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?