How would a merfolks spaceship take off?

TrEs-2b 07/26/2016. 6 answers, 1.892 views
reality-check spaceships merfolk

If on a water covered planet, an aquatic species such as the merfolk evolved sapience and now wishes to go into space, how would their spaceship take into account the lack of land? How would a space ship built underwater be able to get into space?

My question differs from this one in that I am asking about how the ship would take off and not at all about suits or design.

1 Avernium 07/26/2016
Possible Duplicate -- some of the info in there will certainly be relevant to you.
1 TrEs-2b 07/26/2016
@Avernium thanks for pointing that out, edited to sepperate
TaylorAllred 07/26/2016
While not an answer, there was a challenge for Kerbal Space Program that had users launch a spacecraft from the bottom of the sea to a different celestial body. The interesting bit is you still had to start on the launch pad or runway. The video I saw had the user use a massive tower of rockets that had wheels to get him to the water, then once he was at the bottom he used the rockets to get him into space.
3 MolbOrg 07/26/2016
Sea Dragon (rocket) - The Sea Dragon was a 1962 design study for a two-stage sea-launched orbital rocket.
1 Keltari 07/27/2016
they do it swimmingly. thank you. thank you. I will be here all night.

6 Answers

JBiggs 07/26/2016.

When we were first getting into space, we started with very fast, high-flying aircraft. Look at the X series of rocket-powered aircraft used by NASA to test all sorts of things related to space travel. For us, it was a logical step to first be able to get into the air, and then get into space from there.

For an underwater species, there would be a third step. Their first phase would be to get out of the water. Once they had the technology to be able to handle working out of their natural habitat, they would have to figure out how to get into the air. THEN would come the leap to space.

Given that, it seems logical that the best place to launch a spacecraft for them would be a large floating platform near the equator. The platform would give them access to the air, so any space ship would not have to deal with water, air, AND space, but only two of the three mediums. The equator is good because of the bulge of the planet and our rotation, on earth, it gives a significant fuel savings to launch as close to the equator as possible.

Rockets are not implausible. In fact, it seems possible that they might develop rockets before they ever worked out advanced aerodynamic theory. This is because you can create a very simple, primitive rocket by using water trapped in a container that can be heated, forced to expand, and provide thrust. If the species had a reliable source of portable heat, they may have developed the basic principles of the rocket engine long before even being able to build a platform on the surface of the ocean.

Water based species have plenty of access to hydrogen if they can generate electricity (separate it out of the water). That is a staple of rocket fuel for us. This all seems to point toward a space program that runs in parallel with our own, at least in general.

I am not convinced that they would necessarily put the pieces together the same way though. We had hundreds of years of experimentation with ballistics and aerodynamics (mostly for warfare) under our belt before the invention of the rocket motor. We had a darn good reason to try to develop flying bombs that could self-propel and drop on our enemies many miles away. The military incentive to develop rockets was critical to the entire space effort, from the "buzzbombs" of WWII to the ICBMs that provided the foundational technology for the lunar launch. An aquatic species would have a long history of under water warfare, but apart from using the surface to scout or spy on their enemies, what experience would they have with trying to lob missiles through the air? Why even develop artillery on the surface if your enemy's base of operations is the bottom of the ocean?

Necessity is the mother of invention, which means that I bet these guys would be considerably MORE advanced than we were before they actually put all the pieces at their disposal together and built a rocket capable of putting them into orbit. (Remember the motives for us to be in space even now: spying on enemies ON LAND -satellites aren't very good at seeing anything on the bottom of the ocean, which is what they are most concerned about). Ironically, they might develop this kind of technology as a reverse to our own nuclear subs. We keep submarines full of ICBMs under the water because it makes them easy to hide, so we know that no enemy can possibly take out all of them at once. Maybe they want to get into orbit (or the air) for the same reason? Hide their nukes from their opposing nations because nobody pays any attention to whatever is flying around in the sky or orbit.

4 Avernium 07/26/2016
I think that careful transition from water to air to space is key. Air travel could be of economic and strategic benefit to an aquatic civilization from a speed perspective, which would require them to solve many of the hardest aquatic-specific problems they’d face with space. It’s also possible that an aquatic species would look at atmosphere and space similarly and equate “leaving their planet” with simply lifting away from the ocean surface.
1 EveryBitHelps 07/26/2016
I like your answer."but apart from using the surface to scout or spy on their enemies, what experience would they have with trying to lob missiles through the air?" I'm pretty sure merfolk would find a way of taking advantage of the lesser air friction to deliver payloads of disaster from the sky. Maybe not for settlements at the very bottom of the deep oceans. But they could have settlements closer to the surface, or they could be aiming at a local sediment source (island/continental shelf) to cause an avalanche down onto said settlement or their underwater farmlands! and many more reasons...
depperm 07/27/2016
In addition to your comment Why even develop artillery on the surface if your enemy's base of operations is the bottom of the ocean? it might be to hide the strike until its too close/from an unusual angle, assuming merfolk can hear quite well under water
Skyler 10/19/2016
"In fact, it seems possible that they might develop rockets before they ever worked out advanced aerodynamic theory." - That explains the tech tree in Kerbal Space Program - the Kerbals must have been merfolk!
1 JBiggs 10/25/2016
@Skyler: the ancient Greeks stumbled across the principles behind rocketry and the ancient Chinese did develop basic gunpowder rockets during the early Middle Ages, so I don't think Kerbal Space Program is too far off.

MozerShmozer 07/26/2016.

Believe it or not, we land-folk have already done something similar!

The Trident-II Ballistic Missile (and its ilk) are designed to be launched from a submerged Ballistic Missile Submarine like the Ohio-class or Typhoon-Class. Obviously this is not a rocket intended for orbit, but the principles would be largely the same in either case: accelerate the vehicle until it breaches the surface of the water, then ignite the rocket motors.

There are a number of possible ways to accomplish this. From near the surface of the sea the rocket could be pushed using a pressurized tank, much like the Trident does. From the ocean floor it could be accelerated using more traditional motors, driving water jets of some sort. Even some sort of magnetic acceleration might be possible.

If I were designing the launch system, I would build a launch platform on a high "peak" near the surface and launch the rocket using pressurized gas or water. The rocket accelerates upward, breaches the surface, and then ignited the engines and off it goes.

Renan 07/30/2016.

Any water covered planet would have an atmosphere, even if it is made only of water vapour. That's because if you start with an ocean interfacing with outer space, the pressure different will cause water to boil and evaporate.

So the best course for your merfolk is building a floating launching station and launch from there. That's because since atmospheric drag should be significantly lower than water drag, launching from air would be cheaper in fuel.

Alternatively, a flying vessel could take off from the sea and gain altitude continuously until it reaches space, where it could then accelerate further to establish an orbital path. I don't think this is as efficient as launching a rocket from a floating platform, but then my experience with this method is limited to Kerbal Space Program. I am not a true rocket scientist.

depperm 07/26/2016.

Depending on the craft shape they could use an underwater launch system. There is a system that in theory can shoot supplies into space and the cannon is mostly underwater.

Basically a long barrel (submerged underwater except for the end) is used to fire the spacecraft, like a gun, into space. This type of system would not require land and could be modified to launch various sized/shaped spacecraft.

Jesse Williams 07/26/2016.

So, the other answers make some very good points, though the Trident-II Ballistic Missile isn't a great starting point just as a surface-to-air missile is much easier that a surface-to-orbit rocket. Part of this is due to the stress of breaking from gravity with heavier objects. A missile's payload is significantly smaller than a rocket that is carrying beings and their sustenance (at a minimum).

Additionally, though you specify that it's not about suits and design, it makes sense that at a minimum, a substantial amount of water would need to be on the craft for waterborne species to survive, and water is heavy (much heavier than air), increasing power requirements for liftoff and reaching sustainable orbit.

Lastly, I agree that having some platform to launch from is nearly imperative as, just like water is heavier than air, water resistance is greater than air resistance, and the force required to launch from even a few hundred feet below surface would be considerably great than from the surface. Especially since, ostensibly, it would be adding a third stage (water-to-surface, surface-to-air, air-to-orbit), meaning more weight and more friction through the water.

It's not impossible, but launching from the bottom of the sea would be extremely difficult.

1 JBiggs 07/26/2016
I was going to mention the weight of the water in the life support system, but my answer got too long as it was. Here's a thought: water vapor atmosphere in the craft. What % of the atmosphere would have to be water and what % could be lightweight gas in order for them to survive? I figure the life support technology step would have been solved for them long before the space technology question just because they would already have had to make "space suits" to walk on land.
1 Jesse Williams 07/26/2016
Sure, well I would say the lightest, least combustible gas for the rest of the craft - or the base atmosphere. But you'd need ENOUGH oxygenated water to last, just like humans need enough oxygen (compressed in tanks or solid with an emitter) to survive for the requisite timeframe. They could, I suppose, reoxygenate the water if oxygen was easier to move. Still, there's a weight there that isn't present for human space travel to the same extent, as far as I can think.
2 JBiggs 07/26/2016
It could get much more complicated if the water-based life forms required not just water, but also pressure to survive. That could change the entire life support system requirements. If they developed near the bottom of the ocean, they may not be able to handle having less than several atmospheres of pressure on them at all times. They may NEED to be in a fluid environment just to keep all their organs where they are supposed to be (like humans trying to deal with vacuum). It could actually get very tricky...
2 Jesse Williams 07/26/2016
Hmm, interesting point. Maybe their suits could be vacuum sealed to their bodies to create positive pressure without the bulk (and mass) of fluid. But yeah, it's a consideration for sure. Now I'm picturing a bipedal fish with a skin tight, pressurized wet suit, and a fish bowl on it's head filled with highly oxygenated water.
1 David K 07/27/2016
You don't have to go quickly through the water. The spacecraft could rise slowly through the water and accelerate to escape velocity only after reaching the atmosphere. If the merfolk can survive in water near the surface (relatively low pressure) but are as vulnerable to rapid decompression as humans are, a slow underwater ascent could make the design of their pressure suits (or pressure chamber) a lot easier.

Solonus 07/27/2016.

Would it be at all possible for the merfolks to build a giant electromagnet and launch using a similar albeit smaller electromagnet of an opposing polarity to the second, apply enough energy and the ability to launch seems feasible in my head. I am not a scientist though by any means and do not know if this could legitimately work, but for a sealocked lifeform this also seems better than trying to light a fire underwater.

JBiggs 07/27/2016
If you are talking about an underwater railgun, you are going to run into a few problems. 1; water is a lot more dense than air and railgun type technology can quickly get something up to a velocity where that will cause massive problems. 2; We experimented with gigantic "superguns" that would actually put a payload into orbit from the ground. It is actually technically doable, but the acceleration of the launch vehicle is so intense to get it up to escape velocity that it isn't useful for most payloads. You crush anything remotely fragile/organic.
Solonus 07/27/2016
I was considering more a slow ramp up to the max power needed to clear the atmosphere. The issue I see with slow vs rail launch is the need to keep the ship geosynchronous with the original launchpad.

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