Although a nuclear submarine might not make a great spacecraft, would it be possible to repurpose it for space travel? Benchmark: USS Illinois (SSN-786), Virginia-class submarine (born in Virginia, lives in Illinois, so I'm a bit biased on the benchmark). To be repurposed for space travel, it must fulfill the following:

  • Be able to propel itself in space. Since a propeller isn't the best option, you're welcome to replace it.
  • Not blow up/implode/burn... can be inhabited for a one to two year stay
  • Keep astronauts safe: minimal permanent damage to astronaut: You may repurpose the hull
  • Cost less than $500 million (you can't just go spending money forever)

This was inspired by the relevant what-if XKCD question

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    $\begingroup$ USS Illinois weighs 7800 tons. Just launching that much weight is going to cost 100x more than your budget... $\endgroup$
    – Hobbes
    Commented May 21, 2018 at 14:16
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    $\begingroup$ Interestingly enough, not only is the answer likely "no, you cannot satisfy all of these requirements" but "No, not a single requirement, in isolation, can be met." However, it does give me inspiration. I think I may ask the follow up question, "maybe if we built a large wooden badger..." $\endgroup$
    – Cort Ammon
    Commented May 21, 2018 at 17:55
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    $\begingroup$ Where did your $500 million figure come from? That is pocket change for either submarines or spacecraft. $\endgroup$
    – fectin
    Commented May 21, 2018 at 18:17
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    $\begingroup$ You could sell the submarine (a Virginia-class would fetch a few billion, if you can close the deal without the USN kicking your butt) and plow the proceeds into building a pretty good spacecraft. $\endgroup$
    – Hobbes
    Commented May 21, 2018 at 18:19
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    $\begingroup$ Very relevant: worldbuilding.stackexchange.com/questions/23521/… $\endgroup$ Commented May 21, 2018 at 20:42

3 Answers 3



  • A rocket can lift a few tons. A submarine weight thousands of tons.
  • Propel itself in space: if you add an rocket or ion engine it could. But it's WAAAAY too heavy for any of theses to work. Similar to pushing a train by hand.
  • A submarine is designed to keep water out. It wouldn't be airtight enough and would leak badly.
  • A nuclear submarine needs LOTS of water to cool down its engine. There is not much water in space so its reactor would melt
  • Cost less than 500M ... A nuclear submarine cost 5 times that.
  • Keep astronauts safe: if we ignore the melting nuclear core and the need for a spacesuit, it would be safe.

Maybe if you ask Leiji Matsumoto, he could make one? The Arcadia have underwater capabilities already :)

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    $\begingroup$ And all of the systems on a submarine are designed to work under gravity. You'd have to replace most of the innards with new designs. $\endgroup$
    – Hobbes
    Commented May 21, 2018 at 14:24
  • $\begingroup$ @Hobbes exactly. Can't wait for the first space based Deadly toilet $\endgroup$
    – Antzi
    Commented May 21, 2018 at 14:32
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    $\begingroup$ The only significant cabin leak in the shuttle program was through the toilet! Deadly toilets indeed. spaceflight.nasa.gov/outreach/SignificantIncidents/assets/… page 53 of pdf $\endgroup$ Commented May 21, 2018 at 16:41
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    $\begingroup$ With regards to the cost, I believe that the 500M was "starting from a working submarine" not "build the submarine then launch it". Still not realistic even if the submarine were simply disassembled and launched in pieces it has way too much mass to reach space for that price, but the cost of building the submarine in the first place doesn't seem like an important factor. $\endgroup$ Commented May 21, 2018 at 17:46
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    $\begingroup$ To put the weight issue into context, it would take 59 launches of a Saturn V, 112 launches of a Falcon Heavy, or 48 launches of the current BFR design to put it in low orbit. $\endgroup$
    – Mark
    Commented May 21, 2018 at 22:41

It would be easier to repurpose a large truck tire, and it would be more effective. Antzi has a great answer for NO but the question shows some lack of knowledge about the difference between imploding at depth in the sea, and exploding in the vacuum of space.

I had the similar misconceptions when I asked Why don't the Space Shuttle's tires explode in the vacuum of space?

Consider the Bigelow inflatables are essentially inflated rubber balloons (oversimplification). Click here to see all questions tagged .

With a submarine, the challenges are keeping it from imploding from the external pressure. In space the challenges of keeping it from exploding from internal pressure are fairly easy compared to radiation, micrometers, getting into space, etc...

At sea level, there is one atmosphere of pressure pushing in/down on everything. This is the weight of the air from the surface to the vacuum of space. When you go into space you remove that one atmosphere of pressure. When a sub goes under water for every 10 meters (32.8 feet) the pressure increases one atmosphere. The submarine (going under water) has to be MUCH stronger to counter the pressure difference of hundreds of atmospheres, while the space vehicle only needs to counter the difference of one atmosphere of pressure.

We often speak of pressure in terms of atmospheres. One atmosphere is equal to the weight of the earth's atmosphere at sea level, about 14.6 pounds per square inch. If you are at sea level, each square inch of your surface is subjected to a force of 14.6 pounds.

The pressure increases about one atmosphere for every 10 meters of water depth. At a depth of 5,000 meters the pressure will be approximately 500 atmospheres or 500 times greater than the pressure at sea level. That's a lot of pressure. SOURCE

  • $\begingroup$ You might want to add something about the pressure difference. A submarine needs to withstand several bar of differential pressure, a space shuttle one bar, albeit in the other direction, but the direction isn't really the factor there. $\endgroup$
    – DonQuiKong
    Commented May 22, 2018 at 7:32
  • $\begingroup$ @DonQuiKong good point, updated $\endgroup$ Commented May 22, 2018 at 10:32

No. Absolutely not.

1) Submarines are prohibitively heavy. Like... WAYYYY too heavy. You couldn't get one into space.

2) If you could do it piece-meal, it would take many, many launches to get all the pieces of the submarine into space, which would blow your budget.

3) One of the biggest problems in space that has mostly gone unrecognized by the general public is that of radiation. On Earth (underwater or not), we have the benefit of Earth's magnetic field that protects us from the worst of the Sun's radiation, as well as cosmic radiation. Spacecraft have little such benefit, and a submarine isn't designed to provide any further radiation protection than existing spacecraft.

4) Nuclear power in space is problematic from a political/bureaucratic perspective. Governments are reluctant to allow the construction of even the simplest of nuclear power sources due to launch risks. If the launch rocket blows up, where does the fallout land? Who collects it? Imagine a situation where a rocket containing nuclear fuel blows up, and that nuclear material then falls back to Earth into the hands of a terrorist organization. Not pretty.

If humans are going to put an actual spaceship into space, they will have to build it in space. It won't be something we have here on Earth that is re-purposed for use in space. And it will cost much more than 500M dollars. The cost of launching the construction materials into space cost about 100M dollars per launch. That doesn't count the cost of the materials themselves, the cost of developing a way to build it, or paying people to actually build the thing.

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    $\begingroup$ 3: a submarine hull is about 10 cm thick. That provides far better shielding than the two thin aluminium walls used by spacecraft. $\endgroup$
    – Hobbes
    Commented May 21, 2018 at 19:27
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    $\begingroup$ It does technicially provide better shielding, but not "far" better shielding. For some kinds of radiation, 10 cm of steel is as transparent as a piece of paper. For still others, radiation causes steel to deform and swell, precluding its use in the hull of a spacecraft. Not to mention that 10 cm of steel is many, many orders of magnitude heavier than aluminum. How do we get THAT much steel into orbit? $\endgroup$
    – Tim
    Commented May 21, 2018 at 19:41
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    $\begingroup$ @Tim: There's no neutron radiation in space, as free neutrons have a half-life of 15 minutes. And there's no hazardous radiation that blows through 10 cm of steel like paper: gamma ray intensity is reduced to about 6.4% of its starting amount, while protons, helium nuclei, and electrons are all but completely stopped. The ludicrous weight is undeniable, but 10 cm of steel would give great protection if we could get it up there. $\endgroup$ Commented May 22, 2018 at 6:20
  • $\begingroup$ "reluctant to allow the construction of even the simplest of nuclear power sources" Radioisotope thermoelectric generators are used in satellites and space probes, and I would describe them as nuclear power sources. $\endgroup$
    – M.Herzkamp
    Commented May 22, 2018 at 13:32
  • $\begingroup$ In some cases thin shielding is much better than thick. In case of very high energy particles, with the thin aluminum the particle passes through the walls, the human behind, and walls on the way out with no effect whatsoever. With a thick shielding, it hits one of particles of the shield and causes a whole cascade of hard ions to sputter into the habitable area and humans inside. $\endgroup$
    – SF.
    Commented May 28, 2018 at 7:53

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