While designing / justifying elements of spacecraft design on this forum over the last year or so, it has struck me that (superficially at least) submarines have a lot in common with my prototypical space ship designs.

  • They are sturdy pressure vessels
  • They have many 'airlock' systems for launching missiles & torpedoes
  • They are narrow and long, reducing forward collision risks
  • They are designed for travel in 3 dimensions

Obviously, submarines are designed to be neutrally buoyant (with the capacity to adjust that for rapid dive/climb) and that mechanism is irrelevant in space because buoyancy isn't a factor outside a gravity well. Also, submarines are designed to withstand external pressure, not internal pressure. So, there are differences that need to be accounted for.

The other problem I see is that oceans and outer space are separated by this pesky layer of the gravity well called the atmosphere (and beyond) in which submarines can't work AT ALL. So, building a spaceship out of a submarine has some clear issues in terms of reality.

But; let's assume that we can take a large strategic submarine out up to a geostationary orbit via a space elevator of some kind. If we can get it there, can we make it into a viable space ship?

I'm not looking for a combat vessel by the way; I'm just wondering if the infrastructure of a submarine is a good starting place to build a space ship from.

Some of my initial thoughts;

  • If the pressure vessel is strong enough, changing the 'polarity' of the pressure differential could be as simple as changing the door from an externally facing (and opening) one to an internal one.
  • The airlock systems for torpedoes and missiles may be able to be re-purposed for escape pods, rescue hatches and the like.
  • Assuming a nuclear submarine, swapping out the turbine / propeller for some other form of propulsion should be relatively 'easy' (another assumption, happy to have it verified OR repudiated)
  • The periscope is likely going to have to go, but you've got plenty of room on the hull for cameras that can create virtual windows via screens inside. These are probably more helpful, especially if the cameras support infra-red, ultra-violet and other spectral ranges for object detection.

Given that ballast tanks are already there, I'm assuming these could be used to keep reserves of air under high pressure for your crew. I'm also assuming that air recycling can be overcome in manners similar to those described by Andy Weir in The Martian (Oxygen Reclaimers).

But, I've also got to assume that if you can get a nuclear submarine into space via a space elevator, you can get all manner of raw materials up there as well.

So; Can a submarine be (viably) turned into a spaceship, and if so, would this be any cheaper or faster than just shipping up the materials and building a spaceship from scratch?

  • 1
    $\begingroup$ Wow, you know that didn't appear in my duplicate list? Happy to close as duplicate. $\endgroup$
    – Tim B II
    Jun 20, 2018 at 5:28
  • $\begingroup$ Harry Harrison already did this in his novel The Daleth Effect (1970), with the variant title of In Our Hands, the Stars (1970). He used a form of antigravity to fly his submarine through space. $\endgroup$
    – a4android
    Jun 20, 2018 at 8:44
  • $\begingroup$ I actually don't think this is a duplicate, which is a real shame, because the answer would have been fascinating. The other question asks "what would happen to a submarine if it were suddenly transported into space". This asks how viable a submarine would be as a starting point to creating a space vessel. (1970 definitely wins, but other, more recent books to have this idea: The Course of Empire, Eric Flint, K. D. Wentworth; and Vorpal Blade (and sequels), John Ringo, Travis Taylor.) $\endgroup$
    – Matthew
    Jun 17, 2019 at 20:43

1 Answer 1


I would say it depends on how much high tech equipment and level you want to put in your world.

Its possible with a few modifications such as gravity, or lack thereof and how your crew would deal with it. Do they put in a gravity generator or live without it? Sealants would also need to be re-looked at by you as some sealants may behave differently in space. You also have the temperature and insulation. The side that faces a star like our sun would be hot and that can play havoc with your systems and same goes for the cold side.

Assuming you can put in a star ship engine or modify the nuclear reactor and install propulsion that would work in space in a cramped sub, then it may be cost effective since one would assume you would need less crew members to man the ship and therefore the supplies would also be affected.

If you have a space elevator then odds are your miniaturisation technology and skill level of your world would be quite advanced already to have these modules in place.

I think another concern would be the material of the sub itself. If it is going for flights that take it out of its native system then you have to consider space "weather and/or hazards" such as gamma radiation, miniature asteroid hits, dust particles etc.

But if your story is that of survivors trying to get off planet to reach another world within the same system then it might work.


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