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In the Martian movie Watney patched a broken door to the martian surface with plastic tarp and duct tape.

The pressure on Mars is 0.5 kPa, which is 200 times smaller, that on Earth (100 kPa), i.e. it is approximately vacuum outside.

The pressure inside is from 0.5 to 1 of atmospheres (depending on it's composition which is not clear from the movie).

So, we have 0.5 atmosphere pressing onto tarp.

1 atmosphere is 10 metric tons per square meter. The surface of the opening was more than 6 square meters. I don't remember visually the radius of the opening, but probably it was enough to human height passing, i.e. 2 * 1 meters. Pi * 1^2 ~ 3.

So, we have 30 tons pressing onto the door.

Although, I can agree that plain new plastic can handle such a pressure, I can't believe it is possible to tie edges so that this huge tension would distribute equally.

The question is: was there some examples of closing such big openings with plastic in reality?

Or what specialists are saying?

PearsonArtPhoto
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    1 atm is ~ 10,332 kg/m², and circular opening of a 2 m diameter (1 m radius) has a surface area of π m². It would have to support around 32,459 kg of pressure. Around 51,66 kg for every cm of the opening's circumference. If a botanist can do that in a pressurized suit with duct tape and some tarp, I'm afraid I'll have to fire my plumber. :) – TildalWave Jan 26 '16 at 12:29
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    @TildalWave This data sheet seems to indicate a tensile strength of 560N/100mm, which would be slightly above 51.66kg/cm? So sounds plausible? – James Thorpe Jan 26 '16 at 12:57
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    @JamesThorpe Sure, if he'd do it to machine precision with absolutely no defects, it could hold it until the duct tape's glue loses all elasticity due to temperature differential (shouldn't take too long). Of course, our protagonist has done that in a pressure suit, in dusty environment and around an opening that is too big to easily reach. And I have no idea how he'd have done it at the bottom. – TildalWave Jan 26 '16 at 13:05
  • @TildalWave Haha... what's really annoying me is I know for a fact that I read this part just last night, but I have no recollection about how the fix was actually described in the book! – James Thorpe Jan 26 '16 at 13:10
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    I think in the book it was described as a very temporary solution that was sufficient for I think 4 minutes of life support, which it might be able to do. I think it more held the pieces together than filled the hole, which would help some... – PearsonArtPhoto Jan 26 '16 at 13:17
  • @PearsonArtPhoto That 4 minutes was the fix to the suit which was leaky through the cut off arm, not to the fix on the large hole in the hab which was still needed for some time – James Thorpe Jan 26 '16 at 13:18
  • You are right about that... I remember now, the hab was fixed by some sort of glue in the book, don't remember anything about tape... – PearsonArtPhoto Jan 26 '16 at 13:19
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    @JamesThorpe: 560N/100mm translates to 56 kg/10cm, so 5.6 kg/cm, i.e. you need a strip of tape 20 cm long applied at a right angle to (across instead of along) the tear. Blanketing the entire tear with a patch of duct tape 20 cm wide should work. – Hobbes Jan 26 '16 at 15:31
  • @Hobbes Right, been a while since I did that sort of math. But I'm not sure 20cm wide tape would work as all the stress would still be in one line across the join in canvases? Rather you'd need something like at least 10 layers of it, with outer layers being wider to still stick to the canvas, where each layer is then capable of taking 5.6kg/cm for a total of 56kg? – James Thorpe Jan 26 '16 at 15:40
  • you're right, you can't add the tensile strength like that. – Hobbes Jan 26 '16 at 15:50
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    In the book, Watney uses a sort of super-glue type resin to fix both the hab and his one-armed suit. It's especially memorable because he accidentally glues his hand to his helmet at one point. – James Jan 26 '16 at 21:29
  • its composition – Federico Jan 27 '16 at 08:19
  • Scanned over the book again last night. The actual details of the repair are really skimmed over (just along the lines of "I fixed and repressurised the hab") but he used "seal-strips and spare hab canvas". I think the "seal-strips" may have been described in a little more detail elsewhere, but I get the impression they're a sort of double sided sticky tape but with something like the resin on the emergency suit repair kit – James Thorpe Jan 27 '16 at 08:31
  • The question is about the film, and in the film they didn't send just anybody, they sent Matt Damon. I think that can explain any discrepancy. – uhoh Jan 27 '16 at 13:27
  • "depending on it's composition which is not clear from the movie". I thought the displays on +every+ +single+ log entry showing pressure and oxygen to 4 digits (12.47Psi), and oxygen (20.68%) were pretty clear. That's normal air for 4000ft altitude, or about 85% of sealevel normal, with normal oxygen ratio. – CuteKItty_pleaseStopBArking Sep 28 '21 at 09:10

2 Answers2

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The fix as show in the movie wouldn't work. To seal off the atmosphere in a more permanent manner, one would need to have something much stronger than Duct tape, or any tape. That wouldn't hold a seal.

The book mentions a resin that they had to patch the hab. I suspect the tape was shown in the movie because it looked more jury-rigged, but in reality, they would have a solution, some sort of a resin, that would seal firmly that would be available for such an issue.

One could make the assumption that the resin was applied off camera, and the tape was merely added to provide some additional structural support, which it indeed might do. I'll go with this option as it sounds the best.

PearsonArtPhoto
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  • I'm not so sure about this. If it were proper duct tape (some of the newer versions are much weaker both in resistance to tearing and the adhesive used), I think it would hold if, and this is a big if, Watney really cleaned the surfaces to which the duct tape were applied. I've seen duct tape survive rather extreme stresses. Regardless, if I had been Watney, I would have used a lot more duct tape than he did... – honeste_vivere Jan 26 '16 at 13:33
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    It's not the stress, it's the sealing capability. I wouldn't use Duct tape to patch a pipe, I wouldn't expect it to hold a vacuum any more. It is worth noting that duct tape isn't vacuum friendly, but they do have vacuum friendly versions, most notably Kapton tape, but that's beside the point. Kapton has a gold tint, and is semi-transparent, which is often seen on spacecraft. – PearsonArtPhoto Jan 26 '16 at 14:11
  • Ah, okay, I see what you mean... Side Note: I've seen duct tape patch a pipe and it held for several days before we were able to properly replace it. The trick was ensuring a proper seal and several layers prior to turning on the water. – honeste_vivere Jan 26 '16 at 14:20
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    In the book he also uses hab fabric, which is way stronger than "tarp". iirc, it is something akin to aramid, folded 3 times, bonded with resin, and armed with strong fibers, possibly kevlar. – njzk2 Jan 26 '16 at 19:25
  • Also a fair point. – PearsonArtPhoto Jan 26 '16 at 19:44
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    It's not clear that he used duct tape at all (even if it looked like it), perhaps it was some sort of super-strength carbon fiber reinforced epoxy infused sealing tape. NASA wouldn't send 99 cent hardware store duct tape on a billon dollar mission, so it's likely that it was expensive specialty tape that just happened to look like duct tape. Though I did have to laugh after he pressurized the Hab and the wind came and his taped over repair billowed in and out with the wind, even as it was under pressure from the Hab's pressurization. – Johnny Jan 31 '16 at 07:48
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    @Johnny yes - e.g. http://boingboing.net/2013/10/30/fiber-fix-repair-tape-with-em.html - just because it is tape form, doesn't mean it's not the emergency repair resin. – Pete Kirkham Mar 01 '16 at 22:36
  • @Johnny That's a neat idea. Though the billowing tarp suggests they thought of it as flimsy. But as a geeky after the event backward fix of the movie it's nice. – Robert Walker Jan 18 '18 at 10:26
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    "NASA wouldn't send 99 cent hardware store duct tape on a billon dollar mission," if only I could post my picture of the duct tape on monitors in the shuttle cockpit. – Organic Marble Feb 12 '18 at 17:06
  • Actually, I can see a good reason to use duct tape--to hold things in place while the proper sealant sets. – Loren Pechtel Feb 13 '18 at 06:00
  • I thought in the movie he placed the tarp around the opening and then tightened it in place using a ratcheting strap behind the lip of the opening. The duct tape was only used to reinforce the tarp. – Dragongeek Sep 08 '18 at 10:21
  • The requirements could be greatly reduced by not pressurizing the interior to a full atmosphere of oxynitrogen mix. Still, even at a minimal 0.16 bar O2, the 0.006 bar Mars atmosphere causing the tarp to billow in like that was ridiculous. – Christopher James Huff Jan 26 '20 at 14:41
  • I just watched the movie, and it's not duct (or duck) tape. It's clearly kapton tape. – foobarbecue May 09 '20 at 04:44
  • a form of duct tape (or something that looks like it) is used on airplanes to hold parts together sometimes, different from a spaceship but relevant nevertheless – Topcode Oct 09 '20 at 15:45
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No normal Duct Tape adhesive works in cold temperatures. I live on Earth, in Ottawa Ontario... And I can't get Duct tape to stick between November to April. And that is still warmer then most areas on Mars.

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