes…that was the exact scene I had in mind….

          b&

          1. “imagine supergluing, say, a ten-pound sack of flour to a quarter, and then supergluing the other side of the quarter to your body”

            Imagine, imagine, imagine…ah…it’s just not happening. But, I think I get your point. 😎

          2. I suspect the bigger problem will be the boiling point/desublimation effect to the fluids on (and just under?) your skin when you seal the hole with your hand. It is not the 15 pounds weight on 1 square inch of skin, but the -103.421359 kpa to the 6.45cm2 of your somewhat wet biomass. The fluids on your skin would instantly boil and then freeze into snow, and I suspect the effects under the skin would be not too pleasant either. See Flash Freezing

            In other words, exposing fragile human bits to hard vacuum is generally held to be an example of having a bad day.

            Now I have learned two somethings new today: wear gloves when sealing a small hole in your spacecraft.

          3. Again, it wouldn’t be pleasant, but it wouldn’t be nearly so dramatic. The vacuum is cold, yes…but there’s no conduction nor convection, the major ways that you lose heat. That only leaves radiation, which is nearly negligible. Indeed, if you’re in a spacesuit in sunlight, your problem may well be staying cool rather than keeping warm — and it’d be the same without the suit, save for the whole asphyxiation thing.

            You really don’t want to expose yourself to vacuum…but, again again, it’s nowhere near as dramatic as they make it seem in the movies.

            b&

          4. It is not the temperature of space, but the boiling point of the water in your cells at 0 atm. I suspect the fluids in the cells on the surface of your skin would instantly vapourise and freeze, shattering and exposing the next layer of skin to freeze and shatter etc… until you have a hole through your hand.

            Agreed it would not suck your whole body through, and agreed – not pleasant.

          5. @Rixaeton

            I don’t think so. I think the skin on e.g. your palm is fairly tough and would slow the evaporation considerably, and if water does freeze then it has a very poor heat conductivity. I don’t know if anyone’s tried the experiment with e.g. a dead chicken.

            Also, it wouldn’t be as if 15 pounds was trying to pull your skin off (a la Rickflick). There would be no ‘pull’ on your skin as such, instead there would be 15 pounds pressure on the back of your hand and the stresses would distribute through your hand.
            You could certainly pull your hand away, and probably without damage if done promptly.

          6. Exactly. Skin is pretty damned tough…many drumheads still to this day are made from non-human skin, and certain primitive barbarians used to use human skin for that, too. And the muscles underneath the skin are even stronger. You can cut them all with a knife, of course, but knives have far more pressure per unit area than the atmosphere. Several orders of magnitude.

            You’d get a really nasty hickey by plugging the hole with your hand or arm or butt or whatever, especially if you stay there for a bit…but that’s it.

            b&

          8. Yes — didn’t remember it until you mentioned it, but now I do remember reading it many many many moons ago.

            It’s both thrilling and sobering to think of how good the science was during the golden age of SF. Thrilling when you think of things like Heinlein’s description of a boy riding his horse in the middle of the New Mexico desert and answering his phone, and how that’s now completely unremarkable when it was nearly laughable when I first read it in the ’80s…and depressing when you realize that they had the rocketry just as right and yet we’ve never sent anybody past the moon and nobody even that far in decades.

            We’ve become much too risk-averse, I think. We could have sent humans to Mars by now, obviously at enormous expense and risk…but the cost in terms of both dollars and lives would still be but a fraction of what we currently spend killing brown-skinned people

            I’m actually marginally more hopeful for the future today than not all that much before. Wind and solar are actually cheaper for utility-scale electricity production than anything other than coal, and it won’t be long before the prices fall to that level, too. Tesla’s utility-scale batteries are significantly cheaper than peaking power plants, opening up the potential for huge demand that would again dramatically drive down prices. It looks like we’re at an inflection point where, very soon, renewables will be so cheap nothing else can compete with them, at the same time as mined energy sources are getting exponentially more expensive.

            If that happens…we open up a new golden age of cheap energy, perhaps enough for little luxuries like manned space exploration.

            Petroleum and its derivatives remain a big question mark…but, with cheap enough electricity you can even make those literally out of thin air….

            b&

  4. And then the Smarter Every Day video had to be ruined at the very end when it noted psalm 8:3-4

  5. I wonder at the verse he shows at the end of the video..

    Psalm 8: 3-4

    3 I think about the heavens. I think about what your fingers have created. I think about the moon and stars that you have set in place.

    4 What are human beings that you think about them? What is a son of man that you take care of him?

    Waxing poetic or attributing causality?

  6. > It turns out that the shutters are actually activated through two holes in the shuttle skin itself…

    “shuttle skin”?

    (OCD never sleeps)

    1. Is it OCD that stops you from spelling it wrong, but in the right alphabetical order?

      CDO, fighting chaos one letter at a time.

  9. I notice that’s a very heavy-looking shield to be operated by a little knob – but of course it doesn’t ‘weigh’ anything in space, though it has hefty inertia.

    As for the ooh-aah totes amazeballs O-ring design, it just seems kinda obvious to any water engineer. How d’you seal a rotating shaft? – use an O-ring. Ask any plumber, your kitchen tap (faucet) does exactly that. You probably want to be a bit careful about your material selection, as the Challenger boosters proved and Feynman demonstrated, but again failure of one of these little O-rings isn’t going to be a big deal.

  10. We seem to take the ISS for granted these days, we need to reclaim the wonder and excitement we had in the early days of Space Exploration, its a truly mindblowing thing that Space Station in the Sky and I am going to start a Petition for Samantha Cristoforetti,to be a permanent residence , she is great.

Comments are closed.