# Is it real to patch an opening to the vacuum with plastic tarp and duct tape as in Martian?

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?

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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 at 12:29
@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 at 12:57
@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 at 13:05
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 at 13:17
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 at 21:29

## 1 Answer

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.

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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 at 13:33
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 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 at 14:20
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 at 19:25
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 at 7:48